Canadian Plant Disease Survey

1

2024 CPDS SECTION EDITORS AND ADDRESSES

Table

SECTION	EDITORS AND ADDRESSES
DIAGNOSTIC LABORATORIES / LABORATOIRES DIAGNOSTIQUES	Manika Pradhan
	Manitoba Agriculture
	Crop Diagnostic Centre
	201-545 University Crescent
	Winnipeg, MB R3T 5S6
	Tel: [phone]; Fax: [phone]
	Email: [e-mail]
CEREALS / CÉRÉALES	Reem Aboukhaddour
	Lethbridge Research Centre | Centre de Recherche de Lethbridge
	Agriculture and Agri-Food Canada | Agriculture et Agroalimentaire Canada
	5403 - 1 Ave. South, P.O. Box 3000 | 5403 1e Avenue Sud, C.P. 3000
	Lethbridge, AB T1J 4B1
	Tel: [phone]; Fax: [phone]
	Email: [e-mail]
OILSEEDS, PULSES, FORAGES AND SPECIAL CROPS / OLÉAGINEUX, PROTÉAGINEUX, PLANTES FOURRAGÈRES ET CULTURES SPÉCIALES	Syama Chatterton
	Lethbridge Research Centre | Centre de Recherche de Lethbridge
	Agriculture and Agri-Food Canada | Agriculture et Agroalimentaire Canada
	5403 - 1 Ave. South, P.O. Box 3000 | 5403 1e Avenue Sud, C.P. 3000
	Lethbridge, AB T1J 4B1
	Tel: [phone]; Fax: [phone]
	Email: [e-mail]
VEGETABLES / LÉGUMES	Janice Elmhirst
	Elmhirst Diagnostics & Research
	5727 Riverside Street
	Abbotsford, British Columbia, V4X 1T6
	Tel: [phone]
	Email: [e-mail]
FOREST TREES / ARBRES FORESTIERS	Jean Bérubé
	Service canadien des forêts
	Centre de foresterie des Laurentides
	Ressources Naturelles Canada
	Gouvernement du Canada
	1055 rue du P.E.P.S. C.P. 10380
	Sainte-Foy (Québec), G1V 4C7
	Tél: [phone]; Télécopieur: [phone]
	Courriel: [e-mail]
FRUITS, NUTS AND BERRIES, ORNAMENTALS AND TURFGRASS / FRUITS, FRUITS À ÉCALE ET BAIES, PLANTES ORNEMENTALES ET GAZON	Siva Sabaratnam
	BC Ministry of Agriculture and Food
	Abbotsford Agriculture Centre
	1767 Angus Campbell Rd.
	Abbotsford, BC V3G 2M3
	Tel: [phone]; Fax: [phone]
	Email: [e-mail]

INDEX – TITLES AND AUTHORS / TITRES ET AUTEURS

DIAGNOSTIC LABORATORIES / LABORATOIRES DIAGNOSTIQUES

P. Burlakoti, V. Joshi, S. Sapkota & L. Ni. Diseases/symptoms diagnosed on commercial crop samples submitted to the British Columbia Ministry of Agriculture and Food, Plant Health Laboratory in 20237

J.F. Elmhirst. Diseases diagnosed on berry, vegetable, ornamental nursery and landscape plant samples submitted to Elmhirst Diagnostics & Research, British Columbia, in 202316

Y. Yang, K. Zahar, H. Fu, S. Xue, J. Jiang, W. Feindel & J. Feng. Diseases/symptoms diagnosed on plant samples submitted to the Alberta Plant Health Lab (APHL) in 202318

A. Akhavan, C. Bawolin, C. Brenzil, J. Cadrain, B. Kelsch, E. Mangwende, B. Rumpel, G. Sweetman, J. Tansy & J. Bush. Diseases and disorders diagnosed on crop samples submitted to the Saskatchewan Ministry of Agriculture Crop Protection Laboratory in 202322

M. Pradhan, V. Bisht & D. Kaminski. 2023 Manitoba Agriculture Crop Diagnostic Centre Laboratory submissions25

T. Blauel and M.R. McDonald. Diagnoses on plant samples submitted to the Ontario Crops Research Centre – Bradford Diagnostic Laboratory in 202329

M. Melzer and X. Shan. Diseases diagnosed on plant samples submitted to the Plant Disease Clinic, University of Guelph, in 202331

G. Arsenault-Labrecque, W. Armstrong, A-M Breton, A. Dionne, L. Pichette et J. Vivancos. Maladies et problèmes abiotiques diagnostiqués sur les échantillons de plantes reçus en 2023 au laboratoire d’expertise et de diagnostic en phytoprotection du Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec40

M.T. Tesfaendrias. Diseases diagnosed on plant samples submitted to the New Brunswick Department of Agriculture, Aquaculture and Fisheries Plant Disease Diagnostic Laboratory in 202358

M.M. Clark. Diseases diagnosed on commercial crop samples submitted to the PEI Analytical Laboratories Plant Disease Diagnostic Service (PDDS) in 202361

CEREALS / CÉRÉALES65

N. Rauhala, T.K Turkington, J. Busaan, S. Waterman, S. Rehman, H. Klein-Gebbinck, E. Day, H. Spence, M.W. Harding, G.C. Daniels, T.B. Hill & L. Stellar. 2023 barley disease survey in Alberta65

B. Rumpel, J. Bush, E. Mangwende, C. Bawolin, B. Kelsh, J. Cadrain, C. Peru & A. Akhavan. Fusarium head blight of barley in Saskatchewan in 202367

S. Bosch, A. Karstens, T. Islam, M.A. Oviedo-Ludena & H.R. Kutcher. Leaf spot diseases of oat and barley in Saskatchewan in 202369

M. Penner, M. Banik & X. Wang. Fusarium head blight of barley and oat in Manitoba – 202371

M. Penner, M. Banik & X. Wang. Barley and oat leaf spot diseases in Manitoba – 202373

R. Aboukhaddour and B. Wei. Foliar diseases of cereals in southern Alberta, 202375

B. Olson, A. Akhavan, T. Blois, B. Ernst, M. Japp, S. Junek, H.R. Kutcher & T. Prasad. Seed-borne fusarium on cereal crops in Saskatchewan in 202278

M. Liu, S. Lim, P. Shoukouhi, S. Hambleton, J. Carey, M. Serajazari, H. Booker, M. Pavone, Z. Zhang, K. Lew, T. Copley & B. McCallum. Cereal rusts and wheat powdery mildew survey and trials in Ontario and Quebec in 202384

X. Zhu, A.Z. Kebede & T. Woldemariam. Status of corn diseases in eastern Ontario, 2023 crop season88

J.G. Menzies, S. Deceuninck & Z. Popovic. Crown rust of oat in Manitoba, Ontario, Quebec, and Saskatchewan in 202292

M.W. Harding, J. Feng, T.K. Turkington, S. Rehman, H. Klein-Gebbinck, R. Aboukhaddour, G.C. Daniels, L. Stellar, S. Xue, Y. Yang, N. Rauhala, J. Busaan & S. Waterman. Wheat foliar disease survey in Alberta, 202394

T.K. Turkington, M.A. Henriquez, R. Aboukhaddour & B. McCallum. 2023 wheat leaf disease survey in Alberta, Saskatchewan, and Manitoba98

M.R. Fernandez, E. Ilyukhin, N. Waelchli, C. Kenny, C. Siemens, A. Wilson, A. Akhavan, C. Peru, J. Bush, C. Bawolin, E. Mangwende, B. Rumpel, B. Kelsch & J. Cadrain. Leaf spotting diseases of common and durum wheat in Saskatchewan in 2023102

B. Rumpel, J. Bush, E. Mangwende, C. Bawolin, B. Kelsh, J. Cadrain, C. Peru & A. Akhavan. Fusarium head blight of common and durum wheat in Saskatchewan in 2023106

B. McCallum, E. Reimer, D. Miranda & N. Dionne. Leaf and stripe rust of wheat in Manitoba and eastern Saskatchewan in 2023108

M.A. Henriquez, D. Kaminski, A. Kirk, O. Gruenke, P. Santhanam & L. Dyck. Fusarium head blight of spring wheat and winter wheat in Manitoba in 2023109

M.A. Henriquez, D. Kaminski, A. Kirk, O. Gruenke, P. Santhanam & L. Dyck. Leaf spot diseases and bacterial leaf streak of spring wheat and winter wheat in Manitoba in 2023111

L. Tamburic-Ilincic. 2023 presence of leaf diseases of winter wheat in Ontario113

E. Johnstone, H. Bradley, R. Matters & A. Foster. Prince Edward Island survey of fusarium head blight and leaf diseases of spring wheat, 2023115

OILSEEDS, PULSES, FORAGES AND SPECIAL CROPS / OLÉAGINEUX, PROTÉAGINEUX, PLANTES FOURRAGÈRES ET CULTURES SPÉCIALES119

M.W. Harding, A. Lutterotti, J. Retzlaff, G.C. Daniels & S. Chatterton. Blossom blight and stem rot in irrigated alfalfa seed fields in Alberta, 2023119

Y.M. Kim, A. Abdelmagid, A. Hou, O. Wally, S. Zatylny, T. Henderson, M. Thompson, J. Doherty & W. Penner. Diseases of dry bean in Manitoba in 2023122

M. W. Harding, G.C. Daniels, T.B. Hill, L. Stellar, A. Van Tryp, S. Xue & J. Feng. Canola disease survey in Alberta, 2023124

X. Dong, H. Yu, K.F. Chang, V.P. Manolii, L.F. Wu, G.D. Turnbull, A. Brinkman, B. Kirk, S. Oh, J. Cordero-Elvia, R. Fredua-Agyeman, S.F. Hwang & S.E. Strelkov. Canola disease survey in north-central Alberta in 2023128

S.E. Strelkov, V.P. Manolii, Y. Aigu, M.W. Harding, G.C. Daniels, N. Charrier & S.F. Hwang. Occurrence and spread of clubroot on canola in Alberta in 2023131

A. Akhavan, C. Peru, R. Avila, D. Fernando, J. Gilroyed, B. Esau, T. Huffman, C. Danyluk, C. Jacob, N. Montreuil, S. Chant, A. Kaminski, A. Noble, S. Marcino, K. Stonehouse, S. Williams, K. Makohoniuk, J. Kwasnicki, C. Neuberger, C. Fennig, B. Johnson, T. Adegeye, M. Robitaille, C. Jurke & W. Ward. Survey of canola diseases in Saskatchewan, 2023135

Y.M. Kim, D. Kaminski, D. Lange, T. Buss, E. Bargen, A. Kirk, L. Kaskiw, V. Owusu, C. Morrison, K. Steuart, N. Clouson, C. Manchur, J. Graham, M. Pradhan, T. Henderson & S. Zatylny. Survey of canola diseases in Manitoba in 2023140

M.W. Harding, G.C. Daniels & T.B. Hill. Lentil disease survey in southern Alberta, 2023144

A. Akhavan, C. Peru, E. Yaskowich, A. Kaminski, N. Montreuil, S. Chant, Q. Cubbon, M. Hladun, S. Selvichan, H. Tur, S. Marcino, D. Risula, K. Makohoniuk, J. Kwasnicki, C. Neuberger, T. Adegeye, C. Fennig & B. Johnson. 2023 survey of lentil diseases in Saskatchewan147

M.W. Harding, G.C. Daniels, T.B. Hill, L. Stellar, S. Xue & J. Feng. Survey for pea diseases in Alberta, 2023152

A. Akhavan, C. Peru, A. Kaminski, N. Montreuil, S. Marcino, A. Noble, Q. Cubbon, S. Solvichan, H. Tur, E. Yaskewich, B. Rumpel, K. Makohoniuk, J. Kwasnicki, C. Neuberger, C. Fennig, T. Adegeye & B. Johnson. 2023 survey of field pea diseases in Saskatchewan155

Y.M. Kim, S. Chatterton, L. Schmidt, G. Winters, S. Zatylny & T. Henderson. Field pea diseases in Manitoba in 2023158

B.D. Olson, A. Akhavan, S. Banniza, T. Blois, M. Brown, B. Ernst, S. Junek, T. Prasad & D. Risula. Seed-borne pathogens of pulse crops in Saskatchewan in 2022161

A. Akhavan, C. Peru, S. Roberts & T. Adegeye. 2023 survey of soybean diseases in Saskatchewan166

Y.M. Kim, A. Abdelmagid, D. Kaminski, D. Lange, L. Schmidt, G. Winters, T. Buss, E. Bargen, C. Morrison, K. Steuart, N. Clouson, A. Farooq, V. Owusu, A. Akhavan, C. Peru, S. Roberts, W. Penner, S. Zatylny, M. Thompson & T. Henderson. Soybean root rot and phytophthora rot in Manitoba and Saskatchewan in 2023168

VEGETABLES / LÉGUMES171

M.W. Harding, G.C. Daniels, P. Ragan, H. Fu & J. Feng. Monitoring of fungal diseases, stem and bulb nematode and aster yellows on garlic in Alberta, 2023171

DISEASE/SYMPTOMS DIAGNOSED ON COMMERCIAL CROP SAMPLES SUBMITTED TO THE BRITISH COLUMBIA MINISTRY OF AGRICULTURE AND FOOD, PLANT HEALTH LABORATORY IN 2023

CROP: Commercial Crops – Plant Health Laboratory Report LOCATION: British Columbia NAMES AND AGENCIES: P. BURLAKOTI, V. JOSHI, S. SAPKOTA & L. NI

Plant Health Laboratory, Plant and Animal Health Branch, B.C. Ministry of Agriculture and Food, Abbotsford Agriculture Centre, 1767 Angus Campbell Road, Abbotsford, BC V3G 2M3 Telephone: [phone]; Facsimile: 604-556-3010; Email: [email protected] Web page: https://www2.gov.bc.ca/gov/content/industry/agriculture-seafood/animals-and-crops/plant-health/plant-health-laboratory

ABSTRACT: The British Columbia Ministry of Agriculture and Food (BCMAF) Plant Health Laboratory (PHL) provides diagnoses of plant health problems affecting agricultural crops in B.C. From January 1^st to December 31^st, 2023, the PHL received 810 samples for disease diagnosis including small fruits, vegetable and floriculture crops, cannabis, herbaceous and woody ornamentals, Christmas trees, canola, forest nursery seedlings, tree fruits, nuts, turf grass and specialty crops. A survey of sweet cherry orchards in the Southern Interior for little cherry disease detected little cherry virus 2 (LChV-2) in one orchard in Cawston and Candidatus Phytoplasma pruni (Western-X phytoplasma) in two samples from an orchard in Kelowna. This is the first detection of the Western-X phytoplasma in Kelowna. A Neopestalotiopsis sp. was identified for the first time in a cranberry sample with upright dieback. In a follow-up from 2022, Phytophthora occultans was identified for the first time in B.C. on a boxwood nursery plant with root and collar rot.

INTRODUCTION AND METHODS: The British Columbia Ministry of Agriculture and Food (BCMAF) Plant Health Laboratory (PHL) provides diagnoses of plant health problems affecting agricultural crops in B.C. Samples are submitted by growers, agri-business representatives, crop insurance personnel, crop consultants, ministry staff, municipalities, and master gardeners. Diagnoses are accomplished by a wide range of methods and procedures, including microscopic examination, culturing onto microbial media, biochemical identification using BIOLOG®, serological testing with micro-well and membrane-based enzyme-linked immunosorbent assays (ELISA’s), and conventional and real-time polymerase chain reaction (PCR) using pathogen-specific primers. In addition, conventional PCR using ITS or UNIC primers was used followed by nucleotide sequencing to identify the associated organisms. The PHL also provides soil testing for clubroot detection, pH, and EC readings. Abiotic disorders and insect-related damage are not included in this report. Multiple disease-causing agents were detected in numerous samples and are detailed under respective diseases/symptoms. The occurrence of diseases diagnosed in the laboratory may not represent their prevalence in the field. In addition to samples submitted for plant health diagnosis, the PHL provided pest identification in 2023 for several surveys targeting specific plant pathogens. The specific methods used in each survey are described below.

A survey of sweet cherry orchards for little cherry disease (LCD) was conducted by BCMAF staff in the cherry growing regions of the BC Southern Interior from June to August, 2023. One hundred and thirty-three foliar samples were collected which were kept on ice and refrigerated until delivery to the PHL. RNA was extracted from the tissues using a modified Qiagen RNeasy Plant Mini Kit extraction protocol. To remove PCR-inhibiting compounds and extract good quality total RNA from the tissues, four reagents were added to the extraction buffer: polyvinylpyrrolidone-40, sodium metabisulfite, antifoam A concentrate, and 20% N-laurylsarcosine sodium salt solution, as described by Beaver-Kanuya et al. (2019). For detection of LChV-1 and LChV-2, TaqMan real-time PCR protocols described by Katsiani et al. (2018) and Shires et al. (2022) were used. Candidatus Phytoplasma pruni (Western-X phytoplasma) was detected using real-time PCR with the primer pairs SXd-F and SXd-R and a SXd probe (Kogej et al. 2020).

Seed samples from conifer species were submitted by the BC Ministry of Forests Tree Seed Centre to test for the presence of three pathogens: 37 samples for Fusarium spp., one for Siroccocus conigenus and two for Caloscypha fulgens. Unsterilized seeds were used for the Fusarium seed assay since Fusarium spp. are surface infectants, whereas seeds were surface-sterilized for S. conigenus and C. fulgens. Seeds were sterilized by soaking in 30% H₂O₂ for 30 min, followed by rinsing with sterile water at least four times and blot-drying in a biosafety cabinet overnight. For the Fusarium assay, 500 seeds were plated on Komada medium (25 seeds / plate on 20 plates) and incubated at incubated at 24/18°C with a 14/10-hour photo period; for Caloscypha, 250 seeds were plated on 2% water agar (25 seeds per plate on 10 plates) and incubated at 15°C; and for Siroccocus, 1500 seeds were plated on 2% water agar (25 seeds per plate on 60 plates) assay and incubated at room temperature. The plates were examined twice per week for three weeks after plating. Fungal colonies were identified based on morphological characteristics as described in Kolotelo et al. (2001). In addition, 55 fungal cultures from diseased needles of Pinus contorta collected in different areas of the province were submitted by the BC Ministry of Forests for confirmation of Dothistroma septosporum. The isolates were submitted on MEA media and were identified using ITS primer-based PCR followed by DNA sequencing and comparison in BLAST.

Two independent clubroot surveys were conducted by BCMAF staff in 2023. In the Fraser Valley, nine soil samples were collected in cole crop and nearby fields to assess the potential impact of flooding on the spread of clubroot disease. In a second survey in the Peace River region in northern B.C., 70 soil samples was collected from canola fields in the Rolla and Fort St. John areas and closer to the Alberta border near Tomslake. The soil was sampled from the top 5-10 cm (2-4 in). For detection of Plasmodiophora brassicae (the causal agent of clubroot of crucifers), DNA was extracted from each sample using the Qiagen DNeasy PowerLyzer PowerSoil Kit and PCR protocols were followed as described by Cao et al. (2007).

RESULTS AND COMMENTS: Diseases and the causal/associated organisms identified on the 810 diagnostic samples received in the PHL from January 1^st to December 31^st, 2023, are summarized in Tables 1 to 11, organized by crop category. The crop categories comprising the majority of the samples in 2023 were field vegetables (19.3%, including 126 garlic samples), followed by berry crops (17.4%), woody ornamentals (14.9%), cannabis (11.3%), and forest nursery trees (10.4%). The total of 810 does not include the 133 sweet cherry samples submitted for LCD testing reported separately in Table 11. Overall, 2023 was hot and dry with little rainfall and many smoky days. Many trees and perennial plants in BC are facing stress from extended hot and dry seasons in consecutive years.

Table 1. Diseases/symptoms detected in cannabis samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Cannabis	Necrotic leaf spots	Alternaria sp.	2
	Necrotic leaf spots	Cladosporium sp.	2
	Crown & root rot, and leaf infection	Fusarium sp.	3
	Leaf distortion, and stunting of bud	Hop latent viroid (HLVd)	12
	Pythium root rot	Pythium sp.	3
	Leaf infection and spot	Penicillium sp.	3
	Powdery mildew	Golovinomyces cichoracearum	1
	Leaf spot	Chaetomium sp.	1
	Black root rot	Thielaviopsis sp.	1

Table 2. Diseases/symptoms detected in floriculture samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Alstromeria	Speckling on leaves	Empoasca decipiens	1
Chrysanthemum	Fusarium wilt	Fusarium oxysporum	3
	Root rot	Fusarium solani	1
	Root rot	Cylindrocarpon sp.	2
	Root rot	Pythium sp.	2
Cotyledon orbuculata	Leaf spots	Cladosporium sp.	1
Dahlia	Tuber infection	Fusarium solani	2
	Tuber infection	Penicillium sp.	2
	White mould	Sclerotinia sclerotiorum	1
	Galls	Agrobacterium sp.	3
Gerbera	Damping off	Phytophthora sp.	1
	Damping off	Fusarium sp.	1
Helleborus	Damping off	Phytophthora sp. and Fusarium sp.	1
	Leaf blotch	Ascochyta infuscans	1
	Leaf spot	Septoria sp., Botrytis cinerea, and Alternaria sp.	1
	Botrytis blight, leaf and petiole blight	Botrytis cinerea	2
Hosta	Leaf spot	Botrytis sp.	1
Lilium auratum	Bulb and neck infection	Fusarium sp.	1
	Bulb and neck infection, and foliar blight	Botrytis sp.	1
	Foliar blight	Pseudomonas syringae	1
Monarda	Bacterial blight	Pseudomonas syringae	1
Phlox subulata	Root rot	Fusarium sp.	1
Salvia	Plant death	Pythium sp., Fusarium sp., and Cylindrocarpon sp.	1

Table 3. Diseases/symptoms detected in forest nursery samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Abies nordmanniana	Needle blight	Phoma herbarum	1
	Needle blight	Rhizosphaera sp. and Hormonema sp.	1
Christmas Tree	Needle blight	Rhizosphaera kalkhoffii	1
Fir	Needle blight	Rhizosphaera kalkhoffii	2
Interior Douglas Fir	Root rot	Fusarium proliferatum	1
Picea engelmanii glauca	Fusarium seed assay^a	Fusarium sp.	1
	Fusarium seed assay^a	Alternaria alternata	1
	Root rot	Oomycete	1
	Root rot	Cylindrocarpon sp.	1
Picea sitchensis	Foliar blight	Phoma sp.	1
Pine	Foliar blight	Alternaria sp.	1
	Foliar blight	Phoma sp.	2
	Root rot	Pythium sp.	1
	Root rot	Cylindrocarpon sp.	2
Pinus albicaulis	Die back	Pythium sp.	1
	Needle dieback	Phoma sp.	1
	Root rot and dieback	Cylindrocarpon sp.	2
	Needle dieback	Cladosporium sp.	1
Pinus contorta	Foliar blight	Botrytis sp.	2
	Foliar blight	Phoma sp.	3
	Fungal cultures^b	Dothistroma septosporum	15
	Root rot	Oomycetes	1
	Root rot	Cylindrocarpon sp.	3
	Root rot	Fusarium sp.	3
	Fusarium seed assay^a	Fusarium sp.	7
Pinus echinata	Foliar blight	Sirococcus sp.	1
Pinus monticola	Fusarium seed assay^a	Fusarium sp.	2
Pinus ponderosa	Foliar blight	Alternaria sp.	2
	Foliar blight	Botrytis sp.	1
	Foliar blight	Phoma sp.	2
	Root rot	Cylindrocarpon sp.	2
	Root rot	Pythium sp.	2
	Root rot	Fusarium sp.	1
Pinus resinosa	Root rot	Fusarium sp.	1
	Root rot	Cylindrocarpon sp.	1
	Root rot	Pythium sp.	1
Pinus strobus	Foliar blight	Phoma sp.	1
	Foliar blight	Botrytis sp.	1
	Root rot	Cylindrocarpon sp.	1
Pseudotsuga menziesii	Blighted needles	Cladosporium sp.	1
	Damping off	Pythium sp.	1
	Foliar blight	Alternaria sp.	2
	Foliar blight	Botrytis sp.	3
	Foliar blight	Phoma sp.	6
	Root rot	Cylindrocarpon sp.	5
	Root rot	Pythium sp.	5
	Root rot	Fusarium sp.	2
	Needle cast	Rhizosphaera kalkhoffii	1
	Fusarium seed assay^a	Fusarium sp.	14
	Caloscypha seed assay^a	Caloscypha fulgens	1
Sitka spruce	Poor growth	Cylindrocarpon sp.	1
	Poor growth	Oomycete	1
	Poor growth	Phoma sp.	1
Thuja	Necrotic spots	Pestalotiopsis sp.	1
Thuja plicata	Fusarium seed assay^a	Fusarium sp.	3
Tsuga heterophylla	Foliar blight	Phoma sp.	1
	Root rot	Pythium sp.	1

^aSeed samples (40) submitted by the BC Ministry of Forests Tree Seed Centre for fungus testing.

^bOut of 55 fungal isolates from diseased pine needles cultured on MEA by staff of the BC Ministry of Forests and submitted to the PHL to confirm D. septosporum.

Table 4. Diseases/symptoms detected in greenhouse vegetable samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Cucumber	Leaf spot	Alternaria cucumerinum	1
	Root rot	Fusarium sp.	2
	Scab	Cladosporium cucumerinum	1
	Ulocladium leaf spot	Ulocladium cucurbitae	1
Lettuce	Powdery mildew	Golovinomyces cichoracearum	1
Pepper	Chlorotic/ necrotic spots and circular bumps on fruit	Tomato spotted wilt virus (TSWV)	2
	Crown and root rot, root infection and vascular wilt	Fusarium oxysporum	5
Radish	Stunted growth	Fusarium proliferatum	1
Tomato^a	Downy mildew and sunken lesions	Hyaloperonospora parasitica	2
	Leaf spots	Alternaria sp.	1
	Sunken lesions	Fusarium sp.	1
	Blotchy fruit	Pepino mosaic virus (PepMV)	1

^aSample from out of province.

Table 5. Diseases/symptoms detected in berry and nut crop samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Blueberry, highbush	Aerial galls	Agrobacterium sp.	3
	Anthracnose	Colletotrichum sp.	1
	Armillaria root rot	Armillaria sp.	5
	Bacterial blight	Pseudomonas syringae	3
	Bacterial blight	Pseudomonas viridiflava	2
	Crown and stem canker	Phomopsis sp.	10
	Crown and stem canker	Godronia sp.	2
	Crown infection	Cytospora sp.	1
	Crown infection	Coniothyrium sp.	2
	Crown infection	Fusarium oxysporum	1
	Fruit rot	Alternaria alternata	1
	Fruit rot	Botrytis cinerea	1
	Lack of fruit	Blueberry shock virus (BIShV)	3
	Mosaic leaf pattern	Blueberry mosaic virus (BlMaV)	1
	Phytophthora root rot	Phytophthora sp.	32
	Root infection	Pythium sp.	2
	Root rot	Oomycete	1
	Scorch and shock test	Blueberry scorch virus (BIScV)	4
	Silver leaf disease	Chondrostereum purpureum	1
	Stem canker	Botryosphaeria sp.	4
	Twig blight	Sporocadus sp.	3
Cranberry	Dieback	Phomopsis sp.	2
	Leaf spot	Allantophomopsis sp.	1
	Root colonization	Pythium attrantheridium	1
	Upright dieback	Neopestalotiopsis sp.^a	1
Haskap	Dieback	Nematodes	1
	Dieback	Oomycete	1
	Dieback	Pythium heterothallicum	1
Raspberry	Cane blight	Botrytis sp.	2
	Cane blight	Paraconiothyrium fuckelii	1
	Cane infection	Phomopsis sp.	2
	Dying plant	Phytophthora sp.	1
	Plant decline	Parasitic nematodes	1
Strawberry	Crown rot	Fusarium sp.	2
	Fruit rot	Botrytis cinerea	1
	Leaf scorch	Marssonina fragariae	1
	Plant death	Verticillium sp.	5
	Root rot	Rhizoctonia sp.	2
	Root rot complex	Pythium sp.	1
Hazelnut	Leaf damage	Phylus corylii	1
	Phomopsis canker	Phomopsis sp.	1

^aFirst report of a Neopestalotiopsis sp. in a cranberry sample with upright dieback.

Table 6. Diseases/symptoms detected in specialty crop and vertical farming samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Arugula	Damping off	Globisporangium irregulare	1
Greens	Anthracnose	Colletotrichum sp.	1
	Foliar blight	Curvularia sp.	1
	Root rot	Pythium sp.	1
Mushroom	Soft spot	Pseudomonas marginalis	1
Pea sprouts	Damping off/seed rot	Globisporangium ultimum	2
Saffron	Bulb infection	Fusarium sp., Rhizopus sp.	1

Table 7. Diseases/symptoms detected in tree fruit and grape samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Apple	Bacterial blight	Pseudomonas syringae	2
	Botryosphaeria canker	Botryosphaeria sp.	1
	Cytospora canker	Cytospora sp.	3
	Fire blight	Erwinia amylovora	1
	Stem colonizer	Kalmusia sp.	1
	Sunken lesions on stem and twig blight	Phomopsis sp.	2
Apricot	Fruit spot and shot hole	Wilsonomyces carpophilus	3
Cherry	Shot hole	Wilsonomyces carpophilus	1
	Stem canker	Cytospora sp. (Leucostoma sp.)	1
Grape	Crown gall	Ti plasmid detected	1
	Trunk rot	Seimatosporium sp.	1
Malus	Fire blight	Erwinia amylovora	1
	Valsa canker	Cytospora sp.	1
Pear	Pear trellis rust	Gymnosporangium sabinae	1

Table 8. Diseases/symptoms detected in field vegetable samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Arugula	Damping off and root rot	Pythium sp.	3
Cole crops (soil)^a	Clubroot	Plasmodiophora brassicae	3
Cucumber	Root rot, weak plant	Fusarium sp.	3
	Leaf spot	Alternaria sp., Ulocladium sp.	1
	Root rot	Pythium sp., Cylindrocarpon sp.	1
	Scab	Cladosporium cucumerinum	1
	Verticillium wilt	Verticillium sp.	1
Eggplant	Crown and stem infection	Pythium sp., Fusarium sp.	1
Garlic	Blue mould	Penicillium sp.	23
	Bulb and neck infection	Rhizopus sp.	7
	Bulb and neck infection	Embellisia allii	30
	Bulb and neck infection	Fusarium sp.	36
	Bulb and neck infection	Botrytis sp.	2
	Bulb and neck infection	Alternaria sp.	2
	Bulb infection	Potyvirus	26
	White rot	Sclerotium cepivorum	1
Kohlrabi	Head discolouration	Alternaria sp.	1
	Head rot	Rhizoctonia solani, Fusarium sp., Botrytis cinerea	1
Leek	Leaf blight	Stemphylium and Alternaria sp.	1
	Leaf blotch	Cladosporium sp.	1
Lettuce	Damping off, and root rot	Pythium sp.	5
	Marginal leaf blight	Pseudomonas marginalis	1
Pepper	Chlorotic/necrotic leafspot	Tomato spotted wilt virus (TSWV)	1
	Poor plant health	Pythium aphanidermatum	1
	Poor plant health	Pythium ultimum	1
Potato	Pink rot	Phytophthora erythroseptica	1
	Silver scurf	Helminthosporium solani	1
	Tuber rot	Pythium ultimum	1
Rhubarb	Crown rot	Cylindrocarpon sp., Rhizoctonia solani	1
	Leaf/stalk spot	Phoma rhei	1
Spinach	Pythium root rot	Pythium sp.	1
Tomato	Leaf mould	Passalora fulva	1
	Tip dieback	Fusarium sp.	1
Vicia faba^b	Seed infection	Stemphylium sp.	1
Watermelon	Root rot	Fusarium sp., Pythium sp.	1

^aSoil samples (9) from cole crop and nearby fields submitted for clubroot detection.

^bSeed submitted to test for presence of seed-borne fungal pathogens.

Table 9. Diseases/symptoms detected in woody ornamental samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Abies grandis	Rhizomorph	Armillaria cepistipes	1
Acer palmatum	Bacterial blight	Pseudomonas syringae	1
	Dieback	Verticillium dahliae	1
	Phomopsis canker	Phomopsis sp.	1
	Stem canker	Phytophthora cambivora	1
Alnus rubra	Leaf scorch	Phoma sp.	1
	Root infection	Pythium sp.	1
Amelanchier	Tree decline	Phytophthora sp.	1
Arctostaphylos	Root rot	Fusarium sp.	1
	Leaf spot	Phyllosticta sp.	1
	Root rot	Cylindrocarpon sp.	1
Brugmansia	Corky tissue on stem	Tobacco mosaic virus (TMV)	1
Buxus	Boxwood blight	Volutella sp., Fusarium sp.	1
	Stem/crown canker	Volutella buxi	1
	Foliar blight	Volutella buxi, Macrophoma sp.	1
	Twig dieback	Phomopsis sp.	1
	Volutella blight	Volutella sp.	2
Caragana arborescens	Powdery mildew	Erysiphe palczewskii	1
Chamaecyparis obtusa	Root rot	Phytophthora lateralis	1
Clematis	Crown gall	Rhizobium radiobacter	1
	Damping off, and crown & root rot	Fusarium sp.	9
	Damping off and root rot	Phytophthora sp.	16
	Foliar blight and leaf spot	Botrytis cinerea	3
	Leaf spot	Phoma/Ascochyta clematidina	9
	Root rot	Rhizoctonia solani	1
	Root rot	Pythium sp	2
	Stem infection	Alternaria sp.	1
Colorado spruce	Dieback	Diplodia mutila	1
Conifer	Butt rot	Phaeolus schweinitzii	1
Cornus	Plant decline	Fusarium sp. and Cylindrocarpon sp.	1
	Plant decline	Phytophthora sp.	1
	Anthracnose	Discula destructiva	2
Cryptomeria japonica	Coryneum blight	Seiridium cardinale	1
	Foliar blight	Pestalotiopsis sp.	1
Fraxinus pennsylvanica	Cracked bark	Neofabraea sp., Seimatosporium sp. and Cytospora sp.	1
Juniper hedge	Dieback	Pestalotiopsis sp.	1
	Dieback	Phoma sp.	1
	Dieback	Botrytis sp. and Cladosporium sp.	1
Juniperus	Foliar blight	Alternaria sp.	1
	Foliar blight	Phomopsis sp.	1
Laurus nobilis	Leaf spot	Coleophoma sp.	2
	Leaf spot	Colletotrichum sp.	1
Lavandula	Foliar blight	Botrytis sp.	1
	Leaf spot	Pseudomonas syringae	1
	Root rot	Phytophthora sp.	1
Magnolia	Leaf spot	Phyllosticta sp.	1
	Leaf spot	Pseudomonas syringae	1
	Twig blight	Phomopsis sp.	1
	Leaf spot/anthracnose	Colletotrichum sp.	1
	Tree decline	Cylindrocarpon sp.	1
Malus	Bacterial canker/blight	Pseudomonas syringae	1
	Leaf blotch/spot	Alternaria alternata	1
	Stem canker	Phomopsis sp.	1
	Twig blight	Nectria cinnabarina	1
Nandina domestica	Stunted growth	Phomopsis sp.	1
Passiflora	Leaf mosaic	Potyvirus	1
Picea	Needle blight	Phoma sp.	2
Pinus contorta	Needle blight	Pestalotiopsis sp.	1
	Needle blight	Phomopsis sp., Hendersonia pinicola	1
Populus	Stem canker	Diaporthe (Phomopsis) sp.	1
Prunus	Root rot	Fusarium sp.	1
	Stem canker	Phomopsis sp.	1
Pseudotsuga menziesii	Wood decay	Perenniporia subacida	1
Pyrus	Fire blight	Erwinia amylovora	1
Rosa	Downy mildew	Peronospora sparsa	1
Salix babylonica	Brown rot	Laetiporus sp.	1
Sambucus	Leaf necrosis	Alternaria sp., Cladosporium sp.	1
Sorbus	Root rot	Fusarium sp.	1
Spiraea	Powdery mildew	Podosphaera sp.	1
Syringa	Leaf mottle	Lilac leaf chlorosis virus (LLCV)	1
	Bacterial blight	Pseudomonas syringae	1
Taxus	Foliar blight	Pestalotiopsis sp.	1
	Phytophthora root rot	Phytophthora sp.	3
	Root rot	Cylindrocarpon sp.	1
Thuja	Coryneum blight	Seiridium cardinale	2
	Cutting damage	Alternaria alternata, Epicoccum sp.	2
	Dead tips	Cylindrocarpon sp.	1
	Dead tips and foliar blight	Pestalotiopsis sp.	6
	Twig blight	Kabatina thujae	1
	Foliar infection	Seiridium cardinale	1
	Root rot	Phytophthora sp.	2
	Root rot	Pythium sp.	1
	Foliar blight	Cytospora sp.	1
Viburnum davidii	Leaf blotch/spot	Phyllosticta sp./Phoma viburnii	1
	Leaf spot	Cladosporium sp.	1

Table 10. Diseases/symptoms detected in turf and grass samples submitted to the BCMAF PHL in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples
Bentgrass	Foliar blight	Leptosphaerulina trifolii	1
Turf grass	Anthracnose	Colletotrichum sp.	2
	Damping off	Pythium sp., Rhizoctonia sp.	1
	Melting out	Drechslera sp.	1
Elymus or Leymus sp.^a	Tar spot	Phyllachora sp.	2

^aGrass growing as a weed among perennial plants in Ottawa, ON; host and pathogen genus identified by ITS sequencing and comparison in Blast to sequences in GenBank.

Table 11. Diseases detected in sweet cherry samples from the BC Southern Interior submitted to the BCMAF PHL for little cherry disease (LCD) testing in 2023.

Crop	Disease/symptom	Causal/associated organism	No. of samples^a
Sweet cherry	Western-X disease	Candidatus Phytoplasma pruni (Western-X phytoplasma)	2
	Little cherry disease	Little cherry virus 2 (LChV-2)	20

^aA total of 133 leaf samples were tested for little cherry virus 1 (LChV-1), little cherry virus 2 (LChV-2), and Candidatus Phytoplasma pruni, a.k.a the Western-X phytoplasma. All 20/20 samples tested positive for LChV-2 in an orchard in Cawston, and two of 10 samples tested positive for Ca. P. pruni in an orchard in Kelowna. This is the first detection of the Western-X phytoplasma in Kelowna.

The PHL examined 89 cannabis samples in 2023, of which 12 (13.5%) tested positive for hop latent viroid (HLVd) (Table 1).

In the forest nursery conifer seed assays (Table 3), Fusarium spp. were detected in 23 of the 37 samples submitted for Fusarium testing. Other fungi detected were Alternaria alternata (one sample) and Caloscypha fulgens (one sample). No Sirococcus spp. were found. Of the 55 fungal cultures from needles of Pinus contorta, 15 were identified by PCR and DNA sequencing as Dothistroma septosporum, the causal agent of dothistroma needle blight (Table 3).

One greenhouse tomato sample submitted from out of province was positive for pepino mosaic virus (PepMV) (Table 4). No tomato samples were submitted from B.C. greenhouses, but two greenhouse pepper samples tested positive for tomato spotted wilt virus (TSMV), five had symptoms of crown and root rot and vascular discolouration associated with Fusarium oxysporum, and one had plant stunting associated with Fusarium proliferatum.

A Neopestalotiopsis sp. was found in a cranberry (Vaccinium macrocarpon) sample with symptoms of upright dieback (Table 5). The fungus was cultured and identified as a Neopestalotiopsis sp. by ITS primer-based PCR followed by sequencing and BLAST comparison to published sequences in GenBank. No other known cranberry pathogens were found in the sample. Neopestalotiopsis spp. have been shown to cause canker and twig dieback of blueberry (V. corymbosum) in Europe, Asia and South America (Rodriguez-Galvez et al. 2020), but this appears to be the first report of an association with dieback of cranberry. A total of 104 highbush blueberry samples were submitted to the PHL, of which 32 (30.8%) were affected by Phytophthora spp. (Table 5).

Among specialty crops (Table 6), the PHL received 14 samples from vertical farming crops for disease diagnosis, including arugula, lettuce, spinach, and edible greens with 64.3% of the samples testing positive for Pythium sp. A saffron sample was submitted to the PHL for the first time for disease diagnosis, revealing the presence of Fusarium sp. and Rhizopus sp. in the bulb.

In the survey conducted by the BCMAF to assess the potential impact of flooding on the spread of clubroot disease in the Fraser Valley, Plasmodiophora brassicae was detected in three out of nine soil samples from cole crop and nearby fields (Table 8). P. brassicae was not detected in any of the 70 samples collected from canola fields in the Peace River region (data not shown).

Tar spot disease caused by a Phyllachora sp. was identified in two weedy landscape grass samples collected in Ottawa, ON and submitted to the PHL (Table 10). DNA sequencing (16sRNA region) and comparison with sequences in GenBank identified the host grass as an Elymus sp. (96.43 % identity with Accession no. NC_050404.1 or a Leymus sp. (96.43 % identity with the Accession no. KP210962.1). ITS sequencing of the pathogen from one sample and comparison in BLAST to sequences in GenBank showed 100% identity with Phyllachora graminis (Accession no. KX451920.1) and P. maydis (Accession no. OL342922.1); ITS sequencing of the pathogen from the second sample showed 93.2% identity with P. graminis (Accession no. KX451920.1) and P. maydis (Accession no. OL342922.1).

Of the 133 sweet cherry samples submitted for detection of the causal agents of LCD (Table 11), the qPCR test was positive for little cherry virus 2 (LChV-2) in 20 out of 20 samples from one orchard in Cawston. Two samples from one orchard in Kelowna tested positive for Ca. P. pruni (Western-X phytoplasma). This is the first detection of the Western-X phytoplasma in Kelowna.

In a follow-up, a sample of boxwood (Buxus sp.) submitted in October 2022 from a commercial nursery in the Fraser Valley was diagnosed with root and collar rot caused by a Phytophthora sp., as reported in the CPDS Vol. 103 (Joshi et al. 2023). The causal agent has since been isolated and identified by culture morphology and DNA sequencing as Phytophthora occultans Man in ‘t Veld & K. Rosend. 2015. P. occultans has a wide host range on woody ornamentals in temperate regions. It has been reported in Europe since 1998 and in the U.S. since 2015 (Gitto et al. 2018, Reeser et al. 2015). This is the first report of P. occultans in B.C.

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DISEASES DIAGNOSED ON BERRY, VEGETABLE, ORNAMENTAL NURSERY AND LANDSCAPE PLANT SAMPLES SUBMITTED TO ELMHIRST DIAGNOSTICS & RESEARCH, BRITISH COLUMBIA, IN 2023

CROP: Diagnostic Laboratory Report LOCATION: British Columbia NAME AND AGENCY: J. F. ELMHIRST

Elmhirst Diagnostics & Research, 5727 Riverside St., Abbotsford, BC V4X 1T6 Telephone: [phone]; Email: [email protected]

ABSTRACT: Diseases of ornamental nursery and landscape plants, greenhouse vegetables and parasitic nematodes found in berry soil samples submitted to Elmhirst Diagnostics & Research in 2023 are listed. Noteworthy diagnoses in 2023 included tar spot of Calamagrostis acutiflora plants imported from Florida and anthracnose leaf spot of Cornus alba ‘Elegantissima’. A strain of Fusarium oxysporum f. sp. cucumerinum was isolated from greenhouse cucumber plants with symptoms of fusarium wilt disease.

METHODS: Elmhirst Diagnostics & Research (EDR) provides diagnosis of diseases of commercial horticultural crops in British Columbia caused by fungi, bacteria, viruses, plant parasitic nematodes, arthropod and mite pests as well as abiotic factors. Laboratory diagnostic services are provided in conjunction with on-site diagnostic consultations. Diagnosis is performed primarily by association of known symptoms with the presence of a pathogen known to cause these symptoms and identified by microscopic examination. If further identification or confirmation is needed, specimens are sent to other laboratories for identification by ELISA, PCR or DNA sequencing. Problems caused by abiotic factors are not included. The frequency of diseases diagnosed in the lab does not reflect their prevalence in the field.

RESULTS AND COMMENTS: The spring of 2023 was cool and wet through to the end of June, followed by high temperatures and drought from July to September. Wildfires affected many parts of the province. Elsewhere, broadleaf trees showed early leaf senescence from drought stress and needle necrosis of conifers and cedar flagging was more severe than usual. A summary of disease diagnoses and causal/associated agents found in ornamental nursery and landscape crop samples is presented in Table 1 and in berry and greenhouse vegetable crop samples in Table 2.

Table 1. Diseases diagnosed on ornamental nursery and landscape plant samples submitted to Elmhirst Diagnostics & Research in 2023.

Crop	Disease/symptom	Causal/associated agent (s)	Number of samples
Alstromeria x ‘Bryce’	Yellowing and wilt	Fusarium oxysporum	1
Bella perennis ‘Bellisima Red’	Root and crown rot, wilt	Rhizoctonia solani	1
Berberis thunbergia	Bacterial blight	Pseudomonas syringae	1
Buxus microphylla koreana x sempervirens ‘Green Gem’, ‘Green Mountain’, ‘Green Velvet’, ‘Winter Gem’	Volutella blight	Volutella buxi	21^a
Calamagrostis acutiflora ‘Avalanche’	Tar spot	Phyllachora sp.^b	1
Clematis montana ‘Fragrant Spring’, ‘Broughton Star’	Stem and root rot, wilt	Phytophthora sp., Pythium/Globosporangium sp., Rhizoctonia sp. and Calophoma (Ascochyta/Phoma) clematidina	2
Clematis x ‘H. F. Young’	Crown and root rot	Phytophthora sp., Pythium/Globosporangium sp. and Fusarium sp.	1
Clematis x ‘Little Lemon’	Leaf and petiole rot	Pythium/Globosporangium sp.	1
Clematis x ‘Pink Fantasy’	Wilt and root rot	Calophoma clematidina, Pythium/Globosporangium and Phytophthora sp.	1
Coreopsis grandiflora ‘Solanna Bright Touch’	Root and crown rot	Fusarium sp. and Pythium/Globosporangium sp.	1
Cornus alba ‘Elegantissima’	Anthracnose	Discula destructiva	1
Crassula ovata ‘Sunset’	Bacterial soft rot	Erwinia sp.	1
Dahlia	Leaf spot	Botrytis cinerea	1
Heuchera x ‘Carnival Black Olive’	Rust	Puccinia heucherae	1
Hydrangea paniculata ‘Moonrock’	Root and crown rot	Rhizoctonia sp., Pythium/Globosporangium sp. and Phytophthora sp.	1
Hydrangea serrata	Shoot dieback	Ascochyta hydrangeae (Boeremia exigua var. exigua)	1
Lupinus polyphyllus	Black root rot	Thielaviopsis basicola (Chalara elegans)	1
Phlox subulata ‘Spring Blue’	Stem and root rot and downy mildew	Phytophthora sp. and Peronospora phlogina	1
Physocarpus opulifolius ‘Savannah Sunset’	Root rot	Phytophthora sp. and Pythium/Globosporangium sp.	1
Rhododendron x ‘Microhirs9 Bloombux’	Root rot	Phytophthora cinnamomi	1
Salix integra ‘Flamingo’, ‘Hakuro Nishiki’	Bacterial twig blight	Pseudomonas syringae	2
Saxifraga x arrendsii	Leaf necrosis and dieback	Phoma sp. and soft rot bacteria	1
Schefflera (Heptapleurum arboricola)	Leaf tip and edge burn	Botrytis cinerea	1
Zamioculcas zamifolia	Root and stem rot	Phytophthora sp. and Fusarium sp.	1

^aOut of 67 samples surveyed at one nursery.

^bOrnamental nursery plants imported from Florida.

Table 2. Diseases diagnosed on field berry and greenhouse (GH) vegetable samples submitted to Elmhirst Diagnostics & Research in 2023.

Crop	Disease/symptom	Causal/associated agent (s)	Number of samples
Blackberry (soil)	Root lesion nematode	Pratylenchus sp.	1^a
Blackberry (soil)	Dagger nematode	Xiphinema americanum	1
Strawberry (soil)	Root lesion nematode	Pratylenchus penetrans	3
Strawberry (soil)	Dagger nematode	Xiphinema americanum	2
Strawberry (soil)	Pin nematode	Paratylenchus sp.	1
Lettuce (GH)	Root rot	Phytophthora sp.	1
Cucumber (GH)	Fusarium wilt	Fusarium oxysporum f. sp. cucumerinum	1

^aNumber of samples in which the nematode species was present.

A tar spot disease was found on Calamagrostis acutiflora ‘Avalanche’ nursery stock imported from Florida. The Canadian Food Inspection Agency (CFIA) confirmed that the pathogen was a Phyllachora sp. P. graminis has been reported on Calamagrostis sp. in Ontario and Quebec but the reports are many decades old (DAOMC, Ottawa, personal communication). There are no previous reports in BC.

Anthracnose (Discula destructiva) caused a leaf spot disease of Cornus alba ‘Elegantissima’ container plants at a wholesale nursery. Tatarian dogwood (C. alba) is considered to be resistant to anthracnose but there is a report of the pathogen causing significant leaf spotting on C. alba ‘Elegantissima’ in the U.S. (Brown et al. 1996). No twig blight or stem canker was observed. The leaf spots strongly resemble those caused by Septoria (Sphaerulina) cornicola, so anthracnose may have been present on this crop previously and mistaken for septoria leaf spot.

A strain of Fusarium oxysporum f. sp. cucumerinum was isolated from a commercial greenhouse cucumber crop by D. Frost, Frost Environmental, Abbotsford, BC and submitted to the laboratory (Table 2). In seedling and plant bioassays, inoculated plants showed symptoms of stunting, yellowing, wilting and vascular browning, but no root necrosis, consistent with fusarium wilt disease.

Root lesion and dagger nematodes were the most common parasitic nematodes recovered from berry crop soils (Table 2).

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DISEASES/SYMPTOMS DIAGNOSED ON PLANT SAMPLES SUBMITTED TO THE ALBERTA PLANT HEALTH LAB (APHL) IN 2023

CROP: All Crops – Plant Health Laboratory Report LOCATION: Alberta NAMES AND AGENCIES: Y. YANG, K. ZAHR, H. FU, S. XUE, J. JIANG, W. FEINDEL & J. FENG

Alberta Plant Health Lab, Alberta Agriculture and Irrigation, Edmonton, AB T5Y 6H3 Telephone: [phone]; E-mail: [email protected]

ABSTRACT: The Alberta Plant Health Lab (APHL) provides plant pest diagnosis and expertise to Alberta’s agricultural industry. The lab accepts samples exclusively from agricultural fieldmen, academic institutions, applied research associations and municipal pest management departments, at no cost. A total of 886 samples were processed for diagnosis in year 2023 (up to Oct 31). No Dutch elm disease was identified in elm tree samples this year. Needle cast pathogens still accounted for largest portion of the conifer samples received. No fusarium head blight caused by Fusarium graminearum was detected in cereals. Clubroot was found in canola samples. No fire blight pathogen, Erwinia amylovora, was detected in Rosaceae samples.

METHODS: Samples were submitted to the APHL by agricultural fieldmen, academic institutions, applied research associations and municipal pest management departments. Diagnoses were based on a combination of visual examination of symptoms and signs, microscopic observation, culturing on artificial media, PCR/qPCR, DNA barcoding and use of commercial diagnostic kits. Fungal barcoding was performed by sequencing DNA fragments of the internal transcribed spacers (ITS) (White et al. 1990), and/or the elongation factor -1α (EF1) gene (Stielow et al. 2015), and/or the β-tubulin gene (Stukenbrock et al. 2012). Bacteria were usually identified based on DNA sequencing of the 16S ribosomal RNA gene (Klindworth et al. 2013) and/or the cpn60 gene (Links et al. 2012). The diagnosis of clubroot was done by probe-based qPCR for Plasmodiophora brassicae according to Zahr et al. (2021). PCR identification of Fusarium graminearum from submitted cultures was performed following methods from Zuzak et al. (2018). For identification of Fusarium species from plant tissues, protocols described by Demeke et al. (2005) were used. Phytoplasma was detected by PCR using the primer pairs P1/Tint and R16MF2n/R16MR2n (Smart et al. 1996). Confirmation of late blight on potato and tomato was done using the Agdia ImmunoStrip® kit for Phytophthora species (http://www.agdia.com). For diagnosis of all other diseases, when PCR techniques were used, quantitative PCR (qPCR) preceded conventional PCR and probe-based qPCR preceded SYBR Green-based qPCR. The primers and protocols were chosen from the most recent literature and verified by the APHL using positive and negative controls.

RESULTS AND COMMENTS: A total of 886 samples were processed for disease diagnosis between January 1 and October 31, 2023. Pathogens including fungi, oomycetes, protists, bacteria and viruses were identified from 447 samples. More than one potential causal agent was identified in the majority of samples. Summaries of symptoms and associated pathogens are presented in Tables 1 to 6, by crop category.

Table 1. Diseases diagnosed on cereal samples submitted to the Alberta Plant Health Lab in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Barley	Bacterial leaf streak	Xanthomonas translucens pv. translucens (Xtt)	42
	Leaf lesions, streak, discolouration	WSMV	3
	Leaf lesions, streak, discolouration	WSMV, Xtt	3
	Leaf lesions, streak, discolouration	WSMV, Phytoplasma	2
	Aster yellows	Phytoplasma	1
	Leaf yellowing	Globisporangium irregulare, Fusarium acuminatum, F. culmorum, F. tricinctum, F. avenaceum	1
	Premature ripening	Phytoplasma, Xtt, Pythium ultimum, Microdochium bolleyi	1
	Post damping off	Pythium arrhenomanes, Fusarium redolens	1
Oat	Leaf lesions and discolouration	Pyrenophora teres	1
	Leaf lesions and discolouration	Wheat streak mosaic virus (WSMV)	2
	Leaf lesions and discolouration	Phytoplasma	1
Triticale	Premature ripening, root rot	Fusarium culmorum	1
Wheat	Aster yellows	Phytoplasma	34
	Bacterial leaf streak	Xanthomonas translucens pv. undulosa (Xtu)	32
	Aster yellows and bacterial leaf streak	Phytoplasma, Xtu	1
	Leaf lesions, streak, discolouration	WSMV	14
	Leaf lesions, streak, discolouration	WSMV, Xtu	7
	Leaf lesions, streak, discolouration	WSMV, Barley yellow dwarf virus (BYDV)	2
	Leaf lesions, streak, discolouration	WSMV, Phytoplasma	1
	Premature ripening	WSMV, Xtu, Microdochium bolleyi	1
Total			151

Table 2. Diseases diagnosed on canola samples submitted to the Alberta Plant Health Lab in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Canola	Clubroot	Plasmodiophora brassicae	145
	Tiny root galls	Agrobacterium tumefaciens	2
	Pod lesion	Alternaria sp.	1
Total			148

Table 3. Diseases diagnosed on potato samples submitted to the Alberta Plant Health Lab in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Potato	Common scab	Streptomyces scabies	1
	Powdery scab	Spongospora subterranea f. sp. subterranea	2
	Soft rot	Pectobacterium astroseptica	1
	Pink rot and blackleg	Phytophthora erythroseptica, Pectobacterium sp., Dickeya sp.	5
	Leaf spot and early blight	Alternaria alternata	1
	Wilting and early dying	Alternaria tenuissima	1
	Stunting and leaf lesions	Phytoplasma, Potato virus Y (PVY)	1
	Purple top	Phytoplasma	1
Total			13

Table 4. Diseases diagnosed on forage legume and pulse samples submitted to the Alberta Plant Health Lab in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Alfalfa	Wilting	Colletotrichum americae-borealis, Leptosphaerulina trifolii	1
Chickpea	Root rot	Fusarium solani	1
Lentil	Root rot	Fusarium redolens, Fusarium sp.	1
Pea	Root rot	Globisporangium ultimum, G. recalcitrans, Pythium kashmirense	2
	Wilting and stunting	Diaporthe columnaris, Globisporangium heterothallicum, G. abappressorium	1
	Wilting and stunting	Fusarium redolens	1
	Wilting, stunting and chlorosis	Verticillium dahliae, Fusarium culmorum, F. equiseti	1
Total			8

Table 5. Diseases diagnosed on tree and fruit samples submitted to the Alberta Health Lab in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Apple	Fruit rot	Penicillium sp.	1
Elm^a	Wilting	Plenodomus tracheiphilus	10
	Wilting	Plenodomus tracheiphilus, Nectria sp.	1
	Wilting	Cytospora sp.	1
Juniper	Dieback	Cytospora chrysosperma	1
	Dieback	Kabatina juniperi	1
Raspberry	Root and crown rot	Valsa salicina or V. populina, Rhizoctonia solani, Ilyonectria destructans	1
Rose	Bud lesions	Botrytis sp.	1
Saskatoon	Leaf lesions	Botrytis sp.	1
Spruce	Needle discolouration and defoliation	Sydowia polyspora	4
	Needle discolouration and defoliation	Cytospora chrysosperma	2
	Needle discolouration and defoliation	Cytospora kunzei	1
	Needle discolouration and defoliation	Cytospora sp.	2
	Needle discolouration and defoliation	Nothophoma quercina	3
	Needle discolouration and defoliation	Rosellinia quercina	1
	Wilting	Nectria sp.	1
	Wilting	Cytospora piceae	1
	Wilting	Cytospora sp.	1
Pine	Wilting, blight	Sydowia polyspora	2
	Needle discolouration	Sydowia polyspora	1
	Needle discolouration	Phoma sp.	1
Poplar	Canker	Cytospora chrysosperma, Kalmusia longispora	1
	Limb drop with rot	Ophiostoma bicolor, Cytospora sp., Fusarium solani	3
	Leaf lesions and discolouration	Cytospora chrysosperma	1
	Leaf lesions and discolouration	Cytospora tritici	1
	Leaf lesions and discolouration	Cytospora parakantschavelii or C. kantschavelii, Microdochium seminicola	1
	Decline	Cytospora chrysosperma	2
	Decline	Phoma sp.	1
Willow	Rust	Melampsora epitea	1
Total			49

^aSamples submitted specifically for Dutch elm disease (Ophiostoma ulmi) testing.

