Annual Meeting, the Canadian Phytopathological Society, 2017/Réunion annuelle, la Société Canadienne de Phytopathologie, 2017

Study on Verticillium longisporum of canola for the first reported farm in North America. A. AGARWAL AND M. TENUTA. Department of Soil Science, University of Manitoba, 13 Freedman Crescent, Winnipeg, MB R3T 2N2, Canada

The soil-borne fungus, Verticillium longisporum (Stark) Karapapa et al., was first identified in North America on canola at a farm in Manitoba, Canada in 2014. Verticillium longisporum is a common pathogen of Brassica crops in Europe and causes verticillium stripe in rapeseed/canola crops. Past research has established V. longisporum is a diploid hybrid of either two species of Verticillium dahliae Kleb. (parental lines D2 or D3) and also either of two other unknown species (A1 or D1). Since this is the first-ever documented case of this pathogen of canola in North America, very little is known about its ease of dispersal, spatial distribution within farms, virulence and hybrid lineage. To help address those uncertainties, a research study was set out with objectives to: (i) investigate the spatial variation of V. longisporum at the farm positive for the pathogen, and (ii) determine the hybrid origin of V. longisporum isolates in Manitoba. The farm was segregated into 57 areas based on differences in management history (e.g. crop sequence) from 2005 to 2015 from field records and historical aerial images. In autumn 2015, one to four composite soil samples were obtained from each area for a total of 194 samples. A real-time direct soil extraction PCR assay developed in our laboratory confirmed 132 of 194 samples were positive for the pathogen. The highest amount of the fungus observed was 69.9 pg V. longisporum genomic DNA g⁻¹ soil with mean across positive samples of 2.71 pg g⁻¹ soil. Hybrid lineage determination of isolates from the farm indicate it to be that of V1D1; this is the most virulent line on canola. The results suggest the pathogen is easily dispersed on a farm and also the hybrid present for the first report on a farm in North America is that which is most aggressive on canola.

Control of microRNA turnover contributes to plant immunity activated by flagelline. R. AJMI, T. ABD EL RAHMAN AND K. BOUARAB. Centre SÈVE, Department of Biology, University of Sherbrooke, 2500 boulevard de l’Université, Sherbrooke, QC J1K 2R1, Canada

Despite the lack of a circulating immune system and the sessile state, plants are not easy hosts and passive organisms. In fact, during a continuous co-evolution with a wide range of pathogens, plants have developed an effective and a specific immune system. PAMPs triggered immunity (PTI) represents the first lane of defence in plant immunity. Although it is based on the recognition of the pathogen molecular pattern (PAMPs) by the pattern recognition receptors (PRRs), this basal immune response depends on different biological phenomenon such as the accumulation of microARN (miRNA). These small non-coding RNAs play a crucial role in the PTI pathway and so does their regulation. Small RNA degrading nucleases (SDN) are essential regulators of miRNA homeostasis by controlling their degradation. Our results showed that SDNs control salicylic acid signalling pathway activated by the flagelline PAMP. We also showed that SDNs are required for local resistance mediated by flagelline against the virulent bacteria Pseudomonas syringae pv. tomato DC3000. Therefore, SDN proteins appear to be a regulatory hub for an optimal immune response.

A shift in the pathotype of Plasmodiophora brassicae at a site in Ontario. F. AL-DAOUD, B. D. GOSSEN AND M. R. MCDONALD. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; and (B.D.G.) Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Plasmodiophora brassicae Woronin causes clubroot disease on Brassica crops worldwide. Genetic resistance is the principal strategy for clubroot management, but resistance has often been overcome by the emergence of new pathotypes. Pathotype 6 is the predominant pathotype in Ontario. Changes over time in the pathotype at the Muck Crops Research Station in King, Ontario, were assessed following observation of changes in the disease reaction of previously resistant canola (Brassica napus L.) cultivars. Clubbed roots of the susceptible canola line ACS-N39 were collected from field trials in 2011 and 2014, and inoculum was increased on a susceptible host. The cultivars that comprise Williams’ differential set were inoculated under controlled conditions at about one week after seeding (four replicates, 10–12 plants per experimental unit). Plants were rated for clubroot symptoms using a 0–3 scale at 6 weeks after inoculation, and a disease severity index (DSI) was calculated. A host was resistant if DSI ± 95% confidence interval < 50%; otherwise it was susceptible. This assessment identified the collections as pathotype 6 in 2011 and pathotype 2 in 2014. This apparent pathotype shift was associated with changes in the Brassica crops grown at this site. Prior to 2009, clubroot experiments at this site were performed exclusively on susceptible cultivars. After 2009, most studies included resistant or moderately resistant lines. Assessment of P. brassicae collections from this site in 2016 is underway to characterize any subsequent changes in pathotype.

First report of clubroot [Plasmodiophora brassicae] on canola in northern Ontario. F. AL-DAOUD, M. MORAN, B. D. GOSSEN AND M. R. MCDONALD. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; (M.M.) Ontario Ministry of Agriculture, Food, and Rural Affairs, 63 Lorne Avenue East, Stratford, ON N5A 6S4, Canada; and (B.D.G.) Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Clubroot, caused by Plasmodiophora brassicae Woronin, is endemic on Brassica vegetables in many regions of Ontario. It has not been a major concern to canola (Brassica napus L.) growers because the most common pathotype in Ontario (pathotype 6, Williams’ system) is not highly aggressive on most canola cultivars. Also, clubroot has not previously been reported in northern Ontario. In 2016, clubroot was found on canola in a field near Verner, Ontario, and a subsequent survey found P. brassicae DNA in soil of 11 of 95 fields that had been planted with canola, including seven fields in northern Ontario. The pathotype from the Verner site was determined as follows. The inoculum was increased by growing a susceptible host (Shanghai pak choy ‘Mei Qing Choi’, Brassica rapa var. chinensis) in field soil from the site for 6 weeks under controlled conditions. The resulting clubs were harvested and cultivars that comprise Williams’ differential set were inoculated 1 week after seeding. Four replicates were used with 11–12 plants per experimental unit. Plants were rated for clubroot symptoms using a 0–3 scale at 6 weeks after inoculation, and a disease severity index (DSI) was calculated. A host was resistant if DSI ± 95% confidence interval < 50%; otherwise it was susceptible. The pathotype of P. brassicae in Verner was pathotype 2, which was previously identified on rutabaga in Ontario in the 1970’s. It is also the pathotype identified on canola in Quebec, but it has not yet been found on canola in western Canada.

Effects of phosphorus sources on soil phosphatase activity, phosphorus availability and dry matter production of corn silage. W. ALI, W. ASHIQ, M. NADEEM, M. ZAEEM, S. M. GILLANI, V. KAVANAGH, R. THOMAS, A. UNC AND M. A. CHEEMA. School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland, 20 University Drive, Corner Brook, NL A2H 5G4, Canada; (M.N.) COMSATS Institute of Information Technology, Vehari, 61100, Pakistan; and (V.K.) Department of Fisheries and Land Resources, P.O. Box 340, Pasadena, NL A0L 1K0, Canada

Insufficient or unavailable soil phosphorus (P) is a key limitation for crop productivity. Dairy manure (DM) adds nutrients to soil, enhances soil phosphatase activity (SPA), and generally stimulates exoenzymatic hydrolytic activities of microbial decomposers of organic matter. Most P added to soil with inorganic fertilizers is rapidly fixed, leading to decreased phosphatase activity, and thus decreasing availability of P to plants. However, DM applications can favour an increase in P availability by enhancing biological activity through provision of easily available carbon sources and by improving soil physicochemical parameters. We carried out a field experiment at Pynn’s Brook Research Station, Pasadena, Newfoundland, on a podzol to: (1) determine the effect of different P sources on soil phosphatase activity and soil P availability; (2) explore the production potential of several corn silage genotypes with different P sources; and (3) examine the correlation matrix between SPA, available P, and dry biomass production. Experimental treatments were P sources (P₀, control; P₁, DM with high P concentration; P₂, DM with low P concentration; P₃, Inorganic P) and five corn silage genotypes. Results showed that, compared with control, P₁ treatment enhanced SPA by 18.91%, available P by 60.11%, and dry biomass production by 28.13%. Higher dry biomass (21.94 Mg ha⁻¹) produced by the Yukon R genotype under P₁ treatment was correlated with greater SPA and soil available P. We thus found a strong positive correlation between SPA and soil available P, and corn silage biomass production.

Investigating the cross kingdom biosynthesis of cytokinin in the Ustilago maydis–Zea mays pathosystem. I. O. ALIMI, R. J. N. EMERY AND B. J. SAVILLE. Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; (R.J.N.E.) Biology Department, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; and (B.J.S.) Forensic Science Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada

Tumour formation in the Ustilago maydis (DC.) Corda–Zea mays pathosystem is a characteristic symptom of common smut of corn. During the development of these tumours, cytokinin levels are elevated. More specifically, the freebase cis-zeatin (cZ), riboside cis-zeatin (cZR), nucleotide cis-zeatin (cZRP) and O-glucoside cis-zeatin (cZROG) are elevated during infection. Although the level of these cis-zeatins are increased, the biosynthetic origins of these cytokinins have not been determined. Are they produced by the corn host or the fungus? Both can produce cis-zeatins when grown independently. To investigate this phenomenon, we identified the genes potentially involved in the biosynthesis of cis-zeatins, via the tRNA degradation pathway, in both organisms. Plant and fungal genes responsible for the common steps in the biosynthetic pathway had distinct sequences and this allowed us to determine the organism-specific changes in transcript levels over the course of infection by using reverse transcription PCR (RT-PCR). The results are consistent with a cis-zeatin pool arising through the activity of host and pathogen enzymes. This led a model of the interaction in which, during early infection, the host attempts to modulate the levels of active cytokinins produced during infection by converting cZR to cZROG and cZRP; and then later during infection, the glucose modulation reverses, possibly due to pathogen glucosidase, causing the conversion of cZROG to cZR which would release glucose that could act as an additional carbon source for U. maydis during teliospore formation. Progress on experiments aimed at testing this model were presented.

Expression of selected Phytophthora infestans RxLR effectors during infection of potato and tomato cultivars. H. A. ALKHER, L. ADAM AND F. DAAYF. Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada

Late blight is a devastating disease of potato and tomato worldwide; it is caused by the hemibiotrophic oomycete Phytophthora infestans (Mont.) de Bary. In major potato/tomato growing regions, the disease causes significant crop losses leading to billions of dollars expenses. The frequent variations in P. infestans strains in the USA and Canada are making late blight management more challenging, with the newest strains being very aggressive on tomato in comparison to potato. To achieve better control of late blight, it is important to understand the pathogenicity factors that lead to the high aggressiveness of some P. infestans isolates on potato and/or tomato. Among seven RxLR effectors, we evaluated the expression of PITG-12737–2 in six P. infestans isolates during their interaction with potato cultivars ‘Kennebec’ (moderately resistant) and ‘Russet Burbank’ (susceptible) and with tomato hybrids Ultra sweet (moderately resistant) and Sun rise (susceptible). Infected plant tissues were collected at 1, 2, 3 and 6 days post-inoculation. Quantitative real-time PCR results showed that PITG-12 737–2 was the most expressed gene among the tested effector genes. Higher expression of this gene was observed at 3 and 6 dpi in infected tomato hybrids compared with potato cultivars. These results correlate with a previous cross-pathogenicity study, where isolates of genotype US-24 caused more symptoms on tomato than potato. Our finding suggests that PITG-12 737–2 could be one of the pathogenicity factors that play a role in facilitating P. infestans infection process while colonizing the host plant.

Use of a Streptomyces sp. in the biocontrol of Rhizoctonia solani, a root rot pathogen of soybean. A. ARFAOUI, L. ADAM AND F. DAAYF. Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada

Several soil-borne diseases routinely damage soybeans in production areas in Canada. Rhizoctonia solani Kühn is a soil-borne pathogen which causes root rot disease in soybean plants. Due to the lack of fungicides for effective management of this disease, alternative techniques such as biological control, are required. A promising bacterium (S11), identified as Streptomyces based on morphological and molecular traits, was tested as a potential biocontrol agent of R. solani. In vitro assays on PDA plates, indicated that this isolate was able to inhibit the radial growth of multiple Rhizoctonia groups. Pathogenicity testing on soybean plants also indicated that this bacterium provided a certain level of protection against Rhizoctonia. Based on these results, Streptomyces could have a potential role in integrative management strategies for several soybean diseases.

Biocontrol agent Streptomyces combined with phosphite activate soybean defence mechanisms against Phytophthora sojae. A. ARFAOUI, L. ADAM AND F. DAAYF. Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada

Phytophthora sojae Kaufmann and Gerdemann is a soil-borne pathogen causing root rot disease in soybean plants. The use of selected bacteria, such as Streptomyces, is a promising strategy for managing phytophthora root rot of soybeans. Phosphite compounds are salts derived from phosphorous acid and were previously shown to protect plants against certain pathogens. We explored the beneficial effect of the endophytic bacterium Streptomyces gelobus (S11) in combination with phosphite in terms of reducing P. sojae disease development in soybeans and the molecular mechanisms behind such effects. Both S11 and phosphite inhibited the growth of P. sojae in vitro on PDA agar plates and pre-treatment of soybeans with S11 and/or phosphite reduced the disease severity. Quantification of P. sojae DNA in soybean roots by real-time PCR, indicated that the growth of P. sojae was restricted in presence of Streptomyces and/or phosphite. Also, both treatments affected the activation of stress hormones and related defence genes in soybean plants. Streptomyces in combination with phosphite may constitute an efficient complementary strategy to protect soybeans from P. sojae.

Phenazine-1-carboxylic acid contributes to the biocontrol of potato common scab through modulation of Streptomyces scabies transcriptome. T. ARSENEAULT, R. ROQUIGNY, A. NOVINSCAK, C. GOYER AND M. FILION. Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada; (R.R., A.N., M.F.) Department of Biology, Université de Moncton, 18 avenue Antonine-Maillet, Moncton, NB E1A 3E9, Canada; and (C.G.) Fredericton Research and Development Centre, AAFC, 850 Lincoln Road, P.O. Box 20280, Fredericton, NB E3B 4Z7, Canada

Potato common scab, mainly caused by the bacterial pathogen Streptomyces scabies (ex Thaxter) Lambert & Loria (Ss), is an economically important disease for which there are no efficient control measures. Pot and field experiments have determined that Pseudomonas fluorescens LBUM223 is able to reduce disease symptoms through its production of the antimicrobial compound phenazine-1-carboxylic acid (PCA). Several potential mechanisms of biocontrol were investigated: (1) reduction of Ss soil populations; (2) induction of plant defence responses; and (3) alteration of virulence gene expression in Ss. Results showed that the reduction in scab symptoms was not associated with reduced Ss soil populations nor changes in plant defence gene expression, but coincided with a reduced expression of txtA, an essential gene for the production of Ss’ major pathogenicity and virulence factor, thaxtomin A. To further characterize this effect, in vitro RNA-seq analyses were conducted to determine how PCA affects Ss’ entire transcriptome. Following exposure to wildtype LBUM223 or purified PCA, reduced mycelium and spore formation in Ss was observed, and 12–14% of all genes were differentially expressed. Among these, we noted a strong down-regulation of the cfa biosynthetic cluster, which produces a virulence factor resembling coronatine. The specific implication of PCA is made clear when treatment with an isogenic PCA-deficient mutant of LBUM223 only up-regulated 0.13% of genes in the pathogen. This demonstrates that these concentrations of PCA cause important physiological changes in Ss, likely leading to biocontrol through mechanisms such as reduced virulence and differentiation, and increased oxidative stress, rather than reduced pathogen populations through toxicity.