Table 6. Diseases diagnosed on vegetable and herb samples submitted to the Alberta Plant Health Lab in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Buttercup squash	Dry rot	Fusarium equiseti	1
Cabbage	Damping off	Globisporangium heterothallicum, Fusarium equiseti	1
	Damping off	Fusarium equiseti, Rhizoctonia solani	1
Carrot	Storage rot	Rhizoctonia solani, Berkeleyomyces basicola, Erwinia rhapontici	1
Cucumber	Damping off	Globisporangium violae or G. recalcitrans or G. intermedium and Fusarium equiseti	1
Garlic	Aster yellows^a	Phytoplasma	5
	Stem and bulb rot^a	Ditylenchus dipsaci	13
	Wilting, stunting or no symptom^a	Fusarium oxysporum	18
	Wilting, stunting or no symptom^a	Fusarium proliferatum	3
	Wilting, stunting or no symptom^a	Rhizoctonia solani	5
	Wilting, stunting or no symptom^a	Alternaria embellisia	5
	Wilting, stunting or no symptom^a	Fusarium equiseti and/or Globisporangium ultimum	2
	Wilting, stunting or no symptom^a	Pythium oligandrum	1
	Bacterial heart rot^a	Pseudomonas fluorescens	3
	Wilting, leaf lesions	Phytoplasma, Fusarium proliferatum, Rhizoctonia solani, Pythium sp.	5
	Storage rot	Ditylenchus dipsaci	1
Onion	Internal black ring	Fusarium proliferatum	4
	White rot	Stromatinia cepivora (= Sclerotium cepivorum)	1
Pumpkin	Storage rot	Fusarium equiseti, F. venenatum	1
Rhubarb	Leaf spot	Botrytis, Fusarium equiseti, F. avenaceum or F. acuminatum	1
Spearmint	Wilting, stunting, chlorosis	Verticillium dahliae, Fusarium culmorum, F. equiseti	1
Sugar beet	Rot	Fusarium proliferatum	1
Tomato	Malformed growth	Phytoplasma	2
Zucchini	Stunting	Fusarium equiseti, F. avenaceum or F. acuminatum	1
Total			78

^aSamples submitted specifically for aster yellows, stem and bulb nematode testing and fungal isolation.

Pythium and Fusarium species were isolated from three barley samples and one triticale sample (Table 1). However, no F. graminearum was isolated. Eighty-seven cereal samples (wheat and barley grain, leaf, soil and water samples) were diagnosed with a bacterial infection associated with Xanthomonas translucens. A phytoplasma, the causal agent of aster yellows disease, was detected in 36 wheat samples, four barley samples and one oat sample. Wheat streak mosaic virus (WSMV) was detected in 25 wheat samples, eight barley samples and two oat samples. Barley yellow dwarf virus (BYDV) was detected in two wheat samples. Pyrenophora teres was found to be associated with leaf lesions in one oat sample.

One hundred and forty-five canola samples (including 120 soil samples) were infected with the clubroot pathogen, Plasmodiophora brassicae (Table 2). Two canola samples tested positive for Agrobacterium tumefaciens, the crown gall pathogen, which causes symptoms similar to clubroot. An Alternaria species was recovered from a pod lesion sample.

A total of 13 potato samples (nine tubers and four plants) were diagnosed for pathogens this year (Table 3). One potato tuber sample was infected with common scab (Streptomyces scabies), two with powdery scab (Spongospora subterranea f. sp. subterranea), one with soft rot (Pectobacterium atrosepticum) and five with pink rot and blackleg (Phytophthora erythroseptica, Pectobacterium spp. and/or Dickeya spp.). One potato plant sample was affected by early blight (Alternaria alternata), one by early dying (Alternaria tenuissima), one by leaf lesions (phytoplasma and PVY) and one by purple top (phytoplasma).

Eight legume and pulse samples with root rot or wilting symptoms were examined for pathogens this year (Table 4). The identified pathogens included: Globisporangium ultimum, G. recalcitrans, G. heterothallicum, G. abappressorium, Pythium kashmirense, Verticillium dahliae, Diaporthe columnaris, Fusarium culmorum, F. redolens, and F. equiseti from five pea samples, F. redolens from one lentil sample, F. solani from one chickpea sample, and Colletotrichum americae-borealis and Leptosphaerulina trifolii from one alfalfa sample.

Twelve elm samples were submitted for Dutch elm disease (DED) testing. However, none of them were positive (Table 5). Plenodomus tracheiphilus was identified from most of the diseased elm samples. Other isolated pathogens included Cytospora sp. and Nectria sp. The fungus Sydowia polyspora, the causal agent of needle cast and dieback, was identified in four spruce and three pine samples. Other pathogens associated with needle cast and dieback included Cytospora spp., Nectria sp., Rosellinia quercina and Nothophoma quercina. Cytospora spp. were frequently isolated from poplar samples causing canker, limb rot, decline or leaf lesions. Other recovered poplar pathogens included Kalmusia longispora, Ophiostoma bicolor, Fusarium solani, Microdochium seminicola and Phoma spp. No fire blight pathogen was detected this year.

Seventy-eight vegetable and herb samples were received for disease diagnosis (Table 6). Fusarium spp. were recovered frequently from vegetables with rot, wilting, damping off, leaf spot and stunting symptoms. Other pathogens included Rhizoctonia solani, Globisporangium spp., Berkeleyomyces basicola, Erwinia rhapontici, Alternaria embellisia and Botrytis spp. Ten garlic samples and two tomato samples tested positive for a phytoplasma. The stem and bulb nematode, Ditylenchus dipsaci, was detected in 14 garlic samples. The white rot pathogen, Stromatinia cepivora, was isolated from an onion sample. Verticillium dahliae, Fusarium culmorum and F. equiseti were isolated from one spearmint sample with wilting, stunting and chlorosis symptoms.

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DISEASES AND DISORDERS DIAGNOSED ON CROP SAMPLES SUBMITTED TO THE SASKATCHEWAN MINISTRY OF AGRICULTURE CROP PROTECTION LABORATORY IN 2023

CROP: Diagnostic Laboratory Report LOCATION: Saskatchewan NAMES AND AGENCIES: A. AKHAVAN¹, C. BAWOLIN², C. BRENZIL¹, J. CADRAIN², B. KELSCH², E. MANGWENDE², B. RUMPEL², G. SWEETMAN¹, J. TANSEY¹ & J. BUSH²

¹Saskatchewan Ministry of Agriculture, Crops and Irrigation Branch, 3085 Albert St., Regina, SK S4S 0B1 ²Saskatchewan Ministry of Agriculture, Crops and Irrigation Branch, Crop Protection Laboratory, 1610 Park St., Regina, SK S4N 2G1 Telephone: [phone]; Facsimile: [phone]; E-mail:[email protected]

ABSTRACT: In 2023, 632 samples were received for diagnosis by the Saskatchewan Crop Protection Laboratory, including 150 client samples and 482 elm samples for Dutch elm disease testing of which 193 were positive. Plant diseases were confirmed on many samples. Abiotic stress and herbicide injury were diagnosed on a large number of samples due to the 2023 growing season conditions.

INTRODUCTION AND METHODS: The Saskatchewan Ministry of Agriculture Crop Protection Laboratory (CPL) provides diagnostic services and treatment recommendations for plant health issues to producers and agrologists, with the goal of allowing these groups to reduce risk in their day-to-day operations. To facilitate this, the CPL provides services including plant health diagnostics, plant and insect identification, herbicide resistance testing in weeds, and supporting the provincial pest-monitoring program. The CPL accepts samples from internal and external clients, especially growers, agribusinesses, and home gardeners. Diagnostics at the CPL are performed using traditional and molecular methods, including microscopy, culturing pathogens on artificial selective media, ELISA tests, and qPCR. These approaches are further complemented by client-reported background information.

RESULTS AND COMMENTS: Summaries of the diseases and abiotic disorders diagnosed and causal agents associated with samples submitted to the CPL in 2023 are presented in Tables 1 through 6, categorized by crop type.

Table 1. Diseases and disorders diagnosed on cereal crop samples submitted to the Saskatchewan Crop Protection Lab in 2023.

Crop	Disease/disorder	Causal/associated agent	Number of samples
Wheat	Fusarium root rot	Fusarium sp.	3
	Tan spot	Pyrenophora tritici-repentis	3
	Aster yellows	Phytoplasma	2
	Sooty mould	Cladosporium herbarum and Alternaria sp.	2
	Bacterial blight	Pseudomonas sp.	1
	Common root rot	Fusarium sp. and Cochliobolus sativus	1
	Environmental	n/a	8
	Herbicide damage	n/a	3
Durum	Environmental	n/a	14
	Herbicide damage	n/a	1
Barley	Fusarium root rot	Fusarium sp.	3
	Net blotch	Pyrenophora teres f. teres and P. teres f. maculata	1
	Environmental	n/a	6
	Herbicide damage	n/a	4
Oats	Oat bacterial blight	Pseudomonas sp.	1
	Environmental	n/a	1
Total			54

Table 2. Diseases and disorders diagnosed on oilseed crop samples submitted to the Saskatchewan Crop Protection Lab in 2023.

Crop	Disease/disorder	Causal/associated agent	Number of samples
Canola	Blackleg	Leptosphaeria biglobosa and L. maculans	2
	Fusarium root rot	Fusarium sp.	2
	Aster yellows	Phytoplasma	1
	Common root rot	Fusarium sp. and Cochliobolus sativus	1
	Fusarium wilt	Fusarium oxysporum	1
	Sooty mould	Cladosporium herbarum and Alternaria sp.	1
	Herbicide damage	n/a	9
	Environmental	n/a	3
Mustard	Common root rot	Fusarium sp. and Rhizoctonia solani	1
	White rust	Albugo candida	1
	Herbicide damage	n/a	1
Flax	Herbicide damage	n/a	1
Total			24

Table 3. Diseases and disorders diagnosed on legume crop samples submitted to the Saskatchewan Crop Protection Lab in 2023.

Crop	Disease/disorder	Causal/associated agent	Number of samples
Lentil	Root rot	Fusarium sp., Rhizoctonia solani, and Oomycetes	11
	Environmental	n/a	1
	Herbicide damage	n/a	6
Field pea	Fusarium root rot	Fusarium sp.	5
	Root rot complex	Fusarium sp., Rhizoctonia solani, and Oomycetes	5
	Ascochyta blight	Peyronellaea pinodes	1
	Herbicide damage	n/a	1
Faba bean	Chocolate spot	Botrytis sp.	3
	Leaf spot complex	Alternaria sp. and Stemphylium sp.	2
	Stemphylium blight	Stemphylium sp.	1
Soybean	Alternaria leaf spot	Alternaria sp.	3
	Septoria brown spot	Septoria glycines	1
	Stemphylium blight	Stemphylium sp.	1
Chickpea	Fusarium root rot	Fusarium sp.	2
Dry bean	Bacterial blight	Xanthomonas sp. and Pseudomonas sp.	1
Total			44

Table 4. Diseases and disorders diagnosed on tree and fruit samples submitted to the Saskatchewan Crop Protection Lab in 2023.

Crop	Disease/disorder	Causal/associated agent	Number of samples
Evergreen	Environmental	n/a	3
Poplar	Cytospora canker	Cytospora chryosperma	1
Elm (American and Siberian)	Dutch elm disease	Ophiostoma ulmi	193^a
	Dothiorella wilt	Dothiorella sp.	22
Saskatoon	Herbicide damage	n/a	2
Sea buckthorn	Verticillium wilt	Verticillium sp.	1
Total			222

^aOf 432 elm samples submitted for Dutch elm disease testing, 193 were positive for DED.

Table 5. Diseases diagnosed on vegetable samples submitted to the Saskatchewan Crop Protection Lab in 2023.

Crop	Disease	Causal/associated agent	Number of samples
Cabbage	White mould	Sclerotinia sp.	1
	Bacterial leaf spot	Xanthomonas sp.	1
	Alternaria leaf spot	Alternaria sp.	1
Garlic	Fusarium root rot	Fusarium sp.	1
Tomato	Bacterial blight	Pseudomonas sp.	1
Total			5

Table 6. Diseases and disorders diagnosed on specialty crop and forage samples submitted to the Saskatchewan Crop Protection Lab in 2023.

Crop	Disease/disorder	Causal/associated agent	Number of samples
Canaryseed	Environmental	n/a	1
	Herbicide damage	n/a	1
Alfalfa	Common leaf spot	Pseudopeziza medicaginis	2
	Anthracnose	Colletotrichum sp.	1
Total			5

Of the 632 samples submitted to the Saskatchewan Crop Protection Laboratory in 2023, 354 samples were diagnosed with a disease caused by a pathogenic agent or an abiotic disorder caused by environmental stress or herbicide damage (Tables 1 to 6). No field crop samples were undiagnosed. Many samples of elm trees tested as part of the Dutch elm disease program were found not to have the disease. Of the 432 elm samples tested for Dutch elm disease, 193 (44.7%) were positive (Table 4).

The year 2023 was characterized by lower-than-normal precipitation and warmer than average temperatures for most of the crop producing regions of Saskatchewan. These conditions led to a high number of environmental stress diagnoses and also contributed to a high frequency of herbicide injury as dry conditions led to low rates of chemical breakdown in the soil.

2023 MANITOBA AGRICULTURE CROP DIAGNOSTIC CENTRE LABORATORY SUBMISSIONS

CROP: Diagnostic Laboratory Report LOCATION: Manitoba NAMES AND AGENCIES: M. PRADHAN¹, V. BISHT² & D. KAMINSKI²

¹Manitoba Agriculture, Crop Diagnostic Centre, 545 University Crescent, Winnipeg, MB R3T 5S6 Telephone: [phone]; E-mail: [email protected] ²Manitoba Agriculture, Crops Industry Branch, Box 1149, Carman, MB R0G 0J0

ABSTRACT: This report summarizes the diseases and disorders diagnosed on plant samples submitted to and analyzed by the Manitoba Agriculture Crop Diagnostic Centre in 2023. Samples received by the laboratory included field crops as well as ornamentals, grasses and trees grown in Manitoba.

METHODS: The Manitoba Agriculture Crop Diagnostic Centre provides diagnoses and control recommendations for disease problems of agricultural crops, both field and horticultural crop plants. Manitoba Agriculture Crop Industry Branch Specialists, extension and other departmental personnel, farmers, agri-business representatives and the public, submit samples to the laboratory. Diagnostic methods used included visual examination for symptoms, microscopy, moist chamber incubation, culturing onto artificial media (general and pathogen specific), Agdia ImmunoStrips®, ELISA and specific molecular (PCR) testing.

RESULTS: Summaries of diseases diagnosed on plants in different crop categories are presented in Tables 1 to 9 and cover the period from January 1 to December 08, 2023.

Table 1. Diseases diagnosed on cereal and corn crop samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	Number of samples
Wheat	Black head moulds	Epicoccum nigrum, Alternaria sp., Cladosporium sp.	2
	Barley yellow dwarf	Barley yellow dwarf virus (BYDV)	3
	Bacterial leaf blight	Pseudomonas syringae pv. syringae	6
	Powdery mildew	Blumeria graminis f. sp. tritici	10
	Root rot	Fusarium sp., Pythium sp., Rhizoctonia sp. and/or Cochliobolus sativus	10
	Rust, leaf	Puccinia triticina	1
	Tan spot	Pyrenophora tritici-repentis	1
Barley	Barley yellow dwarf	Barley yellow dwarf virus (BYDV)	1
	Powdery mildew	Blumeria graminis	1
	Net blotch	Pyrenophora teres	2
	Common root rot	Bipolaris sorokiniana, Rhizoctonia sp., Fusarium sp.	5
Oat	Bacterial blight	Pseudomonas syringae	3
	Glume blotch	Septoria sp.	1
	Rust, crown	Puccinia coronata	2
	Root rot	Fusarium sp., Helminthosporium sp.	2
Corn	Goss’s wilt	Clavibacter michiganensis subsp. nebraskensis	14
	Bacterial streak	Xanthomonas sp.	1
	Damping off/seedling blight	Alternaria sp., Fusarium sp., Penicillium sp., Bipolaris sp., Rhizopus sp.	4
	Holcus spot	Pseudomonas syringae	4
	Northern corn leaf blight	Bipolaris sp.	7
	Southern corn leaf blight	Helminthosporium maydis	6
	Root rot complex	Fusarium sp., Helminthosporium sp., Rhizoctonia sp., Pythium sp.	12
Fall rye	Bacterial leaf spot	Bacterial sp.	1

Table 2. Diseases diagnosed on herbaceous annual, perennial, and woody ornamental shrub samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Crop	Disease/symptom	Causal/associated agent	Number of samples
Barberry	Stem and twig blight	Phomopsis sp.	1
Gomphrena	Powdery mildew	Oidium sp.	1
Hydrangea	Leaf spot	Alternaria sp., Phyllosticta sp.	1
Lilac	Stem canker	Cytospora sp.	3
Ninebark	Fire blight	Erwinia sp.	1
Peony	Leaf spot	Botrytis sp., Alternaria sp.	1
Zinnia	Leaf spot	Alternaria sp., Phyllosticta sp.	2

Table 3. Diseases diagnosed on vegetable crop samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	Number of samples
Cucumber	Root /stem rot	Fusarium sp.	2
Garlic	Fusarium basal plate rot	Fusarium culmorum	1
	Bacterial rot	Pseudomonas syringae	1
Leek	Bulb rot	Fusarium sp.	1
Onion	Basal plate rot	Fusarium sp.	1
Pumpkin	Sclerotinia fruit rot	Sclerotinia sclerotiorum	2
Sweet potato	Root soft rot	Fusarium sp., Rhizopus sp.	2

Table 4. Diseases diagnosed on potato crop samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Disease/symptom	Causal/associated agent(s)	Number of samples
Bacterial soft rot	Pectobacterium carotovorum subsp. carotovorum	3
Black dot(tuber/stem)	Colletotrichum coccodes	8
Blackleg	Pectobacterium carotovorum subsp. atrosepticum	3
Brown spot (foliar)	Alternaria alternata	4
Early blight (foliar)	Alternaria solani	2
Fusarium dry rot	Fusarium sambucinum	2
Leathery rot	Geotrichum sp.	4
Scab	Streptomyces scabies	1
Silver scurf	Helminthosporium solani	4
Potato mop top	Potato mop top virus (PMTV)	1

Table 5. Diseases diagnosed on shelterbelt and ornamental tree samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	Number of samples
Ash (Fraxinus sp.)	Anthracnose	Gloeosporium aridum, Discula sp.	5
	Canker, stem/twig	Cytospora sp., Phoma sp.	2
	Fire blight	Erwinia amylovora	1
Basswood/Linden	Canker, stem	Cytospora sp.	2
(Tilia sp.)	Anthracnose	Mycosphaerella sp.	1
	Leaf spot	Phoma sp.	1
Butternut	Anthracnose	Colletotrichum sp.	1
(Juglans sp.)
Cedar	Needle blight	Kabatina sp.	1
(Thuja sp.)	Stem & twig canker	Phomopsis sp., Phoma sp.	1
Crabapple	Canker	Cytospora sp., Nectria sp.	2
(Malus sp.)	Frogeye leaf spot	Botryosphaeria obtusa	1
	Fire blight	Erwinia amylovora	3
	Leaf spot	Stemphylium sp.	1
Elm, American	Anthracnose	Gnomonia ulmea	2
(Ulmus americana)
	Botryosphaeria canker	Botryosphaeria sp.	3
	Coniothyrium canker	Coniothyrium sp.	4
	Cytospora canker	Cytospora sp.	2
	Canker and twig blight	Phoma sp.	13
	Dutch elm disease	Ophiostoma ulmi	34
	Verticillium wilt	Verticillium sp.	6
Poplar (Populus sp.)	Canker	Cytospora sp.	1
	Leaf spot	Botrytis sp.	1
	Twig blight	Venturia inaequalis	1
Spruce (Picea sp.)	Needle blight	Lirula sp.	1
	Needle cast	Rhizosphaera kalkhoffii	5
	Needle cast	Stigmina lautii	1
	Canker	Cytospora kunzei	1

Table 6. Diseases diagnosed on oilseed crop samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	Number of samples
Canola	Alternaria black spot	Alternaria sp.	9
	Anthracnose	Colletotrichum sp.	9
	Aster yellows	Phytoplasma	1
	Blackleg	Leptosphaeria maculans	11
	Cladosporium leaf spot	Cladosporium sp.	1
	Grey stem	Pseudocercosporella capsellae	1
	Root rot	Fusarium sp., Pythium sp.,
		Rhizoctonia solani	13
	Sclerotinia stem rot	Sclerotinia sclerotiorum	1
	Stem stripe	Verticillium sp.	9
Flax	Aster yellows	Phytoplasma	1
	Pasmo	Septoria linicola	1
	Root rot	Fusarium sp., Rhizoctonia sp., Pythium sp.	2
Sunflower	Anthracnose stem	Colletotrichum sp.	1
	Leaf spots	Alternaria sp., Bacterial sp.	1
	Root rot and stem rot	Fusarium sp.	3
	Stem rot	Phomopsis sp.	1

Table 7. Diseases diagnosed on fruit and berry crop samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Crop	Disease/symptom	Causal/associated agents	Number of samples
Apple	Canker	Cytospora sp.	2
	Fire blight	Erwinia amylovora	2
	Black rot/ frogeye leaf spot and twig canker	Botryosphaeria sp.	2
	Scab	Venturia inaequalis	1
Grape	Leaf spot	Bacterial sp.	1
Raspberry	Cane blight	Coniothyrium fuckelii	1
Saskatoon	Leaf and berry spot	Entomosporium sp.	1
Strawberry	Black root rot	Fusarium spp., Cylindrocarpon sp., Pythium sp.	3
	Anthracnose crown rot	Colletotrichum fragariae	2
	Crown rot	Phoma sp.	1
	Root rot	Fusarium sp., Pythium sp.	2

Table 8. Diseases diagnosed on pulse and legume crop samples submitted to the Manitoba Agriculture Crop Diagnostic Centre in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	Number of samples
Alfalfa	Leptosphaerulina leaf spot	Leptosphaerulina sp.	1
	Spring black stem and leaf spot	Phoma medicaginis	2
	Leaf spot	Stemphyllium sp.	1
Dry bean	Bacterial blight	Pseudomonas syringae	1
	Leaf spot	Stemphylium sp.	1
	Root rot	Fusarium oxysporum, Fusarium sp., Pythium sp.	1
Pinto bean	Root rot	Fusarium sp.	1
Faba bean	Leaf spot	Alternaria sp.
	Root rot
Field pea	Alternaria leaf spot	Alternaria sp.	1
	Ascochyta leaf blight	Mycosphaerella sp., Phoma sp.	4
	Bacterial blight	Pseudomonas syringae	4
	Root rot	Aphanomyces sp.	1
	Root rot	Fusarium sp.	6
	Root rot complex	Fusarium sp., Rhizoctonia sp., Pythium sp.	4
	Leaf spot	Septoria sp.	1
Soybean	Alternaria leaf spot	Alternaria sp.	1
	Anthracnose	Colletotrichum sp.	1
	Bacterial blight	Pseudomonas sp.	1
	Brown spot	Septoria glycines	2
	Cercospora leaf spot	Cercospora sp.	1
	Downy mildew	Peronospora sp.	3
	Charcoal rot	Macrophomina phaseolina	2
	Root rot	Fusarium sp.	6
	Root rot	Fusarium sp., Pythium sp., Rhizoctonia sp.	4
	Root rot	Phytopthora sp.	1

DIAGNOSES ON PLANT SAMPLES SUBMITTED TO THE ONTARIO CROPS RESEARCH CENTRE - BRADFORD DIAGNOSTIC LABORATORY IN 2023

CROP: Diagnostic Laboratory Report LOCATION: Bradford/Holland Marsh, Ontario NAMES AND AGENCY: T. BLAUEL AND M.R. MCDONALD

Ontario Crops Research Centre - Bradford, Dept. of Plant Agriculture, University of Guelph, 1125 Woodchoppers Lane, King, ON L7B 0E9 Telephone: [phone]; E-mail: [email protected]; Website: https://bradford-crops.uoguelph.ca/

ABSTRACT: The Integrated Pest Management (IPM) program provided by the Ontario Crops Research Centre - Bradford (OCRC-B) offers diagnostic services to support the vegetable growers of the Holland Marsh and surrounding area. In 2023, 126 plant samples were submitted to the diagnostic laboratory for identification and management recommendations. The plant samples submitted had symptoms of infectious disease (71%), abiotic disorders (18%) and insect damage (11%).

INTRODUCTION AND METHODS: In addition to the scouting and forecasting services provided by the Integrated Pest Management (IPM) program, the diagnostic laboratory at the Ontario Crops Research Centre - Bradford (OCRC-B), formerly the Muck Crops Research Station, provides diagnostic services and management recommendations for plant diseases, insect feeding damage, abiotic disorders and weeds to vegetable growers in and around the Holland Marsh. In 2023, plant samples were submitted to the OCRC-B diagnostic laboratory by growers, IPM scouts and industry representatives. Diagnosis of plant symptoms and issues involved visual and microscopic assessment and culturing of pathogens on growth media. These samples were analysed in addition to the regular identification and quantification of diseases and insect pests provided by the pest management scouts as part of the IPM program.

RESULTS AND DISCUSSION: The diagnostic laboratory received 126 samples between March 14 and November 6, 2023. Of these, 71% were diagnosed with infectious diseases (89 samples), 18% were diagnosed with an abiotic disorder (23 samples) and 11% with insect issues (14 samples). The percentage of samples submitted comprising each crop is as follows: onion (46%), carrot (30%), celery (14%) and other crops (10%). Some storage carrot samples were submitted in early 2023 with severe Sclerotinia white mold and Botrytis rot which is possibly the result of harvesting in dry and warm conditions and poor cooling in storage the year prior. The 2023 growing season started off fairly wet but, soon after, conditions became good for transplanting and seeding. Near the end of May, a period of hot, dry weather resulted in some heat canker and increased the use of irrigation. Crops established well throughout June. There were higher amounts of precipitation than usual throughout July, along with some long periods of reduced sun intensity and air quality due to smoke from forest fires. The increased precipitation resulted in longer leaf wetness periods and higher relative humidity which was favourable for disease development. Stemphylium leaf blight was found in every onion field and disease severity was moderate to high for most fields in the Holland Marsh. Conditions were also favourable for the development of onion downy mildew which was identified in several onion fields. Most fields experienced minor onion downy mildew severity; however, a couple fields had moderate to high disease severity. Botrytis leaf blight was not identified in any onion field, although spores were found in traps and there were periods of favourable conditions for the diseases during the season. The diseases and/or disorders due to plant pathogens diagnosed on crop samples submitted to the OCRC-B diagnostic laboratory in 2023 are presented in Table 1.

Table 1. Plant samples and associated diseases submitted to the OCRC-B diagnostic laboratory in 2023.

Crop	Disease/ insect/ disorder	Causal/associated agent	No. of samples
Beet	Fusarium dry rot	Fusarium spp.	1
Carrot	Alternaria leaf blight	Alternaria dauci	5
	Aster yellows	Candidatus Phytoplasma asteris	2
	Botrytis rot	Botrytis cinerea	1
	Carrot cyst nematode	Heterodera carotae	2
	Cavity spot	Pythium spp.	2
	Cercospora leaf blight	Cercospora carotae	5
	Crown rot	Rhizoctonia solani	2
	Fusarium root rot	Fusarium spp.	1
	Northern root-knot nematode	Meloidogyne hapla	2
	Pythium root dieback	Pythium spp.	1
	Sclerotinia white mold	Sclerotinia sclerotiorum	7
Celery	Bacterial rot	Pectobacterium carotovorum subsp. carotovorum	1
	Early blight	Cercospora apii	3
	Leaf curl	Colletotrichum fioriniae	2
	Late blight	Septoria apiicola	1
	Pink rot	Sclerotinia sclerotiorum	2
Onion	Bacterial soft rot	Pectobacterium carotovorum subsp. carotovorum	5
	Basal rot	Fusarium oxysporum f. sp. cepae	3
	Downy mildew	Peronospora destructor	9
	Pink root	Setophoma terrestris	2
	Purple blotch	Alternaria porri	5
	Smut	Urocystis cepulae	2
	Stemphylium leaf blight	Stemphylium vesicarium	10
	White rot	Stromatinia cepivora	7
Potato	Early blight	Alternaria solani	1
	Late blight	Phytophthora infestans	4
	Verticillium wilt	Verticillium dahliae	1
DISEASE SAMPLES			89
TOTAL SUBMISSIONS			126

ACKNOWLEDGEMENTS: Funding for this work was provided in part by the Bradford Cooperative Storage Ltd., agrochemical companies and growers participating in the Ontario Crops Research Centre - Bradford IPM program.

DISEASES DIAGNOSED ON PLANT SAMPLES SUBMITTED TO THE PLANT DISEASE CLINIC, UNIVERSITY OF GUELPH IN 2023

CROPS: Commercial Crops - Diagnostic Laboratory Report LOCATION: Ontario NAMES AND AGENCY: M. MELZER & X. SHAN

Plant Disease Clinic, Laboratory Services Division, University of Guelph, 95 Stone Road W, Guelph, ON N1H 8J7 Telephone: [phone]; Facsimile: [phone]; Email: [email protected] Web page: www.guelphlabservices.com

ABSTRACT: Diseases and their causal agents diagnosed on plant samples received by the Plant Disease Clinic, University of Guelph in 2023 are summarized in this report. Samples included greenhouse vegetables, annual and perennial ornamental plants, field crops, berry crops, tree fruits, turfgrass, and trees. The Clinic received samples in over 100 plant genera for disease diagnosis in 2023 and most diseases identified are commonly diagnosed on the respective plant hosts.

METHODS: The Plant Disease Clinic of the University of Guelph provides plant pest diagnostic services to growers, agri-businesses, provincial and federal governments, and the general public across Canada. Services include plant disease diagnosis, plant parasitic nematode identification and enumeration, pathogen detection from soil and water, and insect identification. The following data are for samples received by the laboratory for disease diagnosis in 2023. Diagnoses were accomplished using microscopic examination, culturing on artificial media, biochemical identification of bacteria using BIOLOG®, enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR) based techniques including DNA multiscan®, PCR and RT-PCR, and DNA sequencing.

RESULTS AND COMMENTS: In 2023, the Plant Disease Clinic received samples in over 100 plant genera for disease diagnosis. Results are presented in Tables 1 to 6. For various reasons, the frequency of diseases diagnosed on samples submitted to the laboratory does not necessarily reflect the prevalence of diseases of various crops in the field. Problems caused by plant parasitic nematodes, insects and abiotic factors are not listed. Most diseases identified in 2023 are commonly diagnosed on the respective plant hosts.

Table 1. Diseases diagnosed on vegetable samples (including greenhouse vegetables) submitted to the University of Guelph Plant Disease Clinic in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Brassica sp.	Black rot	Xanthomonas campestris	1
Cabbage (Brassica oleracea var. capitata)	Black rot	Xanthomonas campestris	1
	Crown and root rot	Fusarium oxysporum and F. solani	1
	Crown and root rot	Pythium ultimum	1
Carrot (Daucus carota)	Root rot	Pythium sulcatum and P. ultimum	2
Cucumber (Cucumis sativus)	Angular leaf spot	Pseudomonas syringae pv. lachrymans	2
	Anthracnose	Colletotrichum orbiculare	1
	Bacterial wilt	Erwinia tracheiphila	1
	Pseudo-yellows	Beet pseudo-yellows virus (BPYV)	1
	Black rot	Phomopsis cucurbitae	10
	Crown rot	Fusarium sp.	1
	Crown and root rot	Fusarium oxysporum or F. solani	4
	Crown and root rot	Pythium sp., P. aphanidermatum, or P. irregulare	9
	Cucumber green mottle mosaic	Cucumber green mottle mosaic virus (CGMMV)	9
	Fruit rot	Phytophthora sp.	1
	Grey mould	Botrytis cinerea	1
	Gummy stem blight	Stagonosporopsis cucurbitacearum	7
	Potyvirus	Potyvirus	2
	Root rot	Fusarium oxysporum or F. solani	24
	Root rot	Pythium sp., P. aphanidermatum, P. dissotocum, P. irregulare or P. sylvaticum	22
	Stem rot	Penicillium sp.	3
	Tomato ringspot	Tomato ringspot virus (ToRSV)	4
	Tobacco ringspot	Tobacco ringspot virus (TRSV)	5
	Tobacco streak	Tobacco streak virus (TSV)	3
Eggplant (Solanum melongena)	Root rot	Fusarium sp.	1
	Root rot	Pythium dissotocum	1
Garlic (Allium sativum)	Anthracnose	Colletotrichum sp.	2
	Basal rot	Fusarium sp. or F. oxysporum	4
	Bulb rot	Fusarium sp.	6
	Bulb rot	Botrytis sp.	2
	Garlic common latent	Garlic common latent virus (GCLV)	2
	Leaf blight	Stemphylium sp.	3
	Neck rot	Botrytis porri	2
	Plate and root rot	Fusarium sp.	3
	Plate and root rot	Pythium sylvaticum	3
	Plate and root rot	Rhizoctonia solani	1
	Potyvirus	Potyvirus	2
	Skin blotch	Embellisia allii	9
	White rot	Sclerotium cepivorum	1
Kale (Brassica oleracea)	Powdery mildew	Oidium sp.	1
Leek (Allium porrum)	Anthracnose	Colletotrichum sp.	3
	Bacterial soft rot	Pectobacterium carotovorum	1
	Leaf blight	Stemphylium sp.	2
Lettuce (Lactuca sativa)	Grey mould	Botrytis sp.	4
	Root rot	Fusarium oxysporum or F. solani	6
	Root rot	Phytophthora drechsleri	8
	Root rot	Pythium sp. or P. dissotocum	14
	Root rot	Thielaviopsis basicola	7
Onion (Allium cepa)	Slippery skin	Burkholderia gladioli	1
Pea (Pisum sativum)	Root rot	Fusarium sp., F. oxysporum or F. solani	2
	Root rot	Pythium sp. or P. dissotocum	2
Pepper (Capsicum sp.)	Anthracnose	Colletotrichum sp.	1
	Bacterial spot	Xanthomonas euvesicatoria	3
	Crown and root rot	Fusarium sp., F. oxysporum or F. solani	6
	Crown and root rot	Phytophthora nicotianae	1
	Crown and root rot	Pythium aphanidermatum	1
	Fruit rot	Fusarium sp.	1
	Fruit rot	Phytophthora capsici	2
	Fruit rot	Pythium aphanidermatum	1
	Root rot	Fusarium sp., F. oxysporum, or F. solani	35
	Root rot	Pythium sp., P. aphanidermatum, P. dissotocum or P. ultimum	12
Potato (Solanum tuberosum)	Black dot	Colletotrichum coccodes	1
	Black leg	Dickeya sp. or D. chrysanthemi	6
	Black leg	Pectobacterium atrosepticum or P. carotovorum	5
	Black scurf	Rhizoctonia solani	1
	Brown spot	Alternaria alternata	1
	Common scab	Streptomyces sp.	1
	Late blight	Phytophthora infestans	2
	Potyvirus	Potyvirus	1
	Root rot	Fusarium sp., F. oxysporum or F. solani	6
	Root rot	Pythium irregulare or P. ultimum	3
	Tuber rot	Fusarium sp.	2
	Wilt	Verticillium albo-atrum	1
Radish (Raphanus sativus)	Downy mildew	Hyaloperonospora brassicae	1
Spinach (Spinacia oleracea)	Anthracnose	Colletotrichum sp.	2
Squash (Cucurbita sp.)	Fruit rot	Phytophthora sp.	1
Tomato (Lycopersicon esculentum)	Bacterial stem rot	Pectobacterium carotovorum	2
	Bacterial wilt	Ralstonia solanacearum	1
	Crown and root rot	Fusarium oxysporum	2
	Crown and root rot	Phytophthora cryptogea	1
	Crown and root rot	Pythium sp., P. aphanidermatum, or P. ultimum	2
	Fruit rot	Penicillium sp.	3
	Fruit rot	Phytophthora capsici	4
	Late blight	Phytophthora infestans	1
	Mosaic	Pepino mosaic virus (PepMV)	15
	Pith necrosis	Pectobacterium carotovorum	1
	Powdery mildew	Oidium lycopersici	1
	Root rot	Colletotrichum coccodes
	Root rot	Fusarium sp., F. oxysporum or F. solani	38
	Root rot	Pythium sp., P. aphanidermatum, P. dissotocum, P. sylvaticum or P. ultimum	17
	Root rot	Rhizoctonia solani	1
	Root rot	Thielaviopsis basicola	1
	Spotted wilt	Tomato spotted wilt virus (TSWV)	1
	Stem rot	Fusarium sp.	1
	Stem rot	Pectobacterium betavasculorum	2
	Tomato bacterial canker	Clavibacter michiganensis subsp. michiganensis	1
	Tomato brown rugose	Tomato brown rugose fruit virus (ToBRFV)	3
	White mould	Sclerotinia sclerotiorum	1

Table 2. Diseases diagnosed on fruit samples submitted to the University of Guelph Plant Disease Clinic in 2023.

Crop	Disease/ symptom	Causal/ associated agent(s)	No. of samples
Apple (Malus sp.)	Apple chlorotic leaf spot	Apple chlorotic leaf spot virus (ACLSV)	3
	Apple stem pitting	Apple stem pitting virus (ASPV)	1
	Canker	Cytospora sp.	1
	Canker	Diaporthe eres	2
	Canker	Phomopsis sp.	4
	Fire blight	Erwinia amylovora	3
	Root rot	Phytophthora cactorum	2
	Root rot	Pythium irregulare	1
	Silver leaf	Chondrostereum purpureum	1
Bitter melon (Momordica charantia)	Anthracnose	Colletotrichum sp.	2
	Black rot	Phoma cucurbitacearum	1
Blueberry (Vaccinium sp.)	Canker	Fusicoccum putrefaciens	1
	Canker	Phomopsis sp. or P. vaccinii	3
	Leaf mottle	Blueberry mosaic associated virus (BlMaV)	1
	Leaf ringspots/mottle	Blueberry latent virus (BSLV)	5
	Ringspot	Tobacco ringspot virus (TRSV)	1
	Twig blight	Pestalotiopsis sp.	2
	Twig blight	Phomopsis sp.	1
Cantaloupe (Cucumis melo)	Root rot	Pythium aphanidermatum	1
Grapevine (Vitis sp.)	Crown gall	Agrobacterium vitis	3
	Downy mildew	Plasmopara sp.	2
	Fruit rot	Cladosporium sp.	1
	Grapevine leafroll	Grapevine leafroll- associated virus (GLRaV)	11
	Grapevine Pinot gris virus	Grapevine Pinot gris virus (GPGV)	8
Melon (Cucumis sp.)	Chlorotic leaf spot	Tobacco ringspot virus (TRSV)	1
	Crown and root rot	Fusarium oxysporum	1
	Crown and root rot	Pythium ultimum	1
	Gummy stem blight	Didymella bryoniae	1
	Root rot	Fusarium oxysporum or F. solani	2
	Root rot	Pythium irregulare	1
	Leaf mosaic	Tobacco streak virus (TSV)	1
Muskmelon (Cucumis melo)	Crown and root rot	Fusarium oxysporum	1
	Crown and root rot	Pythium irregulare and P. ultimum	1
Pear (Pyrus sp.)	Canker	Diplodia sp.	1
	Fire blight	Erwinia amylovora	1
	Leaf spot	Entomosporium sp.	1
Pumpkin (Cucurbita pepo)	Blight	Phytophthora capsici	1
	Fruit rot	Phytophthora capsici	2
Raspberry (Rubus sp.)	Anthracnose	Colletotrichum sp.	1
	Cane blight	Leptosphaeria coniothyrium	1
	Crown and root rot	Phytophthora sp.	1
	Crown and root rot	Pythium irregulare	1
	Root rot	Fusarium sp.	1
	Root rot	Rhizoctonia sp.	1
	Rubus yellow net	Rubus yellow net virus (RYNV)	1
	Spur blight	Didymella applanata	1
Strawberry (Fragaria sp.)	Anthracnose	Colletotrichum sp. or Colletotrichum acutatum	15
	Crown and root rot	Fusarium oxysporum	12
	Crown and root rot	Neopestalotiopsis sp. or N. rosae	24
	Crown and root rot	Pythium dissotocum or P. ultimum	2
	Crown and root rot	Phytophthora sp. or P. cactorum	18
	Crown and root rot	Rhizoctonia sp. or R. solani	5
	Crown rot	Phytophthora cactorum	2
	Grey mould	Botrytis cinerea	8
	Leaf blight	Phomopsis obscurans	8
	Leaf scorch	Marssonina fragariae	1
	Leaf spot	Mycosphaerella fragariae	1
	Leaf spot	Neopestalotiopsis sp.	5
	Polerovirus	Strawberry polerovirus-1 (SPV-1)	4
	Powdery mildew	Oidium sp.	3
	Powdery mildew	Podosphaera aphanis	4
	Red stele root rot	Phytophthora fragariae	1
	Root rot	Cylindrocarpon destructans	1
	Root rot	Fusarium sp. or F. oxysporum	22
	Root rot	Phytophthora cactorum	4
	Root rot	Pythium dissotocum, P. irregulare, P. sylvaticum, or P. ultimum	33
	Root rot	Rhizoctonia sp., R. fragariae, or R. solani	15
	Strawberry mild yellow edge	Strawberry mild yellow edge virus (SMYEV)	2
	Strawberry mottle	Strawberry mottle virus (SMoV)	2
	Strawberry pallidosis	Strawberry pallidosis virus (SpaV)	2
	Strawberry vein banding	Strawberry vein banding virus (SVBV)	1
	Target spot	Corynespora cassiicola	1
	Wilt	Verticillium dahliae	2
Watermelon (Citrullus lanatus)	Crown and root rot	Fusarium sp.	1
	Crown and root rot	Pythium aphanidermatum	1
	Wilt	Verticillium dahliae	1

Table 3. Diseases diagnosed on herbaceous ornamental samples submitted to the University of Guelph Plant Disease Clinic in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Ajuga sp.	Root rot	Pythium sp.	1
Alocasia sp.	Crown and root rot	Fusarium oxysporum	1
	Crown and root rot	Phytophthora nicotianae	1
	Crown and root rot	Pythium sp.	1
Aloe sp.	Rot	Fusarium sp.	8
Begonia (Begonia sp.)	Root rot	Pythium dissotocum	1
Brunnera sp.	Crown and root rot	Phytophthora nicotianae	2
	Root rot	Thielaviopsis basicola	2
Calathea sp.	Leaf spot	Bipolaris sp.	1
	Root rot	Pythium sp.	1
Calla lily (Zantedeschia sp.)	Rot	Fusarium solani	3
	Rot	Pythium sp.	2
	Soft rot	Pectobacterium carotovorum	1
Canna lily (Canna sp.)	Potyvirus	Potyvirus	1
Chrysanthemum (Chrysanthemum sp.)	Bacterial leaf spot and stem necrosis	Pseudomonas cichorii	1
	Pith necrosis	Pectobacterium carotovorum	1
	Powdery mildew	Golovinomyces chrysanthemi	1
Cyclamen sp.	Root rot	Fusarium oxysporum	1
Dieffenbachia sp.	Anthracnose	Colletotrichum sp.	1
Dipladenia (Mandevilla sp.)	Blight	Botrytis sp.	1
	Rot	Fusarium solani	1
	Rot	Pythium aphanidermatum	1
Easter cactus (Hatiora gaertneri)	Rot	Fusarium oxysporum	1
	Root rot	Fusarium oxysporum or F. solani	1
	Root rot	Pythium dissotocum or P. ultimum	1
	Root rot	Rhizoctonia solani	1
Euphorbia sp.	Anthracnose	Colletotrichum sp.	1
	Blue mould	Penicillium sp.	1
	Grey mould	Botrytis cinerea	1
Gerbera (Gerbera sp.)	Root rot	Pythium irregulare	1
Gramineae	Necrotic ring spot	Leptosphaeria korrae	1
	Pink snow mold	Microdochium nivale	1
Hibiscus sp.	Grey mould	Botrytis sp.	1
Hosta sp.	Leaf mosaic	Hosta virus X (HVX)	1
Kalanchoe (Kalanchoe sp.)	Crown and root rot	Fusarium oxysporum or F. solani	2
	Crown and root rot	Phytophthora nicotianae	3
	Leaf spot	Stemphylium sp.	1
	Root rot	Thielaviopsis basicola	1
	Stem canker	Corynespora cassiicola	4
	Stem rot	Phytophthora nicotianae	1
Lavender (Lavandula sp.)	Grey mould	Botrytis cinerea	2
	Rot	Fusarium oxysporum	2
	Root rot	Pythium irregulare	1
	Root rot	Thielaviopsis basicola	1
Lisianthus (Eustoma grandiflorum)	Crown rot	Myrothecium sp.	1
Mandevilla sp.	Grey mould	Botrytis cinerea	1
Million bells (Calibrachoa sp.)	Blight	Botrytis cinerea	2
	Crown and root rot	Pythium irregulare	1
	Root rot	Fusarium oxysporum or F. solani	3
	Root rot	Pythium dissotocum	1
	Root rot	Thielaviopsis basicola	3
Pothos (Epipremnum aureum)	Anthracnose	Colletotrichum sp.	1
	Soft rot	Pectobacterium carotovorum	1
Pelargonium sp.	Grey mould	Botrytis sp.	1
	Root rot	Fusarium oxysporum or F. solani	3
	Root rot	Pythium sylvaticum or P. ultimum	2
	Root rot	Thielaviopsis basicola	1
Peony (Paeonia sp.)	Bacterial leaf spot	Xanthomonas campestris	1
	Crown and root rot	Fusarium sp.	3
	Root rot	Phytophthora cactorum	1
Petunia (Petunia sp.)	Leaf mosaic	Tomato mosaic virus (ToMV)	1
Philodendron sp.	Crown and root rot	Phytophthora nicotianae	1
Phlox subulata	Anthracnose	Colletotrichum sp.	1
Poinsettia (Euphorbia pulcherrima)	Bacterial leaf spot	Curtobacterium flaccumfaciens	1
	Crown and root rot	Fusarium oxysporum	4
	Crown and root rot	Pythium irregulare	2
	Mosaic	Poinsettia mosaic virus (PnMV)	1
Primula sp.	Grey mould	Botrytis cinerea	2
Sansevieria sp.	Anthracnose	Colletotrichum sp.	2
	Crown rot	Fusarium solani	1
	Crown rot	Pythium sp.	1
Sedum (Sedum sp.)	Anthracnose	Colletotrichum sp.	3
	Root rot	Phytophthora sp. or P. drechsleri	3
	Root rot	Pythium sp. or P. dissotocum	3
Speedwell (Veronica sp.)	Downy mildew	Peronospora sp.	1
Statice (Limonium sp.)	Leaf spot	Cercospora sp.	1
	Potyvirus	Potyvirus	1
Sunflower (Helianthus annuus)	Root rot	Fusarium oxysporum	1
	Root rot	Pythium ultimum	1
Zygocactus (Schlumbergera sp.)	Crown and root rot	Fusarium oxysporum	1
	Crown and root rot	Phytophthora nicotianae	1

Table 4. Plant diseases diagnosed on woody ornamental samples submitted to the University of Guelph Plant Disease Clinic in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Austrian pine (Pinus nigra)	Needle blight	Mycosphaerella pini	2
Barberry (Berberis sp.)	Root rot	Pythium dissotocum	1
Black cherry (Prunus pensylvanica)	Root rot	Phytophthora cactorum	1
	Root rot	Pythium aphanidermatum, P. sylvaticum, and P. ultimum	1
	Root rot	Thielaviopsis basicola	1
Blue spruce (Picea pungens)	Needle cast	Rhizosphaera kalkhoffii	1
Boxwood (Buxus sp.)	Blight	Cylindrocladium buxicola	1
	Stem canker and leaf blight	Volutella buxi	3
Burning bush (Euonymus alatus)	Root rot	Pythium sp.	1
	Root rot	Rhizoctonia solani	1
	Root rot	Thielaviopsis basicola	1
Cedar (Thuja sp.)	Needle blight	Phyllosticta thujae	2
	Root rot	Pythium sp.	1
	Tip blight	Pestalotiopsis sp.	4
	Tip blight	Phomopsis sp.	1
Crabapple (Malus sp.)	Blotch	Marssonina sp.	1
	Powdery mildew	Oidium sp.	1
Cypress (Cupressus sp.)	Dieback	Phomopsis sp.	3
	Root rot	Fusarium oxysporum	1
	Root rot	Phytophthora nicotianae	1
	Root rot	Pythium dissotocum	2
	Leaf spot	Sphaerulina sp. or Sphaerulina cornicola	1
Elderberry (Sambucus canadensis)	Anthracnose	Colletotrichum sp.	1
Elm (Ulmus sp.)	Black spot	Stegophora ulmea	2
	Canker	Botryosphaeria sp.	1
	Dutch elm disease	Ophiostoma sp.	1
English ivy (Hedera helix)	Crown and root rot	Fusarium sp.	1
	Crown and root rot	Phytophthora sp.	1
	Crown and root rot	Pythium irregulare	1
	Stem rot	Phytophthora sp.	1
Euonymus sp.	Anthracnose	Colletotrichum sp.	1
	Crown and root rot	Pythium irregulare	1
European beech (Fagus sylvatica)	Anthracnose	Discula sp.	1
Fir (Abies sp.)	Needle cast	Rhizosphaera pini	4
Fragrant sumac (Rhus aromatica)	Powdery mildew	Oidium sp.	1
Fraser fir (Abies fraseri)	Needle cast	Rhizosphaera pini	1
Gaultheria sp.	Root rot	Fusarium oxysporum	1
	Root rot	Pythium sp. or P. dissotocum	2
Holly (Ilex sp.)	Anthracnose	Colletotrichum fioriniae	1
	Canker	Phomopsis sp.	1
Hemlock (Tsuga sp.)	Canker	Diaporthe eres	2
	Root rot	Phytophthora nicotianae	1
Hornbeam (Carpinus sp.)	Anthracnose	Monostichella robergei	1
	Powdery mildew	Oidium sp.	1
Hydrangea (Hydrangea sp.)	Powdery mildew	Oidium sp.	1
	Root rot	Fusarium sp.	1
	Root rot	Pythium sylvaticum	1
Hypericum sp.	Root rot	Pythium aphanidermatum	1
	Root rot	Thielaviopsis basicola	1
Japanese maple (Acer palmatum)	Wilt	Verticillium dahliae	1
Juniper (Juniperus sp.)	Anthracnose	Colletotrichum sp.	1
	Root rot	Pythium sp.	2
Lily-of-the-valley shrub (Pieris japonica)	Dieback	Pestalotiopsis sp.	1
Maple (Acer sp.)	Anthracnose	Aureobasidium sp.	2
	Anthracnose	Colletotrichum sp.	1
	Canker	Eutypella parasitica	1
	Root rot	Fusarium sp.	1
	Root rot	Pythium irregulare or P. sylvaticum	1
	Twig blight	Phomopsis sp.	1
Myrtle (Myrtus sp.)	Root rot	Phytophthora nicotianae	1
Ninebark (Physocarpus sp.)	Leaf spot	Cercospora sp.	1
Pin cherry (Prunus pensylvanica)	Root rot	Phytophthora sp.	1
	Root rot	Pythium sp.	1
	Root rot	Thielaviopsis basicola	1
Poplar (Populus sp.)	Blight	Marssonina sp.	1
Prunus virginiana	Crown and root rot	Phytophthora cactorum	1
	Root rot	Pythium dissotocum	1
Red maple (Acer rubrum)	Anthracnose	Aureobasidium sp.	1
Red osier dogwood (Cornus sericea)	Powdery mildew	Phyllactina guttata	1
Red pine (Pinus resinosa)	Root rot	Cylindrocarpon destructans	3
	Root rot	Fusarium sp.	3
	Root rot	Pythium sp., P. irregulare or P. sylvaticum	3
Rose (Rosa sp.)	Black spot	Diplocarpon rosae	1
	Crown and root rot	Fusarium oxysporum	2
	Grey mould	Botrytis cinerea	1
	Powdery mildew	Podosphaera pannosa	1
	Root rot	Fusarium oxysporum or F. solani	4
	Root rot	Pythium sp. or P. dissotocum	2
	Rose rosette disease	Rose rosette virus (RRV)	3
Scots pine (Pinus sylvestris)	Brown spot needle blight	Lecanosticta acicola	1
Serviceberry (Amelanchier laevis)	Canker	Neonectria sp.	1
	Crown and root rot	Fusarium sp.	1
	Crown and root rot	Phytophthora cactorum	1
	Crown and root rot	Pythium sylvaticum	1
Siberian cypress (Microbiota decussata)	Needle blight	Phyllosticta sp.	1
	Root rot	Phytophthora sp.	1
	Root rot	Pythium sp.	1
Silver maple (Acer saccharinum)	Canker	Botryosphaeria sp.	1
Spiraea sp.	Root rot	Fusarium oxysporum	1
	Root rot	Pythium dissotocum	1
Spruce (Picea sp.)	Needle cast	Rhizosphaera kalkhoffii	3
	Root rot	Fusarium sp.	1
	Root rot	Pythium dissotocum	1
Staghorn sumac (Rhus typhina)	Powdery mildew	Oidium sp.	1
Sugar maple (Acer saccharum)	Wilt	Verticillium sp. or V. dahliae	4
Viburnum sp.	Grey mould	Botrytis cinerea	1
White pine (Pinus strobus)	Blister rust	Cronartium ribicola	1

Table 5. Diseases diagnosed on field crop samples submitted to the University of Guelph Plant Disease Clinic in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Adzuki bean (Vigna angularis)	Bacterial blight	Pseudomonas syringae	2
Barley (Hordeum vulgare)	Spot blotch	Bipolaris sp.	1
Canola (Brassica napus)	Root rot	Pythium sp.	1
	Root rot	Rhizoctonia solani	1
Corn (Zea mays)	Northern corn leaf spot	Bipolaris zeicola	1
Soybean (Glycine max)	Anthracnose	Colletotrichum sp.	5
	Charcoal rot	Macrophomina phaseolina	5
	Root rot	Fusarium sp., F. oxysporum or F. solani	8
	Root rot	Phytophthora sp.	5
	Root rot	Pythium sp., P. irregulare, P. sylvaticum or P. ultimum	7
	Root rot	Rhizoctonia solani	1
	Root rot	Thielaviopsis basicola	1
	Sudden death	Fusarium virguliforme	3
	Target spot	Corynespora cassiicola	3
	Vein necrosis	Soybean vein necrosis virus (SVNV)	2
Wheat (Triticum sp.)	Anthracnose	Colletotrichum sp.	1
	Crown and root rot	Pythium sp.	1
	Leaf streaking	Cereal yellow dwarf virus- RPV (CYDV- RPV)	1
	Leaf streaking	Wheat streak mosaic virus (WSMV)	3
	Leaf spot	Septoria sp.	1
	Pink snow mould	Microdochium nivale	2
	Root rot	Pythium sp.	1
	Root rot	Rhizoctonia solani	1

Table 6. Diseases diagnosed on herb and specialty crop samples submitted to the University of Guelph Plant Disease Clinic in 2023.

Crop	Disease/symptom	Causal/associated agent(s)	No. of samples
Cannabis sp.	Hop latent viroid	Hop latent viroid (HLVd)	25
	Leaf spot	Septoria sp.	1
	Root rot	Fusarium sp., F. oxysporum or F. solani	6
	Root rot	Pythium dissotocum	5
Fenugreek (Trigonella foenum-graecum)	Bacterial blight	Pseudomonas syringae	3
Ginseng (Panax sp.)	Root rot	Cylindrocarpon destructans	4
	Root rot	Fusarium oxysporum or F. solani	3
	Root rot	Phytophthora cactorum	2
	Root rot	Pythium sp., P. irregulare or P. ultimum	5
Hazelnut (Corylus sp.)	Canker	Diplodia seriata	1
Hop (Humulus lupulus)	Apple mosaic	Apple mosaic virus (ApMV)	1
	Downy mildew	Pseudoperonospora humuli	1
	Hop mosaic	Hop mosaic virus (HpMV)	3
	Root rot	Phytophthora sp.	1
Sesame (Sesamum indicum)	Bacterial leaf spot	Pseudomonas syringae	1
Sunflower (Helianthus annuus)	Root rot	Fusarium sp.	3
	Root rot	Pythium dissotocum	1

MALADIES ET PROBLÈMES ABIOTIQUES DIAGNOSTIQUÉS SUR LES ÉCHANTILLONS DE PLANTES REÇUS EN 2023 AU LABORATOIRE D’EXPERTISE ET DE DIAGNOSTIC EN PHYTOPROTECTION DU MINISTÈRE DE L’AGRICULTURE, DES PÊCHERIES ET DE L’ALIMENTATION DU QUÉBEC

CULTURES: Les échantillons reçus en 2023 au Laboratoire d’expertise et de diagnostic en phytoprotection (LEDP) regroupent de nombreuses cultures NOMS ET ORGANISME: G. ARSENAULT-LABRECQUE, W. ARMSTRONG, A.-M. BRETON, A. DIONNE, L. PICHETTE ET J. VIVANCOS

Laboratoire d’expertise et de diagnostic en phytoprotection (LEDP), Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec (MAPAQ), Complexe scientifique, 2700, rue Einstein, D.1-200h, Québec, QC G1P 3W8 Téléphone: 418-643-5027, poste 2700; Télécopieur: 418-646-6806; Courriel: [email protected] Sites Internet: http://www.mapaq.gouv.qc.ca/fr/Productions/Protectiondescultures/diagnostic/Pages/diagnostic.aspx http://www.agrireseau.qc.ca/lab/

RÉSUMÉ: Du 13 décembre 2022 au 8 novembre 2023, 2254 échantillons ont été traités dans la section phytopathologie du LEDP. Les échantillons reçus comprennent des plantes maraîchères (serres et champs), des arbres et arbustes fruitiers, des petits fruits, des grandes cultures et céréales, des plantes à usage industriel, des plantes ornementales herbacées, des plantes fourragères, des arbres et arbustes ornementaux (serres et pépinières) ainsi que des plantes aromatiques et médicinales.

MÉTHODES: Le laboratoire de phytopathologie du LEDP offre des services de diagnostic et de détection des maladies parasitaires aux conseillers agricoles, aux producteurs, aux particuliers et aux instances gouvernementales. Les échantillons reçus font d’abord l’objet d’un examen visuel, généralement suivi d’examens au stéréomicroscope et au microscope photonique. Selon les symptômes observés, un ou plusieurs tests diagnostiques sont réalisés dans le but de détecter ou d’identifier l’agent ou les agents phytopathogènes.

Voici les principaux tests de laboratoire réalisés afin d’appuyer le diagnostic: les nématodes vermiformes sont extraits du sol et des tissus végétaux par la méthode de l’entonnoir de Baermann, tandis que les nématodes à kystes sont extraits du sol à l’aide d’un appareil de Fenwick. Leur identification (au genre et, lorsque possible, à l’espèce) est réalisée par un examen microscopique des caractères morphologiques et par des techniques de biologie moléculaire. Ditylenchus sp. est détecté dans la plante par qPCR. Les champignons et oomycètes sont isolés sur des milieux de culture gélosés et identifiés selon leurs caractéristiques morphologiques et/ou par le séquençage d’un ou de plusieurs gènes. De nombreuses espèces sont détectées dans la plante par des outils de biologie moléculaire (PCR, qPCR). Les bactéries sont isolées sur des milieux de culture gélosés, puis identifiées à l’aide de tests biochimiques Biolog^R et/ou par le séquençage d’un ou de plusieurs gènes. Comme pour les nématodes et les champignons, certaines espèces de bactéries sont détectées dans la plante par des outils de biologie moléculaire (PCR, qPCR). Les phytoplasmes sont détectés par des techniques de biologie moléculaire (PCR nichée et séquençage d’ADN). Les virus, quant à eux, sont détectés par des tests sérologiques ELISA ou par RT-PCR, PCR ou RT-qPCR. Une liste exhaustive des techniques utilisées est disponible au: https://www.agrireseau.net/documents/Document_87998.pdf

RÉSULTATS ET DISCUSSIONS: Les tableaux 1 à 7 présentent le sommaire des maladies identifiées sur les échantillons de plantes reçus, quelle que soit leur origine (champ, serre ou entrepôt). Notez que le nombre de maladies rapportées ne correspond pas au nombre d’échantillons réellement reçus et traités durant l’année, puisque plus d’un problème peut être identifié sur un même échantillon (plante reçue) et que le diagnostic de certains cas n’a pas été inclus dans ce rapport. Cela concerne notamment les causes indéterminées, les causes incertaines ou hypothétiques, les détections négatives et les données potentiellement nominatives. Étant donné que les problèmes abiotiques (non parasitaires) diagnostiqués sur les échantillons sont, en majorité, de nature hypothétique, ils ont rarement été cités dans ce rapport; ces diagnostics sont établis en fonction de l’observation des symptômes, du résultat de certains tests de laboratoire et d’informations obtenues à la suite de discussions avec les clients.

REMERCIEMENTS: Les auteurs remercient Marion Berrouard, Jaëlle Falardeau, Bassirou Idrissou-Abdoulaye, Ludovic Jacques, Carlos-Mario Jimenez, Dominic Lafleur, Chantal Malenfant, Mathilde Williatte-Battet, Carolle Fortin et Annie-Pier Hachey pour leur assistance technique ainsi que les étudiants Megan Lemay, Clovis Tremblay, Elisabeth Thiboutot et Maude Bélanger.

Tableau 1. Sommaire des maladies diagnostiquées parmi les plantes maraîchères reçues au Laboratoire d’expertise et de diagnostic en phytoprotection du MAPAQ en 2023.

Culture	Maladie/symptôme	Agent pathogène/cause	Nombre
Ail (Garlic)	Pourriture du col / Dépérissement	Botrytis allii	1
	Pourriture du col / Dépérissement	Botrytis porri	1
	Pourriture bactérienne	Botrytis sp.	12
	Désordre génétique	Chimère	1
	Nématode des tiges et des bulbes	Ditylenchus dipsaci	7
	Suie des bulbes	Embellisia allii	1
	Suie des bulbes	Embellisia sp.	11
	Pourriture fusarienne	Fusarium oxysporum	2
	Pourriture fusarienne	Fusarium sp.	66
	Asymptomatique	GCLV (Garlic common latent virus)	64
	Virus de la striure chlorotique du poireau	LYSV (Leek yellow stripe virus)	20
	Moisissure bleue	Penicillium sp.	6
	Potyvirus	Potyvirus (groupe des Potyvirus)	54
	Pourriture pythienne	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
	Septoriose	Septoria sp.	1
Asperge (Asparagus)	Moisissure grise	Botrytis sp.	1
	Piétin fusarien	Fusarium oxysporum	1
	Piétin fusarien	Fusarium sp.	3
	Dépérissement	Gel	1
	Rouille	Puccinia asparagi	1
	Rouille	Puccinia sp.	1
Aubergine (Eggplant)	Tache alternarienne	Alternaria sp.	3
	Moisissure grise	Botrytis sp.	2
	Fusariose	Fusarium sp.	5
	Pourriture	Phytophthora sp.	2
	Chancre sec	Plectosporium sp.	2
	Nématode des lésions racinaires	Pratylenchus sp.	1
	Pourriture pythienne	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
	Sclérotiniose	Sclerotinia sclerotiorum	1
	Pourriture noire des racines	Thielaviopsis sp.	1
	Verticilliose	Verticillium dahliae	2
	Tache bactérienne	Xanthomonas arboricola	1
Bette à carde (Chard)	Pourriture molle bactérienne	Pectobacterium carotovorum	1
Betterave (Beet)	Pourriture fusarienne	Fusarium sp.	1
	Pourriture pythienne	Pythium sp.	1
	Gale commune	Streptomyces scabiei	1
Brocoli (Broccoli)	Tache noire alternarienne	Alternaria brassicicola	8
	Fusariose	Fusarium sp.	1
	Pourriture molle	Pectobacterium carotovorum	1
	Pourriture molle	Pectobacterium sp.	1
	Malformation	Phytotoxicité à un herbicide	1
	Hernie des crucifères	Plasmodiophora brassicae	1
	Pourriture pythienne	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
	Nervation noire	Xanthomonas campestris	3
Cantaloup (Cantaloupe)	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	1
	Anthracnose	Colletotrichum sp.	1
	Flétrissement bactérien	Erwinia tracheiphila	2
	Fusariose	Fusarium sp.	2
	Pourriture sure	Geotrichum sp.	1
	Pourriture molle	Pectobacterium brasiliense	1
	Pourriture molle	Pectobacterium carotovorum	2
	Plectosporiose	Plectosphaerella sp.	1
	Pourriture	Plectosporium sp.	3
	Potyvirus	Potyvirus (groupe des Potyvirus)	2
	Tache angulaire	Pseudomonas syringae	1
	Mildiou	Pseudoperonospora sp.	1
	Pourriture pythienne	Pythium sp.	1
Carotte (Carrot)	Tache alternarienne	Alternaria dauci	1
	Fusariose	Fusarium sp.	1
	Nématode à galle	Meloidogyne sp.	2
	Pourriture pythienne	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Céleri (Celery)	Tache alternarienne	Alternaria sp.	2
	Virus de la mosaïque du céleri	CeMV (Celery mosaic virus)	1
	Anthracnose	Colletotrichum sp.	1
	Fusariose	Fusarium sp.	1
Chou Chinois (Chinese cabbage)	Cercosporiose	Cercospora sp.	3
	Fusariose	Fusarium sp.	1
	Pourriture molle	Pectobacterium brasiliense	2
Chou de Bruxelles (Brussels sprouts)	Tache grise alternarienne	Alternaria brassicae	1
	Tache alternarienne	Alternaria sp.	1
	Moisissure grise	Botrytis cinerea	1
	Pourriture	Botrytis sp.	1
	Anthracnose	Colletotrichum sp.	1
	Tache bactérienne	Pseudomonas viridiflava	1
	Brûlure	Toxicité en cuivre	1
Chou Kale (Kale)	Pourriture	Botrytis sp.	1
	Tache bactérienne	Pseudomonas syringae	1
Chou pommé (Cabbage)	Tache alternarienne	Alternaria sp.	2
	Pourriture	Botrytis sp.	1
	Moisissure noire	Cladosporium sp.	1
	Cœur creux	Cœur creux	1
	Nervation noire	Xanthomonas campestris	1
	Nervation noire	Xanthomonas campestris pv. campestris	1
	Pourriture en entreposage	Phytophthora brassicae	2
Chou-fleur (Cauliflower)	Rouille blanche	Albugo sp.	1
	Virus de la mosaïque du chou-fleur	CaMV (Cauliflower mosaic virus)	1
	Brûlure	Carence en calcium	1
	Tache noire	Alternaria brassicicola	2
	Pourriture	Fusarium sp.	2
	Pourriture des racines	Pythium sp.	1
	Nervation noire	Xanthomonas campestris pv. campestris	2
Citrouille (Pumpkin)	Anomalie de coloration	Macule physiologique	3
	Pourriture molle	Pectobacterium brasiliense	1
	Dépérissement phytophthoréen	Phytophthora sp.	1
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
	Pourriture des fruits	Pythium sp.	1
	Virus de la mosaïque de la courge	SqMV (Squash mosaic virus)	2
	Virus de la mosaïque de la pastèque	WMV (Watermelon mosaic virus)	1
	Virus de la mosaïque jaune de la courgette	ZYMV (Zucchini yellow mosaic virus)	2
Concombre (Cucumber)	Tache alternarienne	Alternaria sp.	4
	Gale	Cladosporium sp.	5
	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	2
	Dépérissement	Conductivité électrique faible	1
	Tache concentrique	Corynespora sp.	1
	Flétrissement bactérien	Erwinia tracheiphila	2
	Fusariose/pourriture	Fusarium sp.	8
	Pourriture molle bactérienne	Pectobacterium carotovorum	1
	Pourriture	Pectobacterium parmentieri	1
	Pourridié phytophthoréen	Phytophthora sp.	1
	Brûlure plectosporienne	Plectosporium sp.	4
	Potyvirus	Potyvirus (groupe des Potyvirus)	6
	Tache angulaire	Pseudomonas syringae	2
	Mildiou	Pseudoperonospora sp.	6
	Pourriture pythienne	Pythium sp.	3
	Rhizoctone commun	Rhizoctonia sp.	3
	Pourriture sclérotique	Sclerotinia sclerotiorum	1
	Pourriture sclérotique	Sclerotinia sp.	2
	Tache septorienne	Septoria sp.	1
	Tache bactérienne	Xanthomonas sp.	1
Courge (Squash)	Tache foliaire	Alternaria sp.	9
	Pourriture des fruits	Choanephora sp.	1
	Gale	Cladosporium sp.	4
	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	1
	Anthracnose	Colletotrichum sp.	7
	Virus du rabougrissement jaune des cucurbitacées	CYSDV (Cucurbit yellow stunting disorder virus)	2
	Pourriture racinaire ou de fruit	Fusarium sp.	6
	Pourriture molle	Pectobacterium brasiliense	1
	Pourriture des fruits	Phytophthora sp.	3
	Malformation	Phytotoxicité - 2,4-D	1
	Malformation	Phytotoxicité - Buctril	1
	Malformation	Phytotoxicité - Dicamba	1
	Tache plectosporienne	Plectosporium sp.	2
	Blanc	Podosphaera sp.	3
	Potyvirus	Potyvirus (groupe des Potyvirus)	4
	Virus des taches en anneau du papayer	PRSV (Papaya ringspot virus)	1
	Tache foliaire	Pseudomonas sp.	2
	Tache angulaire	Pseudomonas syringae	3
	Mildiou	Pseudoperonospora sp.	1
	Pourriture pythienne	Pythium sp.	1
	Tache septorienne	Septoria sp.	4
	Virus de la mosaïque de la courge	SqMV (Squash mosaic virus)	6
	Pourriture noire	Stagonosporopsis sp.	1
	Tache bactérienne	Xanthomonas campestris	1
Courge musquée (Butternut squash)	Anthracnose	Colletotrichum sp.	1
	Virus du rabougrissement jaune des cucurbitacées	CYSDV (Cucurbit yellow stunting disorder virus)	2
	Potyvirus	Potyvirus (groupe des Potyvirus)	2
	Virus des taches en anneau du papayer	PRSV (Papaya ringspot virus)	2
	Virus de la mosaïque de la courge	SqMV (Squash mosaic virus)	2
	Virus de la mosaïque jaune de la courgette	ZYMV (Zucchini yellow mosaic virus)	1
Courgette (Zucchini)	Tache plectosporienne	Plectosporium sp.	1
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
	Chance gommeux	Stagonosporopsis sp.	1
Échalote (Shallot)	Moisissure bleue	Penicillium sp.	1
Épinard (Spinach)	Virus de la mosaïque de la laitue	LMV (Lettuce mosaic virus)	1
Fenouil / Aneth doux (Fennel)	Anthracnose	Colletotrichum sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
	Pourriture	Sclerotinia sp.	1
Gourgane / Féverole (Field beans)	Alternariose	Alternaria sp.	1
	Moisissure grise	Botrytis sp.	1
	Anomalie de coloration	Humidité de l’air élevée	1
Haricot (Beans)	Pourriture	Bipolaris sp.	1
	Moisissure grise	Botrytis sp.	3
	Fusariose	Fusarium brasiliense	1
	Fusariose	Fusarium sp.	5
	Fusariose	Fusarium virguliforme	1
	Pourriture des racines et de la tige	Phytophthora sp.	2
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
	Tache auréolée	Pseudomonas sp.	1
	Graisse bactérienne	Pseudomonas syringae	1
	Pourriture pythienne	Pythium sp.	2
	Rhizoctone commun	Rhizoctonia sp.	3
	Pourriture racinaire	Thielaviopsis sp.	1
Haricot vert (Green beans)	Anthracnose	Colletotrichum sp.	1
	Fusariose	Fusarium sp.	1
Laitue (Lettuce)	Alternariose	Alternaria sp.	1
	Moisissure grise	Botrytis cinerea	1
	Fusariose	Fusarium sp.	1
	Pourriture molle	Pectobacterium carotovorum	1
	Pourriture molle	Pectobacterium sp.	1
	Nématode des lésions racinaires	Pratylenchus sp.	1
	Tache bactérienne	Pseudomonas cichorii	5
	Pourriture des racines	Pythium dissotocum	1
	Pourriture pythienne	Pythium sp.	3
	Rhizoctone commun	Rhizoctonia sp.	1
	Pourriture noire des racines	Thielaviopsis sp.	2
Laitue pommée / Laitue iceberg (Iceberg lettuce)	Pourriture molle	Pectobacterium carotovorum	1
	Tache plectosporienne	Plectosporium sp.	1
Luffa (Luffa)	Pourriture	Pythium sp.	1
Maïs sucré (Sweet corn)	Alternariose	Alternaria sp.	1
	Tache helminthosporienne	Bipolaris sp.	1
	Brunissement des tiges	Fusarium sp.	2
	Rhizoctone commun	Rhizoctonia sp.	1
Melon (Melon)	Tache alternarienne	Alternaria sp.	6
	Gale	Cladosporium sp.	1
	Flétrissement bactérien	Erwinia tracheiphila	1
	Fusariose	Fusarium sp.	2
	Tache plectosporienne	Plectosporium sp.	2
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
	Tache angulaire	Pseudomonas syringae	2
	Mildiou	Pseudoperonospora sp.	6
	Pourriture pythienne	Pythium sp.	2
	Tache	Sphingomonas sp.	1
	Tache bactérienne	Xanthomonas sp.	1
Melon d’eau/Pastèque (Watermelon)	Tache alternarienne	Alternaria sp.	1
	Fusariose	Fusarium sp.	2
	Tache	Phoma sp.	1
	Tache plectosporienne	Plectosporium sp.	1
	Potyvirus	Potyvirus (groupe des Potyvirus)	2
	Milidou	Pseudoperonospora sp.	2
	Pourriture pythienne	Pythium sp.	3
Oignon (Onion)	Tache pourpre	Alternaria sp.	4
	Pourriture du col	Botrytis aclada	1
	Pourriture du bulbe	Enterobacter cloacae	4
	Fusariose	Fusarium sp.	6
	Pourriture	Geotrichum sp.	1
	Pourriture	Pantoea ananatis	1
	Mildiou	Peronospora destructor	1
	Mildiou	Peronospora sp.	1
	Brûlure stemphylienne	Stemphylium sp.	1
Oignon vert (Green onion)	Moisissure grise	Botrytis cinerea	1
	Pourriture de l’oignon	Botrytis squamosa	1
Panais (Parsnip)	Tache cercosporéenne	Cercospora sp.	1
Patate douce (Sweet potato)	Alternariose	Alternaria sp.	1
Piment (piment fort) (Chili pepper)	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	1
	Anomalie de coloration	Conductivité électrique faible	1
	Pourriture fusarienne	Fusarium sp.	1
	Virus de la marbrure bénigne du piment	PMMoV (Pepper mild mottle virus)	1
Poireau (Leek)	Tache pourpre	Alternaria sp.	1
	Tache stemphylienne	Stemphylium sp.	2
Poivron (piment doux) (Sweet pepper)	Alternariose	Alternaria sp.	3
	Virus de la mosaïque de la luzerne	AMV (Alfalfa mosaic virus)	1
	Moisissure grise	Botrytis cinerea	1
	Pourriture	Cladosporium sp.	2
	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	2
	Fusariose	Fusarium sp.	3
	Malformation	Intumescence (Œdème)	2
	Dépérissement phytophthoréen	Phytophthora capsici	1
	Tache plectosporienne	Plectosporium sp.	1
	Virus de la marbrure bénigne du piment	PMMoV (Pepper mild mottle virus)	1
	Pourriture pythienne	Pythium sp.	1
	Virus de la maladie bronzée de la tomate	TSWV (Tomato spotted wilt virus)	1
Pomme de terre (Potato)	Alternariose	Alternaria alternata	1
	Brûlure hâtive	Alternaria solani	4
	Brûlure hâtive	Alternaria sp.	14
	Virus de la mosaïque de la luzerne	AMV (Alfalfa mosaic virus)	4
	Moisissure grise	Botrytis sp.	3
	Tache	Carence en manganèse	1
	Anomalie de coloration	Cœur noir	1
	Dartrose	Colletotrichum coccodes	17
	Dartrose	Colletotrichum sp.	13
	Pourriture molle bactérienne	Dickeya spp.	2
	Pourriture fusarienne	Fusarium sp.	24
	Mauvaise levée	Gel	1
	Pourriture caoutchouc	Geotrichum candidum	1
	Pourriture caoutchouc	Geotrichum sp.	19
	Tache argentée	Helminthosporium sp.	1
	Tache	Intumescence (Œdème)	1
	Tache	Lenticelles élargies	1
	Périderme gercé	Peau d’éléphant	1
	Pourriture molle/jambe noire	Pectobacterium atrosepticum	10
	Pourriture molle/jambe noire	Pectobacterium brasiliense	10
	Pourriture molle/jambe noire	Pectobacterium carotovorum	20
	Pourriture molle/jambe noire	Pectobacterium parmentieri (syn. P. wasabiae)	21
	Pourriture molle/jambe noire	Pectobacterium sp.	6
	Pourriture molle/jambe noire	Pectobacterium versatile	2
	Pourriture rose	Phytophthora erythroseptica	5
	Mildiou	Phytophthora infestans	47
	Mildiou	Phytophthora sp.	1
	Phytoplasme	Phytoplasme	1
	Pourriture	Plectosporium sp.	1
	Virus Y de la pomme de terre	PVY (Potato virus Y)	13
	Pourriture aqueuse	Pythium sp.	12
	Rhizoctone commun	Rhizoctonia sp.	4
	Gale commune	Streptomyces sp.	2
	Verticilliose	Verticillium dahliae	3
	Anomalie de coloration	Vitrescence	1
Rabiole / Navet blanc (White turnip)	Rouille blanche	Albugo candida	1
	Hernie des crucifères	Plasmodiophora brassicae	1
Radis (Radish)	Malformation	Fente de croissance	1
	Fusariose	Fusarium sp.	2
	Hernie des crucifères	Plasmodiophora brassicae	1
Rhubarbe (Rhubarb)	Pourriture racinaire	Fusarium sp.	1
	Pourriture racinaire	Pythium sp.	1
Rutabaga (Turnip)	Rhizoctone commun	Rhizoctonia sp.	1
Tatsoi (Tak choy)	Tache alternarienne	Alternaria brassicae	3
	Tache noire	Alternaria brassicicola	3
Tomate (Tomato)	Chancre sec	Acremonium sp.	8
	Alternariose	Alternaria solani	2
	Alternariose	Alternaria sp.	6
	Virus de la mosaïque de la luzerne	AMV (Alfalfa mosaic virus)	23
	Anomalie de coloration	Argenture	1
	Moisissure grise	Botrytis sp.	2
	Tache	Carence en bore	1
	Désordre génétique	Chimère	2
	Moisissure olive	Cladosporium sp.	12
	Chancre bactérien	Clavibacter michiganensis subsp. michiganensis (Cmm)	15
	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	2
	Anthracnose	Colletotrichum sp.	3
	Brûlure	Conductivité électrique élevée	1
	Anomalie de coloration	Conductivité électrique faible	1
	Tache	Diaporthe longicolla	1
	Pourriture molle	Dickeya dianthicola	1
	Blanc	Erysiphe neolycopersici	2
	Blanc (Oïdium)	Euoidium longipes	2
	Fusariose	Fusarium oxysporum	11
	Fusariose	Fusarium sp.	54
	Fusariose	Fusarium verticillioides	1
	Pourriture caoutchouc	Geotrichum sp.	1
	Anomalie de coloration	Intumescence (Œdème)	3
	Nodosité des racines	Meloidogyne sp.	3
	Blanc (Oïdium)	Oidium sp.	1
	Moisissure olive	Passalora fulva	2
	Virus de la mosaïque du pépino	PepMV (Pepino mosaic virus)	8
	Pourriture des racines et du collet	Phytophthora capsici	2
	Mildiou	Phytophthora infestans	28
	Pourriture	Phytophthora nicotiana	1
	Anomalie de coloration	Phytotoxicité à un pesticide	1
	Chancre sec	Plectosporium sp.	28
	Potyvirus	Potyvirus (groupe des Potyvirus)	3
	Moelle noire	Pseudomonas corrugata	2
	Moucheture bactérienne	Pseudomonas syringae	3
	Moucheture bactérienne	Pseudomonas syringae résistant au cuivre	4
	Pourriture pythienne	Pythium sp.	4
	Rhizoctone commun	Rhizoctonia sp.	1
	Tache septorienne	Septoria sp.	3
	Virus des taches chlorotiques de la tomate	TCSV (Tomato chlorotic spot virus)	1
	Virus de la gravure du tabac	TEV (Tobacco etch virus)	3
	Virus de la mosaïque du tabac	TMV (Tobacco mosaic virus)	8
	Virus du fruit brun rugueux de la tomate	ToBRFV (Tomato brown rugose fruit virus)	22
	Anomalie de coloration	Toxicité en manganèse	1
	Virus de la maladie bronzée de la tomate	TSWV (Tomato spotted wilt virus)	1
	Verticilliose	Verticillium dahliae	2
	Tache bactérienne	Xanthomonas arboricola	1
	Tache bactérienne	Xanthomonas campestris	1
	Tache bactérienne	Xanthomonas hortorum pv. gardneri	1
	Tache bactérienne	Xanthomonas sp. résistant au cuivre	1
	Tache bactérienne	Xanthomonas sp. sensible au cuivre	1
	Chancre sec	Acremonium sp.	1
Tomate cerise (Cherry tomato)	Alternariose	Alternaria sp.	1
	Moisissure grise	Botrytis sp.	1
	Moissure olive	Cladosporium sp.	1
	Chancre bactérien	Clavibacter michiganensis subsp. michiganensis (Cmm)	2
	Anthracnose	Colletotrichum sp.	2
	Fusariose	Fusarium sp.	17
	Anomalie de coloration	Intumescence (Œdème)	1
	Blanc	Oidium sp.	2
	Moissure olive	Passalora fulva	1
	Mildiou	Phytophthora infestans	1
	Chancre sec	Plectosporium sp.	9
	Blanc (Oïdium)	Pseudoidium neolycopersici	1
	Pourriture pythienne	Pythium sp.	2
	Pourriture sclérotique	Sclerotinia sp.	1
	Virus du fruit brun rugueux de la tomate	ToBRFV (Tomato brown rugose fruit virus)	1

Tableau 2. Sommaire des maladies diagnostiquées parmi les arbres fruitiers et petits fruits reçus au Laboratoire d’expertise et de diagnostic en phytoprotection du MAPAQ en 2023.

Culture	Maladie/symptôme	Agent pathogène/cause	Nombre
Airelle rouge (Lingonberry)	Pourriture noire	Allantophomopsis cytisporea	1
	Pourriture noire	Allantophomopsis sp.	1
	Anthracnose	Colletotrichum sp.	1
	Dépérissement	Conductivité électrique faible	1
	Anomalie de coloration	pH bas	1
	Malformation	Phoma sp.	1
	Brûlure phomopsienne	Phomopsis sp.	1
	Tache phyllostictéenne	Phyllosticta sp.	4
	Malformation	Phytoplasme	3
	Rouille	Pucciniastrum sp.	3
Airelle sauvage (Wild lingonberry)	Pourriture noire des fruits	Allantophomopsis sp.	1
	Tache noire	Ramularia sp.	1
	Rhizoctone commune	Rhizoctonia sp.	1
Airelle vigne-d’Ida	Pourriture des baies	Coleophoma empetri	1
	Pourriture hâtive des baies	Phyllosticta vaccinii	1
Amélanchier (Serviceberry)	Chancre	Cytospora sp.	1
	Pourriture des racines et du collet	Phytophthora cactorum	1
Argousier (Sea buckthorn)	Chancre	Basidiomycète	1
	Pourriture de fruits	Colletotrichum fioriniae	2
	Anthracnose	Colletotrichum sp.	7
	Chancre	Diaporthe cotoneastri	1
	Brûlure phomopsienne	Phomopsis sp.	3
Bleuetier en corymbe (Highbush blueberry)	Tumeur du collet	Agrobacterium sp.	1
	Pourriture du fruit	Aureobasidium sp.	1
	Virus du choc du bleuet	BlShV (Blueberry shock virus)	4
	Moisissure grise	Botrytis sp.	3
	Anthracnose	Colletotrichum sp.	5
	Dépérissement	Conductivité électrique élevée	2
	Chancre	Cytospora sp.	2
	Fusariose	Fusarium sp.	2
	Chancre	Fusicoccum sp.	1
	Dépérissement	pH bas	2
	Dépérissement	pH élevé	2
	Chancre phomopsien	Phomopsis sp.	2
	Malformation	Phytotoxicité - Glyphosate	2
	Brûlure	Phytotoxicité à un insecticide	1
	Rouille	Pucciniastrum sp.	3
	Dépérissement	Seimatosporium sp.	2
	Tache septorienne	Septoria sp.	1
	Virus de la tache annulaire de la tomate	ToRSV (Tomato ringspot nepovirus)	1
Bleuetier nain (Dwarf blueberry)	Moisissure grise	Botrytis sp.	1
	Chancre à fusicoccum	Fusicoccum sp.	1
	Tache septorienne	Septoria sp.	2
Camarine noire (Black crowberry)	Pourridié phytophthoréen	Phytophthora sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Camérisier (Haskap)	Anthracnose	Colletotrichum fioriniae	1
	Pourriture	Cylindrocarpon sp.	1
	Chancre	Diaporthe eres	1
	Blanc (Oïdium)	Erysiphe lonicerae	1
	Pourriture fusarienne	Fusarium sp.	4
	Nématode phytopathogène	Paratylenchus sp.	1
	Chancre	Pestalotiopsis sp.	1
	Dépérissement	pH bas	1
	Tache foliaire	Phoma sp.	2
	Brûlure phomopsienne	Phomopsis sp.	2
	Faible développement	Phytoplasme	1
	Anomalie de coloration	Phytotoxicité à un herbicide	1
	Anomalie de coloration	Polluant gazeux - ozone	1
	Nématode des lésions racinaires	Pratylenchus sp.	1
	Pourriture des racines	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Canneberge/Atoca (Cranberry)	Anomalie de coloration	Carence minérale	2
	Pourriture des baies	Coleophoma empetri	1
	Anthracnose	Colletotrichum acutatum	1
	Pourriture fusarienne	Fusarium sp.	1
	Avortement des fruits	Pollinisation inadéquate	1
	Pourriture des racines	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Cassissier (Black currant)	Anthracnose	Colletotrichum sp.	2
	Rouille vésiculeuse du pin blanc	Cronartium sp.	2
	Tache septorienne	Septoria ribis	1
	Tache septorienne	Septoria sp.	2
Cerise de terre (Ground cherry)	Alternariose	Alternaria sp.	1
	Cercosporiose	Cercospora sp.	1
	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	3
	Virus de la tache nécrotique de l’impatiente	INSV (Impatiens necrotic spot virus)	1
	Malformation	Intumescence (Œdème)	1
	Virus de la mosaïque du pépino	PepMV (Pepino mosaic virus)	1
	Moucheture bactérienne	Pseudomonas syringae	1
	Virus Y de la pomme de terre	PVY (Potato virus Y)	1
	Pourriture pyhtienne	Pythium sp.	1
Cerisier (Cherry)	Alternariose	Alternaria sp.	1
	Nodule noir	Apiosporina morbosa	1
	Tache foliaire	Blumeriella sp.	2
	Fusariose	Fusarium sp.	1
Cerisier nain (Sand cherry)	Tache foliaire	Aureobasidium pullulans	1
	Dépérissement	Cadophora sp.	1
	Carie blanche spongieuse	Irpex lacteus	1
Chicoutai (Chicouté) (Cloudberry)	Moisissure grise	Botrytis sp.	1
	Chancre	Fusicoccum sp.	2
	Tache bactérienne	Pseudomonas marginalis	1
	Tache foliaire	Pseudomonas viridiflava	1
	Blanc	Oidium sp.	1
Fraisier cultivé (Strawberry)	Nématode foliaire	Aphelenchoides sp.	3
	Moisissure grise	Botrytis cinerea	3
	Moisissure grise	Botrytis sp.	16
	Dépérissement à cadophora	Cadophora sp.	5
	Anomalie de coloration	Carence en potassium	1
	Pourriture racinaire	Chaetomium sp.	3
	Anomalie de coloration	Chimère	1
	Tache	Cladosporium sp.	1
	Anthracnose	Colletotrichum sp.	9
	Dépérissement	Conductivité électrique faible	5
	Dépérissement	Gel	3
	Tache foliaire / Anomalie de coloration	Hainesia sp.	1
	Tache pourpre	Marssonina sp.	2
	Dépérissement neopestalotiopsien	Neopestalotiopsis spp.	6
	Faible croissance	pH bas	6
	Brûlure	Phomopsis obscurans	1
	Brûlure	Phomopsis sp.	3
	Malformation	Phyllodie non parasitaire	1
	Pourriture du collet et des racines	Phytophthora cactorum	41
	Stèle rouge	Phytophthora fragariae	11
	Pourriture du collet et des racines	Phytophthora sp.	2
	Malformation	Phytoplasme	1
	Brûlure	Phytotoxicité - Glufosinate d’ammonium	1
	Blanc (Oïdium)	Podosphaera aphanis	3
	Blanc (Oïdium)	Podosphaera sp.	1
	Pourriture des racines	Pourriture noire des racines^a	107
	Nématode des lésions racinaires	Pratylenchus sp.	7
	Tache commune	Ramularia sp.	2
	Virus de la frisolée du friaisier	SCrV (Strawberry crinkle virus)	23
	Virus de la marbrure du fraisier	SMoV (Strawberry mottle virus)	87
	Virus du bord chlorotique du fraisier	SMYEV (Strawberry mild yellow edge virus)	93
	Virus de la pallidose du fraisier	SPaV (Strawberry pallidosis virus)	1
	Virus du liséré des nervures du fraisier	SVBV (Strawberry vein banding virus)	6
	Pourriture noire des racines	Thielaviopsis sp.	1
	Nématode	Tylenchus sp.	1
	Verticilliose	Verticillium dahliae	16
	Verticilliose	Verticillium sp.	2
	Tache bactérienne	Xanthomonas fragariae	5
	Nématode à dague	Xiphinema sp.	1
	Tache foliaire	Zythia sp.	10
Framboisier (Raspberry)	Tumeur du collet	Agrobacterium sp.	8
	Pourridié-agaric	Armillaria sp.	1
	Moisissure grise	Botrytis sp.	16
	Pourriture des fruits	Cladosporium cladosporioides	8
	Pourriture des fruits	Cladosporium pseudocladosporioides	3
	Pourriture des fruits	Cladosporium sp.	9
	Pourriture des fruits	Colletotrichum godetiae	1
	Pourriture des fruits	Colletotrichum sp.	2
	Pourriture	Cylindrocarpon sp.	2
	Brûlure bactérienne	Erwinia amylovora	1
	Fusariose	Fusarium sp.	10
	Nématode phytopathogène	Helicotylenchus sp.	2
	Mildiou	Peronospora sp.	1
	Pourridié phytophthoréen	Phytophthora rubi	6
	Pourridié phytophthoréen	Phytophthora sp.	2
	Anomalie de coloration	Phytotoxicité - Glyphosate	1
	Pourriture noire des racines	Complexe d’organismes^a	4
	Nématode des lésions racinaires	Pratylenchus sp.	5
	Virus du rabougrissement buissonnant du framboisier	RBDV (Raspberry bushy dwarf virus)	2
	Rhizoctone commun	Rhizoctonia sp.	1
	Virus des taches annulaires de la tomate	ToRSV (Tomato ringspot nepovirus)	1
	Nématode à dague	Xiphinema sp.	2
Framboisier noir / Ronce occidentale (Black raspberry)	Fusariose	Fusarium sp.	1
	Pourridié phytophthoréen	Phytophthora rubi	1
	Moisissure grise	Botrytis sp.	1
	Blanc	Podosphaera aphanis	1
Framboisier rouge (Red raspberry)	Tumeur du collet	Agrobacterium sp.	1
	Moisissure grise	Botrytis sp.	1
	Anthracnose	Colletotrichum sp.	1
	Brûlure bactérienne	Erwinia amylovora	1
	Pourridié phytophthoréen	Phytophthora rubi	1
	Pourriture noire des racines	Pourriture noire des racines^a	4
	Dépérissement à Ascospora	Seimatosporium lichenicola	1
	Tache septorienne	Septoria sp.	1
Goji (Goji berry)	Anthracnose	Colletotrichum sp.	1
Groseillier (Gooseberry)	Anthracnose	Colletotrichum sp.	1
Kiwi	Tache	Moucheture noire	1
	Tache de suie	Schizothyrium sp.	1
Mûrier (Mulberry)	Moisissure grise	Botrytis sp.	1
	Mildiou	Peronospora sp.	2
Noyer (Walnut)	Chancre	Diplodia sp.	1
Poirier (Pear tree)	Anthracnose	Colletotrichum sp.	1
	Chancre	Cytospora sp.	1
	Brûlure bactérienne	Erwinia amylovora	1
	Chancre	Phomopsis sp.	1
Pommier (Apple tree)	Alternariose	Alternaria sp.	9
	Virus de la mosaïque du pommier	ApMV (Apple mosaic virus)	1
	Moisissure grise	Botrytis sp.	1
	Malformation	Carence en bore	1
	Pourriture	Cladosporium sp.	2
	Pourriture amère	Colletotrichum salicis	1
	Pourriture amère	Colletotrichum sp.	2
	Chancre	Cytospora sp.	1
	Chancre	Diaporthe eres	3
	Chute des feuilles	Diplocarpon coronariae	3
	Pourriture noire	Diplodia seriata	1
	Chancre	Diplodia sp.	2
	Brûlure bactérienne	Erwinia amylovora	2
	Brûlure bactérienne	Erwinia sp.	1
	Dépérissement	Fusarium solani	1
	Dépérissement	Fusarium sp.	1
	Chancre	Gel	3
	Rouille du genévrier	Gymnosporangium sp.	3
	Nématode spiralé	Helicotylenchus sp.	1
	Tache	Lenticelles élargies	3
	Chancre	Neofabraea alba	1
	Chancre	Phomopsis sp.	2
	Pourriture du collet	Phytophthora cactorum	1
	Blanc (Oïdium)	Podosphaera leucotricha	1
	Nématode des lésions racinaires	Pratylenchus sp.	1
	Coulure bactérienne	Pseudomonas syringae	1
	Rhizoctone commun	Rhizoctonia sp.	1
	Anomalie de coloration	Tache amère	1
	Tavelure	Venturia inaequalis	9
	Tavelure	Venturia sp.	4
Prunier (Plum tree)	Moniliose	Monilia sp.	1
	Maladie des pochettes	Taphrina sp.	1
Sureau (Elderberry)	Virus de l’enroulement des feuilles du cerisier	CLRV-e (Cherry leaf roll virus-elderberry)	1
	Fusariose	Fusarium sp.	4
	Chancre européen	Neonectria ditissima	1
	Pourriture des tiges	Pectobacterium polaris	1
	Pourriture des tiges	Pectobacterium sp.	3
	Pourriture des tiges	Pectobacterium versatile	1
	Malformation	Phytoplasme	1
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
	Pourriture molle	Pseudomonas fluorescens	1
	Tache bactérienne	Xanthomonas sp.	1
Sureau noir / Grand sureau (Black elderberry)	Pourriture molle bactérienne	Pectobacterium sp.	1
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
Vigne (Grape)	Alternariose	Alternaria sp.	1
	Pourridié-agaric	Armillaria sp.	1
	Brunissement de la rafle	Aureobasidium sp.	3
	Dépérissements à botryosphaeria	Botryosphaeria dothidea	1
	Moisissure grise	Botrytis cinerea	9
	Moisissure grise	Botrytis sp.	7
	Dépérissement à cadophora	Cadophora luteo-olivacea	1
	Dépérissement à cadophora	Cadophora sp.	3
	Anomalie de coloration	Carence en fer	1
	Pourriture des baies	Cladosporium sp.	1
	Pourriture	Colletotrichum fioriniae	1
	Pourriture	Colletotrichum sp.	8
	Pourriture blanche	Coniella vitis	1
	Pied noir	Cylindrocarpon sp.	8
	Dépérissement à botryosphaeria	Diplodia seriata	2
	Anthracnose	Elsinoe ampelina	1
	Eutypiose	Eutypa lata	1
	Fusariose	Fusarium oxysporum	2
	Virus de la marbrure de la vigne	GFkV (Grapevine fleck virus)	3
	Virus de l’enroulement	GLRaV-1 et 3 (Grapevine leafroll-associated virus-1 et 3)	12
	Virus du pinot gris de la vigne	GPGV (Grapevine Pinot gris virus)	1
	Pied noir	Ilyonectria macrodidyma	1
	Pourriture acide	Levure	2
	Dépérissement	Microsphaeropsis sp.	1
	Dépérissement	Pestalotiopsis sp.	2
	Esca / Maladie de Pétri	Phaeoacremonium aleophilum	4
	Esca / Maladie de Pétri	Phaeomoniella sp.	1
	Esca / Maladie de Pétri	Phialophora sp.	1
	Tache	Phoma glomerata	1
	Tache foliaire	Phoma sp.	8
	Excoriose	Phomopsis sp.	5
	Excoriose	Phomopsis viticola (Diaporthe ampelina)	2
	Pourriture noire	Phyllosticta sp.	1
	Dépérissement	Pied noir	2
	Mildiou	Plasmopara sp.	2
	Mildiou	Plasmopara viticola aestivalis	9
	Mildiou	Plasmopara viticola riparia	1
	Rhizoctone commun	Rhizoctonia sp.	2
	Pourriture noire	Stagonosporopsis sp.	1
	Virus de la tache annulaire de la tomate	ToRSV (Tomato ringspot nepovirus)	5
	Blanc (Oïdium)	Uncinula necator	1
	Nématode à dague	Xiphinema sp.	3

^aCausée par un complexe formé de plusieurs de ces organismes : Pythium sp., Fusarium sp., Rhizoctonia sp., Cylindrocarpon sp. 

Tableau 3. Sommaire des maladies diagnostiquées parmi les grandes cultures/céréales et cultures industrielles reçues au Laboratoire d’expertise et de diagnostic en phytoprotection du MAPAQ en 2023.

Culture	Maladie/symptôme	Agent pathogène/cause	Nombre
Avoine (Oat)	Fusariose	Fusarium sp.	1
	Septoriose	Parastagonospora nodorum	1
	Nématode des lésions racinaires	Pratylenchus sp.	1
	Rouille	Puccinia sp.	2
	Tache foliaire	Pyrenophora tritici-repentis	1
	Fonte des semis / piétin brun	Pythium sp.	1
	Nématode à dague	Xiphinema sp.	1
Blé (Wheat)	Fumagine	Alternaria sp.	1
	Tache helminthosporienne	Bipolaris sp.	1
	Blanc (Oïdium)	Blumeria sp.	1
	Fumagine	Cladosporium sp.	1
	Fusariose	Fusarium sp.	1
	Moisissure nivéale	Microdochium sp.	1
	Anomalie de coloration	Moucheture physiologique	1
	Rouille	Puccinia sp.	1
	Tache bronzée	Pyrenophora tritici-repentis	1
	Pourriture pythienne	Pythium sp.	1
Brome	Anomalie de coloration	Carence en phosphore	2
	Anomalie de coloration	Froid	1
	Brûlure	Gel	1
Canola/Colza	Tache alternarienne	Alternaria brassicae	1
	Fusariose	Fusarium sp.	2
	Mildiou	Peronospora parasitica	1
	Hernie des crucifères	Plasmodiophora sp.	1
	Pourriture	Plectosphaerella sp.	1
	Pourriture pythienne	Pythium sp.	2
Houblon (Hops)	Alternariose	Alternaria alternata	1
	Alternariose	Alternaria sp.	4
	Fumagine	Cladosporium sp.	1
	Dépérissement phomopsien	Diaporthe humulicola	1
	Fusariose	Fusarium sp.	1
	Mildiou	Pseudoperonospora sp.	3
Maïs fourrager (Fodder corn)	Fusariose	Fusarium sp.	1
	Anthracnose	Colletotrichum sp.	1
Maïs grain (Corn)	Anomalie de coloration	Carence en phosphore	1
	Faible croissance	Compaction du sol	1
	Fusariose	Fusarium sp.	4
	Faible croissance	pH bas	1
	Pourriture pythienne	Pythium sp.	3
Moutarde blanche (White mustard)	Fusariose	Fusarium sp.	1
	Pourriture pythienne	Pythium sp.	1
Orge (Barley)	Tache helminthosporienne	Bipolaris sp.	2
	Fusariose	Fusarium sp.	1
	Pourriture pythienne	Pythium sp.	1
Seigle d’automne (Fall rye)	Rouille	Puccinia sp.	1
Soya (Soy)	Alternariose/Fumagine	Alternaria sp.	2
	Nématode	Boleodorus sp.	1
	Fumagine	Cladosporium sp.	1
	Anthracnose	Colletotrichum sp.	17
	Tache concentrique	Corynespora sp.	4
	Anomalie de coloration	Désordre physiologique	1
	Fusariose	Fusarium equiseti	2
	Fusariose	Fusarium sp.	21
	Mort subite	Fusarium virguliforme	29
	Nématode à kyste du soya	Heterodera glycines	4
	Brûlure phomopsienne	Phomopsis sp.	9
	Pourridié phytophthoréen	Phytophthora sansomeana	5
	Pourridié phytophthoréen	Phytophthora sojae	17
	Pourridié pythien	Pythium sp.	17
	Rhizoctone commun	Rhizoctonia sp.	9
	Pourriture sclérotique	Sclerotinia sclerotiorum	1
	Pourriture sclérotique	Sclerotinia sp.	1
	Tache septorienne	Septoria sp.	3

Tableau 4. Sommaire des maladies diagnostiquées parmi les plantes fourragères reçues au Laboratoire d’expertise et de diagnostic en phytoprotection du MAPAQ en 2023.

Culture	Maladie/symptôme	Agent pathogène/cause	Nombre
Fléole des prés (Timothy)	Anomalie de coloration	Carence en phosphore	1
	Fumagine	Cladosporium sp.	1
	Tache septorienne	Parastagonospora nodorum	1
Luzerne (Alfalfa)	Virus de la mosaïque de la luzerne	AMV (Alfalfa mosaic virus)	1
	Tache poivrée	Leptosphaerulina sp.	4
	Tache foliaire	Phoma sp.	1
Pâturin annuel (Annual bluegrass)	Brûlure de la feuille estivale	Curvularia coatesiae	1
	Moisissure nivéale	Microdochium bolleyi	1
	Moisissure nivéale	Microdochium sp.	2
	Pourriture pythienne	Pythium sp.	1
	Pourriture pythienne	Pythium torulosum	2
Trèfle (Clover)	Anthracnose	Colletotrichum sp.	1
	Tache foliaire	Phoma sp.	1
	Nématode des lésions racinaires	Pratylenchus sp.	1

Tableau 5. Sommaire des maladies diagnostiquées parmi les arbres et arbustes ornementaux ou d’utilisation industrielle reçues au Laboratoire d’expertise et de diagnostic en phytoprotection du MAPAQ en 2023.

Culture	Maladie/symptôme	Agent pathogène/cause	Nombre
Cerisier à grappe de Virginie (Chokecherry)	Maladie des pochettes	Taphrina sp.	1
Chêne rouge / Chêne boréal (Red oak)	Chancre	Diplodia corticola	1
Cotonéastre (Cotoneaster)	Tache bactérienne	Pseudomonas syringae	1
Épinette (Spruce)	Pourriture des racines	Cylindrocarpon sp.	1
	Pourriture des racines	Ilyonectria estremocensis	1
Épinette blanche (White spruce)	Pourriture des racines	Cylindrocarpon sp.	1
	Brûlure des rameaux	Diplodia sapinea	1
	Pourriture des racines	Fusarium sp.	1
	Pourriture des racines	Ilyonectria cyclaminicola	1
	Pourriture des racines	Phytophthora abietivora	1
Épinette noire (Black spruce)	Moisissure grise	Botrytis cinerea	1
	Moisissure grise	Botrytis sp.	2
	Dépérissement à cadophora	Cadophora sp.	1
	Pourriture des racines	Cylindrocarpon sp.	2
	Chancre cytosporéen	Cytospora sophorae	1
	Brûlure des rameaux	Diplodia sapinea	1
	Fusariose	Fusarium foetens	2
	Pourriture des racines	Ilyonectria destructans	1
	Brûlures à phoma	Phoma herbarum	3
	Brûlures à phoma	Phoma sp.	3
	Brûlures à phoma	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Érable (Maple)	Tache foliaire	Grovesinia moricola	1
Érable de l’Amur (Amur maple)	Verticilliose	Verticillium dahliae	1
Érable de Norvège / Érable platane (Norway maple)	Chancre	Diplodia sp.	1
	Structures fongiques	Massaria sp.	1
Noisetier (Hazel)	Brûlure orientale du noisetier	Anisogramma anomala	1
	Fusariose	Fusarium sp.	1
	Tache bactérienne	Xanthomonas arboricola	2
Pin (Pine)	Pourriture des racines	Cylindrocarpon sp.	2
	Pourriture des racines	Fusarium solani	1
	Pourriture des racines	Fusarium sp.	1
	Pourriture du collet et des racines	Phytophthora cactorum	1
	Pourriture des racines	Pythium sp.	1
Pin gris (Jack pine)	Brûlures à phoma	Phoma herbarum	1
Pin rouge (Red pine)	Pourriture racinaire	Fusarium sp.	1
	Brûlures à phoma	Phoma herbarum	1
	Pourriture du collet et des racines	Phytophthora cactorum	1
	Pourriture pythienne	Pythium sp.	1
Sapin (Fir)	Pourridié-agaric (Armillaire)	Armillaria solidipes	1
	Pourriture racinaire	Cylindrocarpon sp.	8
	Pourriture racinaire	Fusarium sp.	10
	Chancre à fusicoccum	Fusicoccum sp.	1
	Pourriture des racines	Ilyonectria estremocensis	1
	Dépérissement	pH bas	1
	Brûlures à phoma	Phoma sp.	1
	Pourriture des racines	Phytophthora abietivora	48
	Pourriture racinaire	Pythium sp.	5
	Rouge des aiguilles	Rhizosphaera sp.	1
Sapin baumier (Balsam fir)	Pourriture racinaire	Cylindrocarpon sp.	3
	Tache foliaire	Didymella sp.	1
	Pourriture racinaire	Fusarium sp.	4
	Dépérissement	Gel	1
	Pourriture racinaire	Ilyonectria robusta	1
	Brûlure à phoma	Phoma sp.	1
	Pourriture des racines	Phytophthora abietivora	5
	Pourriture racinaire	Phytophthora sansomeana	1
	Pourriture racinaire	Phytophthora sp.	1
	Pourriture racinaire	Pythium sp.	3
	Rouge des aiguilles	Rhizosphaera sp.	2
Sapin de Fraser (Fraser fir)	Pourriture des racines	Cylindrocarpon sp.	1
	Chancre	Diaporthe eres	1
	Pourriture racinaire	Fusarium sp.	1
	Chancre scléroderrien	Gremmeniella abietina	1
	Chancre nectrien	Nectria balsamea	1
	Pourriture des racines	Phytophthora abietivora	3
	Pourriture racinaire	Pythium sp.	1
Saule (Willow)	Tumeur du collet	Agrobacterium sp.	1
	Chancre	Cytospora chrysosperma	1
	Rouille du saule et des conifères	Melampsora epitea	1
Thuya / Cèdre (Cedar)	Brûlure des aiguilles	Pestalotiopsis funerara	1
	Brûlure des aiguilles	Pestalotiopsis sp.	2
	Brûlures à phoma	Phoma sp.	1
Troène (Privet)	Anthracnose	Colletotrichum sp.	1

Tableau 6. Sommaire des maladies diagnostiquées parmi les plantes herbacées ornementales reçues au Laboratoire d’expertise et de diagnostic en phytoprotection du MAPAQ en 2023.

Culture	Maladie/symptôme	Agent pathogène/cause	Nombre
Agrostemma (Corn-cockle)	Virus de la mosaïque de l’alternanthera / Virus de la mosaïque de la papaye	AltMV/PapMV (Alternanthera mosaic virus/Papaya mosaic virus)	1
	Virus de la marbrure de l’œillet	CarMV (Carnation mottle virus)	1
Agrostide (Turf)	Brûlure	Bipolaris sp.	1
	Pourridié pythien	Pythium sp.	1
Anemanthele (Stipa)	Tache helminthosporienne	Cochliobolus sativus	1
Anémone (Anemone / Windflower)	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	1
	Virus du rabougrissement buissonnant de la tomate	TBSV (Tomato bushy stunt virus)	1
Bacopa	Moisissure grise	Botrytis sp.	1
	Dépérissement aérien	Gibbellulopsis sp.	1
	Rouille	Melampsora epitea	1
Calibrachoa	Fusariose	Fusarium sp.	2
	Pourridié pythien	Pythium sp.	1
	Pourriture des racines	Thielaviopsis sp.	4
Canna	Tache foliaire	Acidovorax avenae	1
	Pourriture	Plectosporium sp.	1
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
Centaurée bleuet (Cornflower)	Fusariose	Fusarium sp.	1
Cosmos	Sclérotiniose	Sclerotinia sp.	1
Cyclamen	Moisissure grise	Botrytis sp.	1
	Virus de la maladie bronzée de la tomate	TSWV (Tomato spotted wilt virus)	1
Dahlia	Virus de la mosaïque du dahlia / Virus commun de la mosaïque du dahlia	DMV/DCMV (Dahlia mosaic virus/Dahlia common mosaic virus)	14
	Potyvirus	Potyvirus (groupe des Potyvirus)	1
	Virus de la maladie bronzée de la tomate	TSWV (Tomato spotted wilt virus)	1
Écheveria (Echeveria)	Fusariose	Fusarium sp.	1
Échinacée (Coneflower)	Désordre génétique	Chimère	1
	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	1
	Virus de la maladie bronzée de la tomate	TBSV (Tomato bushy stunt virus)	2
Eucalyptus	Moisissure grise	Botrytis sp.	1
	Tache foliaire	Fumagine	1
	Tache foliaire	Phoma sp.	1
	Sclérotiniose	Sclerotinia sp.	2
Fusain (Euonymus)	Anthracnose	Colletotrichum sp.	1
Gazon (Turf)	Curvulariose	Curvularia sp.	1
	Fusariose	Fusarium sp.	1
	Moisissure nivéale	Microdochium bolleyi	1
	Moisissure nivéale	Microdochium sp.	3
	Rouille	Puccinia sp.	3
	Pourriture pythienne	Pythium sp.	4
	Pourriture pythienne	Pythium torulosum	1
	Rhizoctone commun	Rhizoctonia sp.	1
Géranium / Pelargonium (Florist’s Geranium)	Rhizoctone commun	Rhizoctonia sp.	1
	Fusariose	Fusarium sp.	1
	Pourriture pythienne	Pythium sp.	1
	Pourriture bactérienne	Xanthomonas hortorum pv. pelargonii	1
Giroflée (Wallflower)	Fusariose	Fusarium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Hémérocalle / Lis d’un jour (Daylily)	Fumagine	Aspergillus sp.	1
	Tache foliaire	Aureobasidium sp.	1
Hibiscus	Fumagine	Cladosporium sp.	1
	Virus de la tache nécrotique de l’impatiente	INSV (Impatiens necrotic spot virus)	1
	Brûlure bactérienne	Pseudomonas syringae	1
Hosta	Tache foliaire	Curtobacterium flaccumfaciens	1
Hoya	Virus en bandes du tabac	TSV (Tobacco streak virus)	1
	Virus de la maladie bronzée de la tomate	TSWV (Tomato spotted wilt virus)	2
Hydrangée / Hortensia / Quatre-saisons (Bigleaf hydrangea)	Virus de la mosaïque de la luzerne	AMV (Alfalfa mosaic virus)	1
	Anthracnose	Colletotrichum sp.	1
	Malformation	Phytotoxicité - 2,4-D	1
	Malformation / Anomalie de coloration	Phytotoxicité - Glyphosate	1
Hydrangée annabelle (Smooth hydrangea)	Tache foliaire	Xanthomonas sp.	1
Hydrangée paniculé (Limelight hydrangea)	Brûlure bactérienne	Pseudomonas syringae	1
Impatiente de Nouvelle-Guinée (New Guinea impatiens)	Virus de la mosaïque de la luzerne	AMV (Alfalfa mosaic virus)	1
	Rhizoctone commun	Rhizoctonia sp.	1
	Virus de la mosaïque du tabac	TMV (Tobacco mosaic virus)	1
Lisianthus (Bluebell)	Fusariose	Fusarium sp.	2
Lupin (Lupine)	Virus de la mosaïque du tabac	TMV (Tobacco mosaic virus)	1
Monarde (Monarda)	Fusariose	Fusarium sp.	1
Œillet d’Inde / Tagète (Marigold)	Moisissure grise	Botrytis sp.	1
Ostéosperme blanc (White osteospermum)	Mildiou	Plasmopara sp.	1
Penstemon (Beardtongue)	Virus de l’ondulation du tabac	TRV (Tobacco rattle virus)	1
Pervenche / Vinca (Periwinkle)	Virus en bandes du tabac	TSV (Tobacco streak virus)	1
Pétunia (Petunia)	Virus de la mosaïque de la luzerne	AMV (Alfalfa mosaic virus)	1
	Virus de la mosaïque du tabac	TMV (Tobacco mosaic virus)	1
Phalaenopsis (Moth orchid)	Virus de la tache nécrotique de l’impatiente	INSV (Impatiens necrotic spot virus)	1
	Virus de la tache annulaire de la tomate	TSWV (Tomato spotted wilt virus)	1
Philadelphus / Seringat (Mock orange)	Fusariose	Fusarium sp.	1
	Brûlure bactérienne	Pseudomonas syringae	1
	Tache foliaire	Pseudomonas viridiflava	1
	Pourriture pythienne	Pythium sp.	1
Phlox	Virus de l’ondulation du tabac	TRV (Tobacco rattle virus)	2
	Virus en bandes du tabac	TSV (Tobacco streak virus)	2
Pivoine (Peony)	Désordre génétique	Chimère	1
	Virus de la mosaïque du concombre	CMV (Cucumber mosaic virus)	1
	Pourriture racinaire	Cylindrocarpon sp.	1
	Malformation	Phytoplasme	3
	Pourriture pythienne	Pythium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Poinsettia	Fusariose	Fusarium sp.	1
	Tache foliaire	Phoma sp.	1
Salvia	Chimère	Désordre génétique	1
Zinnia	Tache alternarienne	Alternaria zinniae	1
	Blanc (Oïdium)	Golovinomyces spadiceus	1
	Tache bactérienne	Xanthomonas axonopodis	1

Tableau 7. Sommaire des maladies diagnostiquées parmi les plantes aromatiques et médicinales reçues au Laboratoire d’expertise et de diagnostic en phytoprotection du MAPAQ en 2023.

Culture	Maladie/symptôme	Agent pathogène/cause	Nombre
Basilic (Basil)	Fusariose	Fusarium sp.	1
	Rhizoctone commun	Rhizoctonia sp.	1
Basilic sacré (Holy basil)	Fusariose	Fusarium sp.	1
Cannabis	Pourriture	Aspergillus sp.	1
	Tache foliaire	Bipolaris gigantea	1
	Désordre génétique	Chimère	1
	Fusariose	Fusarium falciforme	1
	Fusariose	Fusarium oxysporum	1
	Fusariose	Fusarium sp.	2
	Brunissement du collet	Lasiodiplodia theobroma	1
	Pourriture	Penicillium sp.	2
	Pourriture pythienne	Pythium sp.	1
	Sclérotiniose	Sclerotinia sclerotiorum	1
	Pourriture noire des racines	Thielaviopsis sp.	3
	Virus de la mosaïque du tabac	TMV (Tobacco mosaic virus)	9
Coriandre (Coriander)	Fusariose	Fusarium sp.	1
	Pourriture pythienne	Pythium sp.	1
Gingembre (Ginger)	Tache alternarienne	Alternaria sp.	1
	Pourriture molle	Dickeya spp.	1
	Fusariose	Fusarium oxysporum	2
	Fusariose	Fusarium sp.	3
	Pourriture molle	Pectobacterium brasiliense	1
	Pourriture molle	Pectobacterium sp.	2
	Pourriture pythienne	Pythium ultimum	1
	Rhizoctone commun	Rhizoctonia sp.	1
Oseille (Sorrel)	Tache alternarienne	Alternaria sp.	1
Romarin (Rosemary)	Moisissure grise	Botrytis sp.	1

DISEASES DIAGNOSED ON PLANT SAMPLES SUBMITTED TO THE NEW BRUNSWICK DEPARTMENT OF AGRICULTURE, AQUACULTURE AND FISHERIES PLANT DISEASE DIAGNOSTIC LABORATORY IN 2023

CROP: Diagnostic Laboratory Report LOCATION: New Brunswick NAME AND AGENCY: M.T. TESFAENDRIAS

New Brunswick Department of Agriculture, Aquaculture and Fisheries1350 Regent Street, Fredericton, NB E3C 2G6 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: The New Brunswick Department of Agriculture, Aquaculture and Fisheries Plant Disease Diagnostic Laboratory provides diagnostic services and disease management recommendations to growers and the agricultural industry in New Brunswick. In 2023, a total of 157 plant tissue samples were submitted to the diagnostic laboratory for problem identification and possible control recommendations.

INTRODUCTION AND METHODS: The New Brunswick Department of Agriculture, Aquaculture and Fisheries (NBDAAF) Plant Disease Diagnostic Laboratory (PDDL) located in Fredericton, NB, provides diagnostic services and control recommendations for diseases of various crops to growers and the agricultural industry in New Brunswick as part of an integrated pest management (IPM) service. Samples are submitted to the diagnostic laboratory by IPM scouts, growers, agribusiness representatives, crop insurance agents and NBDAAF crop specialists and extension officers. Disease diagnoses are based on a combination of visual examination of symptoms, microscopic observations, and culturing onto growth media.

RESULTS AND COMMENTS: In 2023, temperatures in May and June were cooler than usual which slowed crop growth until July. Warm temperatures in July closed the gap on growing degree days. The season was wetter than usual. The warm temperatures and wet conditions provided ideal conditions for infection by fungal and bacterial pathogens. From January 1 to November 30, 2023, the PDDL received 157 diseased plant samples for diagnosis. Samples diagnosed as physiological disorders, as well as samples diagnosed during scouting and field visits are not included in this report. Diseases and causal/associated agents diagnosed on plant tissue samples submitted to the NBDAAF PDDL in 2023 are summarized in Tables 1 to 5, by crop category.