Potential of biochar in reducing global warming potential and greenhouse gas intensities in corn silage cropping systems amended with different nitrogen sources. W. ASHIQ, W. ALI, M. NADEEM, M. ZAEEM, S. M. GILLANI, J. WU, L. GALAGEDARA, V. KAVANAGH AND M. A. CHEEMA. School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland, 20 University Drive, Corner Brook, NL A2H 5G4, Canada; (M.N.) COMSATS Institute of Information Technology, Vehari, 61100, Pakistan; and (V.K.) Department of Fisheries and Land Resources, P.O. Box 340, Pasadena, NL A0L 1K0, Canada

Greenhouse gases (GHGs) emissions from the agriculture sector have been accelerating global warming potential (GWP) and greenhouse gas intensities (GHGI) (GHG emission per unit of crop yield). About 8% of GHG emissions in Canada are contributed by the agriculture sector largely through methane (CH₄) and nitrous oxide (N₂O). Out of these emissions 50% are contributed by manure and fertilizer application to land. Biochar (BC), a carbon-rich material has been observed to reduce the GHG emissions in different cropping systems. A field experiment was conducted to (i) determine the effect of different N sources on GWP and GHGI and (ii) elucidate the effect of biochar application on the reduction of GWP and GHGIs in corn silage cropping systems. Experimental treatments were (i) dairy manure with high nitrogen (DM₁) (0.37% N); (ii) dairy manure with low nitrogen (DM₂) (0.14% N); (iii) inorganic nitrogen (IN); (iv) DM₁ + BC; (v) DM₂ + BC; (vi) IN + BC; (vii) N₀ (Control). Results showed that nitrogen sources and BC had a significant effect on GHGs emission, GWP and GHGI. BC application significantly reduced the GHGs, GWP and GHGI. Minimum GWP was noted in IN+B (6 t CO₂eq. ha⁻¹ season⁻¹), whereas maximum was observed in DM₁ (8 t CO₂eq. ha⁻¹ season⁻¹). GHGI was high in control 0.4 t CO₂eq. t⁻¹ dry matter, while low in IN+B (0.28 t CO₂eq. t⁻¹ dry matter). Results revealed that BC application could be considered a useful approach in reducing GWP and GHGI of corn silage cropping systems under different nitrogen sources application.

Aphanomyces and phytophthora root rot tolerance in alfalfa: recurrent selection and marker development under stringent disease conditions. P. AUDY, S. ROCHER AND A. CLAESSENS. Quebec Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Hochelaga Boulevard, Québec, QC G1V 2J3, Canada

Aphanomyces euteiches Drechs. (Ae) and Phytophthora medicaginis Hansen & Maxwell (Pm) are two major pathogens causing the decline of established stands of alfalfa in northern production areas particularly in wet and poorly drained soils. Marker-assisted selection could help accelerate the introgression of resistance genes in germplasm of high agronomic value. In this study, alfalfa cultivars were used for marker selection linked to aphanomyces root rot (ARR) or to phytophthora root rot (PRR) superior tolerance. For each cultivar, 1500 seedlings were challenged with a mixture of four Ae or Pm pathogenic isolates. The best 100 ARR- or PRR-tolerant phenotypes were selected and DNA was extracted from each plant individually (first cycle of the recurrent selection; ARR1 and PRR1). Pooled DNA samples (50 genotypes per pool sample) for each population were generated and used for a bulk segregant analysis of DNA polymorphisms using the SRAP (sequence related amplified polymorphism) technique. Polymorphic fragments associated with tolerance to ARR or PRR tolerance were identified within each genetic background. A second cycle of recurrent selection was completed with seeds resulting from crosses of the best 100 genotypes of the first round of selection (ARR2 and PRR2). A third cycle was completed for PRR tolerance (PRR3) and is in progress for ARR tolerance (ARR3). In the case of PRR tolerance, we improved the initial alfalfa populations from sensitive (S, 0–5% resistant plants) to highly resistant (HR, >50% resistant plants) after three cycles of recurrent selection. The same progression was observed with ARR tolerance but to a lesser extent.

Quantitative PCR analysis of Fusarium spp. dynamics in fusarium head blight of oat and barley. M. BANIK, M. BEYENE AND X. WANG. Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada

Fusarium head blight (FHB) is caused by a complex of Fusarium spp. in North America. Fusarium graminearum Schwabe is the predominant species in wheat. Fusarium graminearum produces several toxic secondary metabolites, among which deoxynivalenol (DON) and zearalenone (ZEN) are the most closely monitored due to their high detection rates and strong toxicity. The predominant Fusarium spp. in barley and oat are different than wheat. FHB in barley and oat was initially, primarily associated with F. graminearum, however, Fusarium poae (Peck) Wollenw. has become more frequently isolated in recent years. Fusarium poae can produce a wide range of type A and B trichothecene mycotoxins as well as several non-trichothecene mycotoxins. In comparison to the abundant information that is available for F. graminearum and its mycotoxins, relatively little is known about F. poae and its impacts on the commercial production of oat and barley. We surveyed Fusarium spp. infecting oat and barley in Manitoba in 2016. Samples were collected from 90 commercial fields in Manitoba. Fusarium biomass in contaminated grains was assessed by real time qPCR using primer sets specific to F. poae, F. graminearum and Fusarium sporotrichioides Sherb. The preliminary results indicate that Fusarium spp. infecting oat and barley are, in fact, more diverse than Fusarium spp. infecting wheat and mycotoxins other than DON need to be considered.

Molecular identification of yeast species colonizing grape fruits in Nova Scotia vineyards. T. BARASUBIYE, L. FAN AND C. DOUCETTE. Ottawa Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (L.F., C.D.) Kentville Research and Development Centre, AAFC, 32 Main Street, Kentville, NS B4N 1J5, Canada

The diversity of yeasts involved in wine fermentation can impact the wine parameters such as pH, alcohol level, viscosity, colour, flavour and aroma. The goal of this study was to isolate and identify naturally occurring yeasts associated with vineyards in Nova Scotia. Grape cultivars of ‘L’Acadie’, ‘Riesling’, ‘New York Muscat’, and ‘Pinot Noir’ were sampled at multiple vineyard sites within the Annapolis Valley of Nova Scotia. Two sub-samples of approximately 25 g each of grapes were blended. Serial diluted samples were surface plated on potato dextrose agar supplemented with 0.1 g L⁻¹ of chloramphenicol and incubated at 25°C for 72 h. Yeasts were isolated and then purified on YM agar. The internal transcribed spacer (ITS), the D1/D2 domains of the nuclear 28S rRNA gene and the second largest subunit of RNA polymerase II were sequenced for 60 isolates. Sequencing data have allowed recognition of the 12 following yeast species: Hanseniaspora uvarum (Niehaus) Shehata, Mrak & Phaff; Saccharomyces bayanus Sacc.; Saccharomycopsis crataegensis Kurtzman & Wick.; Pichia kluyveri Bedford; Aureobasidium pullulans (de Bary & Löwenthal) G. Arnaud; Sporidiobolus pararoseus Fell & Tallman; Rhodotorula glutinis (Fresen.) Harrison; Filobasidium magnum (Lodder & Kreger-van Rij) Liu, Bai, Groenew. & Boekhout; Rhodotorula mucilaginosa (Jörg.) Harrison; Bullera alba (Hanna) Derx; Papiliotrema flavescens (Saito) Liu, Bai, Groenew. & Boekhout; and Naganishia diffluens (Zach) Liu, Bai, Groenew. & Boekhout. This study represents the first attempt to determine yeast species colonizing grape fruits in vineyards in Nova Scotia.

A brief history of INIAP and Puccinia striiformis in Ecuador. C. W. BARNES, J. GARÓFALO, D. CAMPAÑA AND J. NOROÑA. Instituto Nacional de Investigaciones Agropecuarias, Estación Experimental Santa Catalina, Programa Cereales, Panamericana Sur Km 1, Sector Cutuglahua, Pichincha, Ecuador

The National Agricultural Research Institute (INIAP–Instituto Nacional de Investigaciones Agropecuarias) was established in 1961 at the public farm previously used by the National Wheat Commission of Ecuador. Its importance in wheat research was recognized by a group of international researchers led by Dr Norman Borlaug, who designated the INIAP Santa Catalina station as the headquarters for High Altitude Wheat Research in 1966. During this time wheat production was at its peak, but has steadily declined since. Puccinia striiformis Westend. on wheat (Pst) and barley (Psh) are the most common diseases in the important cereal growing areas of Ecuador. However, Puccinia triticina Eriks. can be more common in some provinces, and Puccinia graminis Pers.:Pers. can be found on several susceptible lines in various parts of the country. While race identification has not been a common practice, Pst differentials have been sown at the Santa Catalina station most years from 2007 to present. Differential lines with Yr10, Yr15 and Yr17 have been consistently resistant to natural populations, while lines with Yr1, Yr7 and Yr9 have always been susceptible during this time frame. Infection levels on Yr2, Yr3, Yr6, Yr8, Yr24 and Yr27 have been very erratic between years. In 2015, 63 P. striiformis samples on wheat and barley were analysed for race identification. Eighty-two per cent of the identified races have never been reported, resulting in potentially 20 new races of P. striiformis in Ecuador.

Collection and characterization of rust species infecting Berberis in Ecuador. C. W. BARNES, M. E. ORDÓÑEZ AND T. FETCH JR. Instituto Nacional de Investigaciones Agropecuarias, Estación Experimental Santa Catalina, Programa Cereales, Panamericana Sur Km 1, Sector Cutuglahua, Pichincha, Ecuador; (M.E.O.) Pontificia Universidad Católica del Ecuador, Escuela de Ciencias Biológicas, Av. 12 de Octubre 1076 y Roca, Quito, Ecuador; and (T.F., J.R.) Brandon Research and Development Centre, Agriculture and Agri-Food Canada, 2701 Grand Valley Road, P.O. Box 1000A, R.R. #3, Brandon, MB R7A 5Y3, Canada

The genus Berberis is well-known historically as the alternate host of Puccinia graminis Pers.:Pers., and now Puccinia striiformis Westend. There are two centres of diversity of Berberis, one in Asia and one in South America, that arose from a vicariance event in the Cretaceous Period. More than 30 species of Berberis have been reported in Ecuador, mostly endemic, but records are outdated and there is no mention of their role in rust epidemiology. Located between the wheat production areas of North and South America, Berberis spp. in Ecuador may serve as a potential bridge for disease movement and source of new races for both rust fungi. Because many of the Berberis collections found in the Ecuadorian herbariums are dated (some 20 years old or more), we have begun to re-survey the regions where Berberis occurs in Ecuador, collecting plant specimens and (when found) rust aecia. Using the internal transcribed spacer (ITS) region for both the plant and its associated rust, we have sequenced six Berberis and six rust species. Generally, each Berberis spp. has a unique rust pathogen, although one Berberis spp. is host to two rust pathogens, and one rust infects two Berberis spp. Five rust pathogens are species of Edythea, while the sixth is as yet unidentified. In the mountainous regions of Ecuador, geographic isolation seems to be the main factor separating the plant and their fungal pathogens.

Pathogen complex on wasabi in British Columbia and evaluation of disease management options. E. C. BETZ AND Z. K. PUNJA. Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada

Wasabi (Wasabia japonica (Miq.) Matsumura) is a greenhouse crop grown under high humidity conditions, which provide an ideal environment for pathogen development. During a survey of five British Columbia greenhouses conducted in the summer of 2016, a range of disease symptoms were observed, which included powdery mildew, leaf spot, root rot, rhizome rot and petiole blight. Some of the prevalent microbes isolated included Verticillium isaacii Inderb., Bostock, Davis & Subbarao; Leptosphaeria biglobosa Shoemaker & Brun; Pythium intermedium de Bary; Pythium irregulare Buisman; and Fusarium avenaceum (Fr.) Sacc. An assessment of the effects of Trichoderma harzianum Rifai strain T-22 from Rootshield® Plus WP, Streptomyces lydicus De Boer, Dietz, Silver & Savage strain WYEC 108 from Actinovate® SP, and Bacillus subtilis (Ehrenberg) Cohn strain QST 713 from Rhapsody® ASO^TM against pathogen growth was made on Luria Broth, potato dextrose and V8-juice agars. In addition, Cueva® Copper Fungicide and Regalia® Biofungicide were also evaluated. Plates were inoculated with the biocontrol agent and left to incubate 24 h before the addition of the pathogen. Pathogen growth was measured 5 days later and compared with control plates on which no treatment was added. All three biological organisms had inhibitory effects on pathogen growth in culture, with S. lydicus and B. subtilis demonstrating clear pathogen inhibition and T. harzianum outcompeting the pathogens for space on the media. Neither Cueva nor Regalia had a visible inhibitory effect in culture. Assessment of these biocontrol products for disease control on wasabi plants is underway.

Update on Manitoba potato and horticultural crops disease and insect pests in 2016. V. BISHT AND M. PRADHAN. Primary Agriculture Branch, Manitoba Agriculture, P.O. Box 667, 65-3rd Avenue NE, Carman, MB R0G 0J0, Canada; and (M.P.) Crop Diagnostics Centre, 201–545 University Crescent, Winnipeg, MB R3T 5S6, Canada

Conditions in the 2016 crop season allowed for early planting and later harvest, resulting in record productivity in many crops. However, frequent rains during the season (110–150% of normal precipitation in potato and vegetable crops areas) and warm conditions (100–114% of normal) created disease favourable conditions. Late blight (LB) was reported in mid-July, when the LB forecast model used in Manitoba had shown high LB risk. The disease spread to potato and tomato crops throughout Manitoba by end of season, and caused significant losses to tomato crop. All Phytophthora infestans (Mont.) de Bary isolates tested were US#23; later collected isolates showed less sensitivity to metalaxyl than earlier ones. European corn borer (ECB) trapping showed widespread occurrence in the province, but lower numbers compared with 2015. The ECB injury creates ports for bacterial entry, which can increase stem rots in many fields. Blackleg disease (Pectobacterium spp.) was quite widespread due to frequent precipitation. Aphid populations trapped in seed potato fields were low, except one field where surge occurred near end of season. For the first time, potato psyllids (PPs) were trapped in three separate locations; one field showing PPs in three separate weeks. All PPs tested negative for the zebra chip pathogen, Candidatus Liberibacter solanacearum. Root maggot (Delia spp.) damage to rutabaga was significant; and even hybrids (resistant in Ontario) were severely damaged. Blackrot (Xanthomonas campestris (Pammel) Dowson) of cauliflower was severe again in 2016. Though observed at low levels in previous years, the black canker (Itersonilia perplexans Derx) of parsnip caused noticeable losses.

Population dynamics survey of plant-parasitic nematode levels in south-western Ontario tomato fields. T. BLAUEL, M. R. MCDONALD, M. J. CELETTI, C. L. TRUEMAN, J. E. LEBOEUF AND K. S. JORDAN. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; (M.C.) Ontario Ministry of Agriculture, Food and Rural Affairs, 1 Stone Road West, Guelph, ON N1G 4Y2, Canada; (C.L.T.) University of Guelph, Ridgetown Campus, 120 Main Street East, Ridgetown, ON N0P 2C0, Canada; and (J.E.L.) Ontario Ministry of Agriculture, Food, and Rural Affairs, 120 Main Street East, Ridgetown, ON N0P 2C0, Canada

Plant-parasitic nematodes (PPN) are damaging soil-borne pests with a wide host range, including tomatoes. Tomatoes are high value crops in south-western Ontario; however, the extent of PPN populations in Ontario tomato fields is currently unknown. Northern root-knot (Meloidogyne hapla Chitwood) and root-lesion nematodes (Pratylenchus penetrans Cobb) are the most concerning in tomatoes due to their known destructiveness. The objective of this study was to examine the population dynamics of PPN in south-western Ontario tomato fields over different seasons and different growing regions. To determine the population dynamics of PPN, three to five soil samples/field were collected throughout the growing season from 50 tomato fields located in Essex, Chatham-Kent and Norfolk counties over 2016–2017. Root tissue samples were collected once per field in 2016. Nematodes were extracted from soil using the sugar centrifugal flotation method and from roots using the shaker method. All PPN were counted and morphologically identified to genus. In 2016, populations of stunt nematodes significantly increased and lance nematodes significantly decreased; all other nematode populations did not change throughout the season. The fields sampled in Chatham-Kent and Essex County had significantly more total PPN than fields in Norfolk County. Norfolk County tended to have higher populations of root-knot nematode, whereas Chatham-Kent County had higher root-lesion populations. Nematode population levels did not surpass currently available thresholds except in one of the fields surveyed.

Mapping quantitative trait loci for fusarium head blight resistance in Canada Western Red Spring wheat cultivar ‘Carberry’. F. E. BOKORE, S. BERRAIES, R. D. CUTHBERT, R. E. KNOX, M. A. HENRIQUEZ, A. BURT, S. KUMAR, A. N’DIAYE, C. J. POZNIAK, Y. RUAN AND A. G. SHARPE. Swift Current Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), P.O. Box 1030, Swift Current, SK S9H 3X2, Canada; (M.A.H.) Morden Research and Development Centre, AAFC, 101 Route 100, Morden, MB R6M 1Y5, Canada; (A.B., S.K.) Brandon Research and Development Centre, AAFC, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; (A.N., C.J.P.) Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada; and (A.G.S.) National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK S7N 0W9, Canada

Fusarium head blight (FHB) is a major disease of wheat causing losses in grain yield and quality. Growing resistant cultivars is one of the best ways to manage the disease. This research was conducted to identify single nucleotide polymorphism (SNP) markers associated with quantitative trait loci (QTL) controlling FHB resistance in a moderately resistant Canadian spring wheat cultivar, ‘Carberry’. A population of 180 lines from a ‘Carberry’ by ‘Vesper’ cross was phenotyped for FHB incidence and severity at Morden, MB in 2015 and 2016, Bratt’s Lake, SK in 2015 and Brandon, MB in 2016. The lines were genotyped with the 90K iSelect SNP genotyping assay (Illumina Inc., San Diego, CA) and the chromosomal positions of loci and SNP markers associated with FHB resistance were identified with multiple QTL analysis using MapQTL.6®. The distribution of incidence and severity were continuous. Transgressive segregant lines more resistant than Carberry were observed indicating both parents contributed to resistance. ‘Carberry’ contributed the resistance QTL on chromosomes 1A, 3B and 4B for FHB incidence and severity, and ‘Vesper’ contributed the resistance QTL on 2B for FHB incidence and 6B for FHB severity. The QTL on 1A and 3B were detected in all environments, the 4B QTL in two environments and the 2B and 6B QTL each in one environment. The 1A QTL explained phenotypic variation approaching 13% in FHB severity and the 3B QTL up to 22.7%. These findings will help to understand the resistance in ‘Carberry’ and develop markers for marker-assisted selection.

How mineral oil impacts non-persistent Potato virus Y transmission. S. BOQUEL AND X. NIE. Fredericton Research and Development Centre, Agriculture and Agri-Food Canada, 850 Lincoln Road, Fredericton, NB E3B 4Z7, Canada; and (S.B.) SIPRE – Comité Nord, Rue des Champs Potez, 62217 Achicourt, France

Potato virus Y (PVY) is an important concern in Canada. It is transmitted from plant to plant exclusively by aphids in a non-persistent manner and can result in significant economic losses to producers. To date, a weekly application of mineral oil is the only reliable method to reduce the spread of PVY in potato seed production, but its mode of action is still poorly understood. Understanding the mechanism of inhibition of PVY infection by mineral oil is a key component in accurately advising seed potato growers on how to efficiently use mineral oil. Experiments on PVY acquisition by aphids were not able to explain the mode of action of mineral oil. However, a strong reduction of PVY transmission by aphids as well as PVY quantity in leaves was observed under field conditions in plants that were treated with mineral oil compared with untreated plants. These results suggest that the mode of action of mineral oil is mainly linked to the effect on the interaction between PVY and the potato host plant. Therefore, we are actively investigating the impact of mineral oil on the replication and accumulation of the virus within the plant. Results obtained this year suggest that mineral oil reduces the number of plants that become infected. The number of leaves becoming infected is also reduced but the leaves that do become infected have a greater quantity of virus. This suggests that mineral oil is limiting virus colonization within the plant by constraining the virus to a few leaves.

Potential for biological control of potato late blight with Pseudomonas chlororaphis strain 189. S. M. BOYETCHKO, P. AUDY, T. DUMONCEAUX AND C. KIRBY. Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 107 Science Place, Saskatoon, SK S7N 0X2, Canada; (P.A.) Quebec Research and Development Centre, AAFC, 2560 Hochelaga Boulevard, Quebec, QC G1V 2J3, Canada; and (C.K.) Charlottetown Research and Development Centre, AAFC, 440 University Avenue, Charlottetown PE C1A 4N6, Canada

Late blight caused by Phytophthora infestans (Mont.) de Bary is a highly aggressive disease of potato (Solanum tuberosum L.). Management of late blight currently requires repeated application of synthetic fungicides each growing season. Pseudomonas chlororaphis strain 189 effectively reduces disease caused by several genotypes of P. infestans, including one of the most common genotypes presently in Canada, US-23. Tests were conducted to assess the effect of spray application of P. chlororaphis strain 189 onto potato plants infected with selected genotypes (US-23, US-8 and CA-09) of P. infestans. Spray application of the biopesticide occurred: (i) 2 days before inoculation with the pathogen; (ii) same day as pathogen; or (iii) 4 days + 6 days after inoculation. Disease severity was based on per cent diseased tissue using a 0–10 rating scale. Spraying before inoculation with the pathogen did not significantly reduce disease severity. The disease severity reached 91%, and was not significantly different from the potato inoculated with only the pathogen. One spray application was required to control all three genotypes. US-8 was more aggressive than US-23 and CA-09, and required a second spray application to provide further disease reduction. The efficacy of P. chlororaphis strain 189 was also compared with three commercial biopesticides (Serenade®, Rhapsody® and Actinovate®) and mancozeb synthetic fungicide. Strain 189 provided similar efficacy to mancozeb (i.e. at least 90% disease control) but the commercial biopesticides did not reduce disease, which reached almost 100% disease severity. Pseudomonas chlororaphis is considered a potential candidate for management of potato late blight.

Development of southern stem canker disease on soybean seedlings in the greenhouse using a modified toothpick inoculation assay. M. A. CAMPBELL, Z. LI AND J. W. BUCK. Institute of Plant Breeding, Genetics, and Genomics/Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30 602, USA; and (J.W.B.) Department of Plant Pathology, University of Georgia, Griffin, GA 30 223, USA

Southern soybean stem canker caused by Diaporthe aspalathi van Rensburg et al. has caused major soybean losses for growers in the south-east USA. The most effective disease management tool for growers is the use of stem canker resistant soybean varieties. A fast, reliable greenhouse assay for stem canker would help develop resistant soybean varieties. An existing toothpick assay was modified to include culturing D. aspalathi on oxgall agar on toothpicks pre-soaked in oxgall liquid medium. Inoculation was performed on 3-week-old seedlings between cotyledons and the first trifoliate leaf, inoculation sites were sealed with petroleum jelly, and seedlings were incubated in humidity chambers for 72 h. Stem canker disease was highly consistent on susceptible lines 4 weeks post-inoculation and was not observed on soybean lines with known stem canker resistance genes (Rdm). High levels of disease (≥98.3%) were observed with cultivars ‘Braxton’, ‘Davis’ and ‘Centennial’ thought to have resistance in field studies. Isolates of D. aspalathi were observed to differ in virulence. This modified greenhouse assay will assist in the efforts for breeding stem canker resistance and better understanding the differences in disease phenotypes for some cultivars.

Elucidation of canola disease resistance pathway against blackleg through characterization of Arabidopsis thaliana mutants. R. M. CELOY, C. YANG AND W. G. D. FERNANDO. Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

Blackleg is an important fungal disease in oilseed rape (canola, Brassica napus L.) caused by Leptosphaeria maculans (Desmaz.) Ces. & De Not. This plant disease causes serious stem canker resulting in substantial yield loss to canola farmers worldwide. The importance of canola ensued to a collaborative global research network in decoding the genetic resistance against the blackleg disease. Results of various studies proposed the involvement of receptors and phytohormone signalling in canola–blackleg pathosystem. In this study, it is our aim to elucidate the canola–blackleg interaction through the characterization of Arabidopsis thaliana mutants against blackleg by studying receptors and phytohormone signalling. Time-course experiments were performed onto A. thaliana wild-type and apoplastic-related mutant plants (suppressor of BIR1 1(sobir1), non race-specific disease resistance 1 (ndr1), required for MLA12 resistance 1/non race-specific disease resistance 1 (rar1ndr1), peroxidase 34 (prx34), antisense French bean oxidative burst peroxidase 1.1 (asFBP1.1), respiratory burst oxidase homologue F (rbohF), respiratory burst oxidase homologue D (rbohD)) that were inoculated with L. maculans isolate #41–2 (carrying AvrLm2, AvrLm4, AvrLm6, AvrLm7 and AvrLmS). Accumulations of super oxide and hydrogen peroxide, lesion sizes and stem canker were assessed. Phenotyping results indicate that the receptors SOBIR1 and NDR1, and the reactive oxygen species (ROS) producers PRX33, PRX34, RBOHD and RBOHF are potentially involved in the apoplastic response against blackleg. Likewise, stem lesions were observed on sobir1, ndr1, asFBP1.1 and rbohD mutant plants wherewith severe lesion is shown by the latter. Transcriptome and metabolic analyses are currently being processed on the above-mentioned experiments.

Host range of Phytophthora sansomeana and the impact of inoculum density on disease severity, seedling emergence and biomass of field pea. K. F. CHANG, S. F. HWANG, H. U. AHMED, H. FU, Q. ZHOU, R. L. CONNER, D. L. MCLAREN, S. E. STRELKOV AND G. D. TURNBULL. Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada; (R.L.C.) Morden Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 101 Route 100, Morden, MB R6M 1Y5, Canada; (D.L.M.) Brandon Research and Development Centre, AAFC, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; and (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada

Root rot is a common disease of pea (Pisum sativum L.) in most regions where the crop is grown. In western Canada, several soil-borne pathogens including Fusarium and Pythium spp., Rhizoctonia solani Kühn and Aphanomyces euteiches Drechs. are associated with root rot of field pea. Recently, Phytophthora sansomeana Hansen & Reeser was identified for the first time as the cause of root rot of field pea in Alberta. To understand its ecology and potential impact on crop production systems, the host range of the fungus was investigated and the relationships between inoculum density and root rot severity, seedling emergence and biomass in pea were evaluated. Eight crops including canola, faba bean, lupin, lentil, pea, soybean, barley and wheat were inoculated with P. sansomeana. The fungus was pathogenic on all of the crops and reduced seedling emergence, plant height and plant biomass compared with non-inoculated control treatments. Analysis of variance showed significant effects of inoculum density on seedling emergence, root biomass and disease severity. Regression analysis showed a strong positive relationship between inoculum density and disease severity, and a strong negative relationship between inoculum density, root weight and seedling emergence. The ability of P. sansomeana to infect a wide range of crops will make it a challenging pathogen to manage via the use of cultural practices.

Evaluation of field-based solutions to mitigate root rot of field pea. S. CHATTERTON, R. S. ERICKSON, R. BOWNESS, B. D. GOSSEN AND M. W. HARDING. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 5403–1 Avenue South, Lethbridge, AB T1J 4B1, Canada; (R.B.) Lacombe Research Centre, Alberta Agriculture and Forestry, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada; (B.D.G.) Saskatoon Research and Development Centre, AAFC, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; and (M.W.H.) Crop Diversification Centre South, Alberta Agriculture and Forestry, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada

Aphanomyces root rot, caused by Aphanomyces euteiches Drechs., was first detected in pea (Pisum sativum L.) fields in Saskatchewan and Alberta in 2012 and 2013, respectively, and has caused significant crop loss in both provinces. Currently, extending the cropping interval between susceptible crops and avoiding infested fields are the only root rot management recommendations. To evaluate potential in-season management options, field trials were conducted in eight locations over 2 years to determine the effect of (a) cultivar tolerances; (b) seed treatments; (c) soil amendments with calcium, Edge or Treflan; and (d) foliar-applied chemical (Phostrol). Trial sites were chosen based on natural inoculum of A. euteiches, Fusarium spp. or both. Emergence, root rot incidence and severity, shoot health and yield were recorded. The experimental design was randomized, complete block with four to six replicates and data were analysed using SAS (PROC Mixed). All cultivars were equally and highly susceptible to root rot. Some seed treatment products provided early season suppression of root rots, but did not result in significant yield differences. None of the chemical products tested reduced root rot or significantly improved yields. Although none of the products tested improved yields, average yields across all treatments varied from 0 to >4000 kg ha⁻¹ at different locations, indicating the variability and difficulty in assessing the impact of root rots on pea yields. Future trials are planned to evaluate the effect of stacking multiple products, as well as varying product rates and application timing, on root rot and pea yield.

Predicting risk of pea root rot using molecular techniques to quantify inoculum of Aphanomyces euteiches in soil. S. CHATTERTON, A. ERICKSON, R. BOWNESS, M. W. HARDING, B. GOSSEN, D. L. MCLAREN AND S. BANNIZA. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 5403–1 Avenue South, Lethbridge, AB T1J 4B1, Canada; (R.B.) Lacombe Research Centre, Alberta Agriculture and Forestry, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada; (M.W.H.) Crop Diversification Centre South, Alberta Agriculture and Forestry, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada; (B.D.G.) Saskatoon Research and Development Centre, AAFC, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; (D.L.M.) Brandon Research and Development Centre, AAFC, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; and (S.B.) Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

Root rot of field pea causes severe yield losses across the Canadian prairies, where 1.5 million hectares of peas are grown annually. Recent surveys in Alberta, Saskatchewan and Manitoba revealed that 40–60% of fields were positive for Aphanomyces euteiches Drechs., while 80–90% were also infested with Fusarium spp. Pathogenicity tests indicated that while A. euteiches was the most damaging, Fusarium avenaceum (Fr.) Sacc. and Fusarium solani (Mart.) Sacc. were also highly pathogenic to pea. To assess risk of aphanomyces root rot prior to planting peas, the relationship of oospore concentrations of A. euteiches to DNA quantification and disease severity was first determined in greenhouse trials. At the same time, inoculum potential of field soils was evaluated using greenhouse bioassays, quantitative PCR and digital droplet PCR. The inoculum potential was then compared with the observed root rot severity in pea crops grown in the corresponding fields. Although there was a linear relationship between oospore concentration, disease severity and DNA quantification, the limit of detection of oospores from soil was too high (100 oospores g⁻¹ soil) to accurately quantify oospores in field soils at damaging levels. As a result, greenhouse bioassays were the most accurate predictor of field disease levels. The number of false negative field soil samples was high (>50%) using real-time quantitative PCR, but was slightly improved using digital droplet PCR. To improve accuracy of molecular quantification, a process to concentrate oospores from soil prior to DNA extraction is under development. Droplet digital PCR techniques are also being refined for simultaneous quantification of A. euteiches, F. avenaceum and F. solani for prediction of the inoculum potential of the pea root rot complex.