Table 1. Summary of diseases/symptoms diagnosed on fruit tree crop samples submitted to the NBDAAF Plant Disease Diagnostic Laboratory in 2023.

Crop	Disease/symptom	Causal/associated agent (s)	No. of samples
Apple	Alternaria leaf blotch	Alternaria sp.	4
	Apple scab	Venturia inaequalis	7
	Bitter rot	Colletotrichum sp.	4
	Black rot	Botryosphaeria obtusa	2
	European canker	Neonectria ditissima	2
	Fire blight	Erwinia amylovora	9
	Flyspeck	Zygophiala jamaicensis	3
	Frogeye leaf spot	Botryosphaeria obtusa	2
	Marssonina leaf blotch	Marssonina coronaria	4
	Nectria twig blight	Nectria cinnabarina	2
	Powdery mildew	Podosphaera leucotricha	3
	Phytophthora root/crown rot	Phytophthora sp.	1
	Silver leaf	Chondrostereum purpureum	2
Total			45

Table 2. Summary of diseases/symptoms diagnosed on berry and grape crop samples submitted to the NBDAAF Plant Disease Diagnostic Laboratory in 2023.

Crop	Disease/symptom	Causal/associated agent (s)	No. of samples
Blueberry (lowbush)	Stem blight	Phomopsis vaccinii	1
	Exobasidium leaf and fruit spot	Exobasidium maculosum	2
Blueberry	Monilinia blight	Monilinia vaccinii-corymbosi	1
(highbush)	Twig blight	Phomopsis vaccinii	1
	Witches’ broom	Pucciniastrum goeppertianum	1
Cranberry	Upright dieback	Phomopsis sp.	2
Grape	Anthracnose	Elsinoe ampelina	1
	Phomopsis cane and leaf spot	Phomopsis viticola	2
Raspberry	Phytophthora root rot	Phytophthora rubi	6
Strawberry	Angular leaf spot	Xanthomonas fragariae	1
	Anthracnose	Colletotrichum sp.	5
	Black root rot	Pythium sp., Rhizoctonia sp. and Fusarium sp.	4
	Crown rot	Colletotrichum sp.	2
	Grey mould	Botrytis cinerea	2
	Leaf blight	Phomopsis obscurans	2
	Leaf scorch	Diplocarpon earlianum	1
	Phytophthora crown rot	Phytophthora cactorum	1
	Powdery mildew	Sphaerotheca macularis f. sp. fragariae	2
Total			37

Table 3. Summary of diseases/symptoms diagnosed on vegetable (field and greenhouse) and basil crop samples submitted to the NBDAAF Plant Disease Diagnostic Laboratory in 2023.

Crop	Disease/symptom	Causal/associated agent (s)	No. of samples
Basil	Grey mould	Botrytis cinerea	1
	Downy mildew	Peronospora belbahrii	1
Beans	Grey mould	Botrytis cinerea	1
	Leaf blight	Alternaria sp.	1
Beet	Cercospora leaf spot	Cercospora beticola	1
	Phoma leaf spot	Phoma betae	1
Carrot	Aster yellows	Phytoplasma	1
	Cavity spot	Pythium sp.	1
	Dry rot	Fusarium sp.	1
	Leaf blight	Alternaria dauci	1
Cucumber	Alternaria leaf blight	Alternaria cucumerina	2
	Downy mildew	Pseudoperonospora cubensis	3
	Powdery mildew	Podosphaera xanthii	2
	Scab	Cladosporium cucumerinum	1
Eggplant	Gray mould	Botrytis cinerea	1
	Early blight	Alternaria solani	1
	White mould	Sclerotinia sclerotiorum	1
Garlic	Blue mould	Penicillium sp.	1
	Botrytis neck and bulb rot	Botrytis allii	2
	Bulb and stem nematode	Ditylenchus dipsaci	1
	Fusarium basal plate rot	Fusarium oxysporum f. sp. cepae	1
	Purple blotch	Alternaria porri	1
	Skin blotch	Embellisia allii	1
	Stemphylium leaf blight	Stemphylium vesicarium	1
Lettuce	Bottom rot	Rhizoctonia solani	1
	Grey mould	Botrytis cinerea	2
Onion	Leaf and neck anthracnose	Colletotrichum sp.	1
	Purple blotch	Alternaria porri	2
	Stemphylium leaf blight	Stemphylium vesicarium	3
Pea	Anthracnose	Colletotrichum sp.	2
Pumpkin	Bacterial wilt	Erwinia tracheiphila	1
	Septoria leaf spot	Septoria cucurbitacearum	1
Squash	Alternaria leaf spot	Alternaria cucumerina	1
	Scab	Cladosporium cucumerinum	1
Tomato	Anthracnose	Colletotrichum sp.	2
	Grey mould/canker	Botrytis cinerea	2
	Leaf mould	Passalora fulva	3
	Powdery mildew	Pseudoidium neolycopersici	1
	White mould	Sclerotinia sclerotiorum	1
Total			53

Table 4. Summary of diseases/symptoms diagnosed on cereal crop samples submitted to the NBDAAF Plant Disease Diagnostic Laboratory in 2023.

Crop	Disease/symptom	Causal/associated agent (s)	No. of samples
Oat	Anthracnose	Colletotrichum graminicola	1
Wheat	Head blight	Fusarium graminearum	1
	Sooty mould	Alternaria sp., Cladosporium sp.	1
Total			3

Table 5. Summary of diseases/symptoms diagnosed on trees, shrubs and ornamental plant samples submitted to the NBDAAF Plant Disease Diagnostic Laboratory in 2023.

Crop	Disease/symptom	Causal/associated agent (s)	No. of samples
Bractheantha	Downy mildew	Plasmopara halstedi	2
	Wilt	Fusarium sp.	1
Calibrachoa	Grey mould	Botrytis cinerea	1
Christmas cactus	Root rot	Pythium sp.	1
Chrysanthemum	Ascochyta ray blight	Ascochyta chrysanthemi	1
	Bacterial leaf spot	Pseudomonas cichorii	1
Coleus	Downy mildew	Peronospora choii	3
Dianthus	Damping off	Pythium sp.	1
Geranium	Root rot	Pythium sp.	1
Impatiens	Wilt	Fusarium sp.	1
	Downy mildew	Plasmopara obducens	2
Cleome	Root rot	Pythium sp.	1
Mountain ash	Fire blight	Erwinia amylovora	1
Osteospermum	Damping off	Pythium sp.	1
Pansy	Anthracnose	Colletotrichum sp.	1
Total			19

DISEASES DIAGNOSED ON COMMERCIAL CROP SAMPLES SUBMITTED TO THE PEI ANALYTICAL LABORATORIES PLANT DISEASE DIAGNOSTIC SERVICE (PDDS) IN 2023

CROP: Diagnostic Laboratory Report - All Crops LOCATION: Prince Edward Island NAMES AND AGENCIES: M. M. CLARK

PEI Department of Agriculture, PEI Analytical Laboratories, Plant Disease Diagnostic Laboratory, 23 Innovation Way, Charlottetown, PE C1E 0B7 Telephone: [phone]; Facsimile: [phone]; Email: [email protected] Web page: https://www.princeedwardisland.ca/en/information/agriculture-and-land/pei-analytical-laboratories-peial

ABSTRACT: The Plant Disease Diagnostic (PDD) Laboratory section of PEI Analytical Laboratories, Prince Edward Island Department of Agriculture, provides diagnosis and surveillance of disease problems caused by fungi, bacteria, viruses and abiotic disorders of commercial crops produced on PEI. In 2023, a total of 203 disease diagnoses were completed on 110 samples processed. The 2023 growing season was a record-breaking year for rainfall on PEI. There were a few potato seed emergence issues caused by bacterial soft rot and silver scurf. No potato late blight or pink rot foliar/tuber infections were identified. The first incidence of apple fire blight in PEI was confirmed this season in the ‘Royal Gala’ variety. The first incidence of strawberry crown rot disease caused by a Neopestalotiopsis sp. was confirmed in two separate areas. An unidentified species of Fusarium was isolated from a rutabaga root exhibiting a punky, blackish rot on the sides and ends with brown vascular tissue.

INTRODUCTION and METHODS: Samples for disease diagnosis are submitted to the PDD laboratory by agriculture extension staff, researchers, producers, greenhouse growers, agri-business representatives, crop insurance agents, and the general public. Diagnoses are based on a combination of investigative work, visual examination of symptoms, microscopic observations, and culturing onto selective media. Culture samples may be sent, with client’s consent, to recognized laboratories for additional identification using polymerase chain reaction (PCR), as required.

RESULTS and COMMENTS: A total of 203 disease diagnoses were completed on 110 samples during the period of May 29^th to October 24^th, 2023. A summary of the diseases diagnosed per crop on samples submitted in 2023 is provided in Table 1. The diagnoses reported may not necessarily reflect the major disease problems encountered in the field during the season, but rather those most prevalent among the samples submitted. Categories of samples received were potatoes (43.84%), cole crops (3.94%), other vegetables (14.29%), fruit (20.19%), cereals (8.87%), and other crops (8.87%).

Table 1. Diseases diagnosed on commercial crop samples submitted to the PEI Analytical Laboratories, Plant Disease Diagnostic Service in 2023.

Crop	Disease/symptom	Causal/associated agent	Frequency of identification
VEGETABLES
Arugula	Damping-off	Pythium/Globisporangium sp.	1
	Damping-off	Rhizoctonia sp.	1
Carrot	Damping-off	Fusarium sp.	2
	Damping-off	Pythium/Globisporangium sp.	1
Cucumber	Crown and root rot	Fusarium sp.	1
	Crown and root rot	Pythium/Globisporangium sp.	1
	Downy mildew	Pseudoperonospora sp.	2
	Fusarium wilt	Fusarium sp.	1
Onion	Leaf blight	Xanthomonas sp.	1
	Leaf blight	Botrytis cinerea	1
	Neck rot	Botrytis cinerea	1
Potato	Black dot	Colletotrichum coccodes	1
	Black dot	Colletotrichum sp.	6
	Bacterial soft rot	Clostridium sp.	2
	Bacterial soft rot	Pectobacterium sp.	7
	Bacterial soft rot	Pseudomonas sp.	8
	Bacterial soft rot	Xanthomonas sp.	1
	Blackleg	Pectobacterium sp.	1
	Botrytis vine rot (grey mould)	Botrytis cinerea	2
	Brown spot	Alternaria alternata	6
	Common scab	Streptomyces sp.	1
	Dry core	Rhizoctonia solani	1
	Early blight	Alternaria solani	3
	Early dying syndrome	Colletotrichum coccodes	5
	Early dying syndrome	Fusarium sp.	2
	Early dying syndrome	Pectobacterium sp.	1
	Early dying syndrome	Pythium/Globisporangium sp.	1
	Early dying syndrome	Rhizoctonia solani	1
	Environmental disorder	Leaf burn	1
	Environmental disorder	Ozone damage	1
	Environmental disorder	Oedema	2
	Environmental disorder	Water soak	1
	Fusarium wilt	Fusarium graminearum	1
	Fusarium wilt	Fusarium sp.	2
	Leak	Pythium/Globisporangium sp.	3
	Leak	Globisporangium ultimum	1
	Nutritional disorder	Unspecified	1
	Physiological disorder	Bruising	3
	Physiological disorder	Enlarged lenticels	1
	Physiological disorder	Hollow heart	1
	Physiological disorder	Nutritional imbalance	2
	Physiological disorder	Translucent end	1
	Physiological disorder	White knot	1
	Root rot	Pythium/Globisporangium sp.	1
	Rhizoctonia skin cracking	Rhizoctonia solani	1
	Rhizoctonia stem girdling	Rhizoctonia solani	4
	Rubbery rot	Geotrichum sp.	1
	Seed piece decay	Pectobacterium sp.	1
	Seed piece decay	Pseudomonas sp.	1
	Seed piece decay	Xanthomonas sp.	1
	Silver scurf	Helminthosporium solani	1
	Verticillium wilt	Verticillium dahliae	1
	Verticillium wilt	Verticillium sp.	5
	White mould	Sclerotinia sp.	1
Tomato	Bacterial canker	Clavibacter michiganensis	1
	Botrytis leaf spot	Botrytis cinerea	1
	Crown and root rot	Pythium/Globisporangium sp.	1
	Fusarium wilt	Fusarium sp.	5
	Leaf spot	Cladosporium sp.	1
	Leaf spot	Ulocladium sp.	1
	Phoma rot	Phoma sp.	1
	Physiological disorder	Nutritional imbalance	1
	Septoria leaf spot	Septoria sp.	1
	Stem canker	Alternaria alternata	1
	Verticillium wilt	Verticillium sp.	1
COLE CROPS
Rutabaga	Black rot	Xanthomonas sp.	2
	Physiological disorder	Boron deficiency	1
	Root rot	Rhizoctonia sp.	1
	Root rot	Fusarium oxysporum	1
	Root and crown rot	Fusarium sp.	3
CEREAL & LEGUME
Barley	Black point	Alternaria sp.	2
	Black point	Biopolaris sp.	2
	Black point	Cladosporium sp.	1
	Fusarium head blight	Fusarium spp.	3
	Kernel blight	Alternaria alternata	2
	Kernel blight	Cladosporium sp.	1
	Net blotch	Helminthosporium sp.	1
	Spot blotch	Bipolaris sp.	1
Oats	Black head moulds	Alternaria alternata	1
	Black head moulds	Aspergillus sp.	1
Wheat	Black point	Alternaria sp.	1
	Black point	Bipolaris sp.	1
	Spot blotch	Bipolaris sp.	1
FRUITS
Apple	Black rot	Botryosphaeria sp.	5
	Black rot	Botryosphaeria dothidea	1
	European canker	Neonectria sp.	3
	Fire blight test^a	Negative	7
	Fire blight	Erwinia amylovora^a	1
	Phomopsis twig blight	Phomopsis sp.	1
	Physiological disorder	‘Honey Crisp’ leaf mottling	1
Black currant	Septoria leaf spot	Septoria sp.	2
Blueberry	Stem canker	Botryosphaeria sp.	1
	Leaf spot	Gloeosporium sp.	2
	Phomopsis twig blight	Phomopsis sp.	4
	Witches’ broom	Pucciniastrum goeppertianum	1
Cranberry	Red shoot	Exobasidium sp.	1
	Upright dieback	Fusicoccum sp.	1
	Upright dieback	Phomopsis sp.	1
Strawberry	Anthracnose	Colletotrichum sp.	1
	Crown rot	Fusarium oxysporum	1
	Crown rot	Neopestalotiopsis sp.	2
	Crown rot	Rhizoctonia sp.	1
	Leaf spot	Neopestalotiopsis sp.	2
	Verticillium wilt	Verticilllium sp.	2
OTHER CROPS
Trees:
Atlantic pine	Physiological disorder	Annual needle drop	1
	White pine blister rust	Cronartium ribicola	1
Inconclusive results			13
Other			3
TOTAL			203

^aIdentified by Agdia Immunostrip™ antibody test and culturing.

The 2023 growing season was a record-breaking year for rainfall on PEI. The PEI Potato Board reported that the 2023 growing season started with a rapid plant growth due to warm growing days and adequate moisture. The spring was exceptionally dry, while June received higher than normal amounts of precipitation. The wet trend continued through July and August, with multiple heavy rainfall events (https://www.cbc.ca/news/canada/prince-edward-island/pei-rainy-summer-1.6959085). Consequently, root diseases caused by Fusarium spp., Pythium spp., and Rhizoctonia spp. were pervasive in crops such as cereals, strawberries, tomatoes, and potatoes.

Airspore (The AIR Program) detected the first Phytophthora infestans spores in their traps on July 26^th, 2023. However, no potato late blight plant or tuber infections were reported or identified this season. The last confirmed incidence of potato late blight was in 2016 with four confirmed cases of the US23 genotype. Two samples of home garden tomatoes suspected of late blight in 2023 were tested for the fungus and deemed to be negative.

Two cases of pythium leak tuber rot were confirmed in ‘Prairie Sun’ and ‘Red Norland’ varieties. An abiotic disorder called oedema was identified in field potatoes for the first time this season. This disorder is caused by roots taking up more water than the leaves can transpire. This excess water ruptures the cells, particularly on the underside, and leads to water-soaked patches that turn corky and unsightly. This disorder was identified in field grown potatoes and greenhouse potatoes.

Eight apple tree samples were tested for fire blight using Agdia’s Immunostrip® test strip for Erwinia amylovora (Agdia Inc., Elkhart, IN) and by culturing and the first recorded positive case of fire blight in PEI was confirmed in the ‘Royal Gala’ variety. Tree damage from the 2022 hurricane Fiona and high winds coupled with heavy rain throughout the apple growing season, may have contributed to this infection. Symptoms included brown leaves and a shepherd’s crook at the shoot tip. Other apple diseases identified this season included European canker and black rot.

A suspected sample of ramularia leaf spot in the ‘Island’ barley variety was transferred to Agriculture & Agri-Food Canada (AAFC) for further testing using DNA sequencing with internal transcribed spacer (ITS) primers. No Ramularia sp. was detected, however other organisms found in the leaf tissue included Alternaria, Neoascochyta, Bipolaris, and Fusarium spp.

The continuous warm, humid, and wet conditions were conducive for fusarium head blight (FHB) and black sooty moulds in cereals. Environmental conditions for FHB in 2023 in PEI were “severe” in the month of July (Adam Foster, AAFC Charlottetown, personal communication). More information on FHB in PEI in 2023 can be found in Johnstone et al. (2024).

The first two cases of crown rot in strawberry caused by a Neopestalotiopsis sp. were confirmed in a nursery stock sample and a field sample. Symptoms included dead leaves with a high level of blackish lesions with concentric rings and leaves cupping downwards, and a reddish to orange coloured necrosis in the lower roots and crowns. Other organisms isolated from the infected tissue included Rhizoctonia sp., Fusarium oxysporum and Verticillium sp.

REFERENCES

• Johnstone E, Bradley H, Matters R, Foster A. 2024. Prince Edward Island survey of fusarium head blight and leaf diseases of spring wheat, 2023. Can Plant Dis Surv. 104: 115–118. In, Can J Plant Pathol. 46:sup 1.
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CEREALS / CÉRÉALES

2023 BARLEY DISEASE SURVEY IN ALBERTA

CROP: Barley LOCATION: Alberta NAMES AND AGENCY: N. RAUHALA¹, T.K. TURKINGTON¹, J. BUSAAN¹, S. WATERMAN², S. REHMAN², H. KLEIN-GEBBINCK³, E. DAY³, H. SPENCE³, M.W. HARDING⁴, G.C. DANIELS⁴, T.B. HILL⁴ & L. STELLAR⁴

¹Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, 6000 C & E Trail, Lacombe, AB T4L 1W1 ²Field Crop Development Centre, Olds College, 5030 50th Street, Lacombe, AB T4L 1W8 ³Beaverlodge Research Farm, Agriculture and Agri-Food Canada, Beaverlodge, AB T0H 0C0 ⁴Crop Diversification Centre South, Alberta Agriculture and Irrigation, 301 Horticulture Station Rd. E, Brooks, AB T1R 1E6 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: In 2023, 103 random commercial barley crops were surveyed for disease levels in Alberta. Disease assessments for leaf spots involved rating penultimate leaf samples for percentage leaf area diseased. Ratings for other diseases were based on incidence and/or presence or absence, especially where only trace levels were found. Overall, barley fungal leaf disease levels in 2023 were lower than those in the previous year, while trace levels generally were observed for head and rust diseases. Bacterial leaf streak was observed in four of the 103 fields surveyed. Stripe rust was observed only in two fields in 2023, while loose smut was noted in 13 fields, and suspected bacterial leaf streak was observed in an additional four fields.

INTRODUCTION AND METHODS: A survey to document diseases of barley was conducted in 103 fields across Alberta from June 29 - August 8, 2023, with evaluations at the head emergence to hard dough stage. Given drought conditions, especially in southern Alberta, crop development had progressed faster than normal, with some fields visited earlier than is typically done. The fields were traversed in a diamond pattern starting at least 25 m in from the field edge, with five leaves collected at each of five locations at least 25 m apart. Penultimate leaves were collected from 103 fields and rated for percent leaf area diseased (PLAD) for scald, net-form net blotch and other leaf spots [a combination of symptoms due to spot-form net blotch (Pyrenophora teres f. maculata), spot blotch (Cochliobolus sativus), and physiological leaf spotting]. Other diseases such as loose smut, stripe rust, bacterial leaf streak, and root rots (in which stunting and/or premature ripening of plants occurred with associated root or stem base symptoms) were rated based on incidence and/or presence or absence, especially where only trace levels were found. Following the survey, a representative tissue sub-sample of diseased plant parts collected at each location was cultured in the laboratory for pathogen isolation and identification.

RESULTS AND COMMENTS: Results for PLAD in the 103 fields surveyed are presented in Table 1. Temperatures across the region were generally warmer than normal for the entire growing season. While the moisture level was low in the entire region in May and June and stayed that way in the south, there were more normal moisture levels in the central and north regions in July and August. Based on the PLAD assessments of the penultimate leaf samples, scald (Rhynchosporium commune) was present in 30 of the 103 fields with 27 of those fields having low levels (PLAD of 10% or less), while the remaining three fields had higher PLAD levels of 27, 31, and 48% (Table 1). Net-form net blotch (Pyrenophora teres f. teres) was found in 32 of the 103 fields, 28 of those fields having low levels (PLAD of 10% or less), while the last four fields had higher PLAD levels of 12, 19, 20, and 25%. Other leaf spot diseases were found in 84 of the 103 fields with 78 of those having low levels (PLAD of 10% or less), and the remaining six fields having PLAD ratings from 11%-37%. These other leaf spots from the 103 fields were identified in the laboratory and the causal agent Cochliobolus sativus (spot blotch) was isolated from 46 fields, while P. teres f. maculata (spot-form net blotch) was isolated from 51 fields. The saprophytic fungi Alternaria spp. and Epicoccum spp. were isolated from 50 and 44, respectively. The presence of these saprophytes is often associated with dead plant tissues as a result of physiological issues or disease-related damage.

Table 1. Disease incidence and severity, based on percent leaf area diseased assessments of penultimate leaf samples in 103 commercial barley fields, Alberta, 2023.

Disease (severity rating scale)	% fields affected	Overall average severity	Range in average severity per field
Scald (PLAD^a)	29	1.4	0 – 48
Netted net blotch (PLAD)	31	1.2	0 – 25
Other leaf spots (PLAD)	82	3.3	0 – 37
Total leaf area diseased (PLAD)	93	5.8	0 – 51

^aPercent leaf area diseased.

Loose smut (Ustilago nuda) in barley was found at trace levels in 13 of the 103 surveyed fields in Alberta in 2023.

Two fields with trace levels of stripe rust (Puccinia striiformis) were found among the 103 commercial barley fields surveyed. Trace levels of bacterial leaf streak were found in four fields, while one field had moderate levels of root rot. No ergot was observed in any of the 103 fields.

Overall, barley leaf disease levels in 2023 were lower than those in the previous year (Rauhala and Turkington 2023).

ACKNOWLEDGEMENTS: The authors would like to acknowledge the support of summer students Selena Delahunty, Jaydon Bick, Ezri Oatway, and Darci Rauhala, and Jordan Hansen. The generous funding of the Canadian Barley Research Coalition, Alberta Grains, Saskatchewan Barley Commission, Manitoba Crop Alliance, Brewing and Malting Barley Research Institute, and the Western Grains Research Foundation under the Sustainable Canadian Agricultural Partnership. The in-kind support of Alberta Agriculture and Irrigation is also gratefully acknowledged.

REFERENCES

• Rauhala NE, Turkington TK, Busaan J, Rehman S, Waterman S, Klein-Gebbinck H, Spence H, Harding MW, Daniels GC, Kennedy MA, et al. 2023. 2022 barley disease survey in central Alberta. Can Plant Dis Surv. 103:58–60. In, Can J Plant Pathol. 45:sup1.
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FUSARIUM HEAD BLIGHT OF BARLEY IN SASKATCHEWAN IN 2023

CROP: Barley LOCATION: Saskatchewan NAMES AND AGENCIES: B. RUMPEL¹, J. BUSH¹, E. MANGWENDE¹, C. BAWOLIN¹, B. KELSH¹, J. CADRAIN¹, C. PERU² & A. AKHAVAN²

¹Saskatchewan Ministry of Agriculture, Crops and Irrigation Branch, Crop Protection Laboratory, 1610 Park St., Regina, SK S4N 2G1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Saskatchewan Ministry of Agriculture, Crops and Irrigation Branch, 3085 Albert St., Regina, SK S4S 0B1

ABSTRACT: In 2023, fusarium head blight (FHB) incidence and severity were assessed in 40 barley crops in Saskatchewan. FHB occurred in 53% of the surveyed barley crops at a mean provincial severity (FHB Index) of 0.04%. The most prevalent Fusarium species was F. poae which was detected in 79% of barley crops with FHB symptoms.

INTRODUCTION AND METHODS: Fusarium head blight (FHB) incidence and severity in Saskatchewan were assessed in 40 barley crops (35 two-row; 5 six-row) in 2023. Field location and results were grouped according to soil zone and data presented for all barley crops (two-row and six-row) combined. Crop adjustors with the Saskatchewan Crop Insurance Corporation randomly collected 50 spikes from barley crops at late milk to early dough stages (Lancashire et al. 1991). A subsample of 30 spikes was analyzed for visual FHB symptoms at the Crop Protection Laboratory in Regina, SK. The number of infected spikes per crop and the number of infected spikelets in each spike, as a proportion of the total, were recorded. An FHB disease severity rating, also referred to as the FHB Index, was determined for each crop surveyed; FHB severity (%) = [% of spikes affected x mean proportion (%) of kernels infected]/100. Mean FHB severity values were calculated for each soil zone and for the whole province. Glumes or kernels with visible FHB symptoms were surface sterilized in 0.6% NaOCl solution for 1 min and cultured on modified potato dextrose agar to confirm presence of Fusarium species on infected kernels. A maximum of 20 symptomatic kernels per sample were selected to represent infected samples to confirm FHB and the Fusarium spp. involved.

RESULTS AND COMMENTS: Approximately 3.0 million ha (7.3 million ac) of barley were seeded in Saskatchewan in 2023 with an average yield of 3.3 metric tonnes per ha (61.3 bu/ac). Barley yields in 2023 were down slightly from 2022 (3.8 metric tonnes per ha; 70.4 bu/ac) and up from 2021 (2.3 metric tonnes per acre; 43.1 bu/ac) (Statistics Canada 2024).

FHB occurred in 50% of the barley crops surveyed in 2023 with a provincial mean severity of 0.04%. The severity of FHB in 2023 was lower than in 2022 and higher than 2021. In 2023, the highest mean FHB severity occurred in the grey soil zone, which is consistent with data from 2021; in 2022, the highest mean FHB severity was in the black soil zone (Table 1).

Table 1. Prevalence and severity of fusarium head blight (FHB) in Saskatchewan barley crops in 2023 grouped by soil zone.

Soil zone	Prevalence^a (number of crops affected)	Mean FHB severity^b (range)
Black	59	0.04
	(10)	(0-0.35)
Brown	14	0.02
	(1)	(0-0.16)
Dark Brown	20	0
	(1)	(0-0)
Grey	73	0.06
	(8)	(0-0.31)
Overall	50	0.04
	(20)	(0-0.35)

^aPrevalence (%) = number of crops affected/total crops surveyed,

^bFHB severity (FHB Index) = [% of spikes affected x mean proportion (%) of kernels infected]/100,

In 2023, 55 isolations were made to confirm the presence of Fusarium and identify the pathogen to the species level (Table 2). The most frequently isolated causal pathogen, F. poae, occurred in 75% of barley crops with FHB symptoms and accounted for 67% of all the Fusarium isolations. Fusarium graminearum was detected in 20% of the barley, which was more than 2022 or 2021. A species other than F. avenaceum, F. culmorum, F. graminearum, F. poae, or F. sporotrichioides was identified in 20% of fields with FHB symptoms.

Table 2. Prevalence of Fusarium species in Saskatchewan barley crops displaying visual symptoms in 2023.

F. avenaceum	F. culmorum	F. graminearum	F. poae	F. sporotrichiodes	Other Fusarium^a
0%	0%	20%	75%	0%	20%

^aOther Fusarium includes species other than those described in this table.

ACKNOWLEDGEMENTS: We gratefully acknowledge the assistance of Saskatchewan Crop Insurance Corporation staff agrologists for the collection of cereal samples for this survey.

REFERENCES

• Lancashire PD, Bleiholder H, Van Den Boom T, Langeluddeke P, Stauss R, Weber E, Witzenberger, A. 1991. A uniform decimal code for growth stages of crops and weeds. Ann Appl Biol. 119:561–601.
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• Statistics Canada. 2024. Table 32–10–0359–01. Estimated areas, yield, production, average farm price and total farm value of principal field crops, in metric units, annual, CANSIM database. [accessed 2024 Jan 23]. https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=3210035901
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LEAF SPOT DISEASES OF OAT AND BARLEY IN SASKATCHEWAN IN 2023

CROP: Oat and Barley NAMES AND AGENCY: S. BOSCH, A. KARSTENS, T. ISLAM, M.A. OVIEDO-LUDENA & H.R. KUTCHER

Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8 Telephone: [phone]; Email: [email protected]

ABSTRACT: In 2023, 38 oat crops and 36 barley crops were surveyed across Saskatchewan. Pyrenophora spp. were found in 4.2% of the oat crops surveyed and 6% of barley crops surveyed. In barley, Cochliobolus sativus was the most prevalent pathogen, found in 12.8% of the crops surveyed.

INTRODUCTION AND METHODS: In 2023, 38 oat crops and 36 barley crops were surveyed in Saskatchewan. All surveys were conducted by Saskatchewan Crop Insurance Corporation between early July and mid-August. Samples were collected from late milk to soft dough stage (Table 1). Ten flag leaves were collected from each crop surveyed. There were no barley kernels collected this year. Ten leaves from each barley and oat sample and 30 oat kernels were plated. Leaves were cut into 1 cm-long pieces for plating. Leaves were sterilized in 70% ethanol and triple-rinsed with sterile distilled water, then dried before being plated onto acidified potato dextrose agar (APDA). Plates were incubated under light at room temperature and pathogens were identified after 5-6 days based on morphology (Zillinsky 1983). Panicles were threshed and kernels sterilized in 5% bleach solution before triple-rinsing with sterile water. Oat kernels were plated on APDA and left for five days under light at room temperature before pathogens were identified by morphology (Zillinsky 1983; Leslie and Summerell 2006). Disease prevalence was measured as the percentage of fields affected by each disease out of all fields surveyed.

Table 1. Prevalence of different growth stages of the oat and barley crops surveyed and tillage operations under which these crops were grown in Saskatchewan in 2023.

		Oat^a	Barley^a
Number of crops		38	36
Growth stage	Late milk	8	7
	Early dough	10	11
	Soft dough	7	10
Tillage operation	Conventional	6	1
	Minimal tillage	6	5
	Zero-till	17	13

^aNot all growth stages and tillage operations were provided for surveyed crops.

RESULTS AND COMMENTS: Oat leaf pathogens were identified in 20.3% of oat kernels surveyed, which was lower than the previous year (35% in 2022; Islam et al. 2023). This was likely due to the lower precipitation over much of the province in 2023 compared to previous years. Pathogens detected in the oat leaf samples were Pyrenophora spp., the cause of leaf blotch (39.5 % of the crops surveyed), which was higher compared to the previous year (26% in 2022), and Cochliobolus sativus, the cause of spot blotch (2.6% of the crops surveyed), which was lower than the previous year (10% in 2022). Other saprophytic fungi, like Alternaria spp. and Epiccocum spp. (100% and 5.3% respectively), were also detected (Table 3).

In oat kernel samples, two different pathogens were isolated: Fusarium spp., the causal agents of fusarium head blight, were found in 36.8% of the field crops surveyed, which was lower than the previous year (56.7% in 2022; Islam et al. 2023), and Cochliobolus sativus was found in 2.6% of the field crops surveyed. Two saprophytes, Alternaria spp. and Epicoccum spp., were also detected in oat kernels, with a prevalence of 100% and 23.7%, respectively (Table 2).

Table 2. Prevalence and incidence of seed-isolated pathogens from oat in Saskatchewan in 2023.

Crops	Pathogens	Prevalence (%)^a	Frequency (%)^b
Oat	Fusarium spp.	36.8	6.0
	Alternaria spp.	100	14.2
	Epicoccum spp.	23.7	2.9
	Cochliobolus sativus	5.3	2.6

^aPrevalence: % of crops surveyed with the pathogen.

^bFrequency: % of the leaf spot pathogen (as the % of the total pathogen isolations).

In barley, leaf pathogens were identified in 24.9% of the 36 field crops surveyed. Cochliobolus sativus, the cause of spot blotch, was identified in 13.9% of the total crops surveyed, which was lower than the previous year (28% in 2022; Islam et al. 2023). Pyrenophora spp., the cause of leaf blotch, was observed in 16.7% of the crops surveyed, which was higher than the previous year (8% in 2022). Two saprophytes, Alternaria spp. and Epicoccum spp. were also detected, with a prevalence of 100% and 8.3%, respectively (Table 3).

Table 3. Prevalence and incidence of each leaf spot pathogen detected in oat and barley survey samples in Saskatchewan in 2023.

Crops	Pathogens	Prevalence (%)^a	Frequency (%)^b
Oat	Alternaria spp.	100	16.0
	Epicoccum spp.	5.3	3.9
	Pyrenophora spp.	39.5	4.2
	Cochliobolus sativus	2.6	2.6
Barley	Alternaria spp.	100	19.4
	Epicoccum spp.	8.3	2.8
	Cochliobolus spp.	13.9	12.8
	Pyrenophora spp.	16.7	6.0

^aPrevalence: % of crops surveyed with the pathogen.

^bFrequency: % of the leaf spot pathogen (as the % of the total pathogen isolations).

ACKNOWLEDGEMENTS: This survey was supported by the leaf samples submitted by the Saskatchewan Crop Insurance Corporation. We thank our colleagues from the province and the members of the Cereal and Flax Pathology Group (CFPATH) - University of Saskatchewan.

REFERENCES

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FUSARIUM HEAD BLIGHT OF BARLEY AND OAT IN MANITOBA – 2023

CROP: Barley and Oat LOCATION: Manitoba NAMES AND AGENCY: M. PENNER, M. BANIK & X. WANG

Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: In Manitoba, 28 barley and 34 oat fields were surveyed in 2023 to assess the severity of fusarium head blight (FHB) and the Fusarium species complex affecting barley. F. poae was the predominant Fusarium species found in barley and oat grain samples, followed by F. sporotrichioides and F. graminearum. Infections caused by F. equiseti and F. avenaceum were also detected in both crops, but at a very low level.

INTRODUCTION AND METHODS: In 2023, the severity of FHB in Manitoba was assessed by surveying 28 barley fields and 34 oat fields from July 18 to August 5, when most crops were at the early- to soft-dough stages of growth (ZGS 79-82, Zadoks et al. 1974). Fields were sampled at regular intervals, approximately 20-25 km along survey routes, depending on crop availability. The areas sampled were bounded by Highways #s 67, 16 to the north, 12 to the east, 3 to the south, 8 to the north and 83 to the west. The fields were traversed in a diamond pattern starting at least 25 m from the field edge. In each field, 100 spikes were collected from five locations, 25 meters apart.

Fifty kernels from each field were randomly selected, surface-sterilized for 90s in 0.3% sodium hypochlorite, rinsed twice with distilled water, dried for 5 min at room temperature in a laminar flowhood, and then placed on potato dextrose agar (PDA, 25% strength) + streptomycin media. Identification of Fusarium species involved microscopic examination, and morphological characterization was performed using the criteria of Leslie and Summerell (2006). The isolation frequency was calculated as (number of isolations of each Fusarium spp./total number of isolations of all Fusarium spp.) x 100.

RESULTS AND COMMENTS: Barley - Fusarium infections were detected in 100% of barley fields surveyed. F. poae was the most frequently detected Fusarium species found in 89.3% of fields, followed by F. sporotrichioides (50.1% of fields) and F. graminearum (32.1% of fields) (Table 1). Infections caused by F. avenaceum and F. equiseti were also detected, but only at very low levels. F. avenaceum was found in 14.3% of fields and F. equiseti in 7.1%.

Table 1. Fusarium species isolated from kernels collected from barley fields in Manitoba in 2023.

Fusarium spp.	% infected fields^a	% infected kernels	Frequency of isolation (%)^b
F. poae	89.3	7.7	68.4
F. graminearum	32.1	0.9	8.2
F. sporotrichioides	50.0	1.9	17.1
F. avenaceum	14.3	0.3	2.5
F. equiseti	7.1	0.4	3.8

^a50 kernels cultured per field; 28 fields surveyed.

^bNumber of isolations of each Fusarium spp. as a percentage of all Fusarium spp. isolations.

A total of 1400 kernels was included in the analysis of the Fusarium species complex affecting barley. F. poae was the predominant Fusarium species infecting barley. F. poae was detected in 7.7% of kernels and had a % isolation frequency of 68.4% (Table 1). F. sporotrichodies was isolated from 1.9% of kernels and had an isolation frequency of 17.1%. F. graminearum was isolated from 0.9% of kernels and had an isolation frequency of 8.3%. The level of infection caused by F. graminearum was much lower than that found in 2022 (Beyene et al. 2023). F. avenaceum and F. equiseti were isolated from 0.3% and 0.4% kernels, respectively. The isolation frequencies of these two Fusarium species were much lower than those of F. poae, F. sporotrichioides and F. graminearum.

Oat - The typical symptom of FHB was observed in 79.4% of fields surveyed. F. poae was the most frequently detected Fusarium species isolated from 73.5% of fields and 6.5% of kernels. F. sporotrichioides was isolated from 38.2% of fields and 1.7 % of kernels. F. graminearum was isolated from 5.9% of fields and 0.1% of kernels. The level of infection caused by F. graminearum was much lower than that reported in 2022 (Beyene et al. 2023). F. avenaceum and F. equiseti were isolated from infected grain samples at a similar level to that found in the previous two years. F. avenaceum was found in 14.7% of fields and isolated from 0.4% of kernels. F. equiseti was found in 11.8% of fields and isolated from 0.3% of kernels. F. poae had the highest isolation frequency (72.5%), followed by F. sporotrichioides (19.0%), F. avenaceum (3.9%), F. equiseti (3.3%) and F. graminearum (1.3%) (Table 2).

Table 2. Fusarium species isolated from kernels collected from oat fields in Manitoba in 2023.

Fusarium spp.	% infected fields^a	% infected kernels	Frequency of isolation (%)^b
F. poae	73.4	6.5	72.5
F. graminearum	5.9	0.1	1.3
F. sporotrichioides	38.2	1.7	19.0
F. avenaceum	14.7	0.3	3.3
F. equiseti	11.8	0.4	3.9

^a50 kernels cultured per field; 34 fields surveyed.

^bNumber of isolations of each Fusarium spp. as a percentage of all Fusarium spp. isolations.

REFERENCES

• Beyene M, Banik M, Wang X. 2023. Fusarium head blight of barley and oat in Manitoba 2022. Can Plant Dis Surv. 103:65–66. In, Can J Plant Pathol. Vol. 45:sup1.
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BARLEY AND OAT LEAF SPOT DISEASES IN MANITOBA – 2023

CROP: Barley and Oat LOCATION: Manitoba NAMES AND AGENCY: M. PENNER, M. BANIK & X. WANG

Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: In Manitoba, 31 barley and 27 oat fields were assessed for leaf spot diseases in 2023. The severity of leaf spot diseases in barley and oats was lighter than in 2021, partially due to dry weather conditions during the growing season, which were not conducive forinfection by leaf spot pathogens. Cochliobolus sativus (spot blotch) and Pyrenophora teres (net blotch) were the main pathogens found in both barley and oats.

INTRODUCTION AND METHODS: In 2023, barley and oat leaf spot diseases in Manitoba were assessed by surveying 31 barley fields and 27 oat fields from July 18 to August 5, when most crops were at the early- to soft-dough stages of growth (ZGS 79-82, Zadoks et al. 1974). Fields were sampled at regular intervals, approximately 20-25 km along survey routes, depending on crop availability. The areas sampled were bounded by Highway #’s 67, 16 to the north, 12 to the east, 3 to the south, 8 to the north and 83 to the west. The fields were traversed in a diamond pattern starting at least 25 m from the field edge. Subsequently, 10 pieces of putatively infected leaf tissues from each field were surface sterilized with a 5% bleach (NaOCl) solution for 1 min and then rinsed three times in sterile distilled water, dried and placed on water agar. The surface-sterilized pieces of infected leaves were incubated on filter paper in moist chambers for 3-5 days to promote sporulation and identify the causal agent(s) of leaf spot disease(s).

RESULTS AND COMMENTS: The severity of leaf spot diseases in barley and oats in 2023 was lighter than in 2021 (Banik et al. 2022) and 2022 (Banik et al. 2023), partially due to dry weather conditions during the growing season, which were not conducive to infection by leaf spot pathogens.

Barley - Out of 31 barley fields, Cochliobolus sativus (the causal agent of spot blotch) was identified in leaf samples from 28 fields (an incidence of 90.3%). Pyrenophora teres (the causal agent of net blotch) was isolated from leaves in nine fields (an incidence of 29.1 %). C. sativus was the predominant barley leaf spot pathogen with an isolation frequency of 88.8%, which was much higher than the isolation frequency of P. teres (11.2%) (Table 1).

Table 1. Incidence and isolation frequency of leaf spot pathogens in barley in Manitoba in 2023.

Pathogens	Incidence (% of infected fields)	Frequency (% of total isolations)
Cochliobolus sativus	90.3	88.8
Pyrenophora teres	29.1	11.2

Oat - Out of 27 oat fields, C. sativus was detected in nine fields (33.3%), whereas P. teres was isolated in leaves from eight fields (29.6%). The isolation frequency of C. sativus from infected leaves was 53.3%, slightly higher than that of P. teres (46.7%) (Table 2).

Table 2. Incidence and isolation frequency of leaf spot pathogens in oats in Manitoba in 2023.

Pathogens	Incidence (% of infected fields)	Frequency (% of isolations)
Pyrenophora avenae	33.3	53.3
Cochliobolus sativus	29.6	46.7

REFERENCES

• Banik M, Beyene M, Wang X. 2022. Barley and oat leaf spot diseases in 2021 in Manitoba. Can Plant Dis Surv. 102:80. In, Can J Plant Pathol. 44:sup1.
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FOLIAR DISEASES OF CEREALS IN SOUTHERN ALBERTA, 2023

CROP: Wheat and Barley LOCATION: Alberta NAMES AND AGENCY: R. ABOUKHADDOUR & B. WEI

Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Ave. South, Lethbridge, AB T1J 4B1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: During the 2023 growing season, surveys were conducted on 18 cereal fields in southern Alberta to assess the incidence and severity of fungal diseases. These fields comprised 10 spring wheat and eight barley fields. Fungal leaf spot was present in half of the barley fields surveyed, at a high incidence of over 80% with average severity of 5%. Only two wheat fields of the 10 surveyed were found to have leaf spot at a high incidence of over 50% but with low severity of 2%. The lack of infection with stripe rust was remarkable; only one infected leaf with a single stripe was found in a barley field in Cardston, and therefore we consider infection with stripe rust to be almost absent. The extreme dry conditions likely contributed to the lower incidence of fungal diseases.

INTRODUCTION AND METHODS: Commercial cereal fields, including spring wheat and barley, were surveyed in southern Alberta in the third week of July, 2023. The survey area was bounded by Highway 508 in the north, Township Road 40 in the south, Range Road 250 in the west, and Highway 845 in the east (Fig. 1). Each field was inspected in a ‘W’ pattern to assess both disease incidence and severity across 10 sites spaced approximately 25 meters apart, to cover a large area of the field. Disease incidence was determined by counting the number of diseased plants within a 1 m² area. Based on disease incidence, field infections were classified as clean (0%), light/trace (1-33%), moderate (34-66%), or severe (67-100%). At each of the sampling locations within the surveyed fields, 10 flag leaves exhibiting leaf spot symptoms were randomly collected and assessed for disease severity by estimating of the percentage of the flag leaf area affected.

Fig. 1 Map illustrating surveyed cereal fields across southern Alberta in 2023. Clean fields are denoted by green pins, while fields infected with fungal leaf spots are marked with red pins. The yellow pin highlights the sole field where stripe rust was detected.

RESULTS AND COMMENTS: In total, 18 commercial fields were surveyed in 2023, consisting of 10 spring wheat fields and eight barley fields (Fig. 1, Table 1). Eleven surveyed fields (61.1%) were clean, including eight wheat fields and three barley fields (Table 1). Fungal leaf spot symptoms were observed in six fields, comprising two wheat fields categorized as exhibiting light symptoms with severity of 2%, and over 80% incidence, and four barley fields exhibiting an average of 5% severity with over 80% incidence rate (Table 1). Stripe rust was observed on only one leaf with a single stripe in one of the barley fields in the Cardston area. From 2021 to 2023, there has been a noticeable decrease in stripe rust infection compared to preceding years (Table 2) (Harding et al. 2023; Wei et al. 2022; Aboukhaddour et al. 2018, 2019, 2020, 2021).

Table 1. Occurrence of fungal leaf spot and stripe rust diseases in 18 cereal fields surveyed during the 2023 growing season in southern Alberta.

	Barley		Spring wheat
Foliar disease	Number of fields	Severity %^a (Incidence %)^b	Number of fields	Severity % (Incidence %)
None	3	0	8	0
Leaf spots	4	5% (80%)	2	2% (50%)
Stripe rust	1	0	0	0
Total	8		10

^aSeverity: percentage of flag leaf area covered with spots.

^bIncidence: percentage of infected plants within 1 m².

Table 2. Stripe rust incidence on wheat and barley in southern Alberta from 2017 to 2023.

Number (percentage) of fields infected
Disease incidence^a	2017b^a	2018^c	2019^d	2020^e	2021^f	2022^g	2023
Clean	48 (75%)	79 (92%)	27 (75%)	43 (54%)	27 (96%)	130 (100%)	18 (100%)
Light/Trace	12 (18%)	0	5 (14%)	18 (23%)	1 (4%)	0	0^h
Moderate	3 (5%)	6 (7%)	4 (11%)	8 (10%)	0	0	0
Severe	1 (2%)	1 (1%)	0	10 (13%)	0	0	0

^aField infection was classified as clean (0%), light/trace (1-33%), moderate (34-66%), or severe (67-100%) based on disease incidence.

^bAboukhaddour et al. 2018

^cAboukhaddour et al. 2019

^dAboukhaddour et al. 2020

^eAboukhaddour et al. 2021

^fWei et al. 2022

^gHarding et al. 2023

^hA single barley field had a stripe rust infection on one leaf surveyed, so was considered as no infection.

REFERENCES

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SEED-BORNE FUSARIUM ON CEREAL CROPS IN SASKATCHEWAN IN 2022

CROP: Cereal crops (Wheat, Durum, Barley and Oats) LOCATION: Saskatchewan NAMES AND AGENCIES: B. OLSON¹, A. AKHAVAN², T. BLOIS³, B. ERNST⁴, M. JAPP⁵, S. JUNEK⁶, H.R. KUTCHER⁷ & T. PRASAD⁸

¹Box 88, Hazlet, SK S0N 1E0; Telephone: [phone]; E-mail: [email protected] ²Saskatchewan Ministry of Agriculture, 3085 Albert St., Regina, SK S4S 0B1 ³20/20 Seed Labs Inc., 507-11^th Ave., Nisku, AB T9E 7N5 ⁴Prairie Diagnostic Seed Lab, 1105 Railway Ave., Weyburn, SK S4H 3H5 ⁵SaskBarley, 212-111 Research Dr., Saskatoon, SK S7N3R2 ⁶Discovery Seed Labs Ltd., 450 Melville St., Saskatoon, SK S7J 4M2 ⁷Crop Development Centre, U. of Saskatchewan, 51 Campus Dr., Saskatoon, SK S7N 5A8 ⁸Lendon Seed Lab, 147 Hodsman Rd., Regina, SK S4N 5W5

ABSTRACT: Commercial plate tests from four seed labs for seed-borne Fusarium graminearum and total Fusarium spp. were summarized. A total of 1656 wheat, 884 durum, 640 barley, and 263 oat samples were reported. Compared to 2021, combined frequency of all four crops F. graminearum-free samples decreased from 95.6% to 70.8% and mean percent infection rates were up from 0.9% to 2.4%. Total Fusarium spp. frequency and severity increased significantly compared to those reported in 2021.

INTRODUCTION AND METHODS: Test results from four seed testing laboratories were acquired and combined. The tests were conducted from September of 2022 through May 2023 and are assumed to be from the 2022 crop. These tests were conducted by either agar-plating or quantitative polymerase chain reaction (PCR) techniques. In the case of PCR tests, the presence or absence of DNA of all Fusarium spp. or of F. graminearum allowed calculation of percent infection. No attempt was made to select fusarium-damaged kernels (FDK) so the samples can be considered random. The percent frequency of all Fusarium spp. including F. graminearum (total Fusarium), and the percent frequency of F. graminearum alone, were calculated. The mean percent infection was calculated for both total Fusarium spp. and F. graminearum. Individual Fusarium spp. other than F. graminearum were not reported, as not all labs provided that information. The results of 3443 tests were combined, reported by Saskatchewan crop district and provincial means determined. Percentage germination was also reported.

RESULTS AND COMMENTS: Growing conditions in western Canada were much improved compared to 2021 although parts of the Prairies still encountered insufficient soil moisture levels (Statistics Canada 2022). Crops matured normally and weather conditions favoured a timely harvest. Problems due to variable soil moisture including drought and spring flooding, Richardson ground squirrels, and grasshopper infestations as well as high winds were reflected in yields, which varied widely across Saskatchewan. Below average yields in southwest and west-central regions were reported while above average yields were reported in the northern and eastern portions of the province. Average yield was estimated at 44 bushels per acre for hard red spring wheat, 31 bushels per acre for durum, 93 bushels per acre for oats, and 64 bushels per acre for barley (Saskatchewan Ministry of Agriculture 2022).

A total of 1656 wheat, 884 durum, 640 barley and 263 oat samples were processed during the period covered by this report. This represented an increase in durum samples (2.0%) and a decrease in oat (29.5%), wheat (32.7%) and barley (16.0%) samples compared to 2021 (Olson et al. 2023).

Fusarium graminearum frequency and severity (mean % infection) were calculated for wheat, durum, barley, and oat individually and combined. Frequency and severity of total Fusarium spp. were calculated individually and combined as well (Tables 1, 2, 3, 4 and 5). The frequency of F. graminearum in 2022 was 29.2%. This was significantly higher than the 4.4% reported in 2021 (Olson et al. 2023) but below the 2020 level of 33.5% (Olson et al. 2022) and the 2019 level of 40.6% (Olson et al. 2021). The 2018 level of 22.0% (Olson et al. 2020) was somewhat lower. At 2.4%, the severity of F. graminearum was the highest level in the past five years (Table 1). Total Fusarium frequency was 78.6%, which was above the previous year (Table 1). Total Fusarium severity was 5.9%, the highest level reported since 2018 (Table 1).

Table 1. Five-year summary of frequency (% PFS) and severity (mean % infection) of Fusarium graminearum and total Fusarium species on wheat, durum, barley and oat combined.

Combined frequency and severity
		Fusarium graminearum		Total Fusarium spp.^a
Year	No. of samples	% PFS^b	Mean % infection	% PFS	Mean % infection
2018^c	3307	78.0	1.4	28.4	3.3
2019	4529	59.4	1.8	17.6	4.5
2020	3983	66.5	1.5	15.8	4.2
2021	4515	95.6	0.9	35.4	2.9
2022	3443	70.8	2.4	21.4	5.9

^aTotal Fusarium spp. = all Fusarium spp. including F. graminearum.

^b% PFS = percent pathogen-free samples.

^c2018 (Olson et al. 2020), 2019 (Olson et al. 2021), 2020 (Olson et al. 2022), 2021 (Olson et al. 2023).

Table 2. Number of wheat samples tested from September 2022 to May 2023 and levels of infection with Fusarium graminearum and Fusarium spp. in each Saskatchewan crop district.

2022 seed-borne pathogens of wheat
	F. graminearum			Total Fusarium spp.
Crop district	# tests	% PFS^a	Mean % infection	# tests	% PFS	Mean % infection
1A	55	38.2	3	51	11.8	3.5
1B	63	58.7	2.7	45	2.2	3.1
2A	28	17.9	2.9	26	11.5	4
2B	105	92.4	2.9	50	4	1.6
3AN	9	100	0	8	87.5	0.5
3AS	9	88.9	0.5	7	85.7	0.5
3BN	52	98.1	0.5	51	49	1.4
3BS	0	ND^b	ND	0	ND	ND
4A	0	ND	ND	0	ND	ND
4B	7	100	0	6	66.7	0.5
5A	56	62.5	1.6	48	8.3	3.9
5B	98	87.8	0.5	98	19.4	2.1
6A	171	87.1	0.7	151	27.2	1.7
6B	208	88	1	207	32.9	1.5
7A	86	97.7	0.5	86	51.2	1
7B	110	92.7	0.7	108	22.2	1.2
8A	63	61.9	1.1	57	3.5	4.5
8B	123	52	1.1	123	4.9	3.7
9A	218	73.4	1.3	198	12.6	1.5
9B	195	70.8	1.3	158	7	4
Total/mean	1656	77	1.5	1478	20.2	2.5

^a% PFS = percent pathogen-free samples.

^bND = no data

Table 3. Number of durum samples tested from September 2022 to May 2023 and levels of infection with Fusarium graminearum and total Fusarium spp. in each Saskatchewan crop district.

2022 seed-borne pathogens of durum
	F. graminearum			Total Fusarium spp.
Crop district	# tests	% PFS^a	Mean % infection	# tests	% PFS	Mean % infection
1A	60	18.3	6.8	62	9.7	7.5
1B	12	83.3	4.0	13	15.4	4.0
2A	157	22.9	5.1	169	14.2	5.6
2B	203	42.9	2.8	189	5.8	4.5
3AN	26	84.6	1.3	23	30.4	1.5
3AS	161	67.1	1.6	145	33.8	2.2
3BN	53	88.7	1.5	53	54.7	2.1
3BS	10	100.0	0.0	10	90.0	1.0
4A	2	100.0	0.0	2	100.0	0.0
4B	20	100.0	0.0	19	68.4	0.8
5A	16	31.3	1.9	14	7.1	5.1
5B	1	100.0	0.0	1	0.0	1.0
6A	52	50.0	1.3	51	9.8	2.9
6B	33	60.6	1.1	30	26.7	2.7
7A	69	94.2	0.8	69	68.1	1.0
7B	8	100.0	0.0	7	28.6	1.4
8A	0	ND^b	ND	0	ND	ND
8B	1	100.0	2.5	1	0.0	9.0
9A	0	ND	ND	0	ND	ND
9B	0	ND	ND	0	ND	ND
Total/mean	884	54	3.6	858	25	4.1

^a% PFS = percent pathogen-free samples

^bND = no data

Table 4. Number of barley samples tested from September 2022 to May 2023 and levels of infection with Fusarium graminearum and total Fusarium spp. in each Saskatchewan crop district.

2022 seed-borne pathogens of barley
	F. graminearum			Total Fusarium spp.
Crop district	# tests	% PFS^a	Mean % infection	# tests	% PFS	Mean % infection
1A	20	35.0	3.3	19	15.8	4.6
1B	10	70.0	0.8	10	50.0	4.7
2A	15	26.7	4.3	18	16.7	2.4
2B	37	89.2	3.2	37	64.9	2.9
3AN	7	100.0	0	7	57.1	1.3
3AS	18	88.9	1.8	19	68.4	2.5
3BN	13	100.0	0	13	61.5	0.8
3BS	3	100.0	0	3	66.7	0.5
4A	0	ND^b	ND	0	ND	ND
4B	9	100.0	0	9	66.7	0.5
5A	16	56.3	1.4	16	31.3	6.2
5B	60	86.7	0.7	60	20.0	3
6A	77	70.1	0.8	77	27.3	2.5
6B	82	81.7	0.6	82	20.7	2
7A	27	88.9	0.5	27	40.7	0.8
7B	26	69.2	0.7	26	7.7	2.2
8A	32	53.1	1.2	30	3.3	6.3
8B	60	41.7	2	60	10.0	5
9A	75	72.0	1.5	73	5.5	5.3
9B	53	49.1	3.3	49	6.1	6.1
Total/mean	640	69.5	1.9	635	23.6	3.8

^a% PFS = percent pathogen free samples.

^bND = no data

Table 5. Number of oat samples tested from September 2022 to May 2023 and levels of infection with Fusarium graminearum and total Fusarium spp. in each Saskatchewan crop district.

2022 seed-borne pathogens of oat
	F. graminearum			Total Fusarium spp.
Crop district	# tests	% PFS^a	Mean % infection	# tests	% PFS	Mean % infection
1A	8	62.5	3	7	14.3	7.2
1B	7	57.1	0.8	6	33.3	4.6
2A	2	0	0.8	2	0	3
2B	9	100	0	8	62.5	2.4
3AN	1	100	0	1	100	0
3AS	2	100	0	2	100	0
3BN	1	100	0	1	100	0
3BS	0	ND^b	ND	0	ND	ND
4A	0	ND	ND	0	ND	ND
4B	0	ND	ND	0	ND	ND
5A	3	100	0	3	0	6
5B	33	87.9	0.5	32	9.4	5
6A	15	100	0	15	13.3	2.5
6B	33	97	0.5	33	18.2	4
7A	5	100	0	5	20	4.6
7B	5	100	0	5	0	7.3
8A	16	87.5	0.5	16	6.3	9.2
8B	16	87.5	0.5	16	0	6
9A	60	91.7	0.6	59	0	10.2
9B	47	91.5	1	38	2.6	1
Total/mean	263	90.1	0.9	249	10.4	5.9

^a% PFS = percent pathogen free samples.

^bND = no data

Wheat – The percentage of F. graminearum-free samples in 2022 was 77.0% (Table 2), down from the 97.2% reported in 2021 (Olson et al. 2023). The mean infection rate was 1.5%, up from the 0.8% reported in 2021. Total Fusarium spp.-free samples were 20.2% compared to 38.0% in 2021. The mean percent infection remained the same as 2021 at 2.5%. The 1676 samples had a mean germination rate of 95.1%. Rates of germination by crop district are shown in Table 6.

Table 6. Germination rates (%) of common and durum wheat, barley and oat from September 2022 to May 2023 in each Saskatchewan crop district.