Genotypic variations in root plasma membrane lipidome of silage corn grown under cool climatic production systems. M. CHEEMA, M. NADEEM, H. PHAM, R. THOMAS, L. GALAGEDARA AND V. KAVANAGH. School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland, 20 University Drive, Corner Brook, NL A2H 5G4, Canada; (M.N.) Department of Environmental Sciences, COMSATS Institute of Information Technology, Vehari 61100, Pakistan; and (V.K.) Department of Fisheries and Land Resources, P.O. Box 340, Pasadena, NL A0L 1K0, Canada

Root membrane lipids play major roles in plant signalling, growth, development and adaptation to varying climatic conditions. The present study was conducted to determine genotypic variation in silage corn root membrane lipid profiling, and its potential impact on agronomic traits. To our best knowledge, this is the first study reporting genotypic variations in root lipidome in silage corn genotypes in a cool climate production system. A field research trial was conducted at Pynn’s Brook Research Station Pasadena, Newfoundland, Canada. Five silage corn genotypes (Fusion-RR, Yukon-R, A4177G3-RIB, DKC23–17RIB, DKC26-28RIB) were seeded in a completely randomized design with four replications per treatment. Root samples were randomly collected from each treatment before final harvest and lipid profile was assessed using ultra high performance liquid chromatography coupled to a high resolution Orbitrap mass spectrometer. Three lipid classes were noted in silage corn roots profile that included phospholipids (PA, PC, PE, PG, PI, LPA, LPC, LPE), glycolipids (DGDG) and sphingolipids (HexCer). Phospholipids was found to be a major lipid class (74 nmol%), irrespective of genotypes. Phosphatidic acid (PA) was the principal phospholipid class (~45 nmole%), and was highly correlated with superior agronomic performance (leaf area, plant height and biomass production). It can be concluded that PA is an emerging secondary signalling lipid under cold stress and higher PA in root lipidome could be used as a potential indicator or biomarker in selecting superior silage corn genotypes with enhanced adaptation in cool climatic conditions.

AeroNet: spore samplers in collecting fungal plant pathogens in the air and rain. W. CHEN, S. HAMBLETON, K. A. SEIFERT, C. A. LÉVESQUE, O. CARISSE, M. S. DIARRA, R. D. PETERS, C. LOWE AND J. T. CHAPADOS. Ottawa Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (O.C.) Saint-Jean-sur-Richelieu Research and Development Centre, AAFC, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada; (M.S.D.) Guelph Research and Development Centre, AAFC, 93 Stone Road West, Guelph, ON N1G 5C9, Canada; and (R.D.P.) Charlottetown Research and Development Centre, AAFC, 440 University Avenue, Charlottetown, PE C1A 4N6, Canada

Spore samplers are widely used in pathogen surveillance but not so much for monitoring the composition of aeromycobiota. The composition of fungal community from air and rain samples collected using three different spore samplers in the summers of 2010 and 2011 was exhaustively characterized based on the Internal Transcribed Spacer (ITS) metabarcodes generated by High-Throughput Sequencing (HTS). Diverse spatial and temporal distribution patterns in the aeromycobiota were observed at the Canadian west and east coasts. The aeromycobiota diversity was found to be higher during the cooler, wetter summer and showed a positive correlation with the speed and northward direction of the wind. The relative abundance and/or richness of some fungal taxa were significantly different based on ITS1 or ITS2 sequencing data; e.g. those of Epicoccum and Ganoderma spp. were significantly higher in ITS1, but those of Botrytis and Fusarium spp. were significantly higher in ITS2. In addition, significant differences were observed between samplers for their ability to collect pathogenic plant fungi. For instance, Cladosporium spp., Drechslera spp. and Entyloma spp. were mainly collected with the air samplers; while Fusarium spp., Microdochium spp. and Ustilago spp. were recovered more frequently with the rain samplers. The usefulness and collection preference of spore samplers in recovering fungal pathogens in air and rain were addressed to provide guidelines in selecting optimal samplers for taxa of concerns. AeroNet, a nationwide spore sampling network, combined with HTS and well-designed sampling strategies, may contribute significantly to the national biovigilance network for protecting plants of agricultural and economic importance in Canada.

Identification, characterization and mapping of the seedling wheat leaf rust resistance gene in RL6071. M. Z. CHE, B. D. MCCALLUM, M. BOYCE, C. A. MCCARTNEY AND C. W. HIEBERT. Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada; (M.Z.C.) Department of Plant Pathology, China Agricultural University, Beijing, 100193, People’s Republic of China; and (M.B.) Global Edible Oil Solutions – Specialties, Cargill Ltd. Canada, 701 Central Avenue, Aberdeen, SK S0K 0A0, Canada

The emergence of a new predominant race of leaf rust, TDBG, in the 2004 Canadian virulence survey led to the identification of a second leaf rust resistance gene in the Thatcher-Lr1 near-isogenic differential line, RL6003, in addition to Lr1. This gene, temporarily named LrCen, produced an unusual mesothetic infection type and was mapped on 7AL. A gene with a very similar infection type was found in the stem and leaf rust susceptible line RL6071 (Prelude/8*Marquis*2/3/Prelude//Prelude/8*Marquis). Using 116 KU168-2/RL6071 double haploid lines we mapped this gene in RL6071 (temporarily named LrMar because of the genetic similarity of RL6071 with Marquis) on 7BL, between markers barc182 and barc50, with linkage distances of 1.8 and 0.9cM, respectively. As Lr14a/Lr14b, LrBi16 and LrFun were also mapped on 7BL, these four genes were compared by SSR markers close to each gene, and differential reaction to 16–45-3 TSBS. Results suggested that LrMar was a different gene from Lr14a, LrBi16 or LrFun. To explore the relationship among LrMar, LrCen and Lr20 since they shared a similar infection type, we tested cfa2240 (close to LrCen on 7AL) and barc182 and barc50 (close to LrMar on 7BL) on lines with each gene. These markers would indicate which lines are likely to carry LrMar or LrCen. Forty-five selected Canadian wheat cultivars were tested with barc182 and cfa2240, eight lines were positive for the allele size indicative of LrMar and eight lines were positive for LrCen, which suggested that the two genes were distributed at a low frequency throughout Canadian germplasm. A number of Canadian wheat lines had a mesothetic response to TDBG, but were not positive for the alleles of either barc182 or cfa2240 associated with resistance. The TDBG resistance in the Tc-Lr20 NIL segregated independently of cfa2240 so was not LrCen, and also segregated independent of a molecular marker for Lr20; this resistance could be due to LrMar or a similar type of gene.

The Ustilago maydis transcription factor Zfp1 regulates the expression of effectors required for full pathogenesis, virulence and anthocyanin production. H. Y. K. CHEUNG, M. E. DONALDSON, K. L. SPENCE, J. L. O. FETSCH, M. C. HARRISON AND B. J. SAVILLE. Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; (K.L.S.) Department of Population Medicine, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; and (M.E.D., B.J.S., J.L.O.F., M.C.H.) Forensic Science Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada

As a biotrophic plant pathogen, Ustilago maydis (DC.) Corda secretes effectors to establish and maintain a relationship with the host, Zea mays. One such effector, tin2, induces host anthocyanin production to facilitate fungal penetration of host cells. The molecular functions of tin2, and other effectors, have been characterized, but there is limited knowledge of how effector gene expression is controlled. We identified a U. maydis transcription factor, Zfp1 that, when deleted, altered transcript levels of 1870 genes, several encoding predicted or confirmed effectors. Notably, 83 predicted effectors, including tin2, were found to be down-regulated. The reduced pathogenesis and arrested virulence exhibited by infection with zfp1 deletion (∆zfp1) strains is consistent with this altered expression of effector genes. Conspicuously ∆zfp1 infected seedlings produced little to no anthocyanin, and hyphal growth of ∆zfp1strains was localized to the epidermis with attenuated hyphal branching, which are consistent with deregulation of tin2. When a zfp1 deletion strain was complemented using wild-type zfp1, tin2 transcript levels were restored to near wild-type levels, and pathogenesis and virulence were partially restored. The partial complementation suggests Zfp1 may have a binding partner or interact with other factors to regulate pathogenesis and virulence. Complementation of the zfp1 deletion strain with wild-type tin2 partially restored pathogenesis and virulence and fully reestablished anthocyanin production, indicating that some ∆zfp1 phenotypes result from altered tin2 regulation. It also indicates that Tin2 acts downstream of Zfp1. We conclude that Zfp1 contributes to U. maydis pathogenesis, virulence and anthocyanin production by regulating effector gene expression.

Management of metalaxyl-m-resistant strains of the potato pink rot pathogen Phytophthora erythroseptica in field and storage. B. CRANE, R. D. PETERS, L. M. KAWCHUK, L. HALE, A. FOSTER, C. LACROIX, A. MILLS, K. A. DRAKE, D. GREGORY, I. MACDONALD, K. MACDONALD, A. MACPHAIL AND M. M. CLARK. Charlottetown Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 440 University Drive, Charlottetown, PE C1A 4N6, Canada; (L.M.K.) Lethbridge Research and Development Centre, AAFC, 5403–1 Avenue South, Lethbridge, AB T1J 4B1, Canada; (L.H., C.L.) University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3, Canada; and (M.M.C.) Government of Prince Edward Island, Charlottetown, PE C1A 7N3, Canada

Phytophthora erythroseptica Pethybr. is the causal agent of pink rot of potato which results in a wet rot and complete tuber breakdown causing significant yield losses under field and storage conditions. Traditionally, the pathogen has been managed with metalaxyl-m based products (Ridomil Gold®), however, in recent years, metalaxyl-m-resistant isolates have been recovered in the USA and Atlantic Canada, signifying a need for alternative management strategies. A national survey was established to determine the distribution of metalaxyl-m-resistant strains in Canada and trials were conducted to assess the efficacy of alternative fungicides to inhibit infection under field and storage conditions. The national survey revealed a high proportion of metalaxyl-m-resistant isolates in pathogen populations from the Maritime Provinces and recovered metalaxyl-m-resistant strains for the first time from Ontario, Manitoba and Alberta. Inoculated field and storage trials evaluated the efficacy of treatments of Phostrol™, Orondis®, Presidio® and Serenade SOIL® to inhibit pink rot. In-furrow applications of Orondis® or Presidio®, or foliar applications of Phostrol™ provided significant suppression of pink rot relative to inoculated controls. Applications of Orondis®, Presidio® or Phostrol™ to daughter tubers 1 h after inoculation also provided significant suppression of pink rot under storage conditions. These results suggest that there are promising new potential management strategies to control metalaxyl-m-resistant strains of P. erythroseptica which are increasing in frequency across Canada. Continued surveys to track metalaxyl-m resistance and the on-going development of new control strategies will aid producers with pink rot management and help mitigate fungicide resistance development in P. erythroseptica.

Possible roles for a cytochrome p450 and ABC transporter in deoxynivalenol tolerance in the biocontrol agent Clonostachys rosea strain ACM941. Z. DEMISSIE AND M. C. LOEWEN. Aquatic and Crop Resources Development Portfolio, National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada

Clonostachys rosea strain ACM941 is a fungal bio-control agent developed and patented in Canada against the fusarium head blight disease causative agent Fusarium graminearum Schwabe. Although the molecular and biochemical basis of its tolerance are yet to be resolved, one peculiar feature of C. rosea is its ability to tolerate high levels of the Fusarium mycotoxin deoxynivalenol (DON). Based on available EST databases arising from mycotoxin treated C. rosea strain IK726, a cytochrome p450 and two ABC-transporter homologues (abcg5 and abcg29) identified as potential targets of interest in C. rosea strain ACM941. The transcriptional activities of the abcg29 were not significantly affected by treatments with either DON or spent F. graminearum growth media. In contrast, the Fg3639 spent media did result in up-regulation of abcg5, and the cytochrome p450 homologue was transcriptionally up-regulated by both DON and Fg3639 growth media. Furthermore, yeast cells transformed with the p450 showed improved growth characteristics compared with control yeast in the presence of DON. Together these data imply potential roles in DON tolerance for the cytochrome p450 and the abcg5 homologues. We are in the process of testing the abcg5 in a recombinant yeast system and determining the reaction catalysed by the CYP450 toward understanding their roles in C. rosea’s antagonistic property against Fg3639.

Sclerotinia sclerotiorum disease severity on canola is influenced by the developmental age of the host’s primary raceme. M. DENTON-GILES, M. C. DERBYSHIRE, Y. KHENTRY AND L. G. KAMPHUIS. Centre for Crop and Disease Management, Curtin University, 210 Kent Street, Bentley, Western Australia, 6102, Australia

Sclerotinia sclerotiorum (Lib.) de Bary is an economically important fungal pathogen of canola (Brassica napus L.). Significant yield loss occurs in canola following the establishment of S. sclerotiorum on the primary raceme. Observations made during routine stem infection assays led us to test the hypothesis that the virulence of S. sclerotiorum on canola is enhanced on mature racemes. We conducted a time of sowing (TOS) experiment by sowing seed of cultivar ‘Charlton’ at 7-day intervals over a 3-week period. Plants were propagated in a temperature controlled glasshouse under natural light, with a controlled watering schedule. The developmental stage of each raceme was documented, by measuring primary raceme height (mm) every 7 days. Eighteen, 17, 16 and 15-week-old racemes (WOR) were collectively inoculated with S. sclerotiorum using 5 mm agar plugs. Weekly lesion length measurements (mm) were conducted for 28 days. Lesions that developed on mature racemes (18 WOR) were significantly larger than lesions on the most immature racemes (15 WOR) (Tukey’s HSD P < 0.05). Following natural raceme desiccation, total sclerotia were extracted and weighed. Mature racemes (18 WOR) developed 16-fold more sclerotia than younger racemes (P < 0.001). Together these data suggest that older, mature racemes are more easily infected by S. sclerotiorum, resulting in a greater mass of sclerotial development. We hypothesize that changes in the source-sink relationship within the plant may contribute to the differences observed.

Control of microRNA homeostasis and the establishment of effector-triggered immunity in Arabidopsis thaliana. M. B. D. DIAM, T. ABD EL RAHMAN AND K. BOUARAB. Centre SÈVE, Department of Biology, University of Sherbrooke, 2500 boulevard de l’Universite, Sherbrooke, QC J1K 2R1, Canada

Plants have developed an effective immune system that is triggered when they recognize effectors secreted by pathogens; this defence pathway is called effector-triggered immunity (ETI). The resistance protein RPS5 senses the bacterial Type-III effector AvrPphB to activate ETI. Small RNAs, including microRNAs, play important roles in numerous aspects of eukaryotes development and host-microbe interactions. MicroRNAs turnover was shown to be properly controlled by Small RNA-Degrading Nucleases (SDNs) to ensure normal development; the possibility that this turnover plays crucial roles in plant immunity remains unknown. Here, we showed that SDNs are required for ETI induced by AvrPphB in Arabidopsis thaliana. We also showed that SDNs are important for AvrPphB-triggered resistance in A. thaliana against Pseudomonas syringae pv. tomato (Okabe) Young et al. DC3000 expressing the effector AvrPphB. These data highlight the importance of microRNAs turnover as a critical step in the establishment of plant immunity.

Molecular characterization of Fusarium resistance from Elymus repens introgressed into bread wheat. G. FEDAK, W. CAO, D. WOLFE, D. CHI AND A. XUE. Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

A cross was made of Elymus repens into wheat cultivar ‘Crocus’ and BC progeny were advanced to BC1 F7 by single seed descent. Sixteen lines were selected based on agronomic performance and evaluated in a fusarium head blight (FHB) epiphytotic nursery. Eight lines with resistance to FHB were selected. GISH analysis revealed many complex chromosome numbers and recombination in the derived lines. The least complex recombinant line was P1142-3-1 with 42 chromosomes with one pair of chromosomes showing telomeric recombinants on both arms. This wheat chromosome was identified as 3D by applying several SSR markers from every arm of every wheat linkage group and noting those that provided no signal. Lines with single telomeric recombinants were produced by additional backcrosses to ‘Crocus’ and inoculated with FHB spores. It was found that the resistance was contributed by the recombinant on the long arm of chromosome 3D. These lines have minimal linkage drag and should be amenable to applications in breeding for disease resistance.

Plant diagnostic research conducted by the Alberta Plant Health Lab. J. FENG, K. ZUZAK, Y. YANG, D. RENNIE, K. ZAHR AND D. FEINDEL. Alberta Plant Health Lab, Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada

To provide authoritative, commercially unavailable plant diagnostic services in Alberta, Alberta Agriculture and Forestry established the Alberta Plant Health Lab (APHL) at the Crop Diversification Centre North, Edmonton, Alberta. The lab became fully functional in 2016 and currently conducts diagnostic analyses of all plant diseases encountered across the province. Currently, all services provided by the APHL are free of charge. Besides diagnostic testing, the APHL also provides a DNA barcoding service on weeds, insects and microbes including fungi, oomycetes and bacteria. Diagnostics-related research has been extensively conducted in the APHL, including (1) descriptions of plant pests new to Alberta or Canada, (2) optimization of diagnostic techniques such as sample preparation and DNA extraction, (3) standardization of existing and new PCR-based diagnostic protocols, (4) development of genetic markers and PCR primers for diagnosis of important or potentially important plant diseases such as clubroot (Plasmodiophora brassicae Woronin) and verticillium wilt (Verticillium longisporum (Stark) Karapapa, Bainbr. & Heale) of canola, (5) identification of fungal pathogenicity-related genes that can be used for diagnosis and (6) investigation of molecular mechanisms of new virulence generation in populations of plant pathogens such as Plasmodiophora brassicae Woronin (clubroot) and Leptosphaeria maculans (Desmaz.) Ces. & De Not. (blackleg) on canola.

A 6-year study reveals the dynamics of avirulence allele profiles, blackleg incidence and mating type alleles of Leptosphaeria maculans populations in canola in Manitoba, Canada. W. G. D. FERNANDO, X. ZHANG, C. SELIN, Z. ZOU, P. S. PARKS, M. H. RASHID, K. RASANIE, E. PADMATHILAKE, L. RONG, C. YANG, S. H. LIBAN, B. N. GNANESH, S. HUANG, D. L. MCLAREN AND A. KUBINEC. Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; (D.L.M.) Brandon Research and Development Centre, Agriculture and Agri-Food Canada, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; and (A.K.) Crops Branch–Industry Development, Manitoba Agriculture, Carman, MB R0G 0J0, Canada

Blackleg, caused by Leptosphaeria maculans (Desmaz.) Ces. & De Not., is the most serious disease of canola (Brassica napus L., oilseed rape) worldwide. Although the disease was well controlled through resistance, in recent years blackleg has emerged as a threat to canola cultivation in Canada. This is mainly due to selection pressure exerted on the pathogen population with tight rotations with canola leading to the breakdown of resistance. This study evaluated blackleg incidence, the avirulence allele, and mating type distributions of L. maculans isolates collected from grower fields in Manitoba, Canada from 2010 to 2015. A total of 964 L. maculans isolates was collected for analysis and the presence of 12 avirulence alleles were identified using differential canola cultivar cotyledon inoculations assays (pathogenicity) and/or PCR assays specific for each allele. AvrLm2, AvrLm4, AvrLm5, AvrLm6, AvrLm7, AvrLm11 and AvrLmS were detected at frequencies ranging from 97% to 33%, where the AvrLm1, AvrLm3, AvrLm9, AvrLepR1 and AvrLepR2 alleles were the least abundant. When the race structure was examined, a total of 170 races were identified from the 964 isolates, with three major races, AvrLm-2–4-5–6-7–11, AvrLm-2–4-5–6-7–11-S and Avr-1–4-5–6-7–11-(S) accounting for 15%, 10% and 6% of the total fungal population respectively. The distribution of the mating type alleles (MAT1-1 and MAT1-2) indicated that sexual reproduction was not inhibited in any of the nine Manitoba regions in any of the years L. maculans isolates were collected. The information derived is helpful in mitigating resistance breakdown, for disease resistance breeding and in implementing innovative methods of blackleg management such as R-gene rotations.

Collection and characterization of species of Berberis in Argentina, Brazil, Chile, Ecuador and Uruguay. T. FETCH, S. HAMBLETON, M. S. CHAVES, J. MARTINELLI, G. B. P. DA SILVA, S. BORDIGNON, P. CAMPOS, R. MADARIAGA, C. W. BARNES, M. E. ORDÓÑEZ, G. AZZIMONTI AND S. GERMAN. Brandon Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; (S.H.) Ottawa Research and Development Centre, AAFC, 960 Carling Avenue, ON K1A 0C6, Canada; (M.S.C.) Centre for Temperate Climate Agricultural Research, Brazilian Agricultural Research Centre, Pelotas, RS, Brazil; (J.M., G.B.P.D.S., S.B.) Universidade Federal Rio Grande du Sul, Porto Alegre, RS Brazil; (P.C.) Instituto Nacional de Tecnologia Agropecuaria, Bordenave, Argentina; (R.M.) Instituto Nacional de Investigaciones Agropecuarias, National Institute of Agricultural Research, Quilamapu, Chile; (C.W.B.) Instituto Nacional de Investigaciones Agropecuarias, Estación Experimental Santa Catalina, Programa Cereales, Panamericana Sur Km 1, Sector Cutuglahua, Pichincha, Ecuador; (M.E.O.) Pontificia Universidad Católica del Ecuador, Escuela de Ciencias Biológicas, Av. 12 de Octubre 1076 y Roca, Quito, Ecuador; and (G.A., S.G.) Instituto Nacional de Investigaciones Agropecuarias, La Estenzuala, Uruguay

South America is one of two centres of diversity for the genus Berberis. As the alternate host for both Puccinia graminis Pers.:Pers. and Puccinia striiformis Westend., Berberis spp. are important in increasing the virulence diversity of races of these rust fungi. However, little is known about the susceptibility of South American Berberis to these cereal rust species. To investigate the role of Berberis in cereal rust diversity, we surveyed Argentina, Brazil, Chile, Ecuador and Uruguay in 2016 for Berberis spp. and aecial infection. While no aecial infection was found in Uruguay, rust aecia on Berberis were found in all other countries. Based on sequence analysis, diversity of Berberis forms two distinct phylogenetic groups, with Berberis from Argentina and Brazil differing from those in Ecuador. Analyses of Berberis samples from Chile and Uruguay are in progress, and we hypothesize that they will likely be related to countries from the Southern Cone. Preliminary analyses of rust aecial samples also indicate distinct grouping by region. However this may be an artifact of the small sample size. As this study continues over the next 2 years we may find some rust fungal species that are more widely dispersed and with wider host ranges.

Field management practices have an effect on disease development in barley in Prince Edward Island. A. F. FOSTER, R. MATTERS AND R. A. MARTIN. Charlottetown Research and Development Centre, Agriculture and Agri-Food Canada, 440 University Avenue, Charlottetown, PE C1A 4N6, Canada

There are many challenges to growing barley in Atlantic Canada. Wet and cool weather in summer contributes to high pressure from a number of economically important diseases such as fusarium head blight (Gibberella zeae (Schwein.) Petch, anamorph: Fusarium graminearum Schwabe), powdery mildew (Blumeria graminis f. sp. hordei (DC.) Speer), scald (Rhynchosporium secalis (Oudem) Davis) and netblotch (Pyrenophora teres Drechs.). Trials were run from 2014–16 at the Harrington Research Farm, Prince Edward Island (PEI) to test different parameters of disease management. Factors tested were foliar fungicide application timing, the timing of planting and the source of seed of different barley cultivars. Application of different registered foliar fungicides showed consistent responses on the different cultivars bred for eastern and western Canadian environments, but the fungicides did produce a variety of responses for disease control and yield. Spray timing and planting timing also had significant influence over agronomic responses. Late planting during 3rd week of May resulted in significantly higher yield than early planting (1st week of May), but negligible differences in disease severity were observed. Western cultivars showed differences in disease and agronomic properties when grown from seed produced in Alberta compared with seed grown in PEI. Plants grown from seeds of western cultivars produced in PEI had significantly less netblotch than plants grown from seeds produced in western Canada, but yield was significantly higher in plants from western-produced seed. These results provide information to improve disease management practices for producers in Atlantic Canada.

Root lesion nematode (Pratylenchus penetrans) mitigation through application of chitin and Ascophyllum nodosum extract in the soil prior to seeding red clover (Trifolium pratense) and birdsfoot trefoil (Lotus corniculatus). Z. L. FRASER, Y. A. PAPADOPOULOS, Z. DONG, J. DUYNISVELD, C. E. GALLANT, T. FORGE, B. LEES AND S. A. E. FILLMORE. Saint Mary’s University, 923 Robie Street, Halifax, NS B3H 3C3, Canada; (Y.A.P., B.L., S.A.E.F.) Kentville Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 32 Main Street, Kentville, NS B4N 1J5, Canada; (J.D.) Kentville Research and Development Centre, Nappan Research Farm, AAFC, Nappan, NS B0L 1C0, Canada; (C.E.G.) Cherry Valley, PE C0A 2E0, Canada; and (T.F.) Summerland Research and Development Centre, AAFC, 4200 Highway 97 South, Summerland, BC V0H 1Z0, Canada

Traditional mitigation strategies for root lesion nematodes (RLN) are typically ineffective and include application of nematicides and crop rotation. This research assessed the effect of a soil drench with chitin or Ascophyllum nodosum extract (ANE) on RLN infection and also compared levels of RLN infection among cultivars of birdsfoot trefoil (Lotus corniculatus) and red clover (Trifolium pratense). Two experimental cultivars of red clover were used, ‘TRC12-156' selected for high isoflavones and ‘TRC12-157' selected for low isoflavones, along with two commercially available birdsfoot trefoil cultivars, ‘AC Langille’ and ‘Leo’. Legumes were seeded into nematode-infested soil with a population of 19 RLN g⁻¹ dry soil and treated by soil drench with 3000 ppm ANE, 350 ppm chitin or water, and grown in a growth chamber. After 19 weeks, nematodes were extracted from roots using the modified Baermann funnel method. Following, 7-day incubation nematode suspensions were examined and roots were dried and weighed. The ANE and chitin treatments both resulted in significantly smaller numbers of RLN g⁻¹ dry root than the water control; ANE had the lowest RLN populations at 5185 RLN g⁻¹ dry root, a 30% reduction relative to water (7424 RLN g⁻¹). Red clover cultivars (3877 RLN g⁻¹) had lower concentrations of RLN than birdsfoot trefoil cultivars (11 276 RLN g⁻¹) in both treated and untreated soil. One cultivar of red clover, ‘TRC12-156', had particularly low RLN populations with 2088 RLN g⁻¹; a 63% decrease compared with ‘TRC12-157' (5666 RLN g⁻¹). These results indicate the potential for new RLN mitigation strategies through application of novel soil treatments and also selection of forage species and cultivar.

Assessment of resistance to ‘new’ virulent pathotypes of Plasmodiophora brassicae in doubled haploid lines derived from Brassica napus ‘Mendel’. R. FREDUA-AGYEMAN, S. F. HWANG, S. E. STRELKOV, Q. ZHOU, H. AHMED, H. FU, I. AKTER, R. NYANDORO, G. TURNBULL AND D. FEINDEL. Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada; and (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada

Resistance derived from the Brassica napus L. cultivar ‘Mendel’ has been overcome in some fields in Alberta, Canada, by the emergence of ‘new’ strains of Plasmodiophora brassicae Woronin. The objective of this study was to assess clubroot resistance in 57 doubled haploid lines derived from ‘Mendel’ which were identified as resistant to P. brassicae single-spore pathotype 3. The lines were evaluated against 15 field populations representing ‘new’ pathotypes of P. brassicae and five single-spore isolates representing the ‘old’ pathotypes 2, 3, 5, 6 and 8. Clubroot development was assessed 42 days after inoculation and expressed as a disease severity index (DSI, 0–100%). The results revealed that the number of resistant (DSI ≤ 30%), moderately resistant (30% < DSI ≤ 50%) and susceptible (DSI > 50%) DH lines inoculated with the ‘old’ pathotypes were 40 resistant, 11 moderately resistant and six susceptible, respectively. With respect to the ‘new’ pathotypes, none of the lines were resistant or moderately resistant to pathotype 5x (L-G1, L-G2, L-G3 and D-G3) while three were moderately resistant and 54 were susceptible to pathotypes Club 1 to K. Using the mean DSI induced by the ‘old’ pathotypes (~13.50%) as the baseline, clubroot severity increased by 300–600% when inoculated with the ‘new’ pathotypes. The findings suggest that ‘Mendel’ resistance has been almost completely overcome by the ‘new’ P. brassicae strains.

Optimization of suitable protocol to evaluate the pathogenicity of different Fusarium spp. affecting soybean in Manitoba. Y. GHARBI, N. GARMA, M. A. HENRIQUEZ, X. WANG, L. ADAM AND F. DAAYF. Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; and (M.A.H., X.W.) Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada

Different Fusarium spp. are associated with root rot disease in soybeans. However, published soil infestation methods have limitations in the expression of disease. Our objective was to compare the efficacy of different inoculation protocols for generating root rot caused by Fusarium graminearum Schwabe, Fusarium avenaceum (Fr.) Sacc. and Fusarium poae (Peck) Wollenw. collected from cereals and pulses. Root dipping of seedlings in conidia suspension, soil spiked with conidia suspension and soil inoculated with agar plugs containing mycelia were used for inoculation. The cultivar ‘TH32004R2Y’ was evaluated at V3 growth stage for plant height, root length and weight; root rot was estimated visually on a per cent scale ranging from 0 to 9. Soil spiked with conidia suspension of F. graminearum produced the greatest root rot severity (40%), followed by root dipping in conidia suspension of F. graminearum (23%), whereas soil infested with agar plugs containing mycelia resulted in less than 10% root rot. Root rot for control plants was less than 5%. Soil spiked with conidia suspension reduced plant height, root length and weight compared with the other two methods (P < 0.05). However, F. avenaceum and F. poae were less aggressive than F. graminearum with disease severity ranging between 15% and 25%. Pathogen colonization was assessed using conventional PCR. The number of positive samples detected by PCR was always higher than that detected by pathogen isolation, which indicates that Fusarium isolates colonize soybean roots without inducing rot disease symptoms. Overall, our study suggests that soil spiking with conidia suspension is more effective for producing seedling root rot.