	2022 combined germination
	Barley		Wheat		Durum		Oat
Crop district	# tests	Mean	# tests	Mean	# tests	Mean	# Tests	Mean
1A	21	95	63	97.2	66	93.6	8	95.7
1B	10	94.8	59	93.6	13	88.8	6	93
2A	17	92.3	30	95	172	90.6	2	95.5
2B	41	93.3	107	96.7	205	86.7	11	94.3
3AN	7	97.4	8	97	26	95.6	1	95
3AS	19	94.6	9	95.5	172	92.8	2	95
3BN	13	97	52	95.1	53	94.2	1	95.3
3BS	3	97	0	ND	10	96.0	0	ND
4A	0	ND^a	0	ND	2	93.6	0	ND
4B	9	98	9	98.3	23	91.0	0	ND
5A	16	96.2	57	90.3	16	87.3	3	96
5B	60	95.4	98	95	1	94.0	33	96.1
6A	77	96.9	171	96.4	52	91.6	15	98
6B	82	94	208	95	33	91.4	33	95.7
7A	27	95	86	97	69	93.7	5	98
7B	26	93	110	96.1	8	91.0	5	91.6
8A	32	94.3	63	94.3	0	ND	16	96
8B	60	94	123	94.4	1	82.8	16	97
9A	77	92.9	225	94.1	0	ND	60	95.4
9B	54	94.1	198	94.3	0	ND	47	93
Total/mean	651	94.6	1676	95.1	922	91	264	95.3

^aND = no data

Durum – Of the 884 samples, 54.0% were found to be F. graminearum-free. Mean percent infection was 3.6% (Table 3). In 2021, the frequency of F. graminearum-free samples was 88.1% and the mean percent infection was 1.0% (Olson et al. 2023). The total Fusarium spp.-free frequency was 25.0%, down from the 48.1% reported in 2021 and the mean percent infection was 4.1%, up from 1.5% in 2021. Mean germination rate of the 922 samples was 91.0%. Rates of germination by crop district are shown in Table 6.

Barley – The percentage of F. graminearum-free samples was 69.5% in 2022, down from 96.3% in 2021 (Olson et al. 2023). Mean infection was 1.9% compared to 0.9% in 2021. Total Fusarium spp.-free samples were 23.6%, down from 24.4% in 2021. The total Fusarium spp. mean infection was 3.8%, up from 3.1% in 2021 (Table 4). The reported mean germination rate of the 651 samples was 94.6%. Rates of germination by crop district are shown in Table 6.

Oat – Of the 263 samples, 90.1% were found to be F. graminearum-free. This was lower than the 99.7% reported in 2021 (Olson et al. 2023). Mean infection was 0.9%, up from 0.5% in 2021. Total Fusarium spp.-free samples were 10.4%, up from 9.7% in 2021. The total Fusarium spp. mean infection was 5.9%, down from 6.5% in 2021 (Table 5). Mean germination of the 264 samples was 95.3%. Rates of germination by crop district are shown in Table 6.

ACKNOWLEDGEMENTS: We would like to acknowledge the cooperation of 20/20 Seed Labs Inc., Lendon Seed Lab, Prairie Diagnostic Seed Lab, and Discovery Seed Labs Ltd. in providing the seed testing results that made this report possible. We also wish to acknowledge the funding support of the Saskatchewan Wheat Development Commission, the Saskatchewan Barley Development Commission and the Saskatchewan Oat Development Commission.

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CEREAL RUSTS AND WHEAT POWDERY MILDEW SURVEY AND TRIALS IN ONTARIO AND QUÉBEC IN 2023

CROP: Winter wheat, spring wheat, oat, barley and winter rye LOCATION: Ontario and Québec NAMES AND AGENCIES: M. LIU¹, S. LIM¹, P. SHOUKOUHI¹, S. HAMBLETON¹, J. CAREY¹, M. SERAJAZARI², H. BOOKER², M. PAVONE², Z. ZHANG², K. LEW², T. COPLEY³ & B. McCALLUM⁴

¹Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6 Telephone: [phone]; E-mail: [email protected] ²Department of Plant Agriculture, University of Guelph, Guelph, ON N1G 2W1 ³Centre de recherche sur les grains (CÉROM), inc, 740, chemin Trudeau, Saint-Mathieu-de-Beloeil, QC J3G 0E2 ⁴Morden Research and Development Centre, 101 Route 100, Morden, MB R6M 1Y5

ABSTRACT: Five winter wheat fields, four spring wheat fields, three oat fields and four barley fields located in Ontario were inspected for rust and/or wheat powdery mildew (Blumeria graminis) in 2023, while a total of 59 winter and spring wheat fields, of which eight were experimental sites, were scouted for wheat rust presence in Québec. Winter and spring wheat fields had light to heavy infection of leaf rust (Puccinia triticina) on many varieties. Crown (P. coronata var. avenae f. sp. avenae) and stem rusts (P. graminis) were observed in oat fields in Ontario, while only crown rust was observed in Québec. Puccinia coronati-hordei and P. graminis were found in patchy infections in barley fields in Ontario. Powdery mildew was found at light to medium levels on several varieties in late June to early July in Ontario, and at light to severe levels in multiple fields in early June in Québec. In an infection trial of B. graminis on winter wheat conducted at Elora Research Station, disease was observed on some varieties with severities ranging from 1 to 7 on a 0-9 scale.

INTRODUCTION AND METHODS: In Ontario, cereals were scouted for rust and powdery mildew on a scheduled timeframe in selected plots at the Central Experimental Farm in Ottawa (CEF, June 28, July 10, 11 and 18, August 1 and 8); the Winchester Agricultural Research Station (WARS, July 5 and 25); winter wheat fields in Casselman (July 10); the barley trial in Osgoode (July 25); a farmer’s winter wheat field in Carleton Place (July 24); a farmer’s barley field in Almonte (July 26); and the West Carleton 4-H Foodgrains Project barley plot in Carp (July 26). In Québec, cereal rusts were scouted two to three weeks post-flowering in winter and spring wheat, oat, barley, and winter rye plots at eight experimental sites located throughout the province, and in 51 producer fields where samples were taken only from wheat fields. The scouting spots were selected randomly at the sites, and the leaves and stems of the plants were examined for symptoms and signs of the diseases. One rust sample was collected from each scouted plot. The causal pathogens were identified based on symptoms and the morphology of pustules. DNA sequence analyses were performed on representative rust samples from Ontario to validate the morphological identifications, which were 17 samples in total accessioned in the Canadian National Mycological Herbarium (Ottawa, ON) as voucher specimens DAOM 985146 - 985162. Detailed methods for DNA extraction, PCR and sequencing were as described previously in Hambleton et al. (2019). A fragment comprising the nrDNA complete ITS2 plus partial 28S region was amplified and sequenced. For one specimen (‘leaf rust’ on ‘winter wheat’), the elongation factor 1-α (EF1-α) gene was sequenced for the rust as described in Liu et al. (2013) and ITS for the host using plant specific primers (Cheng et al. 2016) for additional validation of the rust ITS result. Sequences were edited using Geneious Prime 2022.2.2 (Biomatters, Auckland, New Zealand) and analyzed in comparison with previously published reference sequences (Liu et al. 2013). Powdery mildew samples were collected from plots, and processed for pathotyping studies (results will be reported separately).

In addition, a powdery mildew infection trial was conducted on winter wheat at the Elora Research Station (University of Guelph, ON). The winter wheat variety ‘Emperor’ was planted as a susceptible spreader in order to facilitate the natural spread of powdery mildew throughout the entire field. A scale ranging from 0 to 9 was used to assess powdery mildew severity in the winter wheat trials. A score of 0 denoted the absence of symptoms, while a score of 9 indicated high susceptibility to powdery mildew. The note-taking process commenced during the first week of July.

RESULTS AND COMMENTS: On winter wheat, leaf rust (Puccinia triticina Erikss.) was found as early as June 8 in Québec and early July in Ontario, and ranged from light to heavy infection depending on the varieties (Table 1). On July 24, a farmer’s field at Carleton Place was checked when the crops were very well advanced and nearly ready for harvest. Leaf rust was still found on some half-green leaves. There was no evidence of stem rust (Puccinia graminis Pers.). One rust sample from a winter wheat plot (PD Fert WW19/114) at WARS was identified as P. recondita Roberge ex Desm. f. sp. secalis (Clade IV-3 in Liu et al. 2013), on rye, based on ITS and EF-1 sequences for the rust and ITS for the host. The infections were heavy in patches, some having telia on the abaxial leaf surface. In Québec, P. recondita f. sp. secalis was also observed on winter rye in experimental plots in St-Mathieu-de-Beloeil, QC, in early July, with infections varying from light to moderate. Stripe rust (Puccinia striiformis Westend. f. sp. tritici Westend.) was observed as early as June 2 in five Québec farmer’s fields.

Table 1. Summary of rust samples collected and infection rates found in sampled fields in Ontario and Québec in 2023.

Pathogen	No. of samples^a	ITS^b	Host	Location^c	Date	Infection rate^d
P. coronata var. avenae f. sp. avenae	10	3	oat	CEF, Cen 2b	2023-07-18	trace to heavy
P. coronata var. avenae f. sp. avenae	4	0	oat	CEF, Fisher Scott 3	2023-07-18	trace to light
P. coronata var. avenae f. sp. avenae	4	0	oat	WARS	2023-07-05	trace
P. coronata var. avenae f. sp. avenae	2	0	oat	WARS	2023-07-25	moderate to heavy
P. coronati-hordei	2	0	barley	Osgoode	2023-07-25	trace
P. coronati-hordei	1	1	barley	WARS	2023-07-25	trace
P. graminis	2	1	barley	CEF, Fisher C5	2023-07-25	trace
P. graminis	3	1	barley	Osgoode	2023-07-25	trace
P. graminis	2	1	oat	WARS	2023-07-25	trace
P. recondita f. sp. secalis	1	1	rye^e	WARS	2023-07-05	patched heavy
P. triticina	1	0	spring wheat	CEF, CEN2A	2023-08-01	trace
P. triticina	6	1	spring wheat	CEF, CEN2A	2023-08-08	light to moderate
P. triticina	6	1	spring wheat	CEF, Fisher CFIA 8	2023-08-01	heavy
P. triticina	3	1	spring wheat	WARS	2023-07-25	moderate to heavy
P. triticina	1	0	spring wheat	Mirabel	2023-07-31	light to moderate
P. triticina	1	0	spring wheat	Ste-Anne-des-Plaines	2023-07-25	light to moderate
P. triticina	1	0	spring wheat	Scott	2023-08-01	trace
P. triticina	1	0	spring wheat	St-Eugène-de-Guigues	2023-07-23	light to moderate
P. triticina	1	0	spring wheat	Ste-Croix	2023-07-26	trace
P. triticina	1	0	spring wheat	St-Sylvère	2023-07-24	trace
P. triticina	9	2	winter wheat	Carleton Place	2023-07-24	trace^f
P. triticina	5	1	winter wheat	Casselman	2023-07-10	n.n.
P. triticina	10	2	winter wheat	CEF, Fisher CFIA	2023-07-10	n.n.
P. triticina	4	1	winter wheat	WARS	2023-07-05	light to moderate
P. triticina	2	0	winter wheat	Mirabel	2023-07-03	light to moderate
P. triticina	1	0	winter wheat	Ormstown	2023-06-08	light to moderate
P. triticina	1	0	winter wheat	St-Mathieu-de-Beloeil	2023-07-03	light to moderate
P. triticina	1	0	winter wheat	St-Anicet	2023-07-06	light to moderate
P. triticina	1	0	winter wheat	St-Césare	2023-07-07	light to moderate
P. striiformis	1	0	spring wheat	Fugèreville	2023-07-25	light to moderate
P. striiformis	1	0	spring wheat	Béarn	2023-07-25	light to moderate
P. striiformis	1	0	spring wheat	St-Eugène-de-Guigues	2023-07-23	light to moderate
P. striiformis	1	0	spring wheat	Coaticook	2023-07-07	trace
P. striiformis	1	0	winter wheat	St-Théodore d’Acton	2023-06-02	heavy
P. striiformis	1	0	winter wheat	St-Mathieu-de-Beloeil	2023-07-03	light to moderate
P. striiformis	1	0	winter wheat	Ormstown	2023-06-08	light to moderate
P. striiformis	1	0	winter wheat	St-Anicet	2023-07-06	trace to light
P. striiformis	1	0	winter wheat	Rivière-Héva	2023-07-11	trace
P. striiformis	1	0	winter wheat	St-Germain-de-Grantham	2023-07-19	trace to light

^aOne sample was collected for each plot.

^bNumber of samples, of which identifications were confirmed by ITS.

^cLocations defined CEF = Central Experimental Farm, Ottawa; WARS = Winchester Agriculture Research Station.

^dThe infection was scored as trace when <10% plants in the plot were infected, light 10 - 30 %, moderate 30 - 80%, heavy > 80%; n.n.= not noted.

^eIn winter wheat field, but ITS confirmed the host as rye.

^fIn a large farm field, not separated into plots.

In Ontario winter wheat fields, powdery mildew Blumeria graminis (DC.) Speer. was found in late June to early July in Ottawa (CFIA 6 plot at CEF), Winchester, and Moose Creek, with light to medium infection and some developing chasmothecia. The wheat varieties or lines were CM18-004, 16WE06-F9, 25W31, CRGBa16172.2.3.1, CRGBa13125.1.0.0, Ca14001-209, OAC Moon, B7000SRW, Hilliard, P25R64, and UGRC C2-5. In Québec, powdery mildew ranging from light to severe was observed in multiple fields in early June. The varieties were URGC-RING, 25R46 and Lexington.

At the Elora Research Station, the severity of powdery mildew in the entire field overall ranged from 1 to 7 on a 0-9 scale, signifying varying levels of infection. In the official winter wheat performance trial, the highest powdery mildew frequency of 22% was observed with a severity score of 4, indicating a significant portion of the wheat exhibited moderate symptoms. Only 2% of the wheat scored a 7, indicating a smaller portion had higher susceptibility to the disease. In an additional independent trial conducted on soft red winter pastry wheat at Elora Research Station, a high frequency of powdery mildew reaching 26% was noted with a severity score of 4, slightly higher than in the official trial. Only 6% had a severity score of 7, once again indicating a smaller portion of wheat had a higher susceptibility to the disease in these trials.

On spring wheat, P. triticina was found in various plots in Winchester in late July, ranging from trace to heavy infection; and in Ottawa in early August (Aug. 1 and 8), with heavy infection in the Fisher plots and light to medium infection at Cen 2a. For B. graminis, very light and sporadic infections were found in late June to early July in Ottawa (Cen 2a plot at CEF) and Winchester. The wheat varieties were ECSW 277, Furano, and Agora. In Québec, P. triticina was observed in plots at several experimental sites and in four producer’s fields from late-July to early August, with infections ranging from light to heavy, while light infection of P. striiformis was observed in four farmer’s fields in mid-July. No cases of B. graminis were observed in spring wheat in Québec.

In oat fields, crown rust (P. coronata Corda var. avenae f. sp. avenae) was found occasionally in early July in Winchester. Two weeks later (July 18), light to heavy infections were observed in various plots in Ottawa (CEF), while a single, elongated, darker pustule suspected to be stem rust (P. graminis Pers. f. sp. avenae) was found on the stem of one plant at CEF. In late July, stem rust was found on several plant patches in Winchester, while light to heavy infections of crown rust were also observed throughout the plots. Crown rust was observed in oat experimental plots throughout July in Québec, with very light to moderate infection levels.

In barley fields, P. graminis and a rust species on leaves were observed in late July in Osgoode, Ottawa, and Winchester as patchy infections. The latter was identified as P. coronati-hordei M. Liu & Hambl. (Liu and Hambleton 2013) based on ITS sequence analyses. A farmer’s barley field (varieties ESMA and BADEN) in Almonte was clean, and the West Carleton 4-H Foodgrain project plots (two-row barley) were free of rust infections. Neither leaf nor stem rust were observed on barley in Québec.

The analyses of ITS sequences of representative rust samples collected in Ontario confirmed all but one ‘leaf rust’ sample on ‘winter wheat’ (noted in the winter wheat paragraph above). The sequence identification was instead P. recondita f. sp. secalis on rye.

In comparison with the previous disease survey reports of cereal crops in Ontario, a noticeable difference was that barley fields were relatively cleaner in terms of rust and powdery mildew diseases in 2023. For example, in 2021 among the 17 surveyed fields, leaf rust (P. hordei) was observed in 13 barley fields with moderate severity (average 3.1) and one field with severe infection; stem rust in seven fields with light infections (average severity 1.3); and powdery mildew in two fields with moderate severity (3.5) and one field with severe infection (Xue and Chen 2022a). However, in 2023, we found only sporadic trace infections of P. graminis and P. coronati-hordei, and no powdery mildew on barley. For oat, the prevalence and severity of crown rust in 2023 were similar to those in 2021 (Xue and Chen 2022b). For spring and winter wheat, moderate to heavy infections of leaf rust (P. triticina) were found in 2023, especially during late of the growing season, whereas in 2021 the severities were rated as slight (avg. 1.6 – 1.8, Xue and Chen 2022c, 2022d). In addition, slight stem rust (P. graminis) infections were reported in 2018, 2019 and 2021 (Xue and Chen 2019, 2020, 2022c), and stripe rust (P. striiformis) in 2018 (Xue and Chen 2019). We did not find any stem or stripe rusts on wheat in 2023 in Ontario plots.

In Québec, wheat leaf rust severity and prevalence were similar to previous years, whereas barley leaf rust was less prevalent (T. Copley, personal observation). For example, in 2022, two registration trial sites reported an average severity of 3 on a scale of 9 (0, absence of disease; 9, more than 50 of the top three leaves affected) for barley leaf rust, compared to an average of 1 from 2019 to 2021. Stripe rust was more prevalent than in previous years, with infections being generally light, except in one field, where severe infections were observed in a localized area of the field on June 2^nd. Severe infections of stripe rust had not been observed in Québec winter wheat or spring wheat since 2019 and 2018, respectively. Oat crown rust was less prevalent in registration trials in 2023 than in previous years; two sites in 2023 compared to six in 2022, seven in 2021, and absent in 2020. Oat crown rust severity was lower in 2023 and 2022 at 2.2 (out of 9) compared to 2021 (4.4). Winter rye leaf rust prevalence and severity were similar to those in 2022, with a presence at three registration trial sites compared to two in 2022 and an average severity of 3 compared to 3.6 in 2022. Winter rye leaf rust was present at three sites in 2021 with a lower severity (1.4) and absent in 2020. Stem rust of oat and barley have not been reported since very mild infections in 2022 in Québec.

ACKNOWLEDGEMENTS: We would like to thank Yuanhong Chen, Christina Thomsen, Xuelian Wang, Oliver Wu, Elsa Reimer, Debbie Miranda, Nadine Dionne, Taye Zegeye-Gebrehiwot for technical support; Andrew Burt, Gavin Humphreys, Raja Khanal, Charlene Wight, and Weikai Yan at Central Experiment Farm; Holly Byker at Winchester Agricultural Research Station; John Norton, Andrew & Jenny Ross (West Carleton); Jean & Paul Sullivan (Carp); and Adam Cochran (Almonte) for granting permission to enter their research or commercial fields. We would also like to thank the agri-environmental consulting clubs (CCAE) in Québec for scouting of fields. This work was made possible by funding from the Agriculture and Agri-Food Canada A-base project ‘Toward a Prairie Biovigilance Network’, AAFC-STB-MRS Project No. J-002517, and by the ministère d’Agriculture, des Pêcheries et de l’Alimentation du Québec through the Programme de recherche bioalimentaire (2023-2028).

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STATUS OF CORN DISEASES IN EASTERN ONTARIO, 2023 CROP SEASON

CROP: Corn LOCATION: Eastern Ontario NAMES AND AGENCIES: X. ZHU¹, A. Z. KEBEDE¹ & T. WOLDEMARIAM¹

¹Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, ON K1A 0C6 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: Fifty-three corn fields were surveyed in Eastern Ontario in 2023. The most damaging diseases were northern corn leaf blight (25, 47.2%), common smut (25, 47.2%), and pythium stalk rot (10, 18.9%). Mean severities or incidences of 1.2±0.4, 1.2±0.2, 1.1±0.2, 1.5±1.0, 1.1±0.3, 1.3±0.2, 1.1±0.2, 1.9±4.8, 0.1±0.2, 0.0±0.1, 1.7±6.8, and 39.2±23.9, were recorded for anthracnose leaf blight, eyespot, grey leaf spot, northern corn leaf blight, northern leaf spot, physoderma brown spot, rust, common smut, head smut, ear rot, pythium stalk rot, and top dieback, respectively. Among 25 NCLB fields, two had a severity of 5.0 and 6.5. Nine (36%) of NCLB fields had resistant lesions, which means 36% of commercial hybrids had NCLB resistant genes. Among 25 common smut fields, six had incidence ranging from 8% to 23%. Three fields had pythium stalk rot incidence ranging from 21% to 41.8%. Stewart’s bacterial wilt, Goss’s bacterial wilt, and tar spot were not detected.

INTRODUCTION AND METHODS: To document the occurrence of various corn diseases in Eastern Ontario, a survey was conducted on September 15^th, September 18^th to 20^th, and October 20^th, 2023. The fifty-three corn fields surveyed, based on GPS coordinates (latitude and longitude), are presented in Figure 1. These fields included four Ontario Corn Committee (OCC) trials, nine seed company demonstration fields, four breeding nurseries, and thirty-nine other corn fields. The surveyed diseases included anthracnose leaf blight (ALB) (Colletotrichum graminicola (Ces.) G.W. Wilson); eyespot [Aureobasidium zeae (Narita & Hiratsuka) Dingley]; grey leaf spot (GLS) (Cercospora zeae-maydis Tehon & E.Y. Daniels); northern corn leaf blight (NCLB) [Exserohilum turcicum (Pass.) K.J. Leonard and E.G. Suggs]; northern corn leaf spot (NLS) [Bipolaris zeicola (G.L. Stout) Shoemaker]; physoderma brown spot (PBS) [Physoderma maydis Miyabe (Miyabe)]; southern corn leaf blight (SCLB) [Bipolaris maydis (Y. Nisik. & C. Miyake) Shoemaker]; tar spot (Phyllachora maydis Maubl.); common rust (Puccinia sorghi Schwein.); southern rust (P. polyspora Underw.); common smut [Ustilago maydis (DC.) Corda]; head smut [Sphacelotheca reiliana (Kuhn) G.P. Clinton]; ear rot (Fusarium spp.), pythium stalk rot (PSR) (Pythium spp.); top dieback (TDB) (C. graminicola); Stewart’s bacterial wilt (Pantoea stewartii); and Goss’s bacterial wilt and blight (Clavibacter michiganensis subsp. nebraskensis).

Fig. 1 2023 Eastern Ontario corn disease survey sampling sites indicated by dot marks. Circles indicate where the severity of northern corn leaf blight was ≥ 5, and x’s where the incidence of pythium stalk rot was ≥ 20%.

A rating scale of 1-7 based on percent area diseased, where 1= no disease and 7= severely diseased, was used for recording leaf disease severity (Reid and Zhu 2005). Disease incidence was based on the number of plants with a particular disease symptom for ear and stalk diseases. Leaf samples showing typical NCLB symptoms (long, elliptical, 2-15 cm, tan, or greyish-green necrotic lesions) were collected from each field visited for E. turcicum race identification and distribution patterns. Additional symptomatic plant parts were also collected for subsequent laboratory analysis, especially for unknown or suspected Goss’s bacterial wilt, Stewart’s bacterial wilt, and tar spot.

RESULTS AND DISCUSSION: The year 2023 saw average temperatures but a rainy corn season in Eastern Ontario. There was 582.8 mm rainfall from May 1^st to October 15^th, about 165 mm more than recent 10-year average at the Central Experimental Farm, Ottawa, ON, in which 349.5 mm (60%) of rain occurred in 10 days: 2, 3, 3, 1, and 1 day(s) in June, July, August, September and October, respectively. The period for kernel filling from August 15 to Oct 5 was dry, with only 71.3 mm of rain. The year 2023 had fewer leaf and ear diseases and less disease severities compared to recent years, while common smut, pythium stalk rot, and top dieback were slightly higher.

Leaf diseases: PBS (33 fields, 62.3%) was the most frequent leaf disease in Eastern Ontario in 2023, followed by NCLB (25 fields, 47.2%), eyespot (22 fields, 41.5%), ALB (17 fields, 32.1%), GLS (13 fields, 24.5%), common rust (seven fields, 13.2%), and NLS (three fields, 5.7%), (Table 1). The average severities were 1.2±0.4, 1.2±0.2, 1.1±0.2, 1.5±1.0, 1.1±0.3, 1.3±0.2, and 1.1±0.2 for ALB, eyespot, GLS, NCLB, NLS, PBS, and rust, respectively (Table 1). Two Ontario Corn Committee trials had an ALB severity of 2.5 (diseased leaf area ≈ 3%) and 3 (diseased leaf area ≈ 5%) at Winchester and Bainsville in the county of Stormont, Dundas and Glengarry. Eight fields had an NCLB severity ≥ 2, one in Frontenac, one in Carleton-Ottawa, five in Stormont, Dundas and Glengarry, and one in Prescott and Russell. The one in Carleton-Ottawa was a demonstration field for four seed companies, where some hybrids had a severity of 5 (diseased leaf area ≈ 20 -50%) (Fig. 1). The field in Prescott and Russell had a severity of 6.5 (diseased leaf area ≈ 80%) near the trees, but only 2.5 (diseased leaf area ≈ 3%) at the far end without trees (Fig. 1). Among all 25 NCLB fields, nine (36%) showed resistant lesions, which meant at least 36% of commercial hybrids had NCLB resistance genes. One leafy (silage) hybrid corn in Stormont, Dundas and Glengarry had both NLS and NCLB severity of 3, for a diseased leaf area ≈ 10%. The fields in Lanark and Renfrew had the least leaf disease severity. Southern corn leaf blight, southern rust, tar spot, Stewart’s bacterial wilt, and Goss’s bacterial wilt were not observed in Eastern Ontario in 2023.

Table 1. Corn disease occurrence and severity or incidence in Eastern Ontario grouped by county.

County	No. fields	Disease severity^b and incidence^c
		ALB^a	Eyespot	GLS	NCLB	NLS	PBS	Rust	Common Smut	Head smut	Ear rot	PSR	TBD
Carleton-Ottawa	15	5	4	4	6	1	14	1	11	0	1	6	10
Frontenac	2	0	1	0	2	0	1	0	0	1	0	2	2
Lanark	3	0	0	0	0	0	2	1	2	0	0	0	3
Leeds & Grenville	5	1	3	3	2	0	2	0	2	1	0	0	5
Prescott and Russell	5	1	2	0	2	0	1	0	2	0	0	0	2
Renfrew	9	0	2	0	0	0	4	2	3	0	0	0	7
Stormont, Dundas & Glengarry	14	10	10	6	13	2	9	3	5	1	0	2	11
Total	53	17	22	13	25	3	33	7	25	3	1	10	40
Overall severity or incidence (%) (Mean±SD)		1.2±0.4	1.2±0.2	1.1±0.2	1.5±1.0	1.1±0.3	1.3±0.2	1.1±0.2	1.9±4.8	0.1±0.2	0.1±0.0	1.7±6.8	39.2±23.9

^aALB = anthracnose leaf blight, GLS = grey leaf spot, NCLB = northern corn leaf blight, PBS = physoderma brown spot, Rust = common rust, Ear rot = includes gibberella ear rot and fusarium ear rot, PSR = pythium stalk rot, TDB = top dieback.

^bDisease severity in affected corn was rated as percentage of leaf area with symptoms; ALB (anthracnose leaf blight), common rust, eyespot, GLS (grey leaf spot), NLS (northern leaf spot), and tar spot were rated on a 1-7 scale, where 1=no symptoms, 2≤1%, 3=1-5%, 4=6-20%, 5=21-50%, 6≥50 % leaf area with symptoms, and 7= most of the leaves dead; NCLB (northern corn leaf blight on a 1-7 scale based on percentage of leaf area with symptoms, where 1=no symptoms; 2≤1% leaves with symptoms; 3≤10% leaves with symptoms; 4≤25% leaves with symptoms; 5≥50% lower leaves and >25% of the center and upper leaves with symptoms; 6=lower leaves dead, >50 center leaves and >25% upper leaves with symptoms; 7=most leaves almost dead. For all leaf diseases, if infected plant incidence was <1% and severity <2 (infected leaf area <1%), severity was rated as 1.5.

^cIncidence (%) = (number of affected plants/total number of plants observed) x 100 for common smut, head smut, ear rot, pythium stalk rot, and top dieback.

Ear diseases: At the time of the 2023 survey, common smut (25 fields, 47.2%), head smut (three fields, 5.7%), and ear rot (one field, 1.9%) had an average incidence of 1.9±4.8, 0.1±0.2, and 0.0±0.1, respectively (Table 1). At two breeding nurseries and two OCC trials in Carleton-Ottawa, some genotypes had common smut incidences ranging from 8% to 23%; at another OCC trial in Stormont, Dundas and Glengarry, one hybrid had a common smut incidence of 14.5%; and one hybrid in Prescott and Russell had a common smut incidence of 8%. In all other fields, common smut incidence was < 1%. Three fields had head smut (Table 1); all had incidences <1%, but the field in Leeds and Grenville, and the field in Stormont, Dundas and Glengarry had had head smut for three years. Only one field of food corn had gibberella ear rot; incidence increased from 5% on September 15^th to 45% on October 20^th. No gibberella ear rot was found on commercial hybrids at the survey time.

Stalk diseases: At the 2023 survey time, PSR (10 fields, 18.9%) and TDB (40 fields, 75.5%) were recorded with an average incidence 1.7±6.8 and 39.2±23.9, respectively (Table 1). Two commercial hybrids had PSR incidences of 21% and 22% in Carleton-Ottawa, and Stormont, Dundas and Glengarry Counties (Figure 1). At a breeding nursery in Carleton-Ottawa, PSR incidence was up to 41.8%. TDB incidence depended on crop maturity and ranged from none to 50, 80 or 100% at the survey time. ALB was not observed in most fields with TDB in 2023.

Other pests: Corn leaf aphid (Rhopalosiphum maydis (Fitch)), corn rootworm, a mix of northern cornroot worm [Diabrotica longicornis (Say)] and western cornroot worm (D. virgifera); European corn borer [Ostrinia nubilalis (Hübner)], grasshoppers (Melanoplus spp.), Japanese beetle (Popillia japonica Newman) and corn blotch leaf miner (Agramyza parvicornis Loew), were found in five (9.4%), 22 (41.5%), two (3.8%), 34 (64.2%), four (7.5%), and 15 (28.3%) fields, respectively. Two-spotted spider mite (Tetranychus urticae Koch = T. bimaculatus Harvey) was observed in five (9.4%) fields. Thirteen fields (24.5%) had bird and other animal damage. Eleven fields (20.8%) hail damage at survey time.

ACKNOWLEDGEMENTS: This survey was supported in part by the AAFC Growing Forward Partnership with the Canadian Field Crop Research Alliance (CFCRA) through funding from the Canadian Agricultural Partnership (CAP) a federal-provincial-territorial initiative which is administered by the Agricultural Adaptation Council. We would also like to thank farmers, our grower co-operators, various seed companies and the Ontario Corn Committee (OCC) for access to their fields.

REFERENCES

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CROWN RUST OF OAT IN MANITOBA, ONTARIO, QUEBEC, AND SASKATCHEWAN IN 2022

CROP: Oat LOCATION: Manitoba, Ontario, Quebec, Saskatchewan NAMES AND AGENCIES: J.G. MENZİES¹, S. DECEUNİNCK¹ & Z. POPOVİC¹

¹Agriculture and Agri-Food Canada, Morden Research and Development Centre, 101 Route 100, Morden, MB R6M 1Y5 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: Fifty-six fields with wild oats and 97 fields of common oats were surveyed for the incidence and severity of crown rust [Puccinia coronata var. avenae f. sp. avenae (Urban and Marková)] in Manitoba and Saskatchewan in 2022. Crown rust-infected plants were found in 100% and 97% of wild and common oat fields at mean incidences of 64% and 38%, and mean severities of 2MR-MS and 4MR-MS, respectively. Virulence was observed to all resistance genes in 209 single pustule isolates from Manitoba and Saskatchewan. There was no virulence expressed to Pc50, Pc96, Pc98, and Pc101 of the 24 differential oat lines for the 25 spi tested from Ontario and Quebec.

INTRODUCTION AND METHODS: Surveys for the incidence and severity of oat crown rust, caused by Puccinia coronata var. avenae f. sp. avenae (Urban and Marková) (Liu and Hambleton 2013), were conducted in Manitoba and Saskatchewan from August 5 to 18, 2022. The areas surveyed were in Manitoba Crop Districts 1, 2, 3, 7, 8, 9, 11, and 13, and Saskatchewan Crop Districts 2B and 6A. Incidence was considered to be the percentage of leaves infected with rust in a given field, and the severity was the mean percentage leaf area with pustules. Crown rust-infected leaf collections were obtained from wild oat (Avena fatua L.) and common oat (A. sativa L.) in the fields, and susceptible and resistant oat lines and cultivars grown in uniform rust nurseries (URN). The URN collections were made at Brandon, MB, Casselman, ON and Ottawa, ON. Samples from fields in Ontario and Quebec were collected from July 5 to 25, and crown rust samples from the Manitoba were also provided by Dr. T. Zegeye (Morden Research and Development Centre). For virulence studies, single-pustule isolates (spi) were established from the rust collections. Races were identified using 16 standard oat crown rust differentials (Table 1) as described by Chong et al. (2000, 2008). In addition, single Pc-gene lines with Pc91, Pc94, Pc96, temp_pc97, temp_Pc98, Pc101, Pc103-1, and Pc104 were used as supplemental differentials.

Table 1. Frequencies (%) of virulence of Puccinia coronata f. sp. avenae isolates on 16 standard and eight supplemental crown rust differential oat lines from Manitoba, Saskatchewan, and Eastern Canada (Ontario and Quebec) in 2022.

Oat lines and Pc gene present	Wild oat^a		Commercial oat^a		URN^b		Eastern Canada
	# isolates	Percent	# isolates	Percent	# isolates	Percent	# isolates	Percent
Standard
Pc38	80	98	126	99	8	100	25	100
Pc39	82	100	127	100	8	100	23	92
Pc40	15	18	15	12	0	0	3	12
Pc45	80	98	113	89	5	63	9	36
Pc46	59	72	89	70	6	75	21	84
Pc48	78	95	114	90	7	88	25	100
Pc50	3	4	12	9	1	13	0	0
Pc51	78	95	117	92	3	38	22	88
Pc52	75	91	108	85	7	88	24	96
Pc54	7	9	5	4	0	0	1	4
Pc56	81	99	127	100	8	100	25	100
Pc58^c	5	6	12	9	0	0	3	12
Pc59^c	12	15	21	17	1	13	7	28
Pc62	12	15	11	9	0	0	5	20
Pc64	8	10	8	6	0	0	4	16
Pc68	79	96	123	97	8	100	25	100
Supplemental
Pc91	71	87	114	90	5	63	11	44
Pc94	4	5	25	20	2	25	3	12
Pc96	1	1	8	6	0	0	0	0
Temp_Pc97	1	1	5	4	0	0	2	8
Temp_Pc98	3	4	3	2	0	0	0	0
Pc101	9	11	114	90	1	13	0	0
Pc103-1	26	32	43	34	1	13	8	32
Pc104	27	33	32	25	3	38	9	36
Total	82		127		8		25

^aSpi (single pustule isolates) from wild oat and commercial oat plants were collected as part of the survey of Manitoba and Saskatchewan during August 5-18, 2022.

^bCollections of infected leaves were made from uniform rust nurseries (URN) planted in Manitoba and Ontario in 2022.

^cThe Pc58-differential was shown to carry three linked genes and the Pc59-differential three unlinked genes (Chong et al. 2008).

RESULTS AND COMMENTS: Fifty-six fields with wild oats and 97 fields of common oat lines were surveyed in Manitoba in 2022. Oat plants infected with P. coronata var. avenae f. sp. avenae were found in 56 (100%) of the wild oat fields, and 94 (97%) of the common oat fields.

Crown rust incidence on wild oats ranged from trace to 100%, with a mean incidence of 64%. The severity of crown rust on wild oats ranged from 1MR to 80S with a mean severity of 2MR-MS. Crown rust incidence on commercial oats ranged from 0 to 100%, with a mean incidence of 38%. The severity of crown rust on common oats ranged from 0 to 30S with a mean severity of 4MR-MS. The incidence and severity of crown rust was greater in South Central Manitoba Crop Districts 7 and 8, and very low in Manitoba Crop District 2.

Eighty-two spi were obtained from wild oat collections from Manitoba and Saskatchewan, and 62 races were identified. Fifty-three (85%) races (Chong et al. 2000) were each represented by only one spi. The most common race was JTQG-91 represented by six spi, followed by JTQG-91, 103-1 represented by five spi. Virulence was observed to all the Pc genes in the spi from wild oat (Table 1). Virulence was <5% for Pc50, Pc94, Pc96, Pc97, and Pc98, and was observed in 85% or more of the spi from wild oat for Pc38, Pc39, Pc45, Pc48, Pc51, Pc52, Pc56, Pc68, and Pc91.

One hundred and twenty-seven spi were made from common oat collections from Manitoba and Saskatchewan, with 99 races identified; 83 (84%) races were represented by only one spi. The two most common races were JTQG-91 and JTQG-91,103-1, which were represented by seven spi each. Virulence was observed to all Pc genes (Table 1). Virulence to Pc54, Pc97 and Pc98 was observed in <5% of the spi. Virulence to Pc38, Pc39, Pc48, Pc51, Pc56, Pc91, and Pc101 was observed in 90% or more of the spi.

Overall, for the wild oat and common oat spi in Manitoba and Saskatchewan, virulence was observed to all Pc genes, but less than 5% of the spi possessed virulence to Pc96, Pc97, and Pc98.

Eight spi were obtained from collections from the URNs in Manitoba and Ontario, and eight races identified. Virulence was not observed to resistance genes Pc40, Pc54, Pc58, Pc62, Pc64, Pc96, Pc97, and Pc98 (Table 1). Virulence was observed in 100% of the spi for resistance genes Pc38, Pc39, Pc 56, and Pc68.

Twenty-five spi were made from collections made in Ontario and Quebec (eastern Canada), and 22 races identified. Twenty races (91%) were represented by one spi. Race DTQK-104 was represented by three spi, and race BTQG-103-1 was represented by two spi. Virulence was not observed to resistance genes Pc50, Pc96, Pc98, and Pc101, and only one of the 26 spi had virulence to Pc54 (Table 1). All spi were virulent to Pc38, Pc48, Pc56, and Pc68, and virulence to Pc38 and Pc52 was observed in >90% of all spi.

Virulence to resistance genes Pc38, Pc39, Pc56, and Pc68 was observed at >95% with all Canadian spi from the 2022 collection. Virulence was observed at 5% or less to Pc96 and Pc98.

REFERENCES

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WHEAT FOLIAR DISEASE SURVEY IN ALBERTA, 2023

CROP: Wheat LOCATION: Alberta NAMES AND AGENCIES: M.W. HARDING¹, J. FENG², T.K. TURKINGTON³, S. REHMAN⁴, H. KLEIN-GEBBINCK⁵, R. ABOUKHADDOUR⁶, G.C. DANIELS¹, L. STELLAR^1, S. XUE^2, Y. YANG², N. RAUHALA², J. BUSAAN² & S. WATERMAN⁴

¹Crop Diversification Centre South, Alberta Agriculture and Irrigation, 301 Horticulture Station Rd. E, Brooks, AB T1R 1E6 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Crop Diversification Centre North, Alberta Agriculture and Irrigation, 17507 Fort Road NW, Edmonton, AB T5Y 6H3 ³Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, 6000 C&E Trail, Lacombe, AB T4L 1W1 ⁴Field Crop Development Centre, Olds College, 5030 50th Street, Lacombe, AB T4L 1W8 ⁵Beaverlodge Research Farm, Agriculture and Agri-Food Canada, Beaverlodge, AB T0H 0C0 ⁶Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1 Ave. S, Lethbridge, AB T1J 4B1

ABSTRACT: Wheat leaf diseases were monitored in 181 fields in 59 counties in Alberta in 2023. Symptoms of foliar fungal diseases such as tan spot, speckled leaf blotch, and stagonospora leaf blotch were rated together as a leaf spot complex. Symptoms of stripe rust, powdery mildew, bacterial leaf streak and wheat streak mosaic virus (WSMV) were also recorded. Fungal leaf spot symptoms were reported in 100% of fields and 67% of plants with an average percent leaf area damaged of 10.6%. Stripe rust of wheat was seen at trace levels in two fields and WSMV, ergot, smut and bacterial leaf streak were observed.

INTRODUCTION AND METHODS: Wheat fields were surveyed between the early heading and hard dough stages from June 28 to August 3, 2023. One hundred and eighty-one fields in 59 wheat-growing counties were evaluated (Fig. 1). In-field assessments were performed at five points along a “diamond-shaped” sampling pattern with the first a minimum of 25 m into the field, and remaining points 25 m apart. Disease symptoms at each sampling point were recorded and five flag leaves were randomly collected at each of the five sampling points in each field (n=25 per field). Leaves were air dried for 48 to 96 h in a cool dry room and subsequently stored at 4°C. The collected leaves were visually assessed for percent leaf area damaged (PLAD) and used for determination of causal agents. Three leaf pieces (5 cm) per sample were flushed with tap water for 1 h, then surface sterilized in 1% NaOCl for 1 min, briefly rinsed and plated on water agar. Leaf spot pathogens were identified under microscope 4-7 days after plating and transferred to a fresh agar plate. Isolates were identified via DNA barcoding using primer sets ITS1/ITS4 (White et al. 1990) for the ITS region and T1/Bt2b (Zhao et al. 2021) for the TUB2 gene T1/Bt2b. In addition to the 25 randomly collected leaves, any leaves with suspicious symptoms of stripe rust, powdery mildew, bacterial leaf streak (BLS) or wheat streak mosaic virus (WSMV) infection were tested for the presence the causal agent(s). DNA and RNA were extracted from symptomatic leaf pieces. Primer and probe sets P-Xtt and P-Xtu (Fu et al. 2023) were used for qPCR detection of the BLS pathogen Xanthomonas translucens. The primer and probe set developed by Price et al. (2010) was used for qPCR of WSMV.

Fig. 1 Wheat disease survey locations, and percent leaf area damaged (PLAD) categories, in Alberta in 2023.

RESULTS AND COMMENTS: Disease prevalence and severity of six wheat leaf diseases are shown in Table 1. Fungal leaf spot symptoms were the most commonly observed, present in 97.9% of fields on 94.9% of leaves. Fungal isolates were recovered from 28 of the 181 fields. The most commonly occurring leaf spot pathogen was Pyrenophora tritici-repentis which was isolated from 21 fields. Other pathogens detected were Parastagonospora nodorum, Selenophoma linicola, Pa. avenae, Pa. teres, and Pa. graminea (Table 2). BLS was reported in 3.9% of fields, followed by powdery mildew and wheat streak mosaic each seen in 0.5% of fields (Table 1). BLS continues to be a problem in wheat in Alberta while stripe rust and powdery mildew are rarely seen (Harding et al. 2022, 2023). Fields with BLS were mainly concentrated in southern Alberta (Fig. 2). The pathogen causing BLS was Xanthomonas translucens pv. undulosa in five of the fields and X. translucens pv. translucens in two of the fields.

Fig. 2 Wheat disease survey locations (small grey dots), and locations where BLS was confirmed (large blue dots) in Alberta, 2023.

Table 1. Disease symptoms observed in 181 wheat fields in Alberta in 2023.

Disease	Prevalence (%)	Incidence (%)	PLAD^a
Fungal leaf spot	100	67	10.62
Stripe rust	0	0	0
WSMV	0.5	n.d.^b	n.d.
Bacterial leaf streak	3.9	n.d.	n.d.
Powdery mildew	0.5	n.d.	n.d.

^aPLAD = percent leaf area damaged.

^bn.d. = not determined.

Table 2. Prevalence of fungi isolated from 28 wheat fields with leaf spot symptoms in Alberta, 2023.

Pathogen	Prevalence
Pyrenophora tritici-repentis	21/28
Parastagonospora nodorum	2/28
Selenophoma linicola	2/28
Pa. avenae	1/28
Pa. teres	1/28
Pa. graminea	1/28

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2023 WHEAT LEAF DISEASE SURVEY IN ALBERTA, SASKATCHEWAN, AND MANITOBA

CROP: Wheat LOCATION: Alberta, Saskatchewan and Manitoba NAMES AND AGENCIES: T.K. TURKINGTON¹, M.A. HENRIQUEZ², R. ABOUKHADDOUR³ & B. MCCALLUM²

¹Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, 6000 C&E Trail, Lacombe, AB T4L 1W1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Morden Research and Development Centre, Agriculture and Agri-Food Canada, Morden, MB R6M 1Y5 ³Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Ave. S, Lethbridge, AB T1J 4B1

ABSTRACT: In 2023, collaborator-collected flag leaf samples were obtained from 50 commercial wheat fields in the Prairie region. These were kindly mailed by collaborators to the Lacombe Research and Development Centre, Agriculture and Agri-Food Canada (AAFC). Disease assessments were done by AAFC staff based on rating the percentage of the flag leaf area that was affected by the leaf spot complex. Leaf spot complex levels were generally low, especially in Manitoba and Saskatchewan. No bacterial leaf streak, stripe rust or leaf rust was observed in the samples collected in 2023.

INTRODUCTION AND METHODS: A survey to document leaf diseases of wheat was conducted in 50 Prairie fields across Alberta, Saskatchewan and Manitoba typically in late July/August 2023. Leaf collections were made at the late milk to soft dough stage by volunteer producers, extension/industry staff and researchers. Collaborators were each sent a kit with survey instructions and materials to collect five flag leaves randomly at each of five sampling sites along a “diamond-shaped” sampling pattern, for a total of 25 leaves per field. In addition to the sampling kit, a questionnaire was included to collect information on cropping practices related to rotation, fungicide use, variety, etc. The leaf samples and completed questionnaires were returned to AAFC Lacombe for rating, assessment of causal agents, and tabulation of questionnaire results. Leaf samples were rated for total symptoms of the wheat leaf disease complex comprised of tan spot (Pyrenophora tritici-repentis), the septoria complex (Zymoseptoria tritici and Parastagonospora nodorum), spot blotch (Bipolaris sorokiniana) and physiological leaf spotting, but were also checked for the presence of leaf rust (Puccinia triticina) and stripe rust (Puccinia striiformis). Each leaf was rated for the percentage of leaf area affected (PLAA) and averages were calculated for each field. Other diseases, such as bacterial leaf streak (BLS), were also noted and rated, if present. Representative leaf samples from each field were placed in moist chambers and incubated for three to four days to promote pathogen sporulation. Causal agents and other saprophytic fungi were identified based on fruiting structures and/or spore morphology.

RESULTS AND COMMENTS: Sampling kits were prepared, and producers contacted in June/early July with kits sent out over the following weeks. In total, samples from 50 wheat fields were sent back for rating and tabulation of cropping information. Samples from 14 fields were submitted from Alberta, 30 fields from Saskatchewan, and six fields from Manitoba. Overall, the average PLAA was 3.7%, with values of 4.9%, 3.4%, and 2.5% for AB, SK, and MB, respectively (Table 1). Identification of causal agents indicated that symptoms in the 50 fields were associated mainly with tan spot, followed by the septoria complex and spot blotch (Bipolaris sorokiniana). The most common fungus observed in all fields was the saprophyte Alternaria spp., which was present on 91.6% of the leaf tissues tested; Epicoccum spp. were associated with about 24.8% of the leaves tested, also. Saprophytes don’t cause damage to leaf tissue, but infect after the leaf has already been damaged due to a pathogen, heat stress, drought, hail damage, or physiological leaf spotting. No symptoms of rust or BLS were observed on the collected leaf samples in 2023.

Table 1. Prairie Biovigilance Network (PBN) wheat leaf disease survey results for Alberta, Saskatchewan and Manitoba, 2023.

		Percent leaf area affected (PLAD)^a			Average percentage of leaves with the causal agents of tan spot, the septoria complex, spot blotch, and saprophytes (Epicoccum spp. and Alternaria spp.)
Province	Number of fields	Average	Minimum	Maximum	Tan spot	Septoria complex	Spot blotch	Epicoccum spp.	Alternaria spp.
AB	14	4.9	0.0	19.4	33.3	28.6	0.0	20.0	94.3
MB	6	2.5	0.7	7.1	30.0	10.0	0.0	15.0	80.0
SK	30	3.4	0.1	20.6	36.7	28.0	20.0	30.0	92.7
Overall	50	3.7	0.0	20.6	34.7	25.7	6.7	24.8	91.6

^aBased on a combination of tan spot, septoria complex, spot blotch, and physiological leaf spotting.

In 2023, fields were classified as to the number of wheat crops planted previously from 2019-2022 (Table 2). Where information from some fields was not complete, these fields were classified as “Unknown”. There was no consistent trend of increasing leaf spot severity as the number of previous wheat crops increased from zero to three, with the highest average levels of disease being where either no wheat crops occurred, or two wheat crops occurred during the previous four years (Table 2). Fields were also classified as to the number of non-host crops planted prior to wheat being grown in 2023 (Table 3). Non-host crops for wheat in relation to leaf diseases include canola, pulses, barley, forage legumes, summer fallow, etc. Complete rotation information was available for all four previous years for 39 crops in total. PLAD was 8.6% in fields planted to wheat on wheat, and 4.0%, 2.2%, 1.5%, and 6.3%, respectively, with one, two, three or four years of non-host crops prior to wheat being grown in 2023 (Table 3). The trends observed for the number of non-host crops preceding the 2023 wheat crop illustrate the potential role of crop rotation in reducing leaf spot risk and impact. However, fields with non-host crops for at least four years had elevated disease levels, although some of this may have been physiological leaf spot.

Table 2. Prairie Biovigilance Network (PBN) 2023 wheat leaf disease survey results based on the number of wheat crops previously grown from 2019-2022.

Number of wheat crops from 2018-2021	Number of fields	Average percent leaf area affected (PLAD)^a
0	7	6.0
1	19	2.1
2	10	6.6
3	2	2.2
≤1^b	3	6.3
Unknown^b	9	1.7

^aBased on a combination of tan spot, septoria complex, spot blotch, and physiological leaf spotting.

^bNo information or only partial data provided.

Table 3. Prairie Biovigilance Network (PBN) 2023 wheat leaf disease survey results based on number of years of non-host crops grown prior to the 2023 wheat crop.

Number of years of non-host crops prior to the 2022 wheat crop	Number of fields	Average percent leaf area affected (PLAD)^a
0	6	8.6
1	11	4.0
2	10	2.2
3	7	1.5
≤2^b	1	6.4
≤3^b	2	5.1
≤4^b	5	6.3
Unknown^b	8	1.2

^aBased on a combination of tan spot, septoria complex, spot blotch, and physiological leaf spotting.

^bNo information or only partial data provided.

Fields were also classified according to whether leaf samples were collected from fungicide-sprayed areas versus samples collected from fields that were not sprayed or where samples were collected from unsprayed strips (Table 4). There was a reduction in leaf spot severity in samples collected from fungicide-sprayed areas (1.8%) versus non-sprayed fields/areas (5.0%) (Table 4). The response to fungicide tended to be slightly more pronounced in fields with a wheat-on-wheat or wheat-non-host-wheat rotation, but less so for the other rotational intervals, although the number of fields in some categories was limited (data not shown).

Table 4. Prairie Biovigilance Network (PBN) 2022 wheat leaf disease survey results based on whether samples were collected from fungicide sprayed or unsprayed fields.

Fungicide applied in areas where leaf samples were collected^a	Number of fields	Average percent leaf area affected (PLAD)^b
Unknown	4	1.5
No	31	5.0
Yes	15	1.8

^aUnknown = incomplete spray information. The unsprayed category also includes samples collected from unsprayed areas within fungicide-sprayed fields.

^bBased on a combination of tan spot, septoria complex, spot blotch, and physiological leaf spotting.

The varieties grown were classified according to their levels of resistance based on provincial variety guides, although for some fields this information was either incomplete or unavailable (Table 5). Leaf spot complex severity tended to be highest for susceptible varieties, lowest for resistant varieties, and in the middle for fields planted to varieties with an intermediate leaf spot resistance rating (Table 5). However, fields planted to moderately susceptible varieties had low levels of disease. Overall, the number of fields in some resistance categories was limited.

Table 5. Prairie Biovigilance Network (PBN) 2023 wheat leaf disease survey results based on overall level of leaf spot resistance.

Level of leaf spot resistance^a	Number of fields	Average percent leaf area affected (PLAD)^b
Unknown	15	2.8
R	5	3.0
I	23	4.3
MS	4	2.2
S	3	6.8

^aUnknown = incomplete variety information or no assigned ratings and thus no rating is given. Variety leaf spot complex resistance ratings: S = susceptible; MS = moderately susceptible; I = intermediate; MR = moderately resistant; R = resistant. Ratings were obtained from the Manitoba and Saskatchewan variety guides.

^bBased on a combination of tan spot, septoria complex, spot blotch, and physiological leaf spotting.

The most common varieties grown were AAC Brandon (13 fields), AAC Wheatland (5), AAC Viewfield (4), and AAC Starbuck and Transcend (3 fields each), with each of the remaining varieties planted in one to two fields (Table 6). For eight fields, the variety information was not available.

Table 6. Prairie Biovigilance Network (PBN) 2023 wheat leaf disease survey and varieties grown.

Variety	Number of fields
AAC Brandon	13
Unknown	8
AAC Wheatland	5
AAC Viewfield	4
AAC Starbuck	3
Transcend	3
Elie	2
AAC Awesome	1
AAC Weyburn, CDC Precision VB	1
Accelerate	1
Alloy	1
Carberry	1
Defy	1
CDC Go	1
Hockley	1
Ortona	1
Redberry	1
Stettler	1
SY Brawn VB	1

^aUnknown = incomplete variety information and no variety name is available.

ACKNOWLEDGEMENTS: The authors would like to acknowledge the support of participating farmers and the assistance of staff from the Saskatchewan Ministry of Agriculture, and crop consultants. The current report is part of the AAFC Prairie Biovigilance Network (PBN) and A-base funding from AAFC is graciously acknowledged. We would also like to thank technicians Noryne Rauhala and Jackie Busaan, and summer students Selena Delahunty and Jaydon Bick of AAFC Lacombe for their assistance with kit assembly and shipment, and leaf ratings and culturing.

LEAF SPOTTING DISEASES OF COMMON AND DURUM WHEAT IN SASKATCHEWAN IN 2023

CROP: Common and durum wheat LOCATION: Saskatchewan NAMES AND AGENCIES: M.R. FERNANDEZ¹, E. ILYUKHIN¹, N. WAELCHLI¹, C. KENNY², C. SIEMENS³, A. WILSON⁴, A. AKHAVAN⁵, C. PERU⁵, J. BUSH⁶, C. BAWOLIN⁶, E. MANGWENDE⁶, B. RUMPEL⁶, B. KELSCH⁶ & J. CADRAIN⁶

¹Agriculture and Agri-Food Canada, Swift Current Research and Development Centre, P.O. Box 1030, Swift Current, SK S9H 3X2 Telephone: [phone]; E-mail: [email protected] ²Agriculture and Agri-Food Canada, Saskatoon Research and Development Centre, 107 Science Place, Saskatoon, SK S7N 0X2 ³Saskatchewan Crop Insurance Corporation, Box 1000, 124 2^nd Ave., Rosetown, SK S0L 2V0 ⁴Saskatchewan Crop Insurance Corporation, #130-800 Central Ave., Prince Albert, SK S6V 6Z2 ⁵Saskatchewan Ministry of Agriculture, Crops and Irrigation Branch, 3085 Albert St., Regina, SK S4S 0B1 ⁶Saskatchewan Ministry of Agriculture, Crop Protection Laboratory, 1610 Park St., Regina, SK S4N 2G1

ABSTRACT: Leaf spot (LS) disease complex was evaluated in 58 common wheat and 23 durum wheat crops in 13 crop districts across Saskatchewan in 2023. Disease severity was compared relative to soil zone, crop district, and wheat species. Due to dry conditions across the province, the mean LS severity on the flag leaf was lower than in 2022 and 2019, and higher than in 2021 and 2020. The highest mean LS severity for common wheat was in the Black/Grey soil, followed by the Dark Brown soil zone. Pyrenophora tritici-repentis (tan spot) was the predominant LS pathogen.

INTRODUCTION AND METHODS: A survey for leaf spot (LS) diseases of common and durum wheat in Saskatchewan was conducted between the milk and dough growth stages in 2023. A total of 58 common wheat and 23 durum wheat crops were sampled in 13 crop districts in the three soil zones (Fig. 1, Table 1). Information on the agronomic practices employed was obtained from the producers for most of the fields sampled.

Fig. 1 Soil zone map with common and durum wheat fields surveyed across Saskatchewan in 2023.

Table 1. Incidence and severity of leaf spotting diseases in common and durum wheat crops surveyed in Saskatchewan in 2023.

Soil zone/ Crop district	Mean severity^a (%)	No. of crops^b	Soil zone/ Crop district	Mean severity (%)	No. of crops
Soil Zone
Common wheat:			Durum wheat:
1 (Brown)	−	0	1 (Brown)	0.8	11
2 (Dark Brown)	1.2	11	2 (Dark Brown)	0.9	9
3 (Black/Grey)	2.6	47	3 (Black/Grey)	1.3	3
Mean/total:	2.4	58	Mean/total:	0.9	23
Crop District
Common wheat:			Durum wheat:
1A	5.0	1	1A	1.0	1
1B	3.2	5	2A	0.9	7
2B	1.0	1	3BN	0.9	7
5A	6.1	6	4B	0.5	4
5B	1.3	6	5A	1.8	2
6A	1.6	9	6A	0.5	1
7A	0.5	3	8B	0.5	1
8A	0.6	4
8B	0.8	4
9A	2.6	19

^aMean percentage of flag leaf area affected.

^bNumber of samples with green leaves that could be evaluated for leaf spot severity.

Cultivars were identified in 42 of the common and 21 of the durum wheat samples. The most popular cultivars (grown in at least five fields) were ‘AAC Brandon’ (6), ‘AAC Starbuck’ (6) and ‘AAC Wheatland’ (10) for common wheat, and ‘CDC Defy’ (5) for durum wheat.

For common wheat, of the 47 samples with a crop rotation history, 35 were preceded by a canola crop, six by a pulse, and five by a cereal. For durum wheat, of the 23 samples with a crop rotation history, 11 were preceded by a pulse crop, nine by canola, and two by a cereal.

Tillage systems were classified as conventional-, minimum-, or zero-till. Of the samples with tillage information, for common wheat, 24 were under zero-till, 13 under minimum-till, and eight under conventional-till, while for durum wheat, 14 were under zero-till, four under minimum-till, and one under conventional-till.

In each field, 50 flag leaves were collected at random and air-dried at room temperature. The mean percentage of flag leaf area affected by LS (% severity) was recorded for each sample, and mean percentage values were calculated for soil zone and crop district. For crops with LS severity ≥5%, 1 cm² surface-disinfested leaf pieces were plated on water agar for identification and quantification of the causal LS pathogens.