Generation and characterization of a Fusarium graminearum mutant overexpressing the MAPK, Mgv1. D. GONZÁLEZ-PEÑA FUNDORA, A. ERANTHODI, R. K. GOYAL, R. SUBRAMANIAM, C. RAMPITSCH, N. THAKOR AND N. A. FOROUD. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 5403 1 Avenue South, Lethbridge, AB T1J 4B1, Canada; (D.G.F., N.T.) Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, AB T1K 6T5, Canada; (R.S.) Ottawa Research and Development Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (C.R.) Morden Research and Development Centre, AAFC, 101 Route 100, Morden, MB R6M 1Y5, Canada

Fusarium graminearum Schwabe is the causal agent of fusarium head blight (FHB), a devastating disease in wheat (Triticum aestivum L.). Three mitogen-activated protein kinase (MAPK) pathways have been identified in this fungus. MAPKs are ERK (extracellular response kinase) -like proteins that relay cellular signals through phosphorylation of various proteins. The F. graminearum MAPK, Mgv1 (MAPK for growth and virulence 1), plays a role in mycotoxin accumulation and disease development, though the latter may be related to a loss of fitness. Many of the components in the F. graminearum MAPK pathways remain unknown. With the aim of identifying downstream elements in the Mgv1 cascade, we generated F. graminearum mutants for in locus over-expression of Mgv1 under the control of a constitutive promoter. The mutants were characterized for changes in their morphocultural pattern and virulence in the spikes of 6-week-old Brachypodium distachyon (L.) P. Beauv. plants. The growth rate of the mutants measured in potato dextrose agar Petri dishes was slower than the wild-type, but no difference was observed in their ability to cause disease. The abundance of phosphorylated (activated) MAPK proteins was assessed by immunoblotting with anti-phosphorylated ERK1/2 antibodies, and showed an increased level of a phosphorylated ERK-like protein (MAPK) in the mutants. Other analyses related to the putative role of Mgv1 in cell wall formation, are underway to further our understanding of Mgv1 signalling pathways. Future directions for this work include the identification of downstream targets of Mgv1 activity.

Transcriptome sequencing of a durum wheat population segregating for ergot resistance, to identify eQTL and enrich for SNPs. A. GORDON, M. SGORI, N. EREFUL, C. A. MCCARTNEY, C. HIEBERT, R. KNOX, J. MENZIES, D. O’SULLIVAN AND L. BOYD. National Institute of Agricultural Botany, Bingham Laboratory, Huntingdon Road, Cambridge CB3 0LE, UK; (C.A.M., C.H., J.M.) Morden Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 101 Route 100, Morden, MB R6M 1Y5, Canada; (R.K.) Swift Current Research and Development Centre, AAFC, P.O. Box 1030, Swift Current, SK S9H 3X2, Canada; and (D.O.S.) School of Agriculture, Policy and Development, University of Reading, Whiteknights Campus, Reading RG6 6UR, UK

Ergot, caused by the ascomycete Claviceps purpurea (Fr.) Tul., is an important disease of wheat in Canada and the UK. Ergots contain toxic alkaloids, which can cause severe health problems if ingested. The durum wheat line 9260B-173A, identified as a source of ergot resistance, was studied in an ‘AC Avonlea’/9260B-173A recombinant inbred line (RIL), and further doubled haploid (DH) population. Genotyping was performed with the wheat iSelect 90K single nucleotide polymorphism (SNP) array and with KASP SNP assays. Linkage maps were developed for the population and QTL analysis conducted. A major QTL on chromosome 2A reduced honeydew production, reduced sclerotia size and weight, and percentage infected florets. In a reciprocal UK experiment, RNA samples were taken from plants 2 days after inoculation with a Canadian Claviceps isolate EL-2. Ten lines were chosen for their phenotypic extremes for honeydew and sclerotia along with parents ‘Avonlea’ and 9260B-173A. Illumina 100bp sequencing was performed and mapped onto IWGSC Chinese Spring genome. Differential expression analysis was performed to identify wheat genes up- and down-regulated at this crucial point in the infection process, and will give insights in the biology of the interaction. Additionally a further set of SNP-based KASP markers were developed from the RNA-Seq data, from genes that were predicted to lie within the QTL regions and were tested on the population. Of the markers developed, a high proportion subsequently mapped into the QTL regions acting to validate the approach and enrich the genetic linkage map.

Gaining insight into biotrophic fungal carbon metabolism through characterization of an Ustilago maydis xylitol dehydrogenase (uxm1). K. M. GOULET, E. R. M. STORFIE AND B. J. SAVILLE. Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; and (B.J.S., E.R.M.S.) Forensic Science Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada

Ustilago maydis (DC.) Corda, the causal agent of common smut of corn, is used as a model to investigate basidiomycete biotrophic pathogenesis. In this fungus, the deletion of UMAG_02150 (uxm1) altered pathogenesis, stimulating us to investigate its function. Comparative sequence analyses revealed that it encodes a protein with similarity to xylitol dehydrogenase (XDH), an enzyme involved D-xylose metabolism (XDH converts xylitol to D-xylulose) via the pentose catabolism pathway. The uxm1 solopathogen deletion strains (Δuxm1) were unable to grow on media containing D-xylose as a sole carbon source, which indicated these mutated cells are inhibited in their ability to process this sugar. Growth of the Δuxm1 U. maydis strain was restored on medium containing D-xylulose as the sole carbon source, which supported the hypothesis that uxm1 encodes a XDH. Further confirmation of this came from complementing the Δuxm1 mutant with a previously characterized XDH gene from Aspergillus oryzae (xdhA). The A. oryzae gene was synthesized using U. maydis optimized codons, and was ectopically inserted into a Δuxm1 mutant strain. Expressing xdhA in the deletion cells resulted in restored growth on D-xylose medium. Together, these data provide strong evidence that uxm1 encodes a xylitol dehydrogenase, which is the first characterized enzyme in the U. maydis pentose catabolism pathway. This confirmation of gene function suggested that the impaired pathogenesis resulting from deletion of uxm1 resulted from a requirement for U. maydis to utilize D-xylose during infection of corn. The results of pathogenesis assays that assess this role will be presented along with the characterization data.

Genome-wide association studies (GWAS) of multiple disease resistance in spring barley. S. GYAWALI, R. AMEZROU, S. CHAO, S. C. BHARDWAJ, R. BRUEGGEMAN, W. G. D. FERNANDO AND R. P. S. VERMA. International Center for Agricultural Research in Dry Areas, BIGM Program, Morocco; (W.G.D.F., present address of S.G.) Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; (present address of R.A.) FAO, West Africa and Sub-Saharan Regions; (S.C.) USDA, ARS, Fargo, ND 58 102, USA; (S.C.B.) Indian Institute of Wheat and Barley Research (IIWBR), Indian Council of Agricultural Research (ICAR), India; and (R.B.) Department of Plant Pathology, North Dakota State University, Fargo, ND 58 102, USA

A world collection of barley genotypes (n = 336) called association mapping 2014 (AM-2014) was collected to study multiple disease resistance (stripe rust (PSH), leaf rust (LR), stem rust (SR), net form of net blotch (NFNB), spot form of net blotch (SFNB) and spot blotch (SB)) and mapping QTL in India, Morocco and USA. The AM-2014 was genotyped with 9K markers using iSelect Illumina Inifinium SNP in USDA, ND. Phenotyping of resistance to multiple diseases was carried out at seedling and adult plant stages. Seedling resistance was assayed in controlled conditions by challenging with virulent isolates of PSH, LR, SR, NFNB, SFNB and SB while evaluation of resistance at adult stages was carried out under field conditions. Population structure (Q) was investigated using Structure and multivariate approaches while Kinship matrix (K) was generated using SNP markers. Genome wide association study (GWAS) was carried out in TASSEL software using MLM model (MLM+Q + K). The significant markers were corrected for false discovery rate (FDR) at P < 0.05. Barley genotypes showed multiple disease resistance to PSH, LR, SR, NFNB, SFNB and SB and furnished important genetic resources for breeding programmes across the globe. Six resistance QTL were detected in 2H, 3H, 4H, 5H, 6H and 7H chromosomes against PSH races M, 24, Q, 57 and 7S0 in India at the seedling stage. At adult stage, five resistance QTL were detected against PSH in the field. For LR, seven QTL, for seedling resistance, were mapped in 3H, 4H, 5H and 7H chromosomes. For SR, three QTL were detected in 2H, 3H and 7H chromosomes. Several novel QTL were detected for resistance to NFNB, SFNB and SB at seedling and adult plant stages in 2015 and 2016. Gene annotation showed several biotic and abiotic stress tolerance genes were associated with resistance to foliar diseases in barley. The fusarium head blight resistance mapping in AM-2014 and AM-2017 panels using virulent isolates originating from the Canadian prairies is in progress at the University of Manitoba. The information generated in these studies should help barley breeders and researchers to enhance selection efficiency using marker assisted selections in the future.

Biocontrol potential of Trichoderma longibrachiatum as an entomopathogenic fungus against Bemisia tabaci. M. S. HAIDER, K. NAWAZ, W. ANWAR, A. A. SHAHID AND S. IFTIKHAR. Institute of Agricultural Sciences, University of the Punjab, 54 590 Lahore, Pakistan; and (A.A.S.) Center of Excellence in Molecular Biology, University of the Punjab, 54 590 Lahore, Pakistan

Bemisia tabaci (Gennadius) is a complex insect species, including many cryptic species or biotypes. Whitefly causes damage to many ornamental and horticultural crops through directly feeding on phloem sap, resulting in sooty mould. Biological control has emerged as one of the most important methods for the management of soil-borne plant pathogens. Among the natural enemies of insects different entomopathogenic fungi are mostly used as biological control of the pest. The purpose of this research was to find indigenous insect-associated fungi and their virulence against B. tabaci. A detailed survey of cotton fields in sample collection was conducted during July and August 2013 from the central mixed zone of Punjab, Pakistan. For the isolation of Trichoderma longibrachiatum, sabouraud dextrose peptone yeast extract agar (SDAY) medium was used and morphological characterization of isolated T. longibrachiatum was studied using different dichotomous keys. Molecular identification of the pathogen was confirmed by amplifying the internal transcribed spacer region and BLASTN analysis showed 100% homology with already reported sequences on the database. For these bioassays, two conidial concentrations 4 × 10⁸ mL⁻¹ and 4 × 10⁴ mL⁻¹ of T. longibrachiatum was sprayed in clip cages for nymph and adult B. tabaci, respectively, under controlled environmental conditions. The pathogenicity of T. longibrachiatum was tested on nymph and adult whitefly to check mortality. Mortality of B. tabaci at nymphal and adult stages was observed after 24-h intervals. Percentage mortality of nymphs treated with 4 × 10⁴ mL⁻¹ conidia of T. longibrachiatum was 20, 24, 36 and 40% after 48, 72, 96, 72, and 96, 120 and 144 h respectively. However, no considerable difference was recorded in percentage mortality of whitefly after 120 and 144 h. Trichoderma longibrachiatum showed maximum activity on nymphal stages of whitefly as compared with adult stages. The present findings indicated that T. longibrachiatum is an entomopathogenic fungus against B. tabaci and many species of Trichoderma were already reported as an antagonistc organism against a wide range of bacterial and fungal pathogens.

Fungicide efficacy against Sclerotinia sclerotiorum biofilms is improved by addition of trace elements. M. W. HARDING, A. OMAR, B. BUZIAK AND J. FENG. Alberta Agriculture and Forestry, Crop Diversification Centre South, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada; (A.O., B.B.) Innovotech Inc. Suite 101 – 2011 94th Street, Edmonton, AB T6N 1H1, Canada; and (J.F.) Alberta Agriculture and Forestry, Crop Diversification Centre North, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada

Sclerotinia sclerotiorum (Lib.) de Bary is a pathogen of many field and horticultural crops grown in Canada. Fungicides are important tools for management of S. sclerotiorum; however, adequate disease control may not always be provided by a fungicide application. This study looked at the effects of trace elements (Ag, Bo, Ca, Cu, Mn, Zn) on the efficacy of six fungicides registered for control of S. sclerotiorum. The fungicides were prepared at three concentrations and mixed separately with each micronutrient at one of three concentrations for a total of 324 treatment combinations. The fungus was grown as a biofilm on pegs using the MBEC® Assay and performed in triplicate. Biofilm survival was quantified by detection of live cells using a Resazurin cell viability assay. Quantification was done using a microplate reader at 570, 595 and 630 nm before and after the fungicide treatment, and compared with untreated growth and sterility control wells. Most fungicides had improved efficacy when combined with one of the trace elements. For example, boscalid treatments were more efficacious when Ag was added, while ciprodinyl and fluazinam were improved when Cu was added. In some instances the efficacy increased more than five times. These results suggest that improvements in fungicide efficacy may be afforded by the addition of trace elements. While the mechanism is not known, the effect is similar to that seen with metallic complexes of antibiotic drugs.

Influence of cover crop residue management on the indigenous arbuscular mycorrhizal fungi, corn growth and yield. M. HIGO, R. SASAKI, T. UNOKI, K. GUNJI, D. SUZUKI AND K. ISOBE. Department of Agricultural Bioscience, College of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252–0880, Japan; and (K.G., D.S.) Graduate school of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252–0880, Japan

Understanding better cover crop managements for arbuscular mycorrhizal fungi (AMF) in cropping systems can be important for rapid colonization, better crop growth and nutrient uptake. However, there is little information regarding the impacts of incorporation and removal of cover crops in rotations on the diversity of AMF and subsequent crop performance. We investigated the impacts of incorporation and removal of cover crops on the AMF and corn growth and yield in a field trial. Four cover crop plots of hairy vetch, wheat, brown mustard and fallow in a rotation were established in the autumn of 2015. A corn test crop was planted in early May 2016. The aboveground plant parts and roots of corn were sampled at V6, V10 and R1 stage. Our results showed that at any of the stages, the AMF root colonization and communities in the corn were significantly influenced by the incorporation and removal of cover crops. The introduction of hairy vetch regardless of residue management increased the corn growth at V6 compared with other plots. In the 1-year trial, the incorporation and removal of cover crops impacted the plant biomass and P uptake of corn at the V6 stage, whilst the AMF colonization and communities in the roots were not strongly related to the corn performance among cover crop species and residue management plots. A consecutive field trial will be needed to understand the benefit of AMF and the optimal residue management strategy on corn growth performance.

Identification of strain-specific sequences in Plasmodiophora brassicae. M. D. HOLTZ, S. F. HWANG AND S. E. STRELKOV. Field Crop Development Centre, Alberta Agriculture and Forestry, 5030–50 Street, Lacombe, AB T4L 1W8, Canada; (S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada; and (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada

Plasmodiophora brassicae Woronin is a serious pathogen of canola (Brassica napus L.) in western Canada. In recent years, new strains of P. brassicae have been identified that can overcome host resistance. To identify genomic loci that are unique to the different strains and develop strain-specific markers for identification purposes, a restriction site associated DNA sequencing data set of 10 million reads covering 21 P. brassicae isolates was filtered to exclude any sequences that aligned with the P. brassicae, B. napus or B. rapa genomes. The remaining 910 000 sequences were assembled into 2017 loci, filtered to remove any that belonged to other species, then filtered to exclude loci that were present in both isolates that can cause disease on resistant varieties and those unable to do so. After filtering, 685 loci remained. Eleven PCR primers were designed for several of the remaining loci and primer specificity and sensitivity was evaluated on P. brassicae, host plants, non-infested soil, soil bacteria and fungi. The markers were able to distinguish isolates of the P. brassicae strains examined here with a sensitivity of 0.7 pg and did not produce the target amplicon in non-P. brassicae DNA samples. This shows that additional variation can be found in P. brassicae in regions that are not represented in the available genome sequence. The identification of loci in P. brassicae that appear to be strain-specific and markers developed from these loci will aid in the identification or monitoring of the pathogen.