RESULTS AND COMMENTS: Most of the southern and central region of the province experienced very dry conditions during the 2023 growing season, receiving only 40 to 60% of average precipitation, while the rest recorded 60 to 85% of the average precipitation (Fig. 2).

Fig. 2 Percentage of average precipitation in the Canadian Prairies from early May to late July of 2023. Normal precipitation based on 1981-2010 (Agriculture and Agri-Food Canada 2023).

LS symptoms were observed in most of the common wheat samples assessed, including 11 in the Dark Brown and 47 in the Black/Grey soil zone (Table 1). LS symptoms were also observed in most of the 23 durum wheat crops assessed (11 in the Brown, nine in the Dark Brown and three in the Black/Grey soil zone). In individual samples, percent flag leaf area affected ranged from 0 to 12.5% for common wheat and 0 to 2.5% for durum wheat. The overall mean percentage of flag leaf spotting was 2.0% (2.4% for common wheat and 0.9% for durum wheat), which was numerically lower than in 2022 (5.4%) and 2019 (2.6%), but higher than in 2020 (1.1%) and 2021 (0.8%) (Fernandez et al. 2020, 2021, 2022, 2023).

Overall, mean LS severity was higher for common than durum wheat, which could be attributed mostly to the location of these fields. For common wheat, the highest mean LS severity was in the Black/Grey soil zone, with the highest values being observed in Crop District 5A (east-central).

Due to the low LS severity in most samples, a low number of samples for some of the crop districts, or lack of information, comparisons among previous crops, tillage categories, fungicide applications, and cultivars were not conducted.

Overall, leaf spots were caused primarily by Pyrenophora tritici-repentis (tan spot).

REFERENCES

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FUSARIUM HEAD BLIGHT OF COMMON AND DURUM WHEAT IN SASKATCHEWAN IN 2023

CROP: Wheat LOCATION: Saskatchewan NAMES AND AGENCIES: B. RUMPEL¹, J. BUSH¹, E. MANGWENDE¹, C. BAWOLIN¹, B. KELSH¹, J. CADRAIN¹, C. PERU² & A. AKHAVAN²

¹Saskatchewan Ministry of Agriculture, Crops and Irrigation Branch, Crop Protection Laboratory, 1610 Park St., Regina, SK S4N 2G1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Saskatchewan Ministry of Agriculture, Crops and Irrigation Branch, 3085 Albert St., Regina, SK S4S 0B1

ABSTRACT: In 2023, fusarium head blight (FHB) incidence and severity were assessed in 119 wheat crops (72 common wheat and 47 durum wheat) in Saskatchewan. FHB occurred in 24% and 4% of the surveyed common and durum wheat crops, respectively. The provincial mean FHB severities (FHB Index) for common wheat and durum wheat were 0.05% and <0.01%, respectively. FHB severity was assessed based on the presence of visual symptoms. Symptomatic kernels were further processed to determine the Fusarium species present. In crops with FHB symptoms, Fusarium poae was the most prevalent species (94%) in common wheat, whereas Fusarium sporotrichioides was the most prevalent species (50%) in durum wheat.

INTRODUCTION AND METHODS: Fusarium head blight (FHB) incidence and severity in Saskatchewan were assessed in 119 wheat crops in 2023: 72 common wheat (Canadian Western Red Spring and Canadian Prairie Spring wheat classes) and 47 durum wheat (Canadian Western Amber Durum class). Field location and results were grouped according to soil zone.

Crop adjustors with the Saskatchewan Crop Insurance Corporation randomly collected 50 spikes from wheat crops at late milk to early dough stages (Lancashire et al. 1991). A subsample of 30 spikes was analyzed for visual FHB symptoms at the Crop Protection Laboratory in Regina, SK. The number of infected spikes per crop and the number of infected spikelets in each spike, as a proportion of the total, were recorded. An FHB disease severity rating, also referred to as the FHB Index, was determined for each crop surveyed: FHB severity (%) = [% of spikes affected x mean proportion (%) of kernels infected]/100. Mean FHB severity values were calculated for each soil zone and for the whole province. Glumes or kernels with visible FHB symptoms were surface sterilized in 0.6% sodium hypochlorite solution for 1 min and cultured on modified potato dextrose agar to confirm presence of Fusarium species on infected kernels. A maximum of 20symptomatic kernels per sample were selected to represent infected samples to confirm FHB and the Fusarium spp. involved.

RESULTS AND COMMENTS: Approximately 7.9 million ha (19.5 million ac) of common wheat and 2.4 million ha (6.0 million ac) of durum wheat were seeded in Saskatchewan in 2023. The average yields were 3.2 metric tonnes per ha (47.5 bu/ac) for common wheat and 1.7 metric tonnes per ha (25.3 bu/ac) for durum wheat. Yields in 2023 were slightly down from 2022 for both common and durum wheat (3.6 metric tonnes per ha; 53.2 bu/ac and 1.7 metric tonnes per ha; 25.3 bu/ac, respectively) (Statistics Canada 2024).

FHB occurred in 24% of the common wheat and 4% of the durum wheat crops surveyed in 2023 (Table 1). The highest prevalence of FHB in common wheat occurred in the black soil zone, while the highest prevalence of FHB in durum wheat occurred in the dark brown soil zone. The prevalence of FHB was the lowest in the dark brown soil zone for common wheat and the black and brown soil zone for durum wheat. The provincial mean severity was 0.05% and <0.01% for common and durum wheat, respectively.

Table 1. Prevalence and severity of fusarium head blight (FHB) in common wheat and durum wheat grouped by soil zone in Saskatchewan in 2023.

	Common wheat		Durum wheat
Soil zones	Prevalence^a (number of crops affected)	Mean FHB severity^b (range)	Prevalence^a (number of crops affected)	Mean FHB severity^b (range)
Black	48	0.09	0	0
	(12)	(0-0.79)	(0)	(0-0)
Brown	20	0.10	0	0
	(1)	(0-0.48)	(0)	(0-0)
Dark Brown	5	0	8	0
	(1)	(0-0)	(2)	(0-0.01)
Grey	15	0.03	n/a	n/a
	(3)	(0-0.46)
Overall	24	0.05	4	0
	(17)	(0-0.79)	(2)	(0-0.01)

^aPrevalence (%) = number of crops affected/total crops surveyed.

^bFHB severity (FHB Index) = [% of spikes affected x mean proportion (%) of kernels infected]/100.

n/a = not applicable. No durum crops were surveyed in the grey soil zone in 2023.

In 2023, 81 isolations were made to confirm the presence of Fusarium and identify the pathogen to the species level (Table 2). The most frequently isolated causal pathogen, F. poae, occurred in 84% of all wheat fields with FHB symptoms (94% of common and 0% of durum wheat crops) and accounted for 86% of all the Fusarium isolations; this is consistent with findings from 2022. F. graminearum, the most aggressive FHB pathogen, was present in 26% of all wheat crops and was more prevalent in common wheat (29%) than in durum wheat (0%) in 2023. F. avenaceum and F. sporotrichioides were also detected and were present in 5% of all wheat fields with FHB symptoms. A species other than F. avenaceum, F. culmorum, F. graminearum, F. poae, or F. sporotrichioides was identified in 16% of fields with FHB symptoms.

Table 2. Prevalence of fields with Fusarium species detected in common and durum wheat crops with FHB symptoms in 2023.

Crop	F. avenaceum	F. culmorum	F. graminearum	F. poae	F. sporotrichiodes	Other Fusarium^a
Common	6	0	29	94	0	12
Durum	0	0	0	0	50	50
Wheat Total	5	0	26	84	5	16

^aOther Fusarium includes species other than those described in this table.

ACKNOWLEDGEMENTS: We gratefully acknowledge the assistance of Saskatchewan Crop Insurance Corporation staff agrologists for the collection of cereal samples for this survey.

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LEAF AND STRIPE RUST OF WHEAT IN MANITOBA AND EASTERN SASKATCHEWAN IN 2023

CROP: Spring and Winter Wheat LOCATION: Manitoba and Eastern Saskatchewan NAMES AND AGENCY: B. MCCALLUM, E. REIMER, D. MIRANDA & N. DIONNE

Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT:The 2023 annual survey for leaf and stripe rust of wheat was conducted from early to mid-July for winter wheat and from early to late August for spring wheat. Winter wheat plots were surveyed at seven Manitoba Crop Variety Evaluation Trial (MCVET) locations with trace levels of leaf rust observed at six sites. One site had a higher disease severity of 5-30% flag leaf coverage in most plots, with some plots reaching as high as 60%. Spring wheat research plots were examined at 18 sites including the MCVET and Uniform Rust Nursery (URN) trials. Symptoms of leaf rust were observed on registered cultivars in Manitoba and Saskatchewan. Most sites visited showed infection at trace levels but up to 85% disease severity on highly susceptible wheat lines. No stripe rust was found in any of the locations surveyed.

INTRODUCTION AND METHODS:  The annual wheat rust survey aims to collect infected leaf samples to determine the prevalence and severity of leaf and stripe rust in Manitoba and eastern Saskatchewan. These samples were analyzed by isolating the leaf rust fungus (Puccinia triticina Erikss.) and identifying the virulence profile for each isolate to determine the race structure of the population. The surveyed sites did not receive any fungicide application. Winter wheat plots were examined at seven Manitoba Crop Variety Evaluation Trial (MCVET) locations and seed increase sites at the University of Manitoba in Winnipeg and Carman, from early to mid-July. Spring wheat was observed at 18 research locations, including seven MCVET trials, one SeCan trial site, eight Uniform Rust Nurseries (URN), and two wheat increases at the Agriculture and Agri-Food Canada (AAFC) Brandon and Morden research centres. Spring wheat trials were surveyed in Manitoba and eastern Saskatchewan for rust incidence and severity in August 2023. Disease severity (infection level) was assessed visually as percent flag leaf area coverage.

RESULTS AND COMMENTS:  The environmental conditions across Manitoba and Saskatchewan in 2023, with low precipitation and high temperatures, were not favourable for rust development, resulting in a low level of rust disease in wheat. The drought and the genetic resistance of the MCVET lines resulted in only trace amounts of rust on most MCVET winter wheat and seed increases at the University of Manitoba. However, the winter wheat MCVET site in Portage, MB showed moderate rust severity ranging from 5-30% in most plots with some as high as 40-60%.

Eighteen spring wheat research locations were surveyed, which included seven MCVET sites, one SeCan trial test, two increase sites at AAFC Brandon and Morden, and eight Uniform Rust Nursery (URN) trials. Leaf rust symptoms were present at all of the locations visited. Trace levels of infection were found in most MCVET and SeCan trials. The MCVET site in Portage showed rust disease severity ranging from 5- 20%. The Brandon increase showed a 5% severity, while the Morden increase plots had an infection level of 30-40%. Symptoms of leaf rust were present in Manitoba and Saskatchewan URN sites, consisting of ‘Morocco’ and ‘Little Club’, which are highly susceptible cultivars. Saskatchewan had an extremely dry summer and only trace levels of disease were found. On highly susceptible lines in Manitoba, infection levels of rust ranged from 10-45% in Emerson and as high as 85% in Brandon, Manitou, St. Adolphe and Portage. No stripe rust was detected in any of the surveyed locations.

FUSARIUM HEAD BLIGHT OF SPRING WHEAT AND WINTER WHEAT IN MANITOBA IN 2023

CROP: Spring Wheat and Winter Wheat LOCATION: Manitoba NAMES AND AGENCIES: M.A. HENRIQUEZ¹, D. KAMINSKI², A. KIRK², O. GRUENKE¹, P. SANTHANAM¹ & L. DYCK¹

¹Agriculture and Agri-Food Canada, Morden Research and Development Centre, 101 Route 100, Morden, MB R6M 1Y5 Telephone [phone]; Facsimile 204-822-7507; E-mail: [email protected] ²Manitoba Agriculture, 65-3rd Avenue NE, Carman, MB R0G 0J0

ABSTRACT: In 2023, fusarium head blight incidence and severity were assessed in 129 spring wheat and two winter wheat fields in Manitoba. In spring wheat, the disease occurred in 8.5% of the wheat fields surveyed with a provincial mean FHB severity (FHB Index) of 0.002%. The most prevalent Fusarium species in spring wheat were F. graminearum and F. sporotrichioides.

INTRODUCTION AND METHODS: In 2023, spring wheat and winter wheat in Manitoba were surveyed for fusarium head blight (FHB) at 129 and two field locations respectively. The survey for FHB was conducted from late July to late August for spring wheat, and July for winter wheat when most of the crops were at growth stage ZGS 73 – 85 (Zadoks et al. 1974). In contrast to other disease surveys conducted in Manitoba, the fields were not surveyed at random. Instead, information on their location was obtained from producers. The proportion of infected spikes per field (incidence) and the proportion of infected spikelets in each spike (severity) were recorded from five heads (main stems) at 10 sites along a W-pattern in the field, while avoiding sampling tillers. An FHB Index (overall % severity) was determined for each field surveyed using the formula [Average % incidence X Average % severity] / 100.

Fifty spikes from each field were processed for pathogen isolation and identification in the laboratory. Kernels from each field surveyed were surface-sterilized in a laminar flow bench and then placed on potato dextrose agar (PDA, 25% strength) + streptomycin media. Fusarium species were identified by microscopic examination and morphological characterization using the criteria of Leslie and Summerell (2006).

RESULTS AND COMMENTS: According to the Manitoba Agricultural Services Corporation’s Variety Market Share Report (MASC 2023), there were approximately 2,824,397 million acres of spring wheat seeded in Manitoba in 2023. The top five cultivars, based on seed acreage, were ‘AAC Brandon’ (37.5%), ‘AAC Starbuck’ (21.6%), ‘AAC Wheatland’ (11.6%), ‘AAC Viewfield’ (6.9%), and ‘AAC Hockley’ (5.0%).

FHB disease levels in spring wheat were lower in 2023 (0.002%; Table 1), than the levels observed in 2022 (0.05%) and 2021 (0.005%) (Henriquez et al. 2023). Provincially, FHB was detected in 11 out of 129 fields for a prevalence of 8.5%. The average incidence of the disease across all fields was 0.23%. The average severity (measured as the percentage of spikelets with infection) was 0.05% across all fields. The provincial mean FHB severity (FHB Index) was 0.002%.

Table 1. Fusarium head blight incidence and severity (FHB index) in spring wheat fields in Manitoba in 2023.

Region	# fields surveyed	Prevalence^a %	Average incidence^b %	Average severity^c %	Average FHB index^d %	Average FHB index % (range)
Central	40	5	0.61	0.005	0.005	0.0 – 0.003
Eastern	11	10	0.36	0.03	0.001	0.0 – 0.012
Interlake	8	0	0.0	0.0	0.0	0.0 – 0.0
Northwest	24	8	0.25	0.17	0.007	0.0 – 0.16
Southwest	46	13	0.35	0.05	0.001	0.0 – 0.02
MANITOBA	129	8.5	0.23	0.05	0.002	0.0 – 0.16

^aPrevalence (%) = number of fields affected/total fields surveyed.

^bIncidence = the proportion of infected spikes per field.

^cSeverity = the proportion of infected spikelets in each spike.

^dMean FHB Index: [Average % incidence X Average % severity]/100.

According to the MASC’s Variety Market Share Report (MASC 2023), approximately 59,403 acres of commercial winter wheat were seeded in Manitoba in 2023. The top cultivars, based on their seed acreage, were ‘AAC Wildfire’ (43.2%), ‘Emerson’ (22.2%), and ‘AAC Goldrush’ (12.5%). FHB was not detected in either of the two fields surveyed.

The results from spring wheat kernels plated on PDA (25% strength) + streptomycin media showed that Fusarium graminearum and F. sporotrichioides were the most frequently isolated pathogen species, accounting for 57.1 % and 23.8% of isolations, respectively, followed by F. poae and F. culmorum (4.8%) (Table 2). The frequency of Fusarium graminearum was higher in 2022 (72.3%) than 2023, while F. sporotrichioides was higher in 2023 than in 2022 (8.9%) (Henriquez et al. 2023).

Table 2. Fusarium species isolated from kernels in FHB-affected spring wheat fields in Manitoba in 2023.

	Prevalence^a %	Frequency^b %
F. graminearum	5.4	57.1
F. poae	0.8	4.8
F. culmorum	0.8	4.8
F. sporotrichioides	3.9	23.8
F. equiseti	0.8	4.8

^aPrevalence = % of spring wheat fields from which the pathogen was isolated.

^bFrequency = % of each Fusarium species (as the % of the total Fusarium isolations).

ACKNOWLEDGEMENTS: We gratefully acknowledge the participation of Manitoba Agriculture Farm Production Extension Specialists, as well as Dr. Henriquez’s summer students.

REFERENCES

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LEAF SPOT DISEASES AND BACTERIAL LEAF STREAK OF SPRING WHEAT AND WINTER WHEAT IN MANITOBA IN 2023

CROP: Spring Wheat and Winter Wheat LOCATION: Manitoba NAMES AND AGENCIES: M.A. HENRIQUEZ¹, D. KAMINSKI², A. KIRK², O. GRUENKE¹, P. SANTHANAM¹ & L. DYCK¹

¹Agriculture and Agri-Food Canada, Morden Research and Development Centre, 101 Route 100, Morden, MB R6M 1Y5 Telephone: [phone]; Facsimile: 204-822-7507; E-mail: [email protected] ²Manitoba Agriculture, 65-3rd Avenue NE, Carman, MB R0G 0J0

ABSTRACT: In 2023, leaf spot diseases were assessed in 129 spring wheat and one winter wheat field in Manitoba. Leaf spot diseases occurred in all spring wheat fields surveyed with a provincial mean severity of 8.6%. The most prevalent LS species was Pyrenophora tritici-repentis, followed by Parastagonospora nodorum. Leaf spot diseases were observed in the winter wheat field surveyed. Pyrenophora tritici-repentis (tan spot) was the most prevalent LS pathogen isolated in that field, with a frequency of 100%.

INTRODUCTION AND METHODS: A survey for leaf spot (LS) diseases of spring and winter wheat in Manitoba was conducted between the milk and dough growth stages in 2023 (ZGS 73 – 85, Zadoks et al. 1974). A total of 129 spring wheat and one winter wheat field were sampled. In contrast to other disease surveys conducted in Manitoba, the fields were not surveyed at random. Instead, information on their location was obtained from producers. In each field, 50 flag leaves were collected at random and the percentage of leaf area affected by LS (severity) was recorded using a scale from 1 (slightly affected) to 50 (leaves dead) (Fernandez 1998). Bacterial leaf streak (BLS) was recorded on a 1- 4 rating scale, where 1=absent, 2=trace, 3=moderate, 4=severe (Harding et al. 2023).

Ten flag leaves from each field were processed in the laboratory, and 1 cm² surface-disinfested leaf pieces were plated on water agar to promote pathogen sporulation for disease identification. Leaf spot pathogens were identified by microscopic examination and morphological characterization.

RESULTS AND COMMENTS: According to the Manitoba Agricultural Services Corporation’s Variety Market Share Report (MASC 2023), there were approximately 2,824,397 million acres of spring wheat seeded in Manitoba in 2023. The top five cultivars, based on seed acreage, were ‘AAC Brandon’ (37.5%), ‘AAC Starbuck’ (21.6%), ‘AAC Wheatland’ (11.6%), ‘AAC Viewfield’ (6.9%), and ‘AAC Hockley’ (5.0%).

Leaf spot diseases were observed in all spring wheat fields surveyed. The provincial mean LS severity was 8.6% (Table 1). This severity was lower than in 2022 (11.7%), but higher than in 2021 (6.0%) and 2020 (6.7%) (Henriquez et al. 2023, 2022, 2021). Pyrenophora tritici-repentis was the most prevalent and widespread LS pathogen in Manitoba in 2023, accounting for 87.5% of isolations. This species was detected in 65.9% of surveyed fields. This was followed by Parastagonospora nodorum (19.4%) detected in 12.5% of surveyed fields. Bacterial leaf streak (BLS), was found in 11 fields with an average disease severity of 2.5 (Table 2).

Table 1. Leaf spot severity in spring wheat fields in Manitoba in 2023.

Region	# fields surveyed	Prevalence^a %	Average LS severity^b %	LS severity^b (range)
Central	40	80	6.3	1.0 – 37.5
Eastern	11	91	19.7	1.0 - 50.0
Interlake	8	100	8.0	1.0 - 20.0
Northwest	24	67	5.7	1.0 - 30.0
Southwest	46	61	3.2	1.0 - 30.0
MANITOBA	129	72.8	8.6	1.0 - 50.0

^aPrevalence (%) = (number of fields affected/total fields surveyed) x 100.

^bSeverity = percentage of leaf area affected on a scale of 1 (slightly affected) to 50 (leaves dead).

Table 2. Bacterial leaf streak (BLS) in spring wheat fields in Manitoba in 2023.

Region	# fields surveyed	# fields affected	Prevalence^a %	Severity^b %
Central	40	4	10.0	2.7
Eastern	11	0	ND^c	ND
Interlake	8	1	12.5	2.0
Northwest	24	2	8.3	3.0
Southwest	46	4	8.7	2.2
MANITOBA	129	11	8.5	2.5

^aPrevalence (%) = (number of fields affected/total fields surveyed) x 100.

^bSeverity = percentage of leaf area affected on a scale of 1-4, where 1=absent, 2=trace, 3=moderate, 4=severe.

^cND = not detected

According to the MASC’s Variety Market Share Report (MASC 2023), approximately 59,403 acres of commercial winter wheat were seeded in Manitoba in 2023. The top cultivars, based on their seed acreage, were ‘AAC Wildfire’ (43.2%) and ‘Emerson’ (22.2%), ‘AAC Goldrush’ (12.5%). Leaf spot diseases were observed in the one winter wheat field surveyed. Pyrenophora tritici-repentis (tan spot) was the most prevalent LS pathogen isolated in that field, with a frequency of 100%.

ACKNOWLEDGEMENTS: We gratefully acknowledge the participation of Manitoba Agriculture Farm Production Extension Specialists, as well as Dr. Henriquez’s summer students.

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2023 PRESENCE OF LEAF DISEASES OF WINTER WHEAT IN ONTARIO

CROP: Winter Wheat LOCATION: Ontario NAME AND AGENCY: L. TAMBURIC-ILINCIC

University of Guelph, Ridgetown Campus, Ridgetown, ON N0P 2C0 Telephone: [phone] x 63557; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: Septoria leaf complex, powdery mildew, stripe rust and leaf rust were present in the winter wheat crop in 2023, across Ontario. Moderate to low severities, for all diseases, were recorded across winter wheat cultivars from the UGRC breeding program and checks. The ratings were recorded at Woodslee and Tupperville (Area 1), Elora and Palmerston (Area 2) and Ottawa (Area 3). Powdery mildew significantly affected yield and thousand kernel weight (TKW), while septoria leaf complex significantly affected thousand kernel weight (TKW).

INTRODUCTION AND METHODOLOGY: The presence of leaf diseases and their effect on yield, test weight (TW) and thousand kernel weight (TKW) was assessed using Canadian Eastern Soft Red Winter Wheat (CESRW) from the University of Guelph Ridgetown College (UGRC) breeding program, and checks. The plots were planted in September or mid-October in 2022, in randomized complete block design, replicated trials. Locations were Woodslee and Tupperville (Area 1), Elora and Palmerston (Area 2) and Ottawa (Area 3). The trials were maintained according to standard agronomic practices for Ontario. Leaf diseases were evaluated using a 0 to 9 scale, where 0 = no disease and 9 = more than 90% of leaf tissue affected by symptoms. No artificial inoculation was used. Yield, TW and TKW were estimated from the harvested grain. Pearson’s correlation coefficients between the disease and yield, TKW and TW, across all locations, were calculated.

RESULTS AND COMMENTS: In 2023, septoria leaf complex was present at all locations except Palmerston, and the highest average level across the cultivars was in ‘11w911-59’ (4.31). Powdery mildew was not present in Area 1, but had the highest average level in ‘Ca1419-252’ (4.25) and the lowest in the check ‘OAC Constellation’ (Table 1). Leaf rust was recorded at Palmerston and Ottawa, with an average rating of 2.02, while a low level of stripe rust (0.69) was recorded only at Elora. Stripe rust was the most important disease of winter wheat in Ontario in 2016 (Tamburic-Ilincic and Rosa 2017) but has not been observed frequently thereafter.

Table 1. Mean leaf disease ratings (0-9 scale), for UGRC breeding lines and check cultivars, in 2023 in Ontario.

	Septoria leaf (0-9)	Powdery mildew (0-9)	Stripe rust (0-9)	Leaf rust (0-9)		Yield (T/ha)
Cultivar	WTEO^a	EPO	E	PO	Area 1	Area 2	Area 3
11w911-59	4.31	3.25	3.75	3.43	7.91	6.84	7.35
12w931-234	4.00	2.90	1.50	1.83	7.46	7.34	7.50
Ca1419-252	3.83	4.25	1.00	3.17	7.57	6.78	8.65
12w933-122	3.38	2.75	0.00	2.88	8.23	7.01	7.99
Ca14015-8	4.00	2.28	0.00	2.22	7.88	7.76	6.51
Ava^b	3.56	3.53	0.00	2.61	8.05	7.90	7.83
Branson^b	3.01	2.65	0.00	1.88	7.78	7.32	8.61
Blaze^b	2.88	2.25	0.00	1.67	8.31	7.61	8.56
OAC Constellation^b	4.19	1.63	0.00	1.10	7.68	8.00	8.50
Mean	3.68	3.47	0.69	2.02	7.87	7.40	8.00
Standard deviation	1.37	2.17	1.27	1.09	0.28	0.45	0.69

^aCapital letters indicate where diseases were evaluated: Woodslee (W), Tupperville (T), Palmerston (P), Elora (E), Ottawa (O).

^bCheck cultivars

In 2023, average yield ranged from 7.46 T/ha to 8.31 T/ha in Area 1, from 6.78 T/ha to 8.00 T/ha in Area 2 and from 6.51 T/ha to 8.61 T/ha in Area 3 (Table 1), and was significantly affected by powdery mildew (r = −0.75). Cultivar ‘12w933-122’ had the highest yield among UGRC cultivars in Area 1 and performed better than three official checks (Table 1). Cultivar ‘Ca14015-8’ had a higher yield than the check ‘Branson’ in Area 2, while ‘Ca1419-252’ had a higher yield than all checks in Area 3. A significant and moderate negative correlation was recorded between powdery mildew and TKW, and between septoria leaf complex and TKW (r = −0.52 and r = −0.59, respectively). Leaf disease severities in winter wheat crops differed across locations in Ontario in 2023. They need to be managed by cultivar resistance and fungicide applications to avoid yield and quality losses.

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PRINCE EDWARD ISLAND SURVEY OF FUSARIUM HEAD BLIGHT AND LEAF DISEASES OF SPRING WHEAT, 2023

CROP: Spring wheat LOCATION: Prince Edward Island NAMES AND AGENCIES: E. JOHNSTONE, H. BRADLEY, R. MATTERS & A. FOSTER

Agriculture and Agri-Food Canada, Charlottetown Research and Development Centre, 440 University Avenue, Charlottetown, PE, C1A 4N6 Telephone: [phone]; Facsimile: 902-370-1444; E-mail: [email protected]

ABSTRACT: Warm, humid conditions on Prince Edward Island (PE) supported the development of fusarium head blight (FHB) epidemics in spring wheat in 2023. Wheat spikes were collected from ten sites and air sampling was carried out at 55 sites across the province. Fusarium was isolated from wheat spikes from all three counties and of the 235 Fusarium isolates collected, 77% were identified as F. graminearum. Fusarium was isolated from 21 air sampling sites with F. sporotrichioides being the dominant airborne species. Low to moderate severity of septoria leaf blotch was observed at wheat head sampling sites.

INTRODUCTION AND METHODS: Fusarium head blight (FHB) was surveyed across Prince Edward Island (PE) at 10 sites, post-anthesis (ZGS 80-87) between July 27 and August 8, 2023 (Fig. 1). At the Harrington site, both ‘AC Walton’ and ‘AC Helena’ were sampled separately from 10 x 60 m epidemiology blocks, however, the data is presented as a single site. Ten flag leaves also were collected from each site to observe the presence of leaf diseases. Air sampling was conducted at 55 sites to determine presence of airborne Fusarium inoculum in the environment; east of Harrington on July 13 and west of Harrington on July 18. Crops grown at these sites included wheat, barley, brassicas, cucurbits, hay, potato, soybean, and corn (Fig. 2). Weather conditions in 2023, recorded by the Environment Canada weather station at Agriculture and Agri-Food Canada Harrington Research Farm (46°20’37.020” N, 63°10’11.050” W) were notably different from the previous 10-year average for June and July. While the average temperature of 14.7°C in June was the same as the 10-year average, July was warmer, at 21.6°C compared to the 10-year average of 19.2°C. Similarly, rainfall was significantly higher in 2023, with 136.5 mm in June and 132 mm in July, compared to the 10-year averages of 97.8 mm and 60.3 mm, respectively. These conditions in 2023 were ideal for disease development.

Fig. 1 Wheat spike survey sites in Prince Edward Island, 2023. ● = Kings County site, ■ = Queens County sites, ▲ = Prince County sites.

Fig. 2 Field edge sites where airborne inoculum of Fusarium spp. was obtained.

On wheat spikes, FHB infection was identified by premature senescence and the presence of orange to pink sporodochia or black perithecia on the spikelets. Severity of FHB was rated on a 0-9 scale (0= no signs of disease, 9= entire spike infected). Leaf disease on flag leaves was identified as septoria blotch (Mycosphaerella graminicola) by the presence of yellow-brown spots and lesions. Powdery mildew (Blumeria graminis f. sp. tritici) was identified by the appearance of white-grey pustules on the leaf surface. Severity of disease on the flag leaves was rated on a 0-9 scale (0= no signs of disease, 9= entire leaf infected).

Twenty-five wheat spikes were randomly collected from each field site to identify the causal species of FHB. Twenty of those spikes were surface sterilized with 70% ethanol for 20s then rinsed in sterile water. Ten of the sterilized spikes from each site were plated on PDA supplemented with 10 μg mL⁻¹ tetracycline, 100 μg mL⁻¹ cefotaxime and 50 μg mL⁻¹ streptomycin. The remaining ten spikes were plated on antibiotic-supplemented PDA that included 5 mg mL⁻¹ pentachloronitrobenzene (PCNB). Isolation of putative Fusarium species and morphological identification was carried out as described by Johnstone et al. (2022). Colony PCR was used to molecularly identify Fusarium spp. A DNA template was obtained by scraping mycelium from each isolate into 2 mL tubes containing 200 µl of AE buffer (Qiagen) and 20 mg of acid-washed silicon dioxide sand then processed at 3 m s⁻¹ for 45s using a Fisherbrand bead mill 24 homogenizer. Two duplex reactions with PrimeTime Gene Expression Master Mix (Integrated DNA Technologies) were prepared with the first containing FgrF4/FgrR4 primers and a FgrP4 probe to identify F. graminearum (Hafez et al. 2022), and SpoF/SpoR primers and SpoPr probe to identify F. sporotrichioides (Zitnick-Anderson et al. 2018). The second reaction contained AveF/AveR primers and AvePr probe to identify F. avenaceum, and Fp-ACL1-F160/Fp-ACL1-R330 primers and PoaeACL1_poae1_pr probe to identify F. poae (Zitnick-Anderson et al. 2018). Putative Fusarium spp. not identified by the qPCR assay were confirmed by PCR and Sanger sequencing at Eurofins Genomics using EF1/EF2 primers as described by Johnstone et al. (2022) and Aiyer (2022).

Statistical analysis of FHB incidence, severity, and number of F. graminearum isolates was conducted between sites in Prince County in western PE and combined data from Queens and Kings counties in central and eastern PE, using least squares ANOVA and means separation by Student’s t-test at a significance level of α = 0.05, in JMP 17.01 (SAS Institute).

Airborne inoculum of Fusarium was surveyed using a Merck MAS-100 microbial air sampler 2 m from the roadside near plant canopies at a height of 1 m, as described by Johnstone et al. (2023). Spores were impacted on a 100 mm petri plate prepared with half-strength PDA supplemented with 10 µg mL⁻¹ tetracycline, 100 µg mL⁻¹ cefotaxime, 100 µg mL⁻¹ ampicillin, and 5 µg mL⁻¹ pentachloronitrobenzene (PCNB). Plates were incubated for 2-4 days at room temperature. Putative Fusarium colonies were isolated onto PDA supplemented with antibiotics and incubated again for 2-4 days. After an additional sub-culture, isolates were incubated for seven days then identified using the PCR assays described above.

RESULTS AND COMMENTS: Damaging and widespread FHB was observed throughout PE in 2023. Visual observations of FHB incidence were significantly greater in central/eastern PE that western PE, where most of the isolates were obtained this year, with a mean rating and standard deviation of 6.2 ± 0.5 and 2.3 ± 0.7, respectively (p < 0.001). No significant difference in disease severity was detected. Prince County accounted for only 8% of Fusarium isolates collected but also saw the lowest field incidence of FHB. A total of 235 Fusarium isolates were obtained from wheat spikes, of which F. graminearum was the dominant species this year, accounting for 77% of the collection (Table 1). Spikes collected from the single Kings County field were heavily infected, accounting for 28% of F. graminearum isolates. Samples from Queens and Prince counties accounted for 68% and 4% respectively, of the remaining F. graminearum isolates. Elevated levels of deoxynivalenol were of concern for many producers across the province. As with visual incidence rating, the mean number of isolates of F. graminearum collected per site was significantly higher in central/eastern PE than western PE with 24.9 ± 5.1 and 2.7 ± 7.8, respectively (p=0.044). Fusarium sporotrichioides accounted for 14% of isolates collected while F. avenaceum and F. poae accounted for 7% and 2% respectively. Fungicides were widely used to manage FHB in PE, and due to heavy rain events throughout the season, lodging was observed in many fields across the province in 2023.

Table 1. Disease incidence and severity of septoria blotch and fusarium head blight and the number of Fusarium spp. isolates collected from wheat spikes in PE spring wheat grower fields in 2023.

Site	County	Septoria sev.	FHB inc.	FHB sev.	F. gram^a		F. sporo^b	F. ave^c	F. poae
Elliotvale	Kings	4	7	5		51	1	0	1
Alberton	Prince	3	3	3		3	2	0	0
Freetown		5	3	3		3	1	0	0
Norway		3	1	1		2	1	4	2
Glencoe	Queens	4	7	3		13	3	3	0
Harrington		5	7	2		32	13	2	0
Kellys Cross		3	4	2		4	6	4	0
South Melville		2	5	3		18	1	0	0
Stanley Bridge		4	7	3		22	1	0	0
West Royalty		7	7	4		34	3	3	2

FHB = fusarium head blight, sev = severity, inc. = incidence

^aF. graminearum

^bF. sporotrichioides

^cF. avenaceum

A total of 53 isolates of FHB causal species were obtained by spore trapping (Table 2). Fusarium was isolated from 21 of 55 sampling sites. Queens County accounted for 51% of isolates while Prince and Kings accounted for 30% and 19% respectively. Fusarium sporotrichioides accounted for 57% of the Fusarium isolates while F. avenaceum accounted for 40%. Only two F. graminearum isolates were obtained from spore trap samples which conflicts with the abundance found in wheat spikes. This may be explained by daytime sampling as it was shown that ascospore collection for this species is more abundant at night (Schmale III et al. 2006). Additionally, edge-based sampling may not fully represent the spatial distribution of Fusarium species within fields.

Table 2. Fusarium spp. isolates collected from airborne inoculum obtained from air samples at PE field edge sites, 2023.

County	Field crop	# sites	F. gram^a	F. sporo^b	F. ave^c	F. poae
Kings	Potato	1	0	4	2	0
	Wheat	2	0	0	4	0
Prince	Barley	4	0	3	7	0
	Potato	2	0	1	1	0
	Wheat	2	0	2	2	0
Queens	Barley	1	0	6	0	0
	Corn	1	0	1	0	0
	Hay	2	0	4	1	0
	Oilseed radish	1	0	3	0	0
	Wheat	5	2	6	4	0

^aF. graminearum

^bF. sporotrichioides

^cF. avenaceum

Again in 2023, powdery mildew was not observed on flag leaves at PE survey sites. Leaf lesions matching the description of septoria blotch were present on flag leaves at each site with moderate to high severity.

ACKNOWLEDGEMENTS: We thank the producers and landowners for allowing site access and the support from summer student, Abbey Saunders.

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OILSEEDS, PULSES, FORAGES AND SPECIAL CROPS / OLÉAGINEUX, PROTÉAGINEUX, PLANTES FOURRAGÈRES ET CULTURES SPÈCIALES

BLOSSOM BLIGHT AND STEM ROT IN IRRIGATED ALFALFA SEED FIELDS IN ALBERTA, 2023

CROP: Alfalfa LOCATION: Alberta NAMES AND AGENCIES: M.W. HARDING¹, A. LUTTEROTTI², J. RETZLAFF², G.C. DANIELS¹ & S. CHATTERTON³

¹Alberta Agriculture and Irrigation, Crop Diversification Centre South, 301 Horticulture Station Road E., Brooks, AB T1R 1E6 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Alfalfa Seed Commission of Alberta, P.O. Box 2158, Brooks, AB T1R 1C8 ³Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, P. O. Box 3000, Lethbridge, AB T1J 4B1

ABSTRACT: Five irrigated seed alfalfa fields in southern Alberta were evaluated for symptoms of blossom blight, stem rot and black stem between July 12 and August 3, 2023. Disease ratings were recorded every two weeks between late flower and late seedpod stages in each field. Racemes were collected and florets plated on semi-selective media for recovery of Botrytis spp. and Sclerotinia sclerotiorum. The growing season was very dry in 2023 with hot temperatures and dry field conditions during the sampling period. The fields were supplemented with moisture via center pivot irrigation, but irrigation events only changed humidity in the canopy for limited periods. Disease levels were very low in all fields, with 0% incidence of blossom blight and stem rot incidence reaching 1%. Black stem was the most commonly observed disease reaching an average of 42.4% incidence at the final rating on Aug. 2. Although no symptoms of blossom blight were observed, Botrytis spp. and S. sclerotiorum were recovered from 16-34% of florets and 46-58% of florets, respectively.

INTRODUCTION AND METHODS: Blossom blight and stem rot are diseases caused by phytopathogenic fungi that can reduce alfalfa seed yields. Blossom blight is frequently caused by Botrytis spp. and Sclerotinia sclerotiorum Lib. deBary (Gossen et al. 1998; Huang et al. 2000), and S. sclerotiorum can also cause stem rot (Huang et al. 2000). Additionally, black stem [Ascochyta medicaginicola Qian Chen & L. Cai, (2015); syn.: Phoma medicaginus Malbr. & Roum., (1886)] is also observed in alfalfa fields in Alberta (Harding et al. 2022).

Five alfalfa seed fields were surveyed and sampled at two-week intervals between July 12 (late flower) and August 3, 2023 (late seedpod). Disease ratings were collected by moving into the field, away from the field margin, and evaluating 20 plants at each of 10 sample points approximately 10-20 m apart (total of 200 plants/field for each sampling date). Each alfalfa plant was rated for blossom blight using a 0-4 scale, and for stem rot using a 0-5 scale (Table 1). At each location, three racemes were collected and placed in a labelled paper bag (30 racemes/field) and transported in an insulated cooler on ice and stored at 4° C for three to seven days until laboratory processing and plating of florets. The presence of Botrytis spp. and S. sclerotiorum was detected by plating five florets per plate on semi-selective, differential media as described in Reich et al. (2017). Briefly, 100 florets per field were sampled randomly from the racemes and surface-sterilized in 0.5% NaClO + 2-3 drops Tween 20 for 1 min, and rinsed three times with sterile distilled water. Fifty florets from each field were then plated on Sclerotinia semi-selective medium (SSM) and 50 florets on Botrytis semi-selective medium (BSM). This plating was performed for each of the three sample dates. Plates were sealed with parafilm and incubated at 21° C in the dark in an Isotemp™ Model 304 incubator (Fisher Scientific). Growth on the plates was evaluated and results recorded after three to five days.

Table 1. Disease severity rating scales for blossom blight and stem rot of alfalfa.

Rating	Blossom blight	Rating	Stem rot
0	no florets infected	0	no infection
1	1–25% florets infected	1	<1% of stem infected
2	26–50% florets infected	2	1–10% of stem infected
3	51–75% florets infected	3	11–25% of stem infected
4	76–100% florets infected	4	26–50% of stem infected
		5	5 = >50% of stem infected

RESULTS AND COMMENTS: Disease levels were very low, but black stem was the most commonly observed disease in seed alfalfa fields in 2023 with an overall average incidence of 32.1%, while blossom blight incidence and stem rot incidence were 0.0% and 0.6%, respectively (Table 2). Black stem levels increased later in the season, whereas blossom blight and stem rot remained at or near 0% throughout (Fig. 1). Despite the lack of disease symptoms, the blossom blight pathogens were detected on alfalfa florets at every sampling date (Fig. 2). Botrytis spp. were present on 46 to 58% of florets and S. sclerotiorum was present on 16 to 34% of florets. Similar to 2022 (Harding et al. 2023), this observation supports the hypothesis that the environmental conditions were conducive to the production and discharge of spores by Botrytis spp. and S. sclerotiorum but were limiting to disease initiation and/or progression during most of the 2023 growing season. Southern Alberta has now experienced three consecutive growing seasons characterized by dry and hot summers. It is easy to speculate that alfalfa blossom blight and stem rot disease levels are declining due to the cumulative effects of successive drought years. This could explain, at least partially, why levels of both disease incidence and pathogen detection on agar media were reduced in 2022 (Harding et al. 2023), and further reduced in 2023.

Fig. 1 Average incidence of alfalfa blossom blight, stem rot and black stem disease symptoms (n=5 fields) at three sampling dates in 2023.

Fig. 2 Average incidence of Botrytis spp. and S. sclerotiorum-infected alfalfa florets (n=5 fields) at three sampling dates in 2023 determined by plating on semi-selective media.

Table 2. Average incidence of three alfalfa diseases in Alberta, 2023.

	Disease incidence^a (%)
Blossom blight	0.0
Stem rot	0.6
Black stem	32.1

^aAverage incidence in five fields at three inspection dates (n = 15).

ACKNOWLEDGEMENTS: The authors acknowledge the support of the Alfalfa Seed Commission of Alberta, Alberta Agriculture and Irrigation, and Agriculture and Agri-Food Canada. Special thanks to the five cooperating alfalfa seed producers who facilitated this work on their farms.

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DISEASES OF DRY BEAN IN MANITOBA IN 2023

CROP: Dry bean LOCATION: Manitoba NAMES AND AGENCIES: Y.M. KIM^1*, A. ABDELMAGID^2*, A. HOU², O. WALLY³, S. ZATYLNY¹, T. HENDERSON¹, M. THOMPSON¹, J. DOHERTY² & W. PENNER²

¹Agriculture and Agri-Food Canada (AAFC), Brandon Research and Development Centre, 2701 Grand Valley Rd., Brandon, MB R7A 5Y3 Telephone [phone]; Facsimile [phone] E-mail: [email protected] ²AAFC, Morden Research and Development Centre, Unit 101, Route 100, Morden, MB R6M 1Y5 Telephone [phone]; Facsimile [phone] E-mail: [email protected] ³AAFC, Harrow Research and Development Centre, 2585 County Road 20, Harrow, ON N0R 1G0 *These authors contributed equally to this work.

ABSTRACT: A total of 41 bean crops in Manitoba were surveyed for both root and foliar diseases in 2023. Fusarium root rot was the most prevalent root disease and common bacterial blight the most widespread foliar disease throughout the province. Halo blight, bacterial brown spot and white mould were also observed. In 2023, rhizoctonia root rot, rust and anthracnose were not detected in any of the surveyed dry bean crops.

METHODS: Crops of dry bean in Manitoba were surveyed in 2023 for root and foliar diseases at 41 different locations. The survey for root diseases was conducted during mid- to late July when most plants were at the early flowering to beginning pod stage. The majority of the crops surveyed were selected at random from regions in southern Manitoba where most of the dry bean crops are grown, with 10% of the crops located outside of the traditional bean growing regions. During the root disease survey, the severity of halo blight (Pseudomonas syringae pv. phaseolicola) also was assessed. When the plants were starting to mature during mid- to late August, the foliar disease survey was carried out in the same fields assessed for root rot.

For the root diseases, at least 10 plants were sampled at each of three random sites in each crop surveyed. Root diseases were rated on a scale of 0 (no disease) to 9 (death of plant). Fifteen symptomatic roots were collected from each of the 41 crops for fungal isolation and identification. Identification of Fusarium species involved visual assessment, microscopic examination and morphological characterization using the criteria of Leslie and Summerell (2006). Fifteen roots from each of the 41 crops surveyed were frozen for future PCR analysis of root rot pathogens. Foliar diseases were identified by their symptoms. Common bacterial blight (CBB) (Xanthomonas axonopodis pv. phaseoli) and bacterial brown spot (BBS) (Pseudomonas syringae pv. syringae) were assessed based on the percent incidence of leaf symptoms and on a severity scale of 0 (no disease) to 5 (50-100% of the leaf area covered by lesions). Anthracnose (Colletotrichum lindemuthianum), rust (Uromyces appendiculatus), white mould (Sclerotinia sclerotiorum) and halo blight (Pseudomonas syringae pv. phaseolicola) severity were assessed as percentages of affected plant tissue.

RESULTS AND COMMENTS: Warm weather conditions in mid-May allowed for the commencement of dry bean planting in the third week. By the end of the month, seeding was about 75% complete, slightly lagging behind the provincial average of 87% and the five-year average of 91% (Manitoba Agriculture 2023a, 2023b). By the beginning of June, the planting of dry bean was nearly completed, with the exception of a few scattered fields (Manitoba Agriculture 2023c). In 2023, 98% of the crop was harvested by mid-October (Manitoba Agriculture 2023d). Despite drier than normal conditions in the growing season, average yield of all bean types was 1700 lbs/acre ranging from 1400 to over 3000 lbs/acre (Manitoba Agriculture 2023e).

Fusarium root rot was observed in all 41 of the surveyed dry bean crops (Table 1), with severity ratings ranging from 1.4 to 5.4, and a mean of 2.9. It has remained the most prevalent root disease of dry bean for a number of years (Conner et al. 2011; Henriquez et al. 2013; Kim et al. 2022, 2023). A number of Fusarium spp. including F. avenaceum, F. equiseti and F. sporotrichioides were isolated from symptomatic root tissue. Rhizoctonia root rot (Rhizoctonia solani) and pythium root rot (Pythium spp.) were not detected in any of the crops surveyed based on microscopic examination and morphological characterization. Four crops (10%) had average root rot severity ratings greater than 4 (i.e., symptoms were present on 50% of the root system and plants were stunted) and this would have had a detrimental effect on yield. In 2023, halo blight was assessed in the 41 crops surveyed and was observed in three (7%) crops with an average of 7.3% leaf area infected.

Table 1. Prevalence and severity of root diseases and halo blight in 41 crops of dry bean in Manitoba in mid- to late July in 2023.

		Disease severity
Disease	# of crops affected (%)	Mean^a	Range
Fusarium root rot^b	41 (100%)	2.9	1.4-5.4
Rhizoctonia root rot	0	0	0
Pythium root rot	0	0	0
Halo blight (%)	3 (7%)	7.3%	2-15%

^aMeans are based on an average of the crops in which the diseases were observed.

^bRoot diseases were rated on a scale of 0 (no disease) to 9 (death of plant).

Three foliar diseases were observed during the survey in August (Table 2). Common bacterial blight symptoms were observed in 38 crops. The incidence of CBB leaf infection ranged from 0.3 to 27% with a mean of 14%, while severity ranged from 0.3 to 3.7, with a mean of 1.9. Bacterial brown spot was present in 44% (18/41) of surveyed crops. The incidence of BBS leaf infection ranged from 0.3 to 13% with a mean of 4.2%, while disease severity ranged from 0.3 to 2.0, with a mean of 0.9. Anthracnose was not detected from 2014 to 2023, unlike many years prior to this period. Rust was not observed in any of the crops surveyed in 2023. White mould symptoms were detected in 5% (2/41) of the crops with 2% of tissue infection in 2023.

Table 2. Prevalence and severity of foliar diseases in 41 crops of dry bean in Manitoba in August in 2023.

		Disease severity^a		Incidence of leaf infection
Disease	# of crops affected (%)	Mean^b	Range	Mean^b	Range
Common bacterial blight	38 (93%)	1.9	0.3-3.7	14%	0.3-27%
Bacterial brown spot	18 (44%)	0.9	0.3-2.0	4.2%	0.3-13%
Anthracnose (%)	0	0	0	0	0
Rust (%)	0	0	0	0	0
White mould (%)	2 (5%)	2%	0.7-3.3%	−	−

^aWhite mould and rust severity were rated as the percentage of infected plant tissue; common bacterial blight and bacterial brown spot severity were rated on a scale of 0 (no disease) to 5 (50-100% of leaf area diseased) and on the incidence of leaves with symptoms.

^bMeans are based on an average of the crops in which the diseases were observed.

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CANOLA DISEASE SURVEY IN ALBERTA, 2023

CROP: Canola LOCATION: Alberta NAMES AND AGENCIES: M.W. HARDING¹, G.C. DANIELS¹, T.B. HILL¹, L. STELLAR, A. VAN TRYP¹, S. XUE² & J. FENG²

¹Alberta Agriculture and Irrigation, Crop Diversification Centre South, 301 Horticulture Station Road E., Brooks, AB T1R 1E6 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Alberta Agriculture and Irrigation, Crop Diversification Centre North, 17507 Fort Road NW, Edmonton, AB T5Y 6H3

ABSTRACT: In 2023, canola fields were selected randomly in each county to represent approximately 1% of canola acreage and four diseases were assessed. Blackleg was found in 91.8% of 357 fields and on 26.4% of the stems rated. Blackleg severity averaged 0.5 on a 0 to 5 scale. Sclerotinia stem rot symptoms on lower main stems were observed in 21.4% of 357 fields on 1.2% of stems. Finally, 18% of 356 fields had suspicious symptoms of verticillium stripe but only one of samples tested positive for Verticillium longisporum (prevalence = 0.3%). This is the first positive test for V. longisporum in the Alberta canola disease survey. Clubroot symptoms were also rated in each field and results will be presented in a separate report.

INTRODUCTION AND METHODS: Canola (Brassica napus L.) was produced on 6.3 million acres in Alberta in 2023 (Statistics Canada 2023). Canola diseases are observed in Alberta each year at generally low levels, but can cause yield loss in some fields. Some of the more commonly found diseases are clubroot, blackleg and stem rot. Monitoring of these diseases can help detect changes in occurrence, prevalence, incidence and severity.

Blackleg of canola, caused by Leptosphaeria maculans (Sowerby) P. Karst., is evaluated annually on canola crops in Alberta in approximately 1% of canola fields in each county/municipality. In total, 357 canola fields were surveyed in 61 counties and municipal districts across the province with the primary objective of characterizing blackleg (L. maculans), sclerotinia stem rot (Sclerotinia sclerotiorum Lib. de Bary) and verticillium stripe [Verticillium longisporum (C. Stark) Karapapa, Bainbr. & Heale (1997)] on canola. Disease prevalence and incidence were calculated for all diseases, but severity was only calculated for blackleg. The survey was performed at swathing timing, or post-harvest, between August 8 and October 6, 2023. Surveyors were encouraged to visit fields within seven days of swathing timing, and collect 10 stems at each of 10 locations along a W-shaped survey transect (100 stems/field). Sampling locations were ≥ 20 m from one another, and from field margins. The lower stems (bottom 6- 12 in; 15-30 cm) were collected and shipped directly to the Crop Diversification Centre South (Brooks, AB) where they were evaluated for the presence of blackleg symptoms such as stem cankers, lesions with pycnidia and internal stem blackening (Fig 1). Blackleg prevalence was calculated as the percentage of fields with symptoms and incidence was calculated as the percentage of stems showing blackleg symptoms. Blackleg severity was estimated using a 0-5 scale for rating vascular discolouration based on the area of diseased tissue in stem cross-section, where 0 = no diseased tissue visible and 5 = diseased tissue occupying 100% of the cross section and plant dead (WCC/RRC 2009; Table 1).

Fig. 1 Blackleg basal stem canker on canola (left) and vascular discolouration in canola stems (right).

Table 1. Disease prevalence, incidence and severity of three canola diseases in Alberta, 2023.

			Disease incidence^b (%)		Disease severity^c (0-5 scale)
Disease	Positive fields	Prevalence^a (%)	Mean	Range	Mean	Range
Blackleg	324/353	91.8	26.4	0-93	0.50	0-3.18
Sclerotinia stem rot	86/357	21.4	1.15	0-37.8	n.d.	n.d.
Verticillium stripe	1/356	0.3	n.d^d	n.d.	n.d.	n.d.

^aPercent diseased fields

^bPercent diseased stems

^cScale of 0-5 based on the area of vascular discolouration in stem cross-section, where 0 = none and 5 = 100% of the cross section diseased and plant dead (WCC/RRC 2009).

^dnot done

Three other diseases were also evaluated on the roots and lower main stems. Sclerotinia stem rot infections occurring on lower main stems were recorded when they were soft and would shred when twisted, and/or when sclerotia were observed inside the stem. Prevalence was calculated as the percentage of fields with stem rot and incidence as the percentage of stems showing symptoms. Stem rot severity was not calculated. Symptoms of verticillium stripe were also recorded when discolouration of the internal stem tissues appeared in a ‘starburst’ pattern, rather than sectoring, or when unilateral striping on stems was observed. Verticillium stripe prevalence and incidence were calculated in the same manner as sclerotinia stem rot. Colonization of symptomatic host tissues by V. longisporum was tested using a triplex qPCR assay for detection of L. maculans, L. biglobosa, and V. longisporum (Fu et al. 2024). For all qPCR tests, DNA from a healthy canola plant, the corresponding fungal culture and known infected plant samples were included as controls. Clubroot symptoms were rated and recorded using a separate protocol and methodology, and are presented in a separate report.

RESULTS AND COMMENTS: Sampling locations and blackleg severity are shown in Fig 2. Blackleg levels were very similar to those reported in 2022, while sclerotinia stem rot was less prevalent compared with the previous year (Harding et al. 2023). Results summarized in Table 1 show that blackleg symptoms were observed in 324 out of 353 fields and on 8071 of 32006 stems for an overall prevalence of 91.8% and an overall incidence of 26.4%. The severity of blackleg averaged 0.5 on a 0 to 5 scale. Sclerotinia stem rot was observed in 140 out of 308 fields and on 291 of 31640 stems for an average prevalence of 21.4% and average incidence of 1.15%. Finally, suspicious symptoms in 64 out of 356 fields were tested for the presence of V. longisporum and qPCR confirmed this pathogen in one field (prevalence = 0.3%). This is the first positive test for V. longisporum in the Alberta canola disease survey. Blackleg and stem rot disease levels varied across jurisdictions (Table 2).

Fig. 2 Location and severity of blackleg symptoms in 353 canola fields in Alberta, 2023.

Table 2. Blackleg and stem rot disease occurrence in 61 counties and municipal districts in Alberta, 2023.

		Blackleg			Sclerotinia stem rot
County/ MD/SA	No. fields surveyed	Prevalence^a (%)	Incidence^b (%)	Severity^c (0-5)	Prevalence (%)	Incidence (%)
Acadia	2	100	10.89	0.16	0.0	0.00
Athabasca	4	100	63.57	1.70	0.0	0.10
Barrhead	6	100	20.11	0.32	0.0	0.06
Beaver	6	67	14.94	0.22	0.0	0.00
Big Lakes	2	100	11.41	0.15	0.0	0.02
Birch Hills	5	100	33.43	0.56	0.0	0.02
Bonnyville	2	100	54.21	1.15	0.0	0.00
Camrose	7	86	13.62	0.22	0.0	0.00
Cardston	6	83	27.79	0.62	NR^d	NR
Clear Hills	3	100	15.69	0.23	0.0	0.00
Cypress	8	100	12.43	0.20	0.0	0.00
Fairview	6	83	10.67	0.13	16.7	0.01
Flagstaff	15	100	48.06	0.93	6.7	0.00
Foothills	2	100	15.36	0.19	0.0	0.00
Forty Mile	5	80	9.68	0.12	0.0	0.00
Grande Prairie	10	100	26.84	0.47	0.0	0.07
Greenview	5	NR	NR	NR	NR	NR
Kneehill	13	100	37.34	0.83	7.7	0.00
Lac La Biche	10	100	75.00	1.75	0.0	0.02
Lac Ste Anne	2	100	20.60	0.27	0.0	0.05
Lacombe	6	100	26.90	0.43	0.0	0.01
Lamont	6	100	19.14	0.33	0.0	0.00
Leduc	5	100	18.60	0.28	20.0	0.01
Lethbridge	6	67	14.36	0.25	0.0	0.00
Mackenzie	7	43	4.64	0.05	0.0	0.00
Minburn	12	100	45.78	1.09	8.3	0.02
MountainView	6	100	22.66	0.35	0.0	0.00
Newell	3	67	19.67	0.48	0.0	0.00
Northern Lights	4	100	18.50	0.28	25.0	0.00
Northern Sunrise	2	100	44.26	0.79	0.0	0.00
Paintearth	4	75	15.94	0.30	0.0	0.00
Parkland	2	100	23.97	0.55	0.0	0.02
Peace	2	50	16.88	0.28	0.0	0.00
Ponoka	3	100	17.53	0.24	0.0	0.00
Provost	6	100	25.42	0.35	0.0	0.00
Red Deer	9	100	30.72	0.48	11.1	0.01
Rockyview	7	86	34.14	0.81	0.0	0.00
Saddle Hills	5	100	29.80	0.47	0.0	0.01
Smoky Lake	4	50	9.95	0.12	25.0	0.00
Smoky River	19	100	46.08	0.86	14.3	0.02
Special Area 2	2	100	14.95	0.34	0.0	0.00
Special Area 3	3	33	0.33	0.00	0.0	0.00
Special Area 4	3	67	23.39	0.42	33.3	0.00
Spirit River	3	67	9.00	0.10	66.7	0.06
St. Paul	4	100	23.35	0.42	0.0	0.03
Starland	7	86	22.45	0.37	0.0	0.00
Stettler	7	100	42.81	0.69	14.3	0.01
Strathcona	3	100	14.93	0.22	0.0	0.01
Sturgeon	9	100	26.53	0.41	0.0	0.03
Taber	5	80	9.40	0.10	0.0	0.00
Thorhild	4	100	13.25	0.16	0.0	0.03
Two Hills	7	100	22.55	0.60	0.0	0.00
Vermilion River	19	100	36.35	0.63	0.0	0.01
Vulcan	14	100	34.08	0.85	0.0	0.00
Wainwright	8	75	14.10	0.20	0.0	0.00
Warner	6	83	8.39	0.14	16.7	0.00
Westlock	9	100	14.72	0.25	11.1	0.01
Wetaskiwin	5	NR	NR	NR	NR	NR
Wheatland	14	93	21.70	0.49	0.0	0.00
Willow Creek	8	88	21.42	0.44	12.5	0.02
Yellowhead	1	100	25.89	0.49	0.0	0.00
Alberta	378	92	26.38	0.50	21.4	1.15

^aPercent diseased fields

^bPercent diseased stems

^cScale of 0-5 based on the area of vascular discolouration in stem cross-section, where 0 = none and 5 = 100% of the cross-section diseased and plant dead (WCC/RRC 2009).