Development of high resolution melting (HRM) and TaqMan assays for Plasmodiophora brassicae strain identification. M. D. HOLTZ, S. F. HWANG AND S. E. STRELKOV. Field Crop Development Centre, Alberta Agriculture and Forestry, 5030–50 Street, Lacombe, AB T4L 1W8, Canada; (S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada; and (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada

Clubroot, caused by Plasmodiophora brassicae Woronin, is a serious disease of canola (Brassica napus L.). In recent years, new pathotypes of P. brassicae have been identified that can overcome host resistance. Single nucleotide polymorphism (SNP) alleles specific to different strains of P. brassicae were identified from pathogen sequence information. These were used for the development of high resolution melting (HRM) and TaqMan assays. Forty-one primer pairs were designed to produce small amplicons including SNP sites for HRM analysis. These were then tested on multiple P. brassicae and B. napus samples. Of these, 23 amplified the product of the expected size in P. brassicae without non-specific amplification in B. napus. The resulting melt curves could be used to identify different strains of the pathogen. Two SNPs that were successfully characterized by HRM analysis were used as the basis of TaqMan assays. TaqMan allelic discrimination probes were designed for both the reference and alternate alleles at each SNP site. The sensitivity of the assays was tested on a dilution series of P. brassicae DNA and was determined to be 7 pg and 0.7 pg. The assays were determined to be specific to P. brassicae by testing on a series of host plants, non-infested soil, soil fungi and bacteria. Both the HRM and TaqMan assays described here allow for the rapid identification of P. brassicae samples.

Evaluation of soybean lines for resistance to iron deficiency chlorosis in southern Manitoba. A. HOU AND K. S. SANDHU. Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada

Soybean iron deficiency chlorosis (IDC) is an economically important and common abiotic disease affecting soybean and production and often causes severe yield losses. Growing IDC resistant varieties is the best management practice to reduce yield loss under severe conditions. In an effort to screen for resistant soybean materials, 160 lines were evaluated under field conditions at Emerson in southern Manitoba. Significant differences were observed among the genotypes; however, substantial errors were also caused by the heterogeneous field conditions. In order to evaluate soybean materials uniformly and reliably, a protocol was also established using calcareous soil and hydroponic conditions in a controlled environment. The same soybean lines that were tested under field conditions were evaluated again using the hydroponic conditions. While a large number of soybean lines that showed resistance in the field conditions were determined to be susceptible or moderately resistant under hydroponic testing, eight lines were confirmed as highly resistant to IDC. The resistant materials selected in the process will be used for crossing for early-maturing variety development and genetic analysis. The protocol established can be used for future screening of soybean breeding materials for resistance to IDC at our research centre.

Quantitative resistance to blackleg disease in three Canadian canola cultivars under elevated temperatures. M. HUBBARD AND G. PENG. Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Blackleg disease, caused by Leptosphaeria maculans (Desmaz.) Ces. & De Not, is a serious threat to canola production in the Canadian prairies. While major resistance (R) genes (qualitative resistance) can provide effective protection, this type of resistance can be rapidly overcome by shifts in pathogen populations. Quantitative resistance (QR) has the potential to provide a more durable, if less complete, protection. However, the effectiveness of QR can vary widely in the field. It has long been suspected that elevated temperatures can reduce the effectiveness of QR. To better understand this impact, we assessed the infection development of blackleg in three Canadian canola (Brassica napus L.) cultivars (CCC1, CCC2 and CCC4) carrying QR, with and without a week-long heat treatment with 7 h of daily exposure to 32°C at the early flowering stage under controlled-environment conditions. The impact of elevated temperatures on the susceptibility of canola cultivars to blackleg was compared with that of 22°C daytime high temperature. A susceptible cultivar, ‘Westar’, was used as a control in both temperature treatments. Elevated temperatures increased blackleg symptoms in the absence of QR and enhanced the effectiveness of QR in the three commercial cultivars tested. CCC1, CCC2 and CCC4 had strong, moderate and weak QR at lower temperatures, respectively. However, at higher temperatures, all three cultivars displayed strong QR relative to ‘Westar’. Our findings suggest that the QR gene(s) carried by CCC1, and QR in general, are promising tools for the control of blackleg when warmer temperatures occur after canola has flowered.

Interaction between spring wheat lines and deoxynivalenol chemotypes of Fusarium graminearum. K. HUDSON, M. SERAJAZARI, M. KAVIANI AND A. NAVABI. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada

Fusarium head blight (FHB), mainly caused by Fusarium graminearum Schwabe in North America, not only reduces grain yield, but also produces trichothecene mycotoxins, such as deoxynivalenol (DON), in the grain. The DON-producing strains of F. graminearum are divided into 3-acetyl (3A) DON and 15-acetyl (15A) DON chemotypes. In this study, heads of 10 different spring wheat genotypes, with different levels of resistance against FHB, were spray- or point-inoculated with 10 different isolates of F. graminearum collected from different provinces of Canada, five of which bear the 3-ADON chemotype, and five bearing the 15-ADON chemotype. The number of infected spikelets was counted 5 days after spray-inoculation to evaluate Type I resistance (resistance to initial infection), and also 10 and 15 days after point-inoculation to evaluate Type II resistance (resistance to spread of infection within head). In both Type I and II resistance evaluations, there were significant differences among wheat genotypes and isolates. Even though the overall genotype by chemotype interaction was not significant, the susceptible cultivars responded differently to infection by different isolates of the pathogen, regardless of their chemotype. The lack of interaction mainly among resistant cultivars demonstrated the non-chemotype-specific behaviour of Type I and Type II resistance against FHB in wheat.

Haplotype analysis of loci associated with fusarium head blight resistance in a collection of Brazilian spring wheat: an update. G. HUMPHREYS, L. LANGILLE, X. WANG, C. MCCARTNEY, S. KHANIZADEH AND H. VOLDENG. Ottawa Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (C.M.) Morden Research and Development Centre, AAFC, 101 Route 100, Morden, MB R6M 1Y5, Canada

Fusarium head blight (FHB) is the most important disease of wheat reducing grain yield, crop grade and end-use quality. FHB can be caused by various Fusarium spp., but F. graminearum Schwabe is the most economically important in North America due in part to the production of mycotoxins such as deoxynivalenol (DON) during infection. Food and feed safety can be compromised because mycotoxin content can make the wheat grain unsuitable for food or feed. A collection of 79 wheat lines from various Brazilian breeding institutions were genotyped using DNA markers at four FHB quantitative trait loci (QTL). These QTL were previously reported on chromosomes 3BS, 5AS and 6BS in the cultivar ‘Sumai 3‘, and 3A in the cultivar ‘Frontana’. Visual Ratings Index (VRI) for reactions to FHB were evaluated in the Ottawa inoculated FHB nursery in 2016, and deoxynivalenol (DON) content was determined from 2016 harvested nursery samples. None of the Brazilian lines possessed the ‘Sumai 3‘ haplotype for FHB resistance QTL on 3BS (Fhb1) or 6BS (Fhb2). While 63% of the lines amplified the ‘Sumai 3‘ allele at gwm415 on 5AS, none amplified the ‘Sumai 3‘ alleles for adjacent SSR markers. Nevertheless, 2016 FHB ratings ranged from 13.3 to 95.0, and DON levels ranged from 1.8 to 30.5 ppm. Some lines in the Brazilian collection appear to possess FHB resistance that is not associated with the three major ‘Sumai 3‘ FHB QTL which would make these lines useful sources of FHB resistance for wheat breeding and research.

Effect of calcium cyanamide on clubroot (Plasmodiophora brassicae) of canola in a greenhouse study. S. F. HWANG, H. U. AHMED, Q. ZHOU, H. FU, G. D. TURNBULL AND S. E. STRELKOV. Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada; and (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada

Clubroot, caused by Plasmodiophora brassicae Woronin, has become a serious threat to canola (Brassica napus L.) production in western Canada. Extensive studies have shown that calcium cyanamide (CaCN₂) and its degradation products calcium and nitrate are associated with reductions in the severity of clubroot of Brassica crops. Experiments were conducted under greenhouse conditions to evaluate the effect of calcium cyanamide on seedling emergence, plant growth parameters, gall weight, and clubroot severity of canola at inoculum concentrations of 1 × 10³ to 1 × 10⁵ spores mL⁻¹ soil. Calcium cyanamide reduced gall weight and clubroot severity compared with the non-treated control. Treatment with this product, however, also reduced seedling emergence, plant height and plant biomass compared with the non-treated control, and the reduction of these parameters was greater at higher application rates. Clubroot severity levels were similar across inoculum concentrations ranging from 1 × 10³ to 1 × 10⁵ spores mL⁻¹ soil. These results suggest that calcium cyanamide has the potential to reduce or prevent clubroot development when P. brassicae resting spore populations are relatively low.

Evaluating fungicidal activity of complex II inhibitors against late blight of potato. S. IFTIKHAR, A. A. SHAHID, K. NAWAZ AND W. ANWAR. Institute of Agricultural Sciences, University of the Punjab, 54 590 Lahore, Pakistan; and (A.A.S.) Center of Excellence in Molecular Biology, University of the Punjab, 54 590 Lahore, Pakistan

Respiratory inhibitors are among the fungicides most widely used for disease control on crops. Modern agriculture depends on efficient tools for controlling fungal diseases that can have a strong impact on yield and quality. Potato late blight is the most significant and damaging disease of potato worldwide. The oomycete pathogen Phytophthora infestans (Mont.) de Bary, causal agent of late blight, is a widely known emerging plant pathogen. New broad spectrum foliar fungicides against complex II were designed using pharmacophore modelling and structure based virtual screening. The enzyme links the carboxcylic acid cycle and the cellular respiration by catalysing the oxidation of succinate to fumarate. The focus of the research work was on finding compounds with high intrinsic activity against P. infestans. The fungus was identified using morphological and molecular characteristics. Fungicidal activity of 12 novel active ingredients targeted against complex II was evaluated for the effect on mycelial growth and spore germination of the fungi using poisoned agar assay. In mycelial growth assay, compounds C6 and C2 were highly active against P. infestans while compound C10 showed second highest antifungal activity. In the case of spore germination assay, compounds C1 and C6 were most effective. All the other compounds displayed intermediate inhibitory activity against P. infestans as compared with commercially available fungicide. This study showed that compound C1, C2, C6 and C10 resulted in the decrease in mycelial growth and spore germination. The complex II inhibitors identified in this work can be recommended as active ingredients for fungicides against P. infestans.

Priming effects of virulent Plasmodiophora brassicae strains on clubroot disease development during primary infection. J. JIANG, R. FREDUA-AGYEMAN, S.F. HWANG AND S. STRELKOV. Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (R.F.-A., S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada

Clubroot, caused by Plasmodiophora brassicae Woronin, causes significant economic losses to canola (Brassica napus L.) production worldwide. Infection by virulent strains of the pathogen is thought to compromise host defences, which can prime the host for infection by avirulent strains. In this study, the effects of virulent P. brassicae populations on host defence were investigated using three pairs of virulent/avirulent strains (2x/2, 3x/3 and 5x/5) and three canola cultivars (‘45H29‘, ‘L135C’ and ‘L241C’). Seven-day-old seedlings were inoculated with low concentrations (10³ spores mL⁻¹) of resting spores of the virulent strains followed by high concentrations (10⁷ spores mL⁻¹) of resting spores of the avirulent strains. The positive control consisted of plants inoculated with low concentrations of the virulent strains followed by high concentrations of the virulent strains, while the negative controls consisted of plants inoculated only with low concentrations of the virulent strains or only high concentrations of the avirulent strains. Six weeks after inoculation, an index of disease (ID) was calculated. Disease severity was highest in the positive control (mean ID = 92%), followed by the virulent/avirulent inoculation treatments (mean ID = 37%), and the negative controls (inoculation with only low concentrations of the virulent strains, mean ID = 23%; or inoculation with only high concentrations of the avirulent strains, mean ID = 7%). Overall, priming effects were observed in seven of the nine (three virulent/avirulent P. brassicae pairs × three cultivars) treatments, suggesting that low concentrations of virulent P. brassicae strains compromised the host defence of the three cultivars.

Epidemiology and management of white mould in dry bean by irrigation and plant architecture. K. A. KADER, P. M. BALASUBRAMANIAN AND S. CHATTERTON. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403–1 Avenue South, Lethbridge, AB T1J 4B1, Canada

In the semi-arid region of southern Alberta, dry bean (Phaeseolus vulgaris L.) is grown under irrigation. White mould (WM) caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary is a major constraint to dry bean production. High irrigation levels to maximize dry bean yield potential can also influence WM development by creating conducive environmental conditions such as high soil moisture and leaf wetness, and cool soil temperatures. Field experiments were conducted during 2015 and 2016 at AAFC-Lethbridge to determine the effect of irrigation and cultivars on WM epidemiology and management. Three levels of irrigation (high, medium and low) and five cultivars with three different architectures (determinate upright bush, indeterminate semi-upright and indeterminate prostrate) were arranged in a split-plot randomized block design. Sensors and data loggers were established to monitor micro-climate data, such as soil moisture within top 5-cm, leaf wetness and soil temperature under the canopy. Canopy porosity, lodging, flower infection and WM disease severity were also measured. Pearson’s correlation coefficient revealed significant relationship of WM severity with soil moisture, leaf wetness and soil temperature. Lodging was positively correlated with WM severity while the relationship was negative for canopy porosity with the disease. Flower infection was highly correlated with WM severity and explained maximum variability. Overall, significantly lower disease was observed in medium and low irrigation plots, but yield was highest in medium irrigation plots. Thus, reduced level of irrigation (medium) and accelerated development of lodging resistant cultivars would be useful for WM management in Alberta.

Evaluation of type II resistance to fusarium head blight in Canadian winter wheat. M. KANG-CHOI, G. HUMPHREYS, S. CLOUTIER, W. CAO, A. XUE AND A. NAVABI. Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (A.N.) Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada

Fusarium head blight (FHB) is a destructive disease that reduces grain yield and end-use quality of wheat. The common causal agent of FHB disease in Canada is Fusarium graminearum Schwabe, which produces mycotoxin deoxynivalenol (DON). Toxin accumulation in grains and the processed products is a serious concern for human and animal health. The Canadian winter wheat varieties, ‘AC Morley’ and ‘Emerson’, are rated in the field as moderately resistant and resistant, respectively. A previous greenhouse experiment that evaluated type II resistance to FHB, showed that both ‘AC Morley’ and ‘Emerson’ were susceptible at 21-days post inoculation (DPI). In the present study, a doubled haploid (DH) population developed from the cross ‘AC Morley’ × ‘Emerson’ was tested for type II resistance in the greenhouse. Single floret inoculation was performed at 50% flowering stage and the inoculated plants were incubated in the misting chamber for 48 h. Initial symptoms were visible after 48–72 h. The level of disease spread was rated at 7, 10, 14, 17 and 21 DPI. Disease rating and disease progress curve for the population, along with morphological characteristics observed, such as awnedness, head density, anther extrusion and plant height, will be presented. The greenhouse experiment will be repeated in winter 2018, and the field screening of this DH population for FHB resistance will be conducted at three locations (Ottawa and Elora, ON and Yangzhou, China) in 2017 and 2018.

Fungal diversity across conventional, oasis and organic farming systems in arid areas of Oman. E. A. KAZEROONI AND A. M. AL-SADI. Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O. Box 34, Al-Khoud 123, Oman

This study examined fungal diversity in conventional, oasis and organic farms in arid areas of Oman. Fungal diversity was assessed using pyrosequencing and culture-based techniques from crops of date palm, acid lime, mango, cucumber and tomato. Pyrosequencing revealed that fungal diversity was variable among different farming systems as well as among different crops within the same farm. Fungal diversity was high in organic farms compared with other farms. In addition, the rhizosphere of date palms had more fungi compared with other crops. Ascomycota was the dominant phylum in most of the soil samples. The other common phyla were Microsporidia, Chytridiomycota and Basidiomycota. Classes Dothideomycetes, ‘Teresporidia’, Sordariomycetes and Eurotiomycetes and fungal genera Systenostrema, Hypocrea, Cladosporium and Oidium dominated soils from all samples. Principal component analysis revealed that fungal diversity was affected by the farming system as well as the type of crops grown. Pyrosequencing was more efficient (4–6 times) than culture based techniques for estimating fungal diversity. Our study indicated that differential levels of fungal diversity are associated with different farming systems and crops, and effects of cultural practices, plant species, soil type and other factors on fungal diversity were discussed.