^dNR = not rated

ACKNOWLEDGEMENTS: We gratefully acknowledge the significant contributions of the Alberta Association of Agricultural Fieldmen and their staff for assistance with collecting canola stems from across the province.

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CANOLA DISEASE SURVEY IN NORTH-CENTRAL ALBERTA IN 2023

CROP: Canola LOCATION: Central and northern Alberta NAMES AND AGENCY: X. DONG, H. YU, K.F. CHANG, V.P. MANOLII, L.F. WU, G.D. TURNBULL, A. BRINKMAN, B. KIRK, S. OH, J. CORDERO-ELVIA, R. FREDUA-AGYEMAN, S.F. HWANG & S.E. STRELKOV

Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: Fifty canola crops were surveyed across central and northern Alberta in September 2023 for the occurrence of various root and stem diseases. The mean incidence of root rot was highest in Wetaskiwin County (15.2%), followed by the counties of Leduc, Camrose, Ponoka, Sturgeon and Smoky Lake. The highest incidence of blackleg was found in Smoky Lake (23.9%), followed by Strathcona and Parkland counties. Clubroot was most severe in Lac Ste. Anne (9.7%) and Smoky Lake (8.9%), although the disease was also identified in Parkland, Leduc, Ponoka, Sturgeon and Thorhild counties. Sclerotinia stem rot incidence was greatest in Thorhild County (17.1%). Root samples from diseased plants were collected and taken to the lab for analysis, where Fusarium spp. were recovered at high rates (74.4%) from roots showing symptoms of root rot. Species of Fusarium often occurred together with Leptosphaeria maculans and Rhizoctonia solani suggesting some synergies among these pathogens.

INTRODUCTION: In Alberta, nearly 2.6 million ha of canola (Brassica napus) were seeded in 2023 (Statistics Canada 2023). Root and stem diseases can, however, be a major cause of yield losses in this important crop, particularly in years with good soil moisture. In September 2023, a survey of 50 canola crops was conducted across central and northern Alberta to monitor the occurrence of various stem and root diseases.

METHODS: Fifty canola crops were visited across 10 counties in north-central Alberta (Figure 1; Table 1) shortly after harvest. Each field was inspected in a W-shaped transect, with all plants in a 1-m² quadrat examined for disease at each of five points along the transect. The incidence of clubroot, blackleg, root rot, and sclerotinia stem rot was recorded at each sampling point, and root samples were collected and taken to the laboratory to confirm the causal organisms. In the lab, a set of 487 samples were selected for pathogen isolation. Briefly, the roots were dissected and examined for discolouration of the vascular tissues. Samples showing vascular staining were placed in a tray (Yu et al. 2023), immersed in 1% sodium hypochlorite for 1-2 min, and then rinsed three times in sterile distilled water. The surface-disinfested root tissue was transferred to Petri dishes filled with potato dextrose agar (PDA) amended with chloramphenicol and streptomycin (0.1 g/L each) to suppress bacterial growth (Strauss and Dillard 2009). The Petri dishes were incubated for 10-12 days under ambient light at room temperature, after which any fungal isolates recovered were identified visually based on their morphological characteristics. The percentage incidence of each pathogen was calculated for samples collected from each field, across fields in each county, and for all 50 surveyed fields (Table 2).

Fig. 1 Locations surveyed for canola diseases (red circles) across north-central Alberta in 2023.

Table 1. Incidence (%) of diseases in canola sampled across north-central Alberta in 2023.

		Root rot		Blackleg		Clubroot		Sclerotinia stem rot
Location (County)	Nf^a	Mean%	Range%	Mean%	Range%	Mean%	Range%	Mean%	Range%
Camrose	5	14.5	8.2-24	8.3	0.8-30	0.0	0.0-0	8.1	2.0-16
Parkland	5	9.1	4.0-20	13.6	2.1-26	1.4	0.0-3	14.2	4.4-19
Lac Ste. Anne	5	4.9	1.9-8	9.4	3.0-18	9.7	0.0-49	7.7	5.1-11
Leduc	5	14.7	9.5-19	10.5	1.7-31	0.4	0.0-2	8.1	4.5-11
Ponoka	5	13.4	8.8-27	2.1	0.0-6	0.6	0.0-2	8.4	0.8-17
Smoky Lake	5	11.7	3.1-27	23.9	6.6-49	8.9	0.0-39	9.0	4.0-12
Strathcona	5	6.9	1.7-16	18.5	1.1-57	4.7	0.0-18	9.4	6.6-16
Sturgeon	5	12.7	4.3-22	2.6	0.7-5	1.8	0.0-5	16.9	3.4-34
Thorhild	5	9.5	1.9-18	10.3	4.5-17	0.1	0.0-1	17.1	7.3-56
Wetaskiwin	5	15.2	5.1-38	0.7	0.0-2	7.8	0.0-25	11.3	10.3-12
Total/Avg/ Range	50	11.2	1.7-38	10.0	0.0-57	3.5	0.0-49	11.0	2.0-56

^aNf = Number of fields surveyed.

RESULTS AND DISCUSSION: Precipitation varied considerably over north-central Alberta from June 3 to August 31, 2023, ranging from near normal to well above average (Alberta Government 2023). A total of 3277 canola root samples were collected and examined across the surveyed fields. The mean incidence of root rot was highest in Wetaskiwin County (15.2%), followed by Leduc, Camrose, Ponoka, Sturgeon and Smoky Lake, all with a mean root rot incidence >10%. Blackleg incidence was greatest in Smoky Lake (23.9%), followed by Strathcona, Parkland, Leduc and Thorhild counties, all with a mean blackleg incidence >10%. Clubroot was most prevalent in Lac Ste. Anne County, where the mean incidence was 9.7%, including one sampling point where 49% of the roots were infected. In Smoky Lake, the mean incidence of clubroot was 8.9%, while a lower incidence of the disease was found in Parkland, Leduc, Ponoka, Sturgeon and Thorhild counties. Sclerotinia stem rot incidence was greatest in Thorhild County (17.1%), followed by Sturgeon, Parkland and Wetaskiwin counties, where the mean incidence was >10%. In Lac Ste. Anne County, the mean incidence of stem rot was 7.7%. In general, the occurrence of root rot and clubroot was lower in 2023 than in 2022 (Yu et al. 2023), while sclerotinia stem rot was more prevalent. The levels of blackleg of canola were similar in both years.

During the processing of plant tissues in the lab, the basal portions of the roots were cut longitudinally and in cross-section. Fusarium spp. were recovered at the highest frequency (74.4%), followed by Leptosphaeria maculans (39.2%), Rhizoctonia solani (19.6%), and Rhizopus spp. (6.4%) (Table 2). During processing, mechanical damage resulting from insect feeding was observed on many roots, similar to what was reported for last year’s survey (Yu et al. 2023). The incidence of Rhizoctonia solani infection varied from a high of 42.9% in Sturgeon County to a low of 2.0% in Thorhild County. Sclerotinia sclerotiorum was recovered from relatively few of the cultured samples, with the pathogen most frequently (4.1%) isolated from samples collected in Thorhild County.

Table 2. Incidence of fungi recovered from diseased canola root samples collected across north-central Alberta in 2023.

County	Fields surveyed (no.)	Roots tested (no.)	Fusarium spp. (mean%^a)	L.m.^b (mean%)	Fus. + L.m.^c	S.s.^d (mean%)	R. solani^e	Fus. + R.s.^f	Alternaria spp. (mean%)	Rhizopus spp. (mean%)	Others^g (mean%)
Camrose	5	87	63.2	39.1	28.7	1.1	9.2	3.4	1.1	2.3	9.2
Lac St. Anne	5	38	76.3	31.6	21.1	2.6	15.8	15.8	0	10.5	5.3
Leduc	5	37	81.1	29.7	24.3	0	40.5	27.0	0	2.7	2.7
Parkland	5	60	73.3	36.7	30	3.3	13.5	6.7	1.7	0	23.3
Ponoka	5	73	79.5	32.9	30.1	0	32.3	19.2	2.7	1.4	5.5
Smoky Lake	5	53	84.2	48.4	34.7	0	8.4	7.4	2.1	13.7	8.4
Strathcona	5	83	73.5	38.6	26.5	1.2	12.0	2.4	3.6	8.4	4.8
Sturgeon	5	7	57.1	42.9	28.6	0	42.9	28.6	0	14.3	0
Thorhild	5	49	81.6	53.1	36.7	4.1	2.0	2.0	2.0	4.1	0
Total/ Average	45	487	74.4	39.2	29.0	1.4	19.6	12.5	1.5	6.4	6.6

^a Mean% = mean percentage incidence

^b L.m. = Leptosphaeria maculans

^c Fus. + L.m. = Fusarium spp. + L. maculans

^d S.s. = Sclerotinia sclerotiorum

^e R. solani = Rhizoctonia solani

^f Fus. + R.s. = Fusarium spp. + Rhizoctonia solani

^g Others include Penicillium spp., Verticillium spp. and unknown species

Combinations of Fusarium spp. and L. maculans (29.0%) or Fusarium spp. and R. solani (12.5%) were recovered from many infected roots (Table 2), suggesting a pathogen complex. Further study is needed to explore the tendency to find Fusarium spp. in combination with other pathogens and to evaluate possible synergies among these fungi on canola. Longer rotations out of canola may help to manage diseases in central and northern Alberta.

ACKNOWLEDGEMENTS: This survey was supported financially by Alberta Canola and Results Driven Agriculture Research (RDAR), with in-kind support from the University of Alberta.

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OCCURRENCE AND SPREAD OF CLUBROOT ON CANOLA IN ALBERTA IN 2023

CROP: Canola LOCATION: Alberta NAMES AND AGENCIES: S.E. STRELKOV¹, V.P. MANOLII¹, Y. AIGU¹, M.W. HARDING², G.C. DANIELS², N. CHARRIER^1,3 & S.F. HWANG¹

¹Department of Agricultural, Food and Nutritional Science, University of Alberta, 410 Agriculture/Forestry Centre, Edmonton, AB T6G 2P5 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Alberta Agriculture and Irrigation, Crop Diversification Centre South, 301 Horticultural Station Road East, Brooks, AB T1R 1E6 ³L’Institut Agro Rennes-Angers, 65 Rue de Saint-Brieuc, 35042 Rennes, France

ABSTRACT: In 2023, clubroot (Plasmodiophora brassicae) was identified in 38 of 611 canola (Brassica napus) crops surveyed across Alberta. The incidence of the disease varied among the affected crops, with 24 exhibiting low levels, 11 moderate levels, and three having high levels of clubroot. An additional 19 cases of the disease were documented in a general canola disease survey conducted in north-central Alberta, while county and municipal personnel identified 122 cases of the disease during independent inspections across the province. Collectively, clubroot was confirmed in 179 canola crops in Alberta in 2023.

METHODS: In 2023, a survey was carried out to assess the occurrence of clubroot, caused by Plasmodiophora brassicae Wor., in 611 canola (Brassica napus L.) crops across Alberta (Table 1). Crops were typically inspected after harvest, and selected randomly or based on reports of clubroot in the vicinity. Visual inspections were performed on approximately 50-100 canola roots within a 20-30 m² area near the field entrance, focusing on the presence of root galls indicative of the disease. If no symptoms were found further surveying was not conducted, since clubroot is most prevalent near field approaches (Cao et al. 2009). When clubroot symptoms were observed, a more extensive survey was carried out, which involved examining the roots of all plants within a 1-m² area at each of 10 points along a ‘W’ sampling pattern. The disease incidence, defined as the percentage of plants showing any symptoms of clubroot relative to the total number of plants assessed, was calculated for each sampling point and crop. When possible, surveys were coordinated with the agricultural personnel in each county or municipal district. Additionally, the clubroot data from a general survey of canola diseases in north-central Alberta (Dong et al. 2024), and information collected independently by the counties/municipal districts, are included for a more comprehensive assessment of the clubroot status in the province.

Table 1. Cases of clubroot identified on canola crops in Alberta in 2023.

County or municipality	Number of crops assessed in province-wide survey	Number of cases identified in province-wide survey	Cases identified by Dong et al. (2024)^a	Cases identified by county/municipal staff^b	Total cases
Acadia	2	0	--	0	0
Athabasca	26	3	--	6	9
Barrhead	6	2	--	6	8
Beaver	32	2	--	1	3
Big Lakes	32	2	--	0	2
Birch Hills	5	0	--	0	0
Bonnyville	2	0	--	0	0
Brazeau	--	--	--	0	0
Camrose	7	0	0	10	10
Cardston	6	0	--	0	0
Clear Hills	3	0	--	0	0
Clearwater	17	2	--	4	6
Cypress	8	0	--	0	0
Fairview	6	0	--	0	0
Flagstaff	46	1	--	0	1
Foothills	2	0	--	0	0
Forty Mile	5	0	--	0	0
Grande Prairie	10	0	--	1	1
Greenview	--	--	--	0	0
Kneehill	13	0	--	0	0
Lac La Biche	--	--	--	0	0
Lac Ste. Anne	23	3	1	9	13
Lacombe	26	4	--	3	7
Lamont	26	2	--	10	12
Leduc	5	2	1	30	33
Lethbridge	4	0	--	0	0
Lesser Slave River	--	--	--	6	6
Mackenzie	7	0	--	0	0
Minburn	12	2	--	1	3
Mountain View	26	0	--	0	0
Newell	3	0	--	0	0
Northern Sunrise	32	0	--	0	0
Paintearth	4	0	--	2	2
Parkland	2	0	3	5	8
Peace	2	0	--	0	0
Pincher Creek	--	--	--	0	0
Ponoka	3	0	2	0	2
Provost	6	0	--	1	1
Red Deer	29	4	--	1	5
Rocky View	7	0	--	0	0
Saddle Hills	5	0	--	0	0
Smoky Lake	4	1	3	3	7
Smoky River	19	0	--	0	0
Special Area #2	2	0	--	0	0
Special Area #4	3	0	--	0	0
Spirit River	3	0	--	0	0
St. Paul	4	2	--	0	2
Starland	7	0	--	0	0
Stettler	7	1	--	0	1
Strathcona	3	0	2	7	9
Sturgeon	9	2	3	5	10
Taber	5	0	--	0	0
Thorhild	4	0	1	3	4
Two Hills	7	0	--	0	0
Vermillion River	19	0	--	3	3
Vulcan	14	0	--	0	0
Wainwright	8	0	--	1	1
Warner	6	0	--	0	0
Westlock	9	2	--	0	2
Wetaskiwin	5	1	3	0	4
Wheatland	14	0	--	0	0
Willow Creek	8	0	--	0	0
Woodlands	--	--	--	3	3
Yellowhead	1	0	--	1	1
TOTAL	611	38	19	122	179

^aDong et al. (2024) conducted a general survey of diseases across 50 canola crops in north-central Alberta in 2023, and identified additional cases of clubroot as indicated.

^bCounty and municipal personnel documented an additional 122 cases of clubroot in independent inspections across the province.

RESULTS AND COMMENTS: Symptoms of clubroot were observed in 38 (6.2%) of the 611 canola crops visited in the province-wide survey in 2023 (Table 1). Among the clubroot-positive crops, 24 exhibited a low incidence (<10%), 11 had a moderate incidence (10-60%), and three recorded a high incidence (>60%) of the disease. An additional 19 cases of clubroot were reported in a general disease survey of 50 canola crops conducted in north-central Alberta (Dong et al. 2024), while county and municipal personnel identified another 122 cases of clubroot in independent inspections across the province. In total, 179 confirmed field infestations were documented in 2023 (Table 1). Since 2005, clubroot has been diagnosed in 5,532 canola crops throughout Alberta, representing nearly 4,000 individual fields (Fig. 1).

Fig. 1 Distribution of clubroot in Alberta. The disease has been diagnosed in 5,532 canola crops in the province from 2005 to 2023, representing nearly 4,000 individual fields.

The occurrence of clubroot in 2023 was lower than reported in 2022 (Strelkov et al. 2023), when 300 field infestations were documented across the province. Additionally, there were no first reports of the disease from any county or municipal district this year. This may reflect generally dry conditions throughout much of Alberta in 2023 (Alberta Government 2023), although other factors, such as the widespread deployment of clubroot-resistant canola, may also have contributed to reduced disease levels. Nonetheless, the vast majority of canola crops found to be positive for clubroot in this year’s survey were clubroot-resistant hybrids, underscoring the continued threat posed by ‘resistance-breaking’ pathotypes of P. brassicae (Hollman et al. 2023). With clubroot confirmed in many of the canola growing-regions across Alberta, the sustainable management of this disease should remain a top priority.

ACKNOWLEDGEMENTS: The authors thank the following individuals for their assistance with the survey: M. Bates, J. Benson, S. Berry, G. Bloom, J. Boden, J. Breadon, J. Culbert, C. Danyluk, C. Dowhan, L. Duncan, N. Dunn, T. Eleniak, C. Erichsen-Arychuk, D. Fath, D. Fortin, T. Green, R. Hallett, C. Heck, R. Hrywkiw, N. Iqbal, S. Kaus, T. Keller, T. Kerr, A. Kihn, K. King, K. Kornelsen, K. Kozdroski, J. Lizotte, S. Majec, J. Makus, J. Marfo, M. Martinson, D. Marynowich, D. McCann, C. McIntosh, T. McNaught, K. Meunier, S. Miller, T. Muntean, H. Musterer, P. O’Neil, D. Orchard, M. Pfeffer, L. Poile, J. Porter, M. Rose, J. Schwindt, B. Scott, F. Sherlock, S. Steffen, C. Stuber, K. Trueblood, S. Thon, D. Ullery, A. Van Beers, C. Verpy, T. Wilson and M. Winchell.

FUNDING: This survey was made possible by financial support from Results Driven Agriculture Research (RDAR) and Alberta Canola. In-kind support from the counties and municipal districts, Alberta Agriculture and Irrigation, and the University of Alberta is also gratefully acknowledged.

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SURVEY OF CANOLA DISEASES IN SASKATCHEWAN, 2023

CROP: Canola LOCATION: Saskatchewan NAMES AND AGENCIES: A. AKHAVAN¹, C. PERU¹, R. AVILA¹, D. FERNANDO², J. GILROYED^3, B. ESAU³, T. HUFFMAN³, C. DANYLUK⁴, C. JACOB¹, N. MONTREUIL¹, S. CHANT¹, A. KAMINSKI¹, A. NOBLE¹, S. MARCINO¹, K. STONEHOUSE¹, S. WILLIAMS¹, K. MAKOHONIUK⁶, J. KWASNICKI⁶, C. NEUBERGER⁶, C. FENNIG⁶, B. JOHNSON⁶, T. ADEGEYE⁶, M. ROBITAILLE⁷, C. JURKE⁷ & W. WARD⁷

¹ Saskatchewan Ministry of Agriculture, 3085 Albert St., Regina, SK S4S 0B1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Dept. of Plant Science, University of Manitoba, Winnipeg, MB R3T 2N2 ³Prairie Co-op, Meadow Lake, SK S9X 1A0 ⁴Nutrien, Saskatoon, SK S7K 7G3 ⁵Bayer Crop Science Inc., Saskatoon, SK S7K 4B5 ⁶Saskatchewan Association of Rural Municipalities, Regina, SK S4V 3A4 ⁷Canola Council of Canada, 400-167 Lombard Ave., Winnipeg, MB R3B 0T6

ABSTRACT: The annual survey in Saskatchewan covered 218 canola fields across six large regions of the province. Blackleg (basal canker) was the most prevalent disease in 72% of crops surveyed with a mean disease incidence of 12% (ranging from 3% to 25%). Sclerotinia stem rot was observed with symptoms in 30% of the crops surveyed. The mean incidence of sclerotinia stem rot among all crops surveyed in Saskatchewan was 4% but ranged from 0% to 10% among regions. Verticillium longisporum was confirmed by PCR in 23 fields surveyed during the general canola disease survey. No new visible clubroot symptoms were recorded through the clubroot monitoring program in 2023 in Saskatchewan.

METHOD: A total of 218 canola crops were surveyed between August 1 and September 27 in the major canola growing regions of Saskatchewan. In 2023, the number of surveyed crops was highest in the East-central with 47 out of 218 fields being in this region. The distribution of surveyed crops across the rest of the province was as follows: 39 (Southeast), 39 (Northwest), 34 (Northeast), 35 (West-central), and 24 (Southwest). Almost all crops were surveyed before swathing while plants were between growth stages 5.1 and 5.5 (Harper and Berkenkamp, 1975). Disease assessments were made by examining 20 plants from each of five sites in each field. Individual sample sites were located at least 30 m from the field edge and separated from each other by at least 20 m. Fields were assessed for both prevalence (percent of fields with symptoms of the disease) and incidence (percent of plants surveyed with symptoms of the disease per field). The diseases assessed include: sclerotinia stem rot (Sclerotinia sclerotiorum), blackleg (Leptosphaeria maculans), aster yellows (AY phytoplasma), foot rot (Rhizoctonia spp., Fusarium spp.), alternaria black spot (Alternaria brassicae, A. raphani), fusarium wilt (F. oxysporum f.sp. conglutinans), verticillium stripe (Verticillium longisporum), powdery mildew (Erysiphe cruciferarum), downy mildew (Peronospora parasitica), white rust (Albugo candida), grey stem (Pseudocercosporella capsellae), bacterial pod spot (Pseudomonas syringae pv. maculicola) and clubroot (Plasmodiophora brassicae). Severity ratings were also conducted for both sclerotinia stem rot and blackleg. For sclerotinia stem rot, each plant (100 per field) was rated for severity according to a rating scale of 0 to 5 described by Kutcher and Wolf (2006) (Table 1). For blackleg, plant stems were cut and then scored for basal stem cankers severity using a rating scale ranging from 0 to 5 (WCC/RRC 2009) (Table 2). Average severity values for blackleg and sclerotinia stem rot in each field were calculated as the sum of the severity ratings divided by the total number of plants examined. Stem lesions were recorded when observed on the upper stem. The prevalence of alternaria black spot (A. brassicae, A. raphani) in the field was recorded. For all of the diseases assessed, prevalence and average disease incidence or severity values were calculated across the entire province and separately for each of six regions within Saskatchewan.

Table 1. Sclerotinia rating scale (Kutcher and Wolf 2006).

Disease rating	Lesion location	Symptoms
0	None	No symptoms
1	Pod	Infection of pods only
2	Upper plant parts	Lesion situated on main stem or branch(es) with potential to affect up to ¼ of seed formation and filling on plant
3		Lesion situated on main stem or on a number of branches with potential to affect up to ½ of seed formation and filling on plant
4		Lesion situated on main stem or on a number of branches with potential to affect up to ¾ of seed formation and filling on plant
5	Lower plant part	Main stem lesion with potential effects on seed formation and filling of entire plant

Table 2. Blackleg rating scale (WCC/RRC 2009).

Rating	Description
0	No disease visible in the cross section
1	Diseased tissue occupies up to 25% of cross-section
2	Diseased tissue occupies 26 to 50% of cross-section
3	Diseased tissue occupies 51 to 75% of cross-section
4	Diseased tissue occupies more than 75% of cross-section with little or no constriction of affected tissues
5	Diseased tissue occupies 100% of cross-section with significant constriction of affected tissues; tissue dry and brittle; plant dead

RESULTS AND COMMENTS: In 2023, approximately 5,018,200 hectares (12,400,400 acres) was seeded to canola in Saskatchewan. As of early April 2024, 4,980,200 hectares (12,306,400 acres) of canola were harvested (Statistics Canada 2023) in Saskatchewan. The Saskatchewan Crop Report (Saskatchewan Ministry of Agriculture 2023) estimated that 96% of the Saskatchewan canola crop had been harvested by October 16, 2023.

Sclerotinia stem rot was observed in 30% of the canola crops surveyed. The average incidence in the province was 4% (12% in infested crops) (Table 3). The overall incidence of sclerotinia stem rot across all the surveyed fields was lower in 2023 than 2022 (6%) but higher than 2021 (2%) (Table 6). Incidence was highest in the Northwest region (10%) and lowest in the Southwest regions (0%). The average severity of sclerotinia stem rot in canola crops in Saskatchewan was 0.11. The severity of sclerotinia stem rot ranged from 0 to 0.36 in different regions (Table 3).

Table 3. Mean disease incidence and severity of sclerotinia stem rot of canola in Saskatchewan in 2023.

	Sclerotinia stem rot all fields surveyed			Sclerotinia stem rot infected fields only
Region (No. of fields)	Prevalence	Incidence	Severity^a	Incidence	Severity^a
Northeast (34)	53	5	0.10 (1.00)	9	0.19 (1.90)
Northwest (39)	54	10	0.36 (1.82)	18	0.68 (3.37)
East-Central (47)	36	4	0.09 (0.80)	10	0.26 (2.22)
West-Central (35)	17	1	0.02 (0.29)	9	0.11 (1.72)
Southeast (39)	8	1	0.01 (0.08)	12	0.12 (1.00)
Southwest (24)	0	0	0 (0)	0	0 (0)
Mean (218)	30	4	0.11 (0.72)	12	0.35 (2.40)

^aSeverity as divided by number of plants surveyed per field (Severity as divided by the number of infected plants).

Table 4. Mean disease incidence and severity of blackleg basal cankers in Saskatchewan in 2023.

	Blackleg basal cankers all fields surveyed			Blackleg basal cankers infected fields only
Region (No. of fields)	Prevalence	Incidence	Severity^a	Incidence	Severity^a
Northeast (34)	65	6	0.08 (0.86)	9	0.12 (1.32)
Northwest (39)	92	25	0.42 (1.40)	27	0.45 (1.52)
East-Central (47)	89	15	0.21 (1.11)	17	0.24 (1.25)
West-Central (35)	49	6	0.08 (0.56)	12	0.16 (1.15)
Southeast (39)	74	13	0.20 (0.97)	17	0.27 (1.30)
Southwest (24)	46	3	0.03 (0.53)	6	0.07 (1.15)
Mean (218)	72	12	0.18 (0.94)	17	0.26 (1.31)

^aSeverity as divided by number of plants surveyed per field (Severity as divided by the number of infected plants).

Table 5. Prevalence of alternaria pod spot, aster yellows, and foot rot of canola fields surveyed in Saskatchewan in 2023.

Region (no. of fields)	Alternaria black spot	Aster yellows^a	Foot rot
Northeast (34)	82	50	6
Northwest (39)	46	62	0
East-Central (47)	55	23	2
West-Central (35)	0	17	0
Southeast (39)	59	23	10
Southwest (24)	42	17	0
Mean (218)	48	33	3

^aPrevalence of aster yellows when identified within 100 plant sample.

Table 6. Mean disease incidence and sclerotinia severity reported as both the average severity across infected plants and the average severity across all plants surveyed per field from 2011-2023 (Akhavan et al. 2023).

Year (no. of fields)	Sclerotinia stem rot, all fields surveyed		Sclerotinia stem rot infected fields only
	Incidence	Severity^a	Incidence	Severity^a
2011 (265)	20	0.56 (2.5)	22	0.61 (2.7)
2012 (253)	19	0.52 (2.5)	21	0.57 (2.8)
2013 (269)	5	0.10 (1.3)	9	0.17 (2.2)
2014 (274)	14	0.40 (2.2)	18	0.51 (2.8)
2015 (253)	7	0.15 (1.6)	11	0.24 (2.4)
2016 (224)	23	0.70 (2.8)	26	0.75 (3.0
2017 (281)	3	0.11 (1.5)	6	0.21 (3.2)
2018 (240)	6	0.14 (1.4)	10	0.26 (2.6)
2019 (229)	13	0.37 (2.17)	16	0.47 (2.4)
2020 (261)	17	0.43 (1.95)	21	0.54 (2.5)
2021(212)	2	0.03 (0.45)	6.3	0.09 (1.3)
2022 (205)	6	0.18 (1.45)	11	0.32 (2.6)
2023 (218)	4	0.11 (0.72)	12	0.35 (2.40)

^aSeverity as divided by number of plants surveyed per field (Severity as divided by the number of infected plants per field).

Symptoms of blackleg basal infection (rated after cutting of lower stems) were present in 72% of the Saskatchewan canola crops included in the survey (Table 4). The average incidence in the province was 12% (17% in infested crops). The levels of blackleg were similar to those in 2022 (73% prevalence), but higher than 2021 (67% prevalence) (Table 7). In 2023, the average incidence was highest in the Northwest region (25%) and lowest in the Southwest regions (3%, respectively). The average severity of blackleg basal cankers in the province was 0.18. Average severity was highest in the Northwest region (0.42) and lowest in the Southwest regions (0.03). Blackleg stem lesions were present in 32% of canola crops with an average incidence of 3% (data not shown). The highest average blackleg stem lesion incidence occurred in the Northwest region (5.4%). The lowest incidence was in the Southeast region (0.4%). Both blackleg basal cankers and stem lesions were present on the same plant in 27% of crops across the province (data not shown).

Table 7. Mean blackleg canker severity reported as both the average severity across infected plants and the average severity across all plants surveyed per field from 2011-2023 (Akhavan et al. 2023).

Year (no. of fields)	Blackleg basal cankersAll fields surveyed		Blackleg basal cankers Infected fields only
	Prevalence	Incidence	Severity^a	Incidence	Severity^a
2011 (265)	42	3	0.041 (0.59)	7	0.10 (1.4)
2012 (253)	34	4	0.069 (0.54)	11	0.21 (1.7)
2013 (269)	25	2	0.029 (0.34)	8	0.12 (1.4)
2014 (274)	55	8	0.10 (0.7)	15	0.19 (1.3)
2015 (253)	59	9	0.11 (0.81)	15	0.19 (1.4)
2016 (224)	61	7	0.11 (0.85)	12	0.18 (1.4)
2017 (281)	73	11	0.18 (1.05)	16	0.25 (1.5)
2018 (240)	74	11	0.16 (1.0)	15	0.22 (1.4)
2019 (229)	69	11	0.18 (0.98)	16	0.25 (1.4)
2020 (261)	81	15	0.21 (1.12)	18	0.25 (1.4)
2021 (212)	67	7	0.09 (0.79)	10	0.13 (1.2)
2022 (205)	73	11	0.16 (0.92)	15	0.22 (1.3)
2023 (218)	72	12	0.18 (0.94)	17	0.26 (1.31)

^aSeverity as divided by number of plants surveyed per field (Severity as divided by the number of infected plants per field).

Aster yellows had a prevalence of 33% (Table 5) with an average incidence of 2% (5% in infested fields), based on the observations in the five surveying sites within each surveyed field looking at the total of 100 plants. The average incidence was drastically higher than in 2022 when the average incidence in Saskatchewan was 0.1% (Akhavan et al. 2023). The highest prevalence of aster yellows in 2023 was in the Northwest region (62%) with an average incidence of 5% (Table 5). Province-wide, aster yellows was observed in a total of 65% of surveyed canola fields (this number also includes observations in surveyed fields where infected plants were seen outside of the 100-plant sample) (data not shown).

In 2023, alternaria pod spot was assessed in all regions in the province with the highest prevalence observed in the Northeast region (82%) (Table 5). Foot rot was recorded in 3% of canola crops in the province. The highest incidence was in the Southeast region (10%). Foot rot was only detected this year in the Northeast, and Southeast regions of Saskatchewan (Table 5).

Symptoms of powdery mildew were seen in thirteen of the surveyed fields. Symptoms suggesting grey stem was found in one field during the survey. Symptoms of downy mildew, white rust, and bacterial pod spot were not found during the survey in any of the surveyed fields.

Verticillium longisporum was confirmed by PCR in 23 fields surveyed during the general canola disease survey. Furthermore, the Saskatchewan Ministry of Agriculture conducted an additional verticillium-specific survey in 2023, targeting 100 fields across Saskatchewan to assess the prevalence and incidence of the disease and to help evaluate the risk this disease poses to canola production in Saskatchewan. This survey was an “after-swath” specific survey in addition to the general canola disease survey. Sample analysis for this specific survey is still in progress.

No new visible clubroot symptoms were recorded through the clubroot monitoring program in 2023, while the clubroot pathogen was detected in one new field through DNA-based testing. Adding the 2023 results to previous years back to 2008, the total number of commercial fields with visible clubroot symptoms remains at 82, while the number of commercial fields identified to have the clubroot pathogen through DNA testing rises from 42 to 43.

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SURVEY OF CANOLA DISEASES IN MANITOBA IN 2023

CROP: Canola LOCATION: Manitoba NAMES AND AGENCIES: Y.M. KIM¹, D. KAMINSKI², D. LANGE³, T. BUSS⁴, E. BARGEN⁵, A. KIRK², L. KASKIW², V. OWUSU², C. MORRISON², K. STEUART², N. CLOUSON⁶, C. MANCHUR⁷, J. GRAHAM⁸, M. PRADHAN⁹, T. HENDERSON¹ & S. ZATYLNY¹

¹Agriculture and Agri-Food Canada, Brandon Research and Development Centre, 2701 Grand Valley Rd., Brandon, MB R7A 5Y3 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Manitoba Agriculture, Box 1149, Carman, MB R0G 0J0 ³Manitoba Agriculture, 536 Stephen St., Morden, MB R6M 1T7 ⁴Manitoba Agriculture, Box 50, Beausejour, MB R0E 0C0 ⁵Manitoba Agriculture, Unit C - 284 Reimer Ave., Steinbach, MB R5G 0R5 ⁶Manitoba Agriculture, 120-6th Ave. N, Swan River, MB R0L 1Z0 ⁷Canola Council of Canada, 400-167 Lombard Ave., Winnipeg, MB R3B 0T6 ⁸81 Ellesmere Ave., Winnipeg, MB R2M 0G5 ⁹Manitoba Agriculture, Crop Diagnostic Centre, 201-545 University Cres., Winnipeg, MB R3T 5S6

ABSTRACT: A total of 129 canola crops were surveyed in Manitoba in 2023 for the prevalence and incidence or severity of sclerotinia stem rot, blackleg, alternaria pod spot, aster yellows, verticillium stripe, foot rot and clubroot. Blackleg (basal cankers) was the most prevalent disease throughout the province. Clubroot symptoms were observed in one of the 129 crops surveyed. In addition, soil samples from three canola crops outside of the regular canola survey tested positive for clubroot. Verticillium stripe was identified in nine canola samples submitted independently to the Manitoba Crop Diagnostic Centre.

METHODS: A total of 129 canola crops were surveyed in the Southwest (46), Northwest (29), Eastern/Interlake (14) and Central (40) regions of Manitoba in August, 2023. All crops were Brassica napus and the majority were surveyed before swathing while plants were between growth stages 5.1 and 5.5 (Harper and Berkenkamp 1975). In each canola crop, 100 plants were selected in a regular pattern starting at a corner of the field or at a convenient access point. The edges of the fields were avoided. Twenty plants were removed from each of five points of a “W” pattern in the field. Points of the “W” were at least 20 paces apart. All plants were pulled up, removed from the field and examined for the presence of diseases. For soil collection from 40 fields, samples were obtained from each of the five points of the “W” or, if the field entrance was identifiable, they were collected at five points near the entrance.

Canola crops were assessed for the prevalence (percent crops diseased) and incidence (percent plants diseased per crop) of sclerotinia stem rot (Sclerotinia sclerotiorum), aster yellows (Candidatus Phytoplasma asteris), foot rot (Fusarium spp. and Rhizoctonia sp.), blackleg (Leptosphaeria maculans), verticillium stripe (Verticillium longisporum) and clubroot (Plasmodiophora brassicae). For sclerotinia stem rot, each plant was also scored based on the possible impact of infection on yield using a disease severity scale of 0 (no symptoms) to 5 (main stem lesion with potential effects on seed formation and filling of entire plant) (Kutcher and Wolf 2006). Blackleg basal stem cankers were scored using a disease severity scale of 0 to 5 based on area of diseased tissue in the stem cross-section where 0 = no diseased tissue visible in the cross section and 5 = diseased tissue occupying 100% of the cross section and plant dead (WCC/RRC 2009). Blackleg lesions that occurred on the upper portions of the stem were assessed separately from basal stem cankers. Stem lesions were recorded as present or absent. If present, clubroot symptoms were rated using a scale of 0 to 3 where 0 = no galling and 3 = severe galling (Kuginuki et al. 1999). The prevalence and percent severity of alternaria pod spot (Alternaria spp.) were also determined (Conn et al. 1990). When diseases were observed in the crop, but not in the sample of 100 plants, they were recorded as “trace” for incidence and counted as 0.1%. Mean disease incidence or severity values were calculated for each region. In addition to the visual assessment of diseases, soil samples were collected from approximately 40 of the surveyed canola fields in Manitoba for DNA analysis (Cao et al. 2007) to test for the presence of the clubroot pathogen. Canola samples symptomatic for verticillium stripe were submitted to the Manitoba Agriculture Crop Diagnostic Centre for confirmation of the disease.

RESULTS: A number of diseases were present in each of the four regions of Manitoba. Clubroot symptoms were observed in one of the 129 Manitoba canola crops surveyed in 2023 and soil samples from three canola crops outside of the regular canola survey were confirmed to have clubroot in tests by the Manitoba Canola Growers Testing Program. Information on the monitoring and occurrence of clubroot in Manitoba in previous years is provided by Froese et al. (2019), Kubinec et al. (2014) and Derksen et al. (2013). A map of clubroot distribution in Manitoba (2009-2022) is available online (Manitoba Agriculture 2023a). The map will be updated for any soil samples positive for clubroot DNA in 2023 once analyses are completed.

Sclerotinia stem rot was prevalent in 13% of the crops surveyed, ranging from a high of 29% in the Eastern/Interlake region to 2% in the Southwest region (Table 1). Mean disease incidence averaged across all crops was 0.6% and ranged from 1.5% in the Northwest region to 0.02% in the Southwest region. For infested crops only, mean disease incidence was 4.6%. Throughout the province, mean severity of sclerotinia stem rot was 0.2 and ranged from 0.5 in the Eastern/Interlake region to 0.1 in the Southwest region.

Table 1. Mean prevalence, incidence and severity of sclerotinia stem rot and blackleg in Manitoba in 2023.

Crop Region (No. of crops)	Sclerotinia stem rot					Blackleg basal cankers					Blackleg stem lesions
	P^a	DI^b	DI^c	Sev.^b	Sev.^c	P^a	DI^b	DI^c	Sev.^b	Sev.^c	P^a	DI^b	DI^c
Central	15	0.4	2.7	0.2	1.3	75	13	17	0.9	1.2	28	0.7	2.6
(40)
East./Inter.	29	1.4	4.8	0.5	1.7	64	17	26	1.2	1.8	7	0.1	1.0
(14)
Northwest	21	1.5	7.0	0.4	2.2	72	6	8	1.0	1.4	21	0.6	3.0
(29)
Southwest	2	0.0	1.0	0.1	4.0	87	7	8	1.2	1.4	41	1.5	3.7
(46)
All regions	13	0.6	4.6	0.2	1.9	78	10	12	1.1	1.4	29	0.9	3.2
(129)

^aPrevalence (P) = % diseased fields.

^bDisease incidence (DI) = % diseased plants or severity (Sev.) = scale of 0-5 across all surveyed crops.

^cDisease incidence or severity in diseased crops.

Aster yellows was observed in 21% of canola crops in Manitoba with an average disease incidence of 3.9% in diseased crops (Table 2). The prevalence of this disease, although high, was substantially less than in 2012 when record high levels of aster yellows (95%) were observed in all regions of Manitoba. Contributing factors to the high level of aster yellows in 2012 included drought in the midwestern United States, the early arrival of aster leafhoppers from the southern U.S. and the higher-than-normal percentage of infected individuals (10-15%) in the leafhopper population. The reduced risk of aster yellows in recent years has been due to lower numbers of leafhoppers and a percentage of infected aster leafhoppers that is normally 2-3% in Manitoba (Gavloski 2017; Manitoba Agriculture 2023b).

Table 2. Mean prevalence and incidence or severity of alternaria pod spot, aster yellows, verticillium stripe and foot rot in Manitoba in 2023.

Crop Region (No. of crops)	Alternaria pod spot		Aster yellows			Verticillium stripe					Foot rot
	P^a	Sev.^c	P^a	DI^b	DI^c	P^a	DI^b	DI^c	Sev.^b	Sev.^c	P^a	DI^b	DI^c
Central	5	1.0	23	0.8	3.3	28	1.2	4.3	n/a	n/a	0	0	0
(40)
East./Inter.	29	1.0	0	0	0	14	1.0	7.0	n/a	n/a	0	0	0
(14)
Northwest	17	1.2	41	1.3	1.3	48	11	23	n/a	n/a	0	0	0
(29)
Southwest	2	1.0	13	0.8	6.3	22	0.4	1.8	n/a	n/a	0	0	0
(46)
All regions	9	1.0	21	0.8	3.9	29	3.1	11	n/a	n/a	0	0	0
(129)

^aPrevalence (P) = % diseased fields.

^bDisease incidence (DI) = % diseased plants and severity (Sev.) = scale of 0-5 across all surveyed crops.

^cDisease incidence and severity in diseased crops.

Blackleg basal cankers occurred in 78% of the crops surveyed in 2023 (Table 1), with prevalence ranging from 87% in the Southwest region to 64% in the Eastern/Interlake region. The mean incidence of basal cankers averaged across all crops was 10%, while the mean incidence in infested crops was 12%. The severity of blackleg basal cankers was similar in recent years with mean ratings of approximately 2 or less. A value of 2 indicates that 26-50% of the basal stem cross-section was diseased. The mean prevalence of blackleg stem lesions in 2023 was 29%. In previous years, 53%, 50%, and 57% of crops had stem lesions in 2020, 2021 and 2022 respectively (Kim et al. 2022, 2023; McLaren et al. 2021). The average incidence of blackleg stem lesions was 3.2% in infested crops and 0.9% in all crops.

The mean prevalence of alternaria pod spot in 2023 was 9% and ranged from 29% in the Eastern/Interlake region to 2% in the Southwest region (Table 2). The mean severity of alternaria pod spot was 1.0% in infested crops.

Verticillium stripe was observed in 29% of canola crops surveyed in Manitoba, with a mean incidence of 11% in diseased fields (Table 2). Disease severity was not rated since a rating scale has not been fully defined. Foot rot was not observed in any survey region. White rust (Albugo candida) has not been confirmed in any crop of B. napus since 2011 (McLaren et al. 2012). Nine samples submitted to the Crop Diagnostic Centre were confirmed positive for verticillium stripe.

The distribution of incidence (sclerotinia, blackleg, aster yellows, verticillium stripe and foot rot) and severity (alternaria pod spot) classes in 129 crops of Brassica napus in Manitoba in 2023 is presented in Table 3.

Table 3. Distribution of incidence (sclerotinia, blackleg, aster yellows, verticillium stripe and foot rot) and severity (alternaria pod spot) classes in 129 crops of Brassica napus in Manitoba in 2023.

Percentage of crops with
Incidence range	Sclerotinia stem rot	Blackleg basal cankers	Blackleg stem lesions	Aster yellows	Verticillium stripe	Foot rot	Alternaria pod spot
0%	87	22	71	79	71	100	91
1-5%	8	33	26	15	17	0	5
6-10%	4	16	2	5	3	0	1
11-20%	2	15	1	1	5	0	0
21-50%	0	12	1	0	2	0	0
>50%	0	2	0	0	2	0	4

ACKNOWLEDGEMENTS: We thank Manitoba canola producers for their continued support of this survey work and both the Manitoba Canola Growers Association and the Canola Council of Canada for their financial assistance.

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LENTIL DISEASE SURVEY IN SOUTHERN ALBERTA, 2023

CROP: Lentil LOCATION: Southern Alberta NAMES AND AGENCY: M.W. HARDING, G.C. DANIELS & T.B. HILL

Alberta Agriculture and Forestry, Crop Diversification Centre South, 301 Horticulture Station Road E., Brooks, AB T1R 1E6 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected]

ABSTRACT: Ten lentil fields were surveyed for root rot, foliar blight and stem rot diseases in southern Alberta in 2023. Prevalence, incidence and severity of root rot, anthracnose, ascochyta blight, stemphylium blight, botrytis grey mould and sclerotinia white mould were monitored based on visual symptoms. Root rot was the most prevalent disease (40%) followed by stemphylium blight (10%). Symptoms of anthracnose, ascochyta, botrytis and sclerotinia diseases were not reported.

INTRODUCTION AND METHODS: Lentil in Alberta is produced primarily in three or four counties in the southeast corner of the province, and is the main pulse crop in rotation in that region. In 2023 there were approximately 199,348 ha in Alberta that produced 162,600 metric tonnes of lentils (Statistics Canada 2023). Lentils can be infected by a number of fungal plant pathogens that cause diseases such as root rots (Aphanomyces euteiches Dreschs., Fusarium spp.), ascochyta blight (Ascochyta lentis Vass.), anthracnose (Colletotrichum lentis Damm), white mould [Sclerotinia sclerotiorum (Lib.) de Bary], grey mould (Botrytis fabae Sardiña; B. cinerea Pers. Fr.), and stemphylium blight (Stemphylium botryosum Wallr.).

A survey to characterize lentil diseases in ten fields in Alberta was conducted between August 10-15, 2023. Ratings were collected by walking a W-shaped pattern in each field and assessing 10 plants at 10 sites each for a total of 100 plants assessed per field. Assessment sites were >20 m from one another and from the field margin. Prevalence was calculated as the percentage of fields with disease symptoms and incidence was calculated as the percentage of plants with disease symptoms. Root rot disease intensity was estimated using a visual 1-7 rating scale (Chatterton et al. 2017). Leaf disease severity was rated using a visual 0-9 scale based on percent leaf area affected (Table 1). Sclerotinia white mould and botrytis grey mould were rated using a visual 1-5 scale of percent canopy area affected (Table 2).

Table 1. Leaf area affected (% LAA): intensity rating scale for foliar blights of lentil.

Rating	Description of symptoms
0	No symptoms
1	<2% leaf area affected (LAA)
2	2% to 5 % LAA
3	5% to 10% LAA
4	10% to 25% LAA
5	25% to 50% LAA
6	50% to 75% LAA
7	75% to 90% LAA
8	>90% LAA
9	Plants dead

Table 2. Canopy area affected (% CAA): rating scale for botrytis grey mould and sclerotinia white mould.

Rating	Description of symptoms
1	No symptoms
2	1% to 25% of green tissue affected
3	26% to 50% of green tissue affected
4	51% to 75% of green tissue affected, plants dying
5	76% to 100% of green tissue affected, plants dead or dying

RESULTS AND COMMENTS: Very few severe disease symptoms were observed on lentils in Alberta in 2023. When compared with results from the previous lentil disease survey, disease levels in 2023 were generally less than half of what was reported in 2020 (Harding et al. 2021). A hot dry growing season was encountered across most of southeastern Alberta in 2023. Root rots had the highest prevalence (40%), incidence (6.8%) and severity (1.1), as shown in Table 3 and Fig. 1. Stemphylium blight was seen in one field (10% prevalence) on two plants (0.2% incidence). No other disease symptoms were reported. Overall, it appeared that drought was a significant issue for lentil producers in Alberta in 2023 and that diseases were less significant in most fields.

Table 3. Disease prevalence, incidence and severity in 10 lentil fields in Alberta in 2023.

Disease	Prevalence^a (%)	Incidence^b (%)	Severity^c
Anthracnose	0	0	0
Root rot complex	40	6.8	1.1
Stemphylium blight	10	0.2	1.0
Ascochyta blight	0	0	1.0
Botrytis grey mould	0	0	1.0
Sclerotinia white mould	0	0	1.0

^aPrevalence = % diseased fields.

^bIncidence = % diseased plants.

^cLeaf disease severity rated on a visual 0-9 scale based on % leaf area affected; root rot disease intensity estimated on a visual 1-7 rating scale (Chatterton et al. 2017), sclerotinia white mould and botrytis grey mould rated on a visual 1-5 scale of % canopy area affected.

Fig. 1 Locations and root rot severity for 10 lentil fields in southeast Alberta in 2023.

ACKNOWLEDGEMENTS: The authors express appreciation to Dr. Manjula Bandara for guidance on lentil field locations.

REFERENCES

• Chatterton S, Harding MW, Bowness R, McLaren DL, Banniza S, Gossen BD. 2019. Importance and causal agents of root rot on field pea and lentil on the Canadian Prairies, 2014-2017. Can J Plant Pathol. 41:98–114.
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• Harding MW, Daniels GC, Burke DA. Lentil disease survey in southern Alberta, 2020. Can Plant Dis Surv. 101:121–122. In, Can J Plant Pathol. 43:sup1.
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• Statistics Canada. 2023. Principal field crop areas, 2023. [accessed 2023 Dec 07]https://www150.statcan.gc.ca/n1/daily-quotidien/230426/dq230426a-eng.htm.
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2023 SURVEY OF LENTIL DISEASES IN SASKATCHEWAN

CROP: Lentil LOCATION: Saskatchewan NAMES AND AGENCIES: A. AKHAVAN¹, C. PERU¹, E. YASKOWICH¹, A. KAMINSKI¹, N. MONTREUIL¹, S. CHANT¹, Q. CUBBON¹, M. HLADUN¹, S. SELVICHAN¹, H. TUR¹, S. MARCINO¹, D. RISULA¹, K. MAKOHONIUK², J. KWASNICKI², C. NEUBERGER², T. ADEGEYE², C. FENNIG² & B. JOHNSON²

¹Saskatchewan Ministry of Agriculture, 3085 Albert St., Regina, SK S4S 0B1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Saskatchewan Association of Rural Municipalities, Regina, SK S4V 3A4

ABSTRACT: A total of 54 lentil crops were surveyed in Saskatchewan in 2023. Anthracnose and root rot were the most prevalent diseases observed in the survey with 74% prevalence each while stemphylium blight was found in 20% of the surveyed fields, though variation in the prevalence of these diseases was found across lentil-growing regions in Saskatchewan. Sclerotinia stem and pod rot was observed in 6% of crops with an average incidence of 0.1%. Botrytis stem and pod rot (Botrytis cinerea) was not noted in fields surveyed in 2023.

INTRODUCTION AND METHODS: A total of 54 lentil fields were surveyed for the presence and incidence of diseases in Saskatchewan. The survey was completed between July 10 to August 09 and ranged in staging from R2 (Full bloom) to R6 (Full pod). The number of surveyed crops was highest in Southwest Saskatchewan, with 23 of the 54 crops surveyed located in this region. The distribution of the surveyed crops across the rest of the province was as follows: 11 (West-central), 11 (Southeast), six (East-central) and three (Northwest).

Disease assessments were made by visually examining 20 plants from each of five sites along a W-pattern in each field. Individual sites were located at least 50 m from the field edge and at least 30 m apart. Crops were assessed for the prevalence and incidence of anthracnose (Colletotrichum truncatum), ascochyta blight (Ascochyta lentis), sclerotinia stem and pod rot (Sclerotinia sclerotiorum), botrytis stem and pod rot (Botrytis cinerea), stemphylium blight (Stemphylium spp.) and the root rot complex (Fusarium spp; / Pythium spp. / Rhizoctonia solani / Aphanomyces euteiches). Incidence was calculated as the percentage of plants assessed (out of 100 plants total per crop) with symptoms of the disease, while prevalence was a measure of the presence or absence of the disease in the field.

The severity of the root rot complex and anthracnose was assessed for each plant using the rating scales described below (Tables 9 and 10). All disease assessments were made based on visual symptoms observed in the field and samples were tested in the lab only if requested by an individual surveyor.

Prevalence of each of these diseases (percentages of the crops surveyed showing symptoms) was calculated for each region surveyed (Tables 1–6), as well as provincial totals (Table 7) and compared to totals from the previous years (Akhavan et al. 2023). The average incidence of anthracnose, ascochyta blight, and stemphylium blight was calculated and averaged for each region and on a provincial level (Table 8).

Table 1. Prevalence of plant diseases in lentil crops surveyed in West-central Saskatchewan, 2012-2023.

Year (Number of crops)	Percentage (%) of lentil crops surveyed with disease symptoms
	Root rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
2012 (17)	76	76	24	24	24	53
2013 (12)	83	83	42	33	17	50
2014 (15)	67	80	7	67	0	40
2015 (15)	87	73	0	0	0	40
2016 (15)	94	88	0	94	69	63
2017 (20)	60	50	10	0	0	55
2018 (15)	80	73	13	13	0	27
2019 (34)	50	88	24	6	0	41
2020 (16)	81	81	69	19	0	81
2021 (15)	80	67	13	0	0	33
2022 (13)	85	100	23	15	0	46
2023 (11)	100	82	9	9	0	0

Table 2. Prevalence of plant diseases in lentil crops surveyed in Southwest Saskatchewan, 2012-2023.

Year (Number of crops)	Percentage (%) of lentil crops surveyed with disease symptoms
	Root rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
2012 (2)	0	0	100	0	0	0
2013 (16)	38	50	38	38	31	38
2014 (2)	100	100	0	0	0	0
2015 (0)	−	−	−	−	−	−
2016 (20)	65	50	0	85	60	100
2017 (15)	73	13	0	7	0	40
2018 (32)	50	84	6	6	0	13
2019 (23)	61	96	39	9	0	35
2020 (36)	64	86	83	17	6	72
2021 (31)	87	71	3	0	0	48
2022 (25)	52	64	0	4	0	52
2023 (23)	61	65	17	9	0	26

Table 3. Prevalence of plant diseases in lentil crops surveyed in Southeast Saskatchewan, 2012-2023.

Year (Number of crops)	Percentage (%) of lentil crops surveyed with disease symptoms
	Root rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
2012 (9)	80	70	30	50	40	10
2013 (9)	89	44	0	22	33	11
2014 (0)	−	−	−	−	−	−
2015 (2)	50	100	0	50	100	100
2016 (6)	33	83	0	67	50	100
2017 (10)	50	10	10	0	0	0
2018 (9)	89	33	11	0	0	22
2019 (12)	75	92	33	0	0	75
2020 (9)	100	67	78	11	44	78
2021 (14)	86	43	0	0	0	29
2022 (11)	73	100	0	0	0	73
2023 (11)	64	64	0	0	0	36

Table 4. Prevalence of plant diseases in lentil crops surveyed in East-central Saskatchewan, 2012-2023.

Year (Number of crops)	Percentage (%) of lentil crops surveyed with disease symptoms
	Root rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
2012	−	−	−	−	−	−
2013	−	−	−	−	−	−
2014 (1)	100	100	0	0	0	100
2015 (1)	100	100	0	100	100	100
2016 (8)	63	100	38	88	88	100
2017 (7)	0	100	0	0	0	0
2018 (11)	36	73	0	9	0	0
2019 (8)	63	100	63	25	0	50
2020 (5)	60	100	20	40	0	0
2021 (5)	80	20	40	0	0	20
2022 (5)	60	60	0	60	0	0
2023 (6)	83	100	0	0	0	0

Table 5. Prevalence of plant diseases in lentil crops surveyed in Northeast Saskatchewan, 2012-2023.

Year (Number of crops)	Percentage (%) of lentil crops surveyed with disease symptoms
	Root rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
2012	−	−	−	−	−	−
2013	−	−	−	−	−	−
2014	−	−	−	−	−	−
2015	−	−	−	−	−	−
2016	−	−	−	−	−	−
2017	−	−	−	−	−	−
2018 (3)	0	74	7	7	0	16
2019 (1)	100	100	100	100	0	100
2020	−	−	−	−	−	−
2021	−	−	−	−	−	−
2022	−	−	−	−	−	−
2023	−	−	−	−	−	−

Table 6. Prevalence of plant diseases in lentil crops surveyed in Northwest Saskatchewan, 2012-2023.

Year (Number of crops)	Percentage (%) of lentil crops surveyed with disease symptoms
	Root rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
2012	−	−	−	−	−	−
2013	−	−	−	−	−	−
2014	−	−	−	−	−	−
2015	−	−	−	−	−	−
2016	−	−	−	−	−	−
2017	−	−	−	−	−	−
2018	−	−	−	−	−	−
2019	−	−	−	−	−	−
2020 (2)	0	100	0	50	0	100
2021 (2)	100	0	0	0	0	0
2022 (1)	100	0	0	0	0	0
2023 (3)	100	100	0	0	0	33

Table 7. Prevalence of plant diseases in lentil crops surveyed in Saskatchewan, 2012-2023.

Year (Number of crops)	Percentage (%) of lentil crops surveyed with disease symptoms
	Root rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
2012 (28)	75	71	32	32	29	36
2013 (37)	65	60	30	32	27	35
2014 (18)	72	83	6	56	0	39
2015 (18)	83	78	0	11	17	50
2016 (50)	70	74	6	86	66	88
2017 (52)	54	38	6	2	0	33
2018 (70)	57	74	7	7	0	16
2019 (78)	59	92	35	9	0	46
2020 (68)	71	84	72	19	9	71
2021 (67)	85	58	8	0	0	37
2022 (55)	65	78	5	11	0	49
2023 (54)	74	74	9	6	0	20

Table 8. Average disease incidence in Saskatchewan lentil crops surveyed in 2023.

Region^b		Incidence of disease (%) (Incidence in infected fields only)^a
	Root Rot	Anthracnose	Ascochyta blight	Sclerotinia stem and pod rot	Botrytis stem and pod rot	Stemphylium blight
SW	24 (39)	12 (19)	0.3 (2)	0.1 (2)	0 (NA)		8 (30)
SE	21 (32)	23 (35)	0 (NA)	0 (NA)	0 (NA)		0.5 (2)
EC	25 (30)	49 (49)	0 (NA)	0 (NA)	0 (NA)		0 (NA)
WC	70 (70)	6 (7)	0.1 (1)	0.1 (1)	0 (NA)		0 (NA)
NW	71 (71)	65 (65)	0 (NA)	0 (NA)	0 (NA)		1 (3)
Overall	35 (48)	20 (27)	0.1 (2)	0.1 (1)	0 (NA)		4 (17)

^aAverage incidence of disease for all crops surveyed (disease incidence averaged across crops with disease symptoms only).

^bRegion: SW – Southwest, SE – Southeast, EC – East-central, WC – West-central, NW - Northwest.

Table 9. Severity scale for root rot complex of lentil (modified from Chatterton et al. 2017).

Rating	Description of lesions	% Affected	Pruning
1	None	0	0
2	small (<1 cm), lesion near seed attachment	0	0
3	Small coalescing lesions approximately 180° around the stem	10-20%	0
4	Lesions extending and completely encircling the stem	>20-95%	5-20%
5	Increasingly discoloured and extended epicotyl lesions	100%	20-50%
6	Epicotyl lesions encircling the stem extending up to 2 cm	100%	>50-80%
7	Tap root (including epicotyl) completely lesioned	Dead	Dead

Table 10. Severity scale for lentil anthracnose (developed by Dr. Michelle Hubbard, Agriculture and Agri-Food Canada).

Rating	Description of lesions
0	No lesions
1	Up to 5% of plant area diseased (lower canopy). A few superficial lesions at stem base
2	>5-25% of stems and leaves affected in infected plants (lower canopy). Lesions, some leaf drop
3	>25-50% of stems and leaves affected in infected plants (lower and mid canopy). Lesions and leaf drop
4	>50-75% of stems and leaves affected in infected plants (lower, mid and upper canopy). Lesions, leaf drop, shoot dieback
5	More than 75% of stems and leaves affected infected plants (lower, mid and upper canopy). Lesions, leaf drop, severe shoot dieback

RESULTS AND COMMENTS: Approximately 1.3 million hectares (3.2 million acres) of lentils were seeded in Saskatchewan in 2023. This was lower than the 1.5 million hectares (3.8 million acres) seeded in 2022 (Statistics Canada 2024). As of early April 2024, 1.3 million hectares (3.1 million acres) of lentils were harvested in Saskatchewan (Statistics Canada 2024). The Saskatchewan Crop Report (Saskatchewan Ministry of Agriculture 2023) estimated that 100% of the Saskatchewan lentil crop had been harvested by October 16, 2023.

Root rot complex symptoms were present in 74% of the surveyed crops (Table 7). Across the regions, prevalence ranged from 61% to 100% of fields in the 2023 survey (Tables 1 to 6). Prevalence was high across all surveyed regions. Root rot was present in all fields surveyed in the West-central and Northwest, 83% in the East-central, 64% in the Southeast and 61% in the Southwest region in 2023. Root rot severity was generally low with an average severity of 1.6 across the province (Table 11). Root rot has been a notable issue in pea and lentil crops in recent years, with several potential pathogenic causes (Fusarium spp. / Pythium spp. / Rhizoctonia solani / Aphanomyces euteiches). No sampling or further testing was performed to confirm causal pathogens.

Table 11. Severity of root rot and anthracnose in Saskatchewan lentil crops in 2023.

Region^a	Root rot complex	Anthracnose
SE	1.31	0.41
SW	1.41	0.17
EC	1.30	0.88
WC	2.49	0.06
NW	2.07	1.14
Province	1.63	0.33

^aRegion: SE – Southeast, SW – Southwest, EC – East-central, WC – West-central, NE – Northeast, NW -Northwest.

Anthracnose (Colletotrichum lentis) was observed in 74% (40 fields) of fields surveyed in 2023 (Table 7). The highest prevalence was found in the Northwest and East-central regions with all crops surveyed found to be infected. The average incidence of anthracnose was 20% when averaged across the province (Table 8). The incidence of anthracnose was highest in Northwest Saskatchewan (65%). Anthracnose average severity was relatively low at 0.33 across the province (Table 11).

Ascochyta blight symptoms (Ascochyta lentis) were rare and only observed in five fields in the province in 2023 with very low incidence (Table 7). It is important to note that diagnosis was only based on visual symptoms in the field. Plants having visual symptoms that were consistent with ascochyta blight were not confirmed with additional testing.

Stemphylium blight (Stemphylium spp.) was found in 20% of lentil fields surveyed (Table 7). The highest prevalence was observed in the Southeast region (36%) followed by the Northwest (33%), and Southwest (26%) regions. The average incidence of stemphylium blight was 4% across all fields surveyed in 2023 (Table 8).

Sclerotinia stem and pod rot was observed in 6% of crops with an average incidence of 0.1% (Tables 7 and 8). Sclerotinia stem and pod rot were found only in one and two fields in each of the Southwest and West-central regions, respectively.

Botrytis stem and pod rot (Botrytis cinerea) was not noted in fields surveyed in 2023.

REFERENCES

• Akhavan A, Peru C, Bond J, Montreuil N, Chant S, Friesen S, Struthers M, Brown M, Marcino S, Rumpel B, et al. 2023. 2022 survey of lentil diseases in Saskatchewan. Can Plant Dis Surv. 103:132–135. In, Can J Plant Pathol. 45:sup1.
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SURVEY FOR PEA DISEASES IN ALBERTA, 2023

CROP: Pea LOCATION: Alberta NAMES AND AGENCIES: M.W. HARDING¹, G.C. DANIELS¹, T.B. HILL¹, L. STELLAR¹, S. XUE² & J. FENG²

¹Alberta Agriculture and Irrigation, Crop Diversification Centre South, 301 Horticultural Station Road E, Brooks, AB T1R 1E6 Telephone: [phone]; E-mail: [email protected] ²Alberta Agriculture and Irrigation, Alberta Plant Health Lab, Crop Diversification Centre North, 17507 Fort Road NW, Edmonton, AB T5Y 6H3

ABSTRACT: A survey of pea diseases was conducted in Alberta in 2023. One hundred fifty-one fields, representing approximately 1% of pea acres in each county, were evaluated for root, stem and foliar disease symptoms. Growing conditions were highly variable across Alberta in 2023. Many areas started the season dry. Drought was persistent in some areas, while others had significant rainfall at times during the latter part of the growing season. Root rot was the most prevalent disease found in 85.4% of pea fields, while mycosphaerella blight prevalence was 76.8%. No downy mildew or white mould was reported.

INTRODUCTION AND METHODS: In 2023, 151 pea fields in 57 Alberta counties were surveyed for the prevalence, incidence and severity of root rot [Aphanomyces euteiches Dreschs.; Fusarium spp.] and mycosphaerella blight [Mycosphaerella pinodes (Berk. & Blox.) Vestergr; Ascochyta pisi Lib.]. Additionally, symptoms of white mould [Sclerotinia sclerotiorum (Lib) de Bary], downy mildew [Peronospora viciae (Berk.) Casp.], and bacterial blight [Pseudomonas syringae pv. pisi (Sackett) Dye & Wilkie] were recorded as present or absent. These totals represented 1% of pea fields in each county across Alberta. Included were 36 processing (succulent pea) fields and 115 dry pea fields. Survey locations are shown in Fig. 1. Field visits occurred from June 10 and July 30, 2023. Five sample locations were visited in each field along a W-shaped transect with each location >20m apart and from the field margin. Ten plants were rated at each location for a total of 50 plants/field. Whole plants were rated for disease severity of root rot and mycosphaerella blight. Root rots were rated on a 1-7 disease intensity scale based on root discolouration and root mass reduction as described by Chatterton et al. (2017). Mycosphaerella blight was rated using a 1-7 scale modified from Liu et al. (2013). The presence or absence of white mould, downy mildew and bacterial blight was noted. Prevalence and incidence were calculated as the percentage of fields and plants with disease symptoms, respectively. Only disease prevalence was recorded for white mould, downy mildew and bacterial blight. Root samples with root rot symptoms were washed and frozen for future identification of A. euteiches and/or Fusarium spp. The identities of root rot pathogens will be presented in a separate report.

Fig. 1 Disease severity at each of the 151 survey locations in Alberta’s 2023 pea disease survey for root rot (RR, left panel) and 150 fields for mycosphaerella blight (Asc, right panel).

RESULTS AND COMMENTS: The prevalence of root rot was slightly lower in 2023 compared with previous years (Table 1). This was not surprising considering the dry soil conditions across most of Alberta in June. Interestingly, the incidence and severity of root rot was higher in 2023 (Table 1). This is partially explained by the influence of high disease incidence and severity in the 36 processing fields. The cultivars used for processing peas have very different ancestral breeding pedigrees than those of field peas and are all produced under overhead irrigation systems. Based on the results of this survey, one or both of these factors may contribute to these cultivars displaying more root rot symptoms (Fig’s. 2 and 3).

Table 1. Comparison of prevalence, incidence and severity of pea diseases in 2021, 2022 and 2023.

	Prevalence (%)			Incidence (%)			Severity (1-7)
Disease	2021^a	2022^b	2023	2021^a	2022^b	2023	2021^a	2022^b	2023
Root rot	90.4	90.9	85.4	57.0	52.4	57.5	2.27	2.17	2.40
Mycosph. blight	45.2	55.0	76.8	20.8	21.9	45.5	1.24	1.41	1.72
White mould	0	0	0	0	0	0	n.d.^c	n.d.	n.d.
Downy mildew	0	5.7	0	0	0.6	0	n.d.	n.d.	n.d.
Bacterial blight	4.3	5.7	22.0	0.2	0.4	1.44	n.d.	n.d.	n.d.

^aHarding et al. 2022

^bHarding et al. 2023

^cnot determined

Fig. 2 Prevalence and incidence of five pea diseases in processing and field peas in Alberta in 2023.

Fig. 3 Severity of root rot and mycosphaerella blight in processing and field peas in Alberta in 2023.

Conversely, overall levels of mycosphaerella blight were higher in 2023 compared with previous years (Table 1), but the survey results indicated lower levels in processing pea and higher levels in field pea (Fig’s. 2 and 3). Finally, no symptoms of white mould or downy mildew were observed in 2023, but bacterial blight was seen in 22% of fields (Table 1).

Plants suspicious for bacterial blight were not confirmed by laboratory testing, so it is possible that inspectors struggled to correctly identify this disease in previous years, and/or overestimated the amount present in 2023. As a result, the bacterial blight results presented should be considered putative and non-confirmed.

ACKNOWLEDGEMENTS: The authors acknowledge support of Alberta Agriculture and Irrigation, and express appreciation to landowners and producers.

REFERENCES

• Chatterton S, Harding MW, Bowness R, McLaren DL, Banniza S, Gossen BD. 2019. Importance and causal agents of root rot on field pea and lentil on the Canadian Prairies, 2014-2017. Can J Plant Pathol. 41:98–114.
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• Harding MW, Daniels GC, Hill TB, Kennedy M. 2022. A survey for pea diseases in Alberta, 2021. Can Plant Dis Surv. 102:120–123. In, Can J Plant Pathol. 44:sup1.
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2023 SURVEY OF FIELD PEA DISEASES IN SASKATCHEWAN

CROP: Field pea LOCATION: Saskatchewan NAMES AND AGENCIES: A. AKHAVAN¹, C. PERU¹, A. KAMINSKI¹, N. MONTREUIL¹, S. MARCINO¹, A. NOBLE¹, Q. CUBBON¹, S. SOLVICHAN, H. TUR¹, E. YASKEWICH¹, B. RUMPEL¹, K. MAKOHONIUK², J. KWASNICKI², C. NEUBERGER², C. FENNIG², T. ADEGEYE² & B. JOHNSON²

¹Saskatchewan Ministry of Agriculture, 3085 Albert St., Regina, SK S4S 0B1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Saskatchewan Association of Rural Municipalities, 2301 Windsor Park Rd., Regina, SK S4V 3A4

ABSTRACT: A total of 42 field pea crops were surveyed in Saskatchewan in 2023. Mycosphaerella/ascochyta blight and the root rot complex were the most prevalent diseases in 2023 and each was present in 90% of the surveyed crops. Symptoms consistent with bacterial blight were identified in 40% of crops. Downy mildew was present in 17% of the surveyed field while sclerotinia white mould was also present in 2% of the surveyed fields this year.

INTRODUCTION AND METHODS: In total, 42 field pea crops were surveyed in Saskatchewan in 2023. The highest number of surveyed crops were in Southwest and East-central Saskatchewan with 11 and nine of the surveyed field located in these two regions. The distribution of fields across the six regions in the province is described in Table 1. The survey was completed between June 28 and July 27. Crop growth stage ranged from R1 (flower bud) to R6 (mid maturity). Disease assessments were made by examining 10 plants from each of five sites along a W-pattern with at least 30 m between sampling sites. Crops were assessed for the incidence of root rot complex (Aphanomyces euteiches, Fusarium spp., Rhizoctonia spp., and Pythium spp.), mycosphaerella/ascochyta blight complex [Peyronellaea (Mycosphaerella) pinodes, Ascochyta pisi and Phoma medicaginis f.sp. pinodella], downy mildew (Peronospora viciae), white mould (Sclerotinia sclerotiorum) and bacterial blight (Pseudomonas syringae pv. pisi). The severity of the root rot complex and mycosphaerella/ascochyta blight complex was assessed for each plant using the rating scales described below (Tables 3 and 4). All disease assessments were made based on visual symptoms in the field. Unless requested by an individual surveyor for a specific sample, no additional testing was conducted to confirm diagnosis.

Table 1. Prevalence of root rot complex, mycosphaerella/ascochyta blight complex, white mould, and bacterial blight in Saskatchewan field pea crops in 2023.

		Percent prevalence (number of fields)
Region^a	Number of fields surveyed	Root rot complex	Mycosphaerella/ ascochyta blight	White mould	Bacterial blight	Downy mildew
SE	8	100 (8)	100 (8)	0	88 (7)	13 (1)
SW	11	91 (10)	73 (8)	0	64 (7)	27 (3)
EC	9	89 (8)	100 (9)	0	22 (2)	11 (1)
WC	7	100 (7)	86 (6)	14 (1)	0	29 (2)
NE	4	50 (2)	100 (4)	0	0	0
NW	3	100 (3)	100 (3)	0	33 (1)	0
Province	42	90 (38)	90 (38)	2 (1)	40 (17)	17 (7)

^aRegion: SE – Southeast, SW – Southwest, EC – East-central, WC – West-central, NE – Northeast, NW -Northwest.

Table 2. Incidence and severity of field pea diseases in Saskatchewan in 2023.

	Root rot complex		Mycosphaerella/ ascochyta blight		White mould	Bacterial blight	Downy mildew
Region	Average incidence (%)	Average severity	Average incidence (%)	Average severity	Average incidence (%)	Average incidence (%)	Average incidence (%)
SE	82	2.6	65	1.9	0	13	0.3
SW	64	2.8	43	1.7	0	9	1.3
EC	53	2.3	68	2.0	0	5	2.9
WC	65	2.8	48	1.7	0.3	0	2.3
NE	23	1.4	35	1.4	0	0	0
NW	79	3.4	75	2.4	0	33	0
Province	62	2.5	55	1.8	0.05	8	1.4

^aRegion: SE – Southeast, SW – Southwest, EC – East-central, WC – West-central, NE – Northeast, NW -Northwest.

Table 3. Severity scale for root rot complex of field pea (modified from Chatterton et al. 2017).

Rating	Description of lesions	% Affected	Pruning
1	None	0	0
2	Small (<1 cm), lesion near seed attachment	0	0
3	Small coalescing lesions approximately 180° around the stem	10-20%	0
4	Lesions extending and completely encircling the stem	>20-95%	5-20%
5	Increasingly discoloured and extended epicotyl lesions	100%	20-50%
6	Epicotyl lesions encircling the stem extending up to 2 cm	100%	>50-80%
7	Tap root (including epicotyl) completely lesioned	Dead	Dead

Table 4. Severity rating scale for mycosphaerella/ascochyta blight of field pea (modified from Liu et al. 2013).

Rating	Description of lesions
1	No disease
2	Mild to moderate disease on less than 5% of plant
3	Moderate to severe disease on ≥5-20% of plant
4	Moderate to severe disease symptoms on >20-50% of plant
5	Moderate to severe disease symptoms >50-80% of plant
6	Disease on all or most of the plant, plant stunted but alive
7	Plant stunted/dying

RESULTS AND COMMENTS: Approximately 646,400 hectares (1.6 million acres) of field pea were seeded in Saskatchewan in 2023. This was lower than the 731,900 hectares (1.8 million acres) seeded in 2022 (Statistics Canada 2024). As of early April 2024, 633,200 hectares (1.56 million acres) of field pea were harvested in Saskatchewan (Statistics Canada 2024). The Saskatchewan Crop Report (Saskatchewan Ministry of Agriculture 2023) estimated that 100% of the Saskatchewan field pea crop had been harvested by October 16, 2023.

Root rot complex was present in 90% of the surveyed field pea crops with an average incidence of 62% across the province (Tables 1 and 2). Average disease incidence ranged from 23% (Northeast) to 82% (Southeast). Disease severity was generally low with an average severity of 2.5 across the province.

Mycosphaerella/ascochyta blight complex was present in 90% the surveyed fields and was assessed based on percent of plants affected. Average incidence was 55% and ranged from 35% (Northeast) to 75% (Northwest) and average severity was quite low at 1.8 across the province.

Downy mildew was present in 17% of the surveyed fields. Average incidence was 1.4%. White mould was present only in one of the surveyed fields this year. Symptoms consistent with rust (Uromyces sp.) were also found in two of the fields surveyed in 2023.

Symptoms consistent with bacterial blight were present in 40% of crops. Bacterial streaming test was conducted with a microscope on representative samples from a portion of assessed fields, but no additional testing was performed to identify/confirm the causal organism. Presence of this disease may be influenced by crop damage due to adverse weather in these regions.

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FIELD PEA DISEASES IN MANITOBA IN 2023

CROP: Field pea LOCATION: Manitoba NAMES AND AGENCIES: Y.M. KIM¹, S. CHATTERTON², L. SCHMIDT³, G. WINTERS³, S. ZATYLNY¹ & T. HENDERSON¹

¹Agriculture and Agri-Food Canada (AAFC), Brandon Research and Development Centre, 2701 Grand Valley Road, Brandon, MB R7A 5Y3 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²AAFC, Lethbridge Research and Development Centre, P.O. Box 3000, Lethbridge, AB T1J 4B1 ³Manitoba Pulse and Soybean Growers, P.O. Box 1760, Carman, MB R0G 0J0

ABSTRACT: A total of 47 pea crops were surveyed in Manitoba in 2023 for root and foliar diseases. Fusarium root rot was the most prevalent root disease and mycosphaerella blight was the most widespread foliar disease throughout the province. Diseases that were less frequently observed included bacterial blight and downy mildew. Rust, powdery mildew, anthracnose and white mould were not observed in any of the crops surveyed in 2023. Root samples collected from a total of 222 pea fields in 2018 (40), 2019 (42), 2020 (46), 2021 (46) and 2022 (48) indicated that Aphanomyces euteiches was present in 56%, 83%, 91%, 89% and 98% of these fields, respectively, with a five-year average of 83%. The 2023 PCR results for A. euteiches from 47 crops were not available at the time of this report.

METHODS: Field pea crops were surveyed for root and foliar diseases at 47 different locations in Manitoba. The crops surveyed were randomly chosen from regions in south-central and southwest Manitoba, where field pea is commonly grown. In 2019, 2020 and 2021, the areas seeded to field pea were approximately 45,600, 63,000 and 96,000 ha, respectively (MASC 2019, 2020, 2021). The area seeded to field pea in Manitoba slightly decreased from approximately 76,000 ha in 2022 to 59,000 ha in 2023 (MASC 2022, 2023).

The survey of root diseases was conducted during late June to early July when most plants were at the late vegetative to mid-reproductive stage. At least 10 plants were sampled from each of three random sites in each crop surveyed. Root diseases were rated on a scale of 0 (no disease) to 9 (death of plant) (Xue 2000). To confirm the visual disease identification, 15 symptomatic roots were collected from each crop for fungal isolation and identification. Identification of Fusarium species involved visual assessment, microscopic examination and morphological characterization using the criteria of Leslie and Summerell (2006). Fifteen roots from each of the 47 pea crops were frozen for future PCR analysis of the root rot pathogens. Soil samples from each of 47 fields were dug up in late June and early July of 2023 during the root rot survey and will be assessed for Aphanomyces euteiches using PCR assays (Gangneux et al. 2014).

Foliar diseases were assessed from mid- to late July when most plants were at the intermediate to round pod stage. A minimum of 30 plants (10 plants from each of three sites) was assessed in each of the 47 fields. Foliar diseases were identified based on their symptoms. The severity of mycosphaerella blight, white mould and anthracnose was estimated using a scale of 0 (no disease) to 9 (whole plant severely diseased). Powdery mildew, downy mildew, rust and bacterial blight were rated as the percentage of foliar area diseased.

RESULTS AND COMMENTS: In 2023, the planting of field pea across the province was completed at 64% by May 16 and 99% by May 30 (Manitoba Agriculture 2023a, 2023b). By the week of August 14, field pea harvest started in most parts of the province with approximately 22% completion (Manitoba Agriculture 2023c). By September 12, the harvest of field peas was fully completed (Manitoba Agriculture 2023d). The average provincial yield for the year was approximately 50 bu/acre, with a range of 40 to 70 bu/acre. This was slightly below the 5-year average yield of 54 bu/acre (Manitoba Agriculture 2023e, 2023f).

Two diseases were identified based on laboratory assessment of the roots collected from 47 pea crops (Table 1). Fusarium root rot was the most prevalent as in previous years (Kim et al. 2022, 2023; McLaren et al. 2020, 2021). The 44 crops from which Fusarium spp. were isolated had root rot severity ratings ranging from 1.3 to 6.8 with a mean of 3.3. Rhizoctonia root rot (Rhizoctonia solani) was not detected in any of the crops sampled. Eleven (23%) pea crops had average root rot severity ratings greater than 4 (i.e., symptoms were present on 50% of the root system) and this would have had a detrimental effect on crop yield. Assessment of frozen samples for root pathogens using PCR is planned for the near future. Aphanomyces euteiches was detected in root samples collected from 91% (42/46), 89% (41/46) and 98% (47/48) of pea fields in 2020, 2021 and 2022, respectively (Gangneux et al. 2014). Assessment of the 2023 samples for A. euteiches is ongoing and results are pending at this time.

Table 1. Prevalence and severity of root diseases in 47 crops of field pea in Manitoba in 2023.

		Disease severity (0-9)^a
Disease	# Crops affected (%)	Mean	Range
Fusarium root rot	44 (94%)	3.3	1.3-6.8
Rhizoctonia root rot	0	0	0
Aphanomyces root rot	TBA^b	n/a	n/a

^aAll diseases were rated on a scale of 0 (no disease) to 9 (death of plant). Mean values are based only on crops in which the disease was observed.

^bAssessment of the 2023 samples for A. euteiches is ongoing and results are pending at this time.

Three foliar diseases were observed (Table 2). Mycosphaerella blight (Mycosphaerella pinodes) was the most prevalent, as in previous years (Kim et al. 2022, 2023; McLaren et al. 2020, 2021), and was present in all the crops surveyed. Disease severity ranged from 1.4 to 5.8 with a mean of 3.0. Downy mildew (Peronospora viciae) was detected in 6% (3/47) of the crops surveyed and the percentage of leaf area affected ranged from <0.1% to 0.2% with a mean of 0.1%. Bacterial blight (Pseudomonas syringae pv. pisi) was observed in 55% of the crops (26/47) surveyed with the percentage of foliar area affected ranging from trace to 17%. Powdery mildew (Erysiphe pisi) was not observed in any of the surveyed crops. All newly registered pea cultivars are required to have resistance to powdery mildew, so the absence of this disease could be mainly attributed to the use of new cultivars by growers. Symptoms of rust (Uromyces spp.), anthracnose (Colletotrichum pisi) and white mould (Sclerotinia sclerotiorum) were not observed in any of the crops surveyed in 2023.

Table 2. Prevalence and severity of foliar diseases in 47 crops of field pea in Manitoba in 2023.

		Disease severity (0-9 or % leaf area affected)^a
Disease	# Crops affected (%)	Mean	Range
Mycosphaerella blight	47 (100%)	3.0	1.4-5.8
Sclerotinia stem rot	0	0	0
Powdery mildew	0	0%	0%
Downy mildew	3 (6%)	0.1%	<0.1-0.2%
Anthracnose	0	0	0
Rust	0	0%	0%
Bacterial blight	26 (55%)	1%	<0.1-17%

^aPowdery mildew, downy mildew, rust and bacterial blight severity were rated as the percentage of leaf area affected; other diseases were rated on a scale of 0 (no disease) to 9 (whole plant severely diseased). Mean values are only based on crops in which the disease was observed.

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SEED-BORNE PATHOGENS OF PULSE CROPS IN SASKATCHEWAN IN 2022

CROP: Pulse crops (Pea, Lentil and Chickpea) LOCATION: Saskatchewan NAMES AND AGENCIES: B. D. OLSON¹, A. AKHAVAN², S. BANNIZA³, T. BLOIS⁴, M. BROWN⁵, B. ERNST⁶, S. JUNEK⁷, T. PRASAD⁸ & D. RISULA²

¹Box 88, Hazlet, SK S0N 1E0 Telephone: [phone]; Facsimile: n/a; Email: [email protected] ²Saskatchewan Ministry of Agriculture, 3085 Albert St., Regina, SK S4S 0B1 ³Crop Development Centre, University of Saskatchewan, 51 Campus Dr., Saskatoon, SK S7N 5A8 ⁴20/20 Seed Labs Inc., 507 - 11th Ave., Nisku, AB T9E 7N5 ⁵Saskatchewan Pulse Growers, 207 - 116 Research Drive, Saskatoon, SK S7N 3R3 ⁶Prairie Diagnostic Seed Lab, 1105 Railway Ave., Weyburn, SK S4H 3H5 ⁷Discovery Seed Labs Ltd., 450 Melville St., Saskatoon, SK S7J 4M2 ⁸Lendon Seed Lab, 147 Hodsman Road, Regina, SK S4N 5W5

ABSTRACT: Results of commercial plate tests for seed-borne pathogens and germinations of 729 field pea, 889 lentil, and 156 chickpea samples were summarized. The percentage of pathogen-free samples in most crops and for most pathogens continues to be very high. Ascochyta levels continue to be elevated in field peas and chickpeas.

METHODS: Commercial agar plate tests for pathogens in seed samples of field pea, lentil and chickpea across Saskatchewan were conducted and results summarized by four companies during the fall of 2022 through early spring of 2023. All samples were assumed to be from the 2022 crop year. Seeds were assessed for the presence of the following pathogens:

Ascochyta (Mycosphaerella/Peyronellaea) pinodes, Didymella (Ascochyta) pisi, and Phoma medicaginis var. pinodella (Ascochyta pinodella) complex, which causes ascochyta blight of field pea;

Didymella (Ascochyta) lentis, causal agent of ascochyta blight of lentil;

Didymella (Ascochyta) rabiei, causal agent of ascochyta blight of chickpea;

Colletotrichum lentis, causal agent of anthracnose of lentil;

Botrytis spp. which causes botrytis stem and pod rot (grey mould) of field pea, lentil and chickpea;

Sclerotinia sclerotiorum, causal agent of sclerotinia stem and pod rot (white mould) of field pea, lentil and chickpea.

A total of 1774 samples were tested for ascochyta blight pathogens, 1749 samples were tested for Botrytis spp., 881 samples for C. lentis and 1749 samples for S. sclerotiorum. The mean incidence (%) of seed infection in diseased samples and percentage of pathogen-free samples were calculated for each crop district and a provincial average was determined.

Germination test results were collected for 1749 samples and the mean percent germination was calculated for each crop district.

RESULTS AND COMMENTS: Growing conditions in western Canada were much improved compared to 2021, although parts of the Prairies still encountered insufficient soil moisture levels (Statistics Canada 2022). Crops matured normally and weather conditions favoured a timely harvest. Problems due to variable soil moisture, including drought and spring flooding, Richardson ground squirrels, and grasshopper infestations, as well as high winds, were reflected in yields, which varied widely across Saskatchewan. Below average yields were reported in the southwest and west-central regions, while above average yields were reported in the northern and eastern portions of the province (Saskatchewan Ministry of Agriculture 2022).

Lentil production in Saskatchewan remained consistent with 2021 at 3.8 million acres in 2022. The 5-year average is 3.7 million acres. The average 2022 lentil yield was 1,175 lbs/acre up from the average of 848 lbs/acre in 2021 but below the 5-year average (2017-2021) of 1,282 lbs/acre (Government of Saskatchewan 2022).

Field pea acreage in 2022 was 1.8 million acres which is below the 5-year average of 2.2 million acres. The average yield in 2022 was reported as 32.1 bu/acre, up significantly from the 20.2 bu/acre reported in 2021. The 5-year average yield (2017-2021) was reported to be 33 bu/acre (Government of Saskatchewan 2022).

Chickpea-seeded acres increased from 140,000 acres in 2021 to 202,800 acres in 2022. This is considerably below the 5-year average of 250,700 acres. The decline in seeded acres was likely related to a world-wide surplus of chickpeas resulting in lower prices. Yields in 2022 were reported at 1225 lbs/acre which was 25% up from the 980 lbs/acre reported in 2021 but below the 5-year average of 1,413 lbs/acre (Government of Saskatchewan 2022).

A total of 779 field pea, 889 lentil and 156 chickpea samples were processed during the period covered by the report. This represents an increase of less than 1% in chickpea samples compared to 2021 (Olson et al. 2023). Chickpea total sample numbers remained relatively low compared to lentil and pea samples. Based on the location of chickpea production, most samples would originate from southern and south-western crop districts but seed testing labs from these areas are under-represented in this report. Lentil samples decreased by 19.4% and field peas decreased by 17.2% compared to 2021. Despite the decrease, the high number of samples received by the seed labs remains indicative of producers’ continued concerns related to disease.

Pea – The percentage of Ascochyta-free samples was 53.6%, down from the 75.9% reported in 2021 (Table 1). The mean percent infection was 1.6% up from 1.2% in 2021. The percentage of Botrytis-free samples was 96.8%, down slightly from the previous year. The mean percent infection level of 0.9% was only a slight increase from the 0.6% reported in 2021. The percentage of S. sclerotorium-free samples was 97.3%, down slightly from the previous year. The provincial mean percent infection was 3.7%. This is up from 0.0% reported in 2021 but was based on only one sample. Levels of infection by crop district are shown in Table 2.

Table 1. Summary of pulse seed samples tested for pathogens from 2018 to 2022 in Saskatchewan.

5-Year Provincial Summary
		2022		2021^a		2020^a		2019^a		2018^a
	Pathogen	% PFS^b	Mean %^c	% PFS	Mean %	% PFS	Mean %	% PFS	Mean %	% PFS	Mean %
Lentil	A. lentis	91.8	0.4	99.3	0.4	97.9	0.5	95.5	0.8	98.0	0.4
	C. lentis	85.6	1.1	97.2	0.9	85.3	1.2	89.2	0.9	94.1	0.5
	Botrytis spp.	97.7	0.9	98.5	0.5	95.9	0.8	93.2	1.0	96.2	1.0
	S. sclerotiorum	97.7	0.7	99.8	0.3	97.8	0.5	96.0	0.7	97.7	0.5
Pea	Ascochyta spp.	53.6	1.6	75.9	1.2	33.9	2.8	36.3	4.7	66.4	2.4
	Botrytis spp.	96.8	0.9	99.5	0.6	93.6	0.8	93.6	1.0	99.1	0.9
	S. sclerotiorum	97.3	1.1	100	0.0	99.1	0.6	99.0	0.6	99.2	0.6
Chick pea	Ascochyta rabiei	62.2	1.4	71.6	0.7	44.1	3.2	51.3	3.2	74.9	1.2
	Botrytis spp.	98.7	0.8	96.7	0.4	87.1	1.1	86.6	1.9	96.3	1.1
	S. sclerotiorum	100	0	98.7	0.7	99.3	0.3	89.8	0.9	98.1	2.2

^a2021 (Olson et al. 2023); 2020 (Olson et al. 2022); 2019 (Olson et al. 2021); 2018 (Olson et al. 2020).

^b% PFS = percent pathogen-free samples

^cMean % = mean percent infection

Table 2. Number of field pea samples tested from September 2022 to May 2023 and levels of infection with Ascochyta spp., Botrytis spp. and Sclerotinia sclerotiorum for each Saskatchewan crop district.

2022 Field Pea
	Ascochyta spp.			Botrytis spp.			Sclerotinia sclerotiorum
Crop District	# tests	% PFS^a	Mean %^b	# tests	% PFS	Mean %	# tests	% PFS	Mean %
1A	31	64.5	1.2	30	100	0	30	100	0
1B	23	52.2	3	19	100	0	19	100	0
2A	43	67.4	1.7	43	100	0	43	100	0
2B	59	86.4	1	59	100	0	59	100	0
3AN	2	100	0	2	100	0	2	100	0
3AS	37	70.3	1.6	37	100	0	37	100	0
3BN	18	44.4	1.7	18	100	0	18	100	0
3BS	1	100	0	1	100	0	1	100	0
4A	0	ND^c	ND	0	ND	ND	0	ND	ND
4B	23	69.6	1	23	100	0	23	100	0
5A	21	66.7	1	20	100	0	20	95	0.5
5B	39	28.2	1.3	39	97.4	0.5	39	100	0
6A	81	56.8	1.8	80	98.8	0.5	80	100	0
6B	119	47.9	1.6	118	97.5	3	118	90.7	6
7A	22	40.9	1	22	100	0	22	100	0
7B	49	40.8	0.9	48	91.7	0.5	48	100	0
8A	20	15	2	19	94.7	0.5	19	94.7	0.5
8B	37	32.4	2.2	37	89.2	0.5	37	97.3	1
9A	58	41.4	1.4	52	90.4	0.8	52	84.2	0.5
9B	46	65.2	2.5	44	90.9	0.7	44	97.7	0.5
Total / Mean	729	53.6	1.6	711	96.8	0.9	711	97.3	3.7

^a% PFS = percent pathogen-free samples

^bMean % = mean percent infection

^cND = no data

Lentil – The percentage of A. lentis-free samples was 91.8%, down from the previous year of 99.3% (Table 1). The provincial mean percent infection was 0.4%, in line with the 0.4% reported for 2021. The percentage of C. lentis-free samples was 85.6% with a mean percent infection of 1.1%, compared to 97.2% and 0.9% in 2021. The frequency of Botrytis-free samples was 97.7%, down slightly from 98.5% in 2021. The mean percent infection rate was 0.9%, an increase from 0.5% in 2021. The frequency of S. sclerotiorum-free samples remained high at 97.7% compared to 99.8% in 2021. The mean percent infection rate was 0.7%, up from 0.3% in 2021. Levels of infection by crop district are shown in Table 3.

Table 3. Number of lentil seed samples tested from September 2022 to May 2023 and levels of infection with Ascochyta lentis. Colletotrichum lentis, Botrytis spp., and Sclerotinia sclerotiorum for each Saskatchewan crop district.

2022 Lentil
		Ascochyta lentis		Colletotrichum lentis			Botrytis spp.			Sclerotinia sclerotiorum
Crop District	# tests	% PFS^a	Mean %^b	# tests	% PFS	Mean %	# test	% PFS	Mean %	# test	% PFS	Mean %
1A	11	100	0	11	45.5	1.8	11	100	0	11	90.9	0.5
1B	2	100	0	2	100	0	2	100	0	2	100	0
2A	86	94.2	0.4	85	75.3	1.8	86	95.3	1.2	86	94.2	0.6
2B	178	90.4	0.6	176	93.8	1.5	178	96.1	1.1	178	96.6	0.8
3AN	27	100	0	27	92.6	0.8	27	100	0	27	100	0
3AS	115	95.7	0.4	113	87.6	1.4	114	98.2	0.3	114	100	0
3BN	59	100	0	59	88.1	0.7	59	100	0	59	100	0
3BS	12	100	0	12	91.7	0.3	12	100	0	12	100	0
4A	3	100	0	3	100	0	3	100	0	3	100	0
4B	24	95.8	0.3	24	87.5	0.3	24	100	0	24	100	0
5A	21	81	0.9	21	100	1.5	21	76.2	1	21	81	1
5B	0	ND^c	ND	0	ND	ND	0	ND	ND	0	ND	ND
6A	66	93.9	0.4	65	83.1	0.8	65	98.5	0.3	65	98.5	0.3
6B	137	89.8	0.3	137	78.8	0.9	137	100	0	137	100	0
7A	95	95.8	0.4	95	84.2	0.7	95	98.9	0.3	95	98.9	0.3
7B	34	79.4	0.4	34	85.3	0.7	34	100	0	34	100	0
8A	1	100	0	1	0	1	1	100	0	1	100	0
8B	5	100	0	5	100	0	5	100	0	5	100	0
9A	8	100	0	6	83.3	0.5	6	100	0	6	83.3	0.3
9B	5	100	0	5	100	0	5	100	0	5	80	0.3
Total / Mean	889	91.8	0.4	881	85.6	1.1	885	97.7	0.9	885	97.7	0.7

^a% PFS = percent pathogen-free samples

^bMean % = mean percent infection

^cND = no data

Chickpea - Chickpea production in Saskatchewan is largely centered in the southern and south-western regions of the province where small numbers of samples were evaluated by the four contributing companies. The overall percentage of Ascochyta rabiei-free samples was 62.2%, down from 71.6% in 2021 (Table 1). The mean infection percentage was 1.4%, up from 2021 when a rate of 0.7% was reported. The frequency of Botrytis-free samples was 98.7%, up from 96.7% in 2021. The mean infection rate was 0.8%, up from the 0.4% reported in 2021. The frequency of S. sclerotiorum-free samples was 100%, up slightly from the 98.7% reported in 2021. The mean percent infection was 0.0%, down from 0.7% in 2021. Levels of infection by crop district are shown in Table 4.

Table 4. Number of chickpea seed samples tested from September, 2022 to May 2023 and levels of infection with Ascochyta rabiei, Botrytis spp., and Sclerotinia sclerotiorum for each Saskatchewan crop district.

2022 Chickpea
	Ascochyta rabiei			Botrytis spp.			Sclerotinia sclerotiorum
Crop District	# tests	% PFS^a	Mean %^b	# tests	% PFS	Mean %	# tests	% PFS	Mean %
1A	0	ND^c	ND	0	ND	ND	0	ND	ND
1B	0	ND	ND	0	ND	ND	0	ND	ND
2A	23	65.2	1.9	22	100	0	22	100	0
2B	35	71.4	0.5	35	100	0	35	100	0
3AN	10	40	1.8	10	100	0	10	100	0
3AS	41	58.5	2.4	40	95	0.8	40	100	0
3BN	12	75	0.3	12	100	0	12	100	0
3BS	0	ND	ND	0	ND	ND	0	ND	ND
4A	0	ND	ND	0	ND	ND	0	ND	ND
4B	7	14.3	0.8	6	100	0	6	100	0
5A	1	0	0.6	1	100	0	1	100	0
5B	0	ND	ND	0	ND	ND	0	ND	ND
6A	1	100	0	1	100	0	1	100	0
6B	16	68.8	0.9	16	100	0	16	100	0
7A	8	62	0.5	8	100	0	8	100	0
7B	2	100	0	2	100	0	2	100	0
8A	0	ND	ND	0	ND	ND	0	ND	ND
8B	0	ND	ND	0	ND	ND	0	ND	ND
9A	0	ND	ND	0	ND	ND	0	ND	ND
9B	0	ND	ND	0	ND	ND	0	ND	ND
Total / Mean	156	62.2	1.4	153	98.7	0.8	153	100	0

^a% PFS = percent pathogen-free samples

^bMean % = mean percent infection

^cND = no data

Percent germination for each crop district is shown in Table 5.

Table 5. Number of seed samples tested from September 2022 to May 2023 and mean percent germination results (%) for each Saskatchewan crop district.

	Field Pea		Lentil		Chickpea
Crop District	# tests	Mean %	# tests	Mean %	# tests	Mean %
1A	32	88.9	11	95.3	0	ND^a
1B	19	83.6	2	95.5	0	ND
2A	43	87.4	86	92.5	22	88.3
2B	59	89.3	179	95.4	35	86.3
3AN	2	81	27	96	10	88.5
3AS	39	86.3	115	87.1	41	88.8
3BN	18	82	59	96.7	12	86.6
3BS	1	73.5	12	97	0	ND
4A	0	ND	3	97.8	0	ND
4B	24	84.2	26	95.8	7	83.5
5A	21	87	26	90.2	1	87
5B	39	90.7	0	ND	0	ND
6A	81	88.5	66	96.4	1	74
6B	119	88.1	137	94.8	16	83.1
7A	22	86.1	95	96.5	8	81.1
7B	53	84.5	34	95.1	2	86.5
8A	24	87.9	1	96	0	ND
8B	37	87.4	5	92.6	0	ND
9A	61	87.2	8	94.7	0	ND
9B	48	87	5	95.8	0	ND
Total/Mean	742	87.3	897	94.1	155	86.6

^aND = no data

ACKNOWLEDGEMENTS: We would like to acknowledge the cooperation of 20/20 Seed Labs Inc., Lendon Seed Lab, Prairie Diagnostic Seed Lab, and Discovery Seed Labs Ltd. for providing seed testing results. We also wish to recognize the financial support of the Saskatchewan Pulse Growers.

REFERENCES

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2023 SURVEY OF SOYBEAN DISEASES IN SASKATCHEWAN

CROP: Soybean LOCATION: Saskatchewan NAMES AND AGENCIES: A. AKHAVAN¹, C. PERU¹, S. ROBERTS¹ & T. ADEGEYE²

¹Saskatchewan Ministry of Agriculture, 3085 Albert St., Regina, SK S4S 0B1 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²Saskatchewan Association of Rural Municipalities, 2301 Windsor Park Rd., Regina, SK S4V 3A4

ABSTRACT: A total of 20 soybean crops were surveyed in Saskatchewan in 2023. Brown spot and bacterial blight were the most prevalent diseases in 2023 soybean crops with 100% and 95% of survey crops showing symptoms. Symptoms suggesting phytophthora root rot were found in one field but was not confirmed at the lab. Iron chlorosis was seen in two fields this year. No additional diseases including frog eye leaf spot, downy mildew, white mould, anthracnose, soybean rust, northern stem canker, sudden death syndrome and charcoal rust were observed in 2023. Symptoms suggesting cercospora leaf blight were found in several fields this year but were not confirmed at the Crop Protection Laboratory following plating and microscopy.

INTRODUCTION AND METHODOLOGY: A total of 20 soybean fields were surveyed and assessed for disease incidence and severity in Saskatchewan. The survey was completed between August 2 and September 6 while crops were between growth stage R3 (beginning pod) to R8 (full maturity). Eighteen of the surveyed fields were in the Southeast and two fields were in East-central. Ten plants were assessed for the incidence and severity of diseases at five sites located in a W-pattern (a total of 50 plants per field). Individual sites were at least 50m apart and located at least 50 m from the field edge. Each of the 50 plants were assessed for the presence of the following diseases: brown spot (Septoria glycines), bacterial blight (Pseudomonas savastanoi pv. glycinea), downy mildew (Peronospora manshurica), white mould (Sclerotinia sclerotiorum), pod and stem blight (Diaporthe sojae), anthracnose (Colletotrichum spp.), frogeye leaf spot (Cercospora sojina) and phytophthora root rot (Phytophthora sojae). Disease severity was also assessed for brown spot, bacterial blight and downy mildew using a 0-5 rating scale with 0 meaning no disease present and five meaning that there were severe symptoms with defoliation. The prevalence of iron chlorosis, sudden death syndrome (Fusarium virguliforme), soybean rust (Phakopsora meibomiae and P. pachyrhizi), charcoal rot (Macrophomina phaseolina), northern stem canker (Diaporthe caulivora) and soybean cyst nematode (Heterodera glycines) was estimated by recording the presence or absence in the field. All disease assessments were made based on visual symptoms in the field.

RESULTS AND COMMENTS: In 2023, approximately 27,500 hectares (68,000 acres) were seeded to soybean in Saskatchewan. This is higher than the 18,400 hectares (45,400 acres) seeded in 2022 (Statistics Canada 2024). As of early April 2024, almost all the seeded soybean fields were harvested in Saskatchewan (Statistics Canada 2024). The Saskatchewan Crop Report (Saskatchewan Ministry of Agriculture 2023) estimated that 92% of the Saskatchewan soybean crop had been harvested by October 16, 2023.

The most prevalent diseases in Saskatchewan were bacterial blight and brown spot. Symptoms consistent with brown spot were observed in all the surveyed crops with an average incidence of 86 % and average severity was 1.6 as rated on a 0 to 5 rating scale. Bacterial blight was present in 95% of fields surveyed with an average incidence of 79 % in infected fields (Table 1). The average disease severity in infected fields was 2.2 as rated on a 0 to 5 rating scale.

Table 1. Prevalence, incidence and severity of bacterial blight, brown spot, and downy mildew in Saskatchewan soybean fields in 2023.

Disease	Prevalence (%)^a	Average incidence in only infected fields (%)^b	Average severity in infected fields^c
Bacterial blight	95	79	2.2
Brown spot	100	86	1.6
Frogeye leaf spot	0	0	0
Downy mildew	0	0	0

^aPrevalence = the percent of crops surveyed with symptoms of the disease.

^bAverage incidence of the disease averaged across crops with disease symptoms (all infected fields in 2023).

^cAverage severity across crops with disease symptoms (all infected fields in 2023).

Symptoms suggesting phytophthora root rot were found in one field. Samples were submitted to Dr. Yong Min Kim for further analysis and the pathogen was not isolated.

Iron chlorosis was seen in two fields this year. No additional diseases including frogeye leaf spot, downy mildew, white mould, anthracnose, soybean rust, northern stem canker, sudden death syndrome and charcoal rust were observed.

Symptoms suggesting cercospora leaf blight (Cercospora kikuchii) were found in several fields this year but were not confirmed at the Crop Protection Laboratory following plating and microscopy.

REFERENCES

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SOYBEAN ROOT ROT AND PHYTOPHTHORA ROT IN MANITOBA AND SASKATCHEWAN IN 2023

CROP: Soybean LOCATION: Manitoba and Saskatchewan NAMES AND AGENCIES: Y.M. KIM¹, A. ABDELMAGID², D. KAMINSKI³, D. LANGE⁴, L. SCHMIDT⁵, G. WINTERS⁵, T. BUSS⁶, E. BARGEN⁷, C. MORRISON³, K. STEUART³, N. CLOUSON⁸, A. FAROOQ⁹, V. OWUSU¹⁰, A. AKHAVAN¹¹, C. PERU¹¹, S. ROBERTS¹², W. PENNER², S. ZATYLNY¹, M. THOMPSON¹ & T. HENDERSON¹

¹Agriculture and Agri-Food Canada (AAFC), Brandon Research and Development Centre, 2701 Grand Valley Road, Brandon, MB R7A 5Y3 Telephone: [phone]; Facsimile: [phone]; E-mail: [email protected] ²AAFC, Morden Research and Development Centre, 101 Route 100, Morden, MB R6M 1Y5 ³Manitoba Agriculture, Box 1149, Carman, MB R0G 0J0 ⁴Manitoba Agriculture, 536 Stephen St., Morden, MB R6M 1T7 ⁵Manitoba Pulse and Soybean Growers, Box 1760, Carman, MB R0G 0J0 ⁶Manitoba Agriculture, Box 50, Beausejour, MB R0E 0C0 ⁷Manitoba Agriculture, Unit C - 284 Reimer Ave., Steinbach, MB R5G 0R5 ⁸Manitoba Agriculture, 120-6th Ave. N, Swan River, MB R0L 1Z0 ⁹Manitoba Agriculture, 1129 Queens Ave., Brandon, MB R7A 1L9 ¹⁰Manitoba Agriculture, 75-7th Ave., Gimli, MB R0C 1B0 ¹¹Saskatchewan Ministry of Agriculture, 125-3085 Albert St., Regina, SK S4S 0B1 ¹²Saskatchewan Ministry of Agriculture, Box 1239, Weyburn, SK S4H 2L5

ABSTRACT: In 2023, 58 and 20 soybean crops were surveyed in Manitoba and Saskatchewan, respectively, for root diseases. Samples from all fields were rated for root rot severity. Root samples from 58 and 20 Manitoba and Saskatchewan fields, respectively, were assessed in the laboratory for root pathogens and fusarium root rot was the most prevalent root disease. Fifty-eight Manitoba soybean crops were assessed for phytophthora rot along with 20 Saskatchewan crops. In 2023, Phytophthora sojae was not detected in any of the soybean plant samples that were received from Manitoba and Saskatchewan.

INTRODUCTION: In 2023, the soybean seeded area in Manitoba increased to 1.59 million acres, up from 1.13 million acres in 2022. This was the highest area in the province since 2018. Producers in Manitoba may have chosen to plant more soybeans due to record yields in 2022. In Saskatchewan, the soybean seeded area also increased to 68,000 acres in 2023 from 45,400 acres in 2022 (Statistics Canada 2023). Root rot has been a problem in Manitoba and Saskatchewan and is also a constraint in other areas of Canada where soybean production has been established (Chang et al. 2013; Nyandoro et al. 2019; OMAFRA 2017). This disease complex may become more of an issue in Manitoba and Saskatchewan with the increased development and cultivation of early maturing soybean varieties as well as the association of Fusarium species with numerous field crops. Phytophthora rot has been identified in Manitoba and Saskatchewan soybean crops and an annual survey for P. sojae is of utmost importance to characterize these isolates and provide information on the pathotype diversity that now exists.

METHODS: Soybean crops were surveyed for root diseases at 58 different locations in Manitoba in 2023. Areas included in the crop survey comprised not only fields from regions in south-central and southwest Manitoba, where soybean is commonly grown, but also fields from non-traditional soybean areas into which the crop is expanding. The survey for root diseases was conducted during mid-July to late August, with at least ten plants uprooted at three sites in a zigzag pattern within each crop surveyed. Root diseases were rated on a scale of 0 (no disease) to 9 (death of plant) for all 58 surveyed fields. Fifteen roots were collected from each of the 58 crops for fungal isolation and identification. For Fusarium spp., identification involved visual assessment, microscopic examination and morphological characterization of fungal colonies on growth media using the criteria of Leslie and Summerell (2006). Fifteen roots from each of the 58 soybean crops surveyed were frozen for future PCR analysis of root rot pathogens.

In Manitoba, the 58 crops that were surveyed for root rot were assessed for phytophthora rot at the same time. Soybean plants were collected by staff from AAFC-Brandon, AAFC-Morden, Manitoba Agriculture, and the Manitoba Pulse and Soybean Growers. Furthermore, soil samples from each of the 58 fields were collected during the root rot survey and will be assessed for P. sojae using PCR assays (Dussault-Benoit et al. 2020). In Saskatchewan during early August to early September, soybean plants were collected from 20 crops by employees from the Saskatchewan Ministry of Agriculture. All plants were shipped to Manitoba, rated for root rot, and those that were symptomatic for phytophthora disease were identified at AAFC-Brandon for further assessment in the laboratory. Approximately 27 stems from Manitoba and and seven stems from Saskatchewan soybean plants were placed on selective media to identify Phytophthora spp. based on their morphological characteristics (Gallegly and Hong 2008).

RESULTS AND COMMENTS: The average soybean harvest completion percentage in Manitoba was 96% by October 24, while in Saskatchewan, it was 89% by October 16 (Manitoba Agriculture 2023, Saskatchewan Agriculture 2023). In Manitoba, reported yields ranged from 20 to over 40 bu/ac, with an average yield of 34 bu/ac (Manitoba Agriculture 2023). Meanwhile, in Saskatchewan, the average soybean yield was estimated at 17 bu/ac, falling below the 10-year (2013-2022) average yield of 25 bu/ac (Saskatchewan Agriculture 2023).

Root rot was observed in all 58 and 20 soybean crops surveyed in Manitoba and Saskatchewan, respectively. Root rot severity ratings ranged from 2.2 to 5.6 with a mean of 4.0 in Manitoba and from 2.8 to 6.8 with a mean of 4.2 in Saskatchewan. Based on laboratory assessment, the microorganisms most frequently isolated from roots of infected plants from 78 crops (58 Manitoba and 20 Saskatchewan) were Fusarium spp. (Table 1). Rhizoctonia root rot (Rhizoctonia solani) was not detected in any of the 58 Manitoba or 20 Saskatchewan crops surveyed in 2023. Pythium root rot was not detected in any of the soybean crops surveyed. Assessment of frozen samples for root pathogens using PCR is planned for the near future. Phytophthora rot was not identified in any of the 58 Manitoba fields and was not detected in any plant samples received from Saskatchewan in 2023 (Table 1). The assessment of the 2023 Manitoba soil samples for P. sojae is ongoing, and the results are pending at this time.

Table 1. Prevalence of phytophthora rot and prevalence and severity of root rot in 58 and 20 crops of soybean in Manitoba and Saskatchewan, respectively, in 2023.

			Disease severity (0-9)^a
	No. crops affected (%)		Mean		Range
Disease	MB	SK	MB	SK	MB	SK
Root rot	58 (100%)	20 (100%)	4.0	4.2	2.2-5.6	2.8-6.8
Fusarium root rot^b	58 (100%)	20 (100%)	4.0	4.2	2.2-5.6	2.8-6.8
Pythium root rot^b	0	0	0	0	0	0
Rhizoctonia root rot^b	0	0	0	0	0	0
Phytophthora rot^c	0	0	0	0	0	0

^aAll diseases, excluding phytophthora rot, were rated on a scale of 0 (no disease) to 9 (death of plant). Mean values are based only on crops in which the disease was observed.

^bBased on isolations from 58 and 20 crops from Manitoba and Saskatchewan, respectively.

^cBased on observations and isolations from 58 and 20 crops in Manitoba and Saskatchewan, respectively.

ACKNOWLEDGEMENTS: We gratefully acknowledge the support of Tayo Adegeye and Joanne Kwasnicki with the Saskatchewan Association of Rural Municipalities for their assistance in the Saskatchewan soybean disease survey.

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VEGETABLES / LÉGUMES

MONITORING OF FUNGAL DISEASES, STEM AND BULB NEMATODE AND ASTER YELLOWS ON GARLIC IN ALBERTA, 2023

CROP: Garlic LOCATION: Alberta NAMES AND AGENCIES: M.W. HARDING¹, G.C. DANIELS¹, P. RAGAN², H. FU³ & J. FENG³

¹Alberta Agriculture and Irrigation, Crop Diversification Centre South, 301 Horticulture Station Road E., Brooks, AB T1R 1E6 Telephone: [phone]; E-mail: [email protected] ²Paul Ragan Horticultural Consulting, Lethbridge, AB T1K 5S6 ³Alberta Agriculture and Irrigation, Crop Diversification Centre North, 17507 Fort Road NW, Edmonton, AB T5Y 6H3

ABSTRACT: In 2023, a survey was performed to monitor eight garlic diseases at two locations. Disease assessments were performed bi-weekly for the presence of the aster yellows pathogen (Candidatus Phytoplasma asteris), the stem and bulb nematode (Ditylenchus dipsaci), the oomycete pathogen Globisporangium spp. and five fungal pathogens (Alternaria spp., Botrytis spp., Fusarium spp., Penicillium spp., and Rhizoctonia solani). The most commonly occurring pathogens were Fusarium spp., Penicillium spp., and D. dipsaci, respectively. Additionally, Botrytis spp., R. solani, and aster yellows phytoplasma were detected.

INTRODUCTION AND METHODS: Production of garlic (Allium sativum L.) in Alberta is increasing. It is produced in many small market gardens that supply local fresh market consumption, and a few larger commercial production/packaging operations, mostly under irrigation in southern Alberta. Often accompanying increases in cultivated acres are opportunities for pests and diseases to become more prevalent. Fungal diseases routinely have a negative impact on onion and garlic production with pathogens such as Fusarium oxysporum Schlechtendal and F. avenaceum (Corda) Saccardo causing basal plate rot, Sclerotium cepivorum Berk. causing white rot, Alternaria alternata (Fries) Keissler (A. embellisia Woudenb. & Crous) causing skin blotch, and Botrytis porri (van Beyma) Whetzel causing neck rot. Aster yellows caused by Candidatus Phytoplasma asteris (Lee, Gundersen-Rindal, Davis, Bottner, Marcone & Seemüller), and stem and bulb nematode (Ditylenchus dipsaci) infections can cause damage as well. Disease monitoring in onion and garlic over the past 10 years has revealed that Fusarium oxysporum is consistently a primary disease agent in Alberta, however other emerging diseases have been recently reported such as embellesia skin blotch, aster yellows, and stem and bulb nematode. These pathogens have all been reported on onion and garlic in Alberta plantings in previous years (Harding et al. 2013, 2015, 2016, 2021, 2022, 2023).

In 2023, two garlic production units were sampled every two weeks. between June 8 and July 27, 2023. Three to five whole plants were collected at each of three sites in both fields. The sample site locations were the same for each sampling event. After collection, plant samples were stored at 4°C until processing. Cultivar names and field locations are not revealed in this report. Fungi were cultured from bulb and neck tissues by dissecting 1 cm tissue pieces with a clean scalpel and surface sterilizing the pieces in 1% NaOCl for 30s, followed by a tap water rinse and blotting dry on sterile paper towel. Nine to 12 surface-sterilized neck and bulb tissue pieces of each cultivar were plated on a botrytis semi-selective medium (BSM) (Gutierrez and Shew 1998) and duplicated on 4% potato dextrose agar (PDA). Plates were incubated for one week at 20°C in the dark after which the presence of Botrytis spp. was recorded based on fungal morphology and colour change on BSM, and other fungi on PDA were recorded based on fungal colony and spore morphology visualized with a phase contrast microscope at 400x.

Past surveys have shown aster yellows to be a commonly occurring and important disease of onion and garlic in Alberta, and that D. dipsaci is an emerging issue for onion and garlic producers (Harding et al. 2021, 2023). To monitor for the presence of phytoplasma, garlic neck and bulb tissues underwent DNA extraction using a DNeasy Plant Pro kit (Qiagen Canada, Toronto, ON). PCR amplification was conducted using the specific primer pair P1/Tint for phytoplasma (Smart et al. 1996) and primer pair DITuniF/DITdipR for detection of D. dipsaci (Jeskze et al. 2015). Identification of fungal species was performed using the barcoding primer pair ITS1/ITS4 (White et al. 1990).

RESULTS AND COMMENTS: Above-average temperatures and below-average rainfall characterized the 2023 growing season. The survey results presented here were from irrigated fields and the yield and quality of the crop was typical. Average incidence of isolates recovered from garlic ranged from 9% (Alternaria spp.) to 65% (Fusarium spp.), and included fungi in the genera Alternaria, Botrytis, Fusarium and Penicillium and the oomycete Globisporangium (Table 1). Phytoplasma detection averaged 11% incidence and D. dipsaci detections averaged 37% incidence. Detections of fungal and oomycete pathogens over the season are shown in Fig. 1, revealing a general trend for higher pathogen detections in mid-June, but decreasing later. Exceptions were Fusarium spp. and Botrytis spp. which increased or remained relatively consistent on garlic samples throughout the season. Aster yellows phytoplasma was present in > 40% of samples in early June but decreased over the summer and was non-detectable at the final sampling date. The stem and bulb nematode (D. dipsaci) was not detected in early June, but detection increased steadily throughout the season until it was found in 100% of the samples by the final sampling date. Overall, the most commonly occurring pathogens were Fusarium spp., Penicillium spp., and D. dipsaci, respectively.

Fig. 1 Incidence of garlic pathogen detections on samples collected at five sampling dates between June 8 and July 27, 2023.

Table 1. Pathogens detected on garlic in Alberta in 2023.

	Average incidence (%)
Alternaria spp.	9.05
Phytoplasma	11.90
Botrytis spp.	21.31
Ditylenchus dipsaci	36.67
Fusarium spp.	65.48
Globisporangium spp.	14.76
Penicillium spp.	43.77
Rhizoctonia solani	21.19

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