Environmental correlates of creeping red fescue (Festuca rubra var. rubra) seed yield in Peace River region of Western Canada. N. KHANAL, R. AZOOZ, J. OTANI AND H. W. KLEIN-GEBBINCK. Lacombe Research and Development Centre, Beaverlodge Research Farm, Agriculture and Agri-Food Canada, P.O. Box 29, Beaverlodge, AB T0H 0C0, Canada

The Peace River region is the largest producer and exporter of creeping red fescue (Festuca rubra L. var. rubra) seed in the world. The seed crop sequence of the fescue comprises one establishment year followed by 2 seed crop years. To understand why there are variable responses to crop management factors, we analysed the correlation between average temperature coupled with total precipitation of 2-week periods of the preceding autumn (September) and prevailing spring (May–June) and seed yield of the fescue cultivar ‘Boreal’ at Beaverlodge, Alberta, from 2012 to 2016. Average temperature and total precipitation data were calculated over the first half and second half of each month. Seed yields over the 4 years showed a negative correlation with 2-week average temperatures and precipitation totals of the preceding September. Prevailing average temperature of later-half of May and total precipitation of both early and later half of May were positively correlated with the seed yield. The total precipitation in June showed a contrasting relationship; warmer temperature coupled with lower precipitation in the early-half and cooler temperature coupled with higher precipitation in the later-half of June were associated with higher seed yield. The results implicated that dormancy-inducing cool-dry weather in the preceding autumn, and growth-promoting warm-moist weather in the prevailing spring season are favourable conditions for seed yield of creeping red fescue. Furthermore, in the later-half of June which is the flowering time for creeping red fescue, moderate temperatures and adequate moisture are critical to minimize the risk of pollen desiccation, hence enhancing pollination.

In-depth studies on fusarium root rot of dry bean in Manitoba. Y. M. KIM, M. A. HENRIQUEZ, D. L. MCLAREN, R. L. CONNER, K. F. CHANG, S. F. HWANG AND S. E. STRELKOV. Brandon Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; (M.A.H., R.L.C.) Morden Research and Development Centre, AAFC, 101 Route 100, Morden, MB R6M 1Y5, Canada; (K.F.C., S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada; and (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada

Fusarium root rot of bean is a serious soil-borne disease and occurs in most bean-growing regions worldwide. In Manitoba, it has occurred in over 95% of commercial dry bean crops for the past decade based on data from annual crop surveys. In order to monitor changes in pathogen populations over time and create pathogen profiles, in-depth studies on root rot pathogen identification were conducted each year for 2 years (2011 and 2016) in three different commercial dry bean crops from the major production areas in Manitoba. A total of 1920 single spore isolates were obtained and pathogen species were identified based on their morphological characteristics on selection media and through microscopic examination. Identification of Fusarium spp. was confirmed by DNA sequencing using the ribosomal intergenic spacer (IGS), the translation elongation factor 1 alpha (EF1-α) gene and the internal transcribed spacer (ITS) region. A set of Fusarium spp. from 2011 were screened for pathogenicity on the cultivar Envoy. An important finding from this research was the identification of Fusarium cuneirostrum O’Donnell & Aoki causing root rot in dry beans. The identification of additional Fusarium spp. known to be associated with root rot of rotational crops stresses the need to acquire more information on dry bean root rot pathogens and cross-pathogenicity studies in order to design effective management strategies.

Isolation and identification of Dickeya solani from hyacinth bulbs imported from the Netherlands. X. LI, J. NIE, K. YUAN, H. XU, C. HUTTER, S. BRIÈRE AND S. H. DE BOER. Canadian Food Inspection Agency, Charlottetown Laboratory, 93 Mount Edward Road, Charlottetown, PE C1A 5T1, Canada

Dickeya and Pectobacterium have caused significant crop losses due to the emergence of new species/subspecies and the wide spread of the pathogens which are highly virulent on a wide variety of hosts. In potatoes, Dickeya spp. and Pectobacterium spp. cause blackleg and soft rot diseases which have become increasingly problematic for potato production in some growing regions. While Pectobacterium spp. have been known as causal agents of these diseases in Canada and the USA since pioneer days, potato blackleg-causing Dickeya dianthicola Samson et al. was only discovered in the USA in 2014. Blackleg outbreaks caused by D. dianthicola have now been reported in more than 10 USA states. Given the trend in the spread of Dickeya spp. (formerly Erwinia chrysanthemi) in European countries during the last 15 years, the USA and Canada need to be alerted and technically prepared for possible introduction of the more aggressive variants of Pectobacterium and Dickeya, such as D. solani. Although it has never been detected in plants grown in Canada, D. solani was isolated, for the first time, from hyacinth bulbs imported from the Netherlands highlighting the potential pathway to North America. Genomic analysis using NGS technology revealed the high similarity between the hyacinth isolate and the type strain of D. solani, which is different from all other Dickeya and Pectobacterium species. This finding is congruent with the variations reported in pathogenicity and virulence in potato. The importation of infected hyacinth bulbs is probably an important pathway for D. solani to enter Canada and the USA under the current horticulture regulatory programme.

A potential biosensor for early detection of Sclerotinia sclerotiorum and Leptosphaeria maculans in canola. X. LI, J. YANG, Y. HAO, X. YANG AND J. CHEN. InnoTech Alberta, Hwy 16A & 75th Street, Vegreville, AB T9C 1T4, Canada; and (Y.H., X.Y., J.C.) Biomedical Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada

A biosensor to detect Sclerotinia sclerotiorum (Lib.) de Bary ascospores and Leptosphaeria maculans (Desmaz.) Ces. & De Not. pycnidiospores was designed and tested. The biosensor involves gold nanoparticles, a pathogen specific antibody, and a real-time cell electronic sensing (RT-CES) system to detect the impedance. Our results indicated that a linear relationship exists between the numbers of S. sclerotiorum ascospores and the impedance of their antibody-spore-gold nanoparticle complex. These signals can be easily processed electronically and converted to rapidly distributable results. Our biosensor also demonstrated an incredibly sensitive threshold of detection of five ascospores of S. sclerotiorum in the sample. A linear relationship was also obtained when L. maculans was used as a pathogen, indicating that the future device could be species-specific and applied to more plant disease pathogens. Based on this study, our biosensor provides a promising and useful tool for plant disease detection in the field.

Evaluating new seed-treatment chemicals to reduce early infection of blackleg on canola. X. LIU AND G. PENG. Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Blackleg (Leptosphaeria maculans (Desmaz.) Ces. & De Not.) is an important disease on canola (Brassica napus L.) in western Canada. Current management strategies rely primarily on resistant varieties and crop rotation, but the disease incidence and severity have increased in recent years. Foliar fungicide treatments, targeting early infection of cotyledons can mitigate the blackleg risk. However this approach is not considered cost effective due to the sporadic pattern of blackleg damage. Seed treatment (quinazoline) is used regularly in Australia to reduce early blackleg infection, but no product has been registered for this purpose in Canada. This investigation assessed several new chemistries in the development pipeline for potential seed treatment. Each candidate was applied to the seed of susceptible (S) and resistant (R) canola cultivars, at a rate deemed economical by developers. Cotyledons were inoculated by applying 10 µL of L. maculans conidial suspension (10⁶ mL⁻¹) to a light wound. The infection severity was evaluated using a 0–9 scale at 14 days after inoculation. The current seed treatment (Helix® Vibrance or Prosper® EverGol) had little effect relative to untreated controls, whereas quinazoline reduced the infection moderately, especially on the R-rate variety. The efficacy of new chemistries varied from ineffective to highly effective. The latter inhibited the infection completely, even on the S-rated cultivar. In addition to the potential fungicidal effect, this new chemistry induced the expression of PR-1 and CHI marker genes, suggesting that it may stimulate plant defence responses. Hence, this new chemistry has potential as a seed treatment against blackleg infection on canola cotyledons.

Introduction of Ac/Ds transposons into oat genome. M. MAHMOUD, R. KAUR AND J. SINGH. Plant Science Department, 21 111 Rue Lakeshore, McGill University, QC H9X 3V9, Canada

Oat (Avena sativa L.) is one of the most important cereals for animal feed, human food and industrial production worldwide, due to its unique nutrition components. However, oat’s complex hexaploid genome and redundancy coupled with limited knowledge of oat germplasm impedes further improvement in oat cultivars. Thus, there is an urgent need to provide a modern functional genomic approach to characterize the oat genome. Here, we employed Ac/Ds transposon-based reverse genetics approach for activation gene tagging for the first time in oat. Highly regenerative callus derived from mature oat seeds, cv. ‘Park’, were bombarded, or co-bombarded by various Ac/Ds genes constructs, using a PDS-1000/He Biolistic gun. Our biochemical and molecular analyses indicate successful introduction of Ac/Ds elements in the oat cultivar. A total of 20 unique transformation events were generated. Individual single copy Ac and Ds lines are being hybridized for the development of a genetic population for the identification of unique transposed Ds mutants.

Fusarium head blight resistance is enhanced by the wheat leaf rust resistance gene Lr34. B. D. MCCALLUM, C. W. HIEBERT, J. THOMAS AND M. A. HENRIQUEZ. Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada

The leaf rust resistance gene Lr34 provides resistance to stripe rust, stem rust, powdery mildew and other diseases. We investigated the effect of Lr34 on fusarium head blight (FHB) using 21 pairs of near isogenic F₃ sister lines from the cross Sumai × 6/Thatcher. One of each pair of sister lines contained the resistant allele for Lr34, while the other line had the susceptible allele; otherwise the sister lines were similar to ‘Sumai 3', which has a high level of resistance to FHB. These lines were evaluated in inoculated and irrigated nurseries each year from 2012 to 2016. The lines were rated for visual FHB Index each year and harvested grains were assayed for DON content in 2014, 2015 and 2016. In each year, FHB severity was lower for the lines with the resistant allele than those with the susceptible allele as determined by the FHB Index and DON content. In most pairs of sister lines the line with the resistant allele was more resistant than the line with the susceptible allele. It appears that Lr34 enhances FHB resistance in the highly resistant ‘Sumai 3‘ background.

Evaluation of products to control stem and bulb nematode on garlic. M. R. MCDONALD, K. VANDER KOOI AND M. J. CELETTI. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; and (M.J.C.) Ontario Ministry of Agriculture, Food and Rural Affairs, 1 Stone Road West, Guelph, ON N1G 4Y2, Canada

The stem and bulb nematode, Ditylencus dipsaci (Kühn) Filipjev, is a threat to garlic production in many parts of the world. It is spread in infected cloves used as seed. Heavy infestations cause the bulbs to rot and can reduce marketable yield to zero. Field trials were conducted at two sites in Ontario, Canada, to evaluate products for control of stem and bulb nematode. The trials were established on mineral soil and high organic matter (muck) soil in the autumn of 2015 and assessed in July 2016. Naturally infested garlic cloves (226 nematodes g⁻¹ dried clove), cv. ‘Music’, were used in both trials. At the muck site, seed was soaked for 4 h in solutions of Velum Prime (fluopyram), Agri-Mek EC and SC (abamectin) and Nimitz (flufensulfone). Velum Prime and Nimitz were also applied as a soil drench at planting and a granular formulation of Nimitz was also applied at seeding. After emergence in the spring, Nimitz EC was applied as a drench and another treatment was three sprays of Movento (spirotetramat). At the mineral soil site, three rates of Velum Prime (0.6, 1.25 and 2.5 g L⁻¹) as a 2 or 4 h soak, were evaluated. At the muck soil site, Velum Prime as a soak was most effective. Agri-Mek as a soak also reduced incidence and severity compared with the check. At the mineral soil site, soaking for 2 or 4 h, with any rate of Velum Prime, effectively reduced damage and nematodes populations in harvested bulbs.

Distribution of carrot cyst nematode in the Holland Marsh, Ontario, 2016. M. R. MCDONALD, K. VANDER KOOI, D. VAN DYK, E. PONOMAREVA, F. SUN AND Q. YU. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; (D.V.D.) Ontario Ministry of Agriculture, Food and Rural Affairs, 1 Stone Road West, Guelph, ON N1G 4Y2, Canada; (E.P., Q.Y.) Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (F.S.) Ottawa Plant Laboratory, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, ON K2H 8P9, Canada

Approximately 25% of all carrots in Canada are produced in the Holland/Bradford Marsh region of Ontario, Canada. Heterodera carotae Jones is a plant parasitic nematode commonly known as the carrot cyst nematode. The distribution of this nematode is limited to a few countries in Europe, and the state of Michigan in the USA. It is only known to infest carrots and wild carrots, and is considered an exotic plant pest in Canada. The nematode causes stunting and deformation of the roots, and loss of marketable yield. In recent years, carrots in commercial fields were found to have patches with poor growth, stunting, smaller and forked carrots with a proliferation of secondary roots, and cysts associated with the damage. Thirty carrot fields in the Holland Marsh region were sampled in November 2016 following carrot harvest. Field size varied from 2–10 ha. Soil samples of the top 20 cm of soil were sampled in an X pattern in each field. Samples were analysed for the presence of carrot cyst nematode. Nematodes were extracted using a Baermann funnel for vermiform nematodes and the Fenwick method for cysts. Second stage juveniles (J2), males and cysts were recovered. The species was confirmed as H. carotae using morphological and molecular methods. Carrot cyst nematodes were found in 90% of the samples and were widespread throughout the sampled area. Population densities of the carrot cyst nematode ranged from 0 to 16 100 juveniles kg⁻¹ of soil. Further surveys, and studies to determine damage thresholds, are needed.

Infection of canola cotyledons by Leptosphaeria maculans in relation to wounding and dew duration. L. MCGREGOR AND G. PENG. Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Blackleg, caused by Leptosphaeria maculans (Desmaz.) Ces. & De Not, is a serious disease of canola in western Canada. The disease is usually more prevalent in the field under high moisture conditions. However, there is evidence suggesting that wounding of canola by flea beetles increases the level of infection, even under low moisture conditions. The objectives of this study were to assess the effect of simulated wounding on infection of L. maculans under short dew or no dew conditions for susceptible canola cultivar ‘Westar’ and a commercial canola cultivar, CCC1 with quantitative resistance. Cotyledons were artificially wounded at three levels of severity; zero, light and moderate wounding. A conidial suspension of an L. maculans isolate possessing the green fluorescent protein gene (GFP) was misted onto the cotyledons. Half of the plants received a dew period and half received no dew. Disease ratings at 14 days after inoculation (dai) and observations of L. maculans GFP hyphal development under a fluorescent dissecting microscope at 10 dai, showed that for ‘Westar’, no disease had developed on the unwounded treatment whereas high levels of infection were observed for the wounded cotyledons. There was no difference between the dew and no dew treatments. For resistant cultivar CCC1, disease symptoms were less severe than ‘Westar’ and the severity of infection increased as wounding increased. There was a slight reduction in symptoms when there was no dew. The results support the hypothesis that wounding increases blackleg infection and emphasizes the need for effective flea beetle control.

Buckwheat (Fagopyrum esculentum) cultivar and seeding date response to Newfoundland growing conditions. D. B. MCKENZIE, P. L. DIXON, C. NORONHA AND K. N. HOBRECKER. St. John’s Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 308 Brookfield Road, Building 25, St. John’s, NL A1E 0B2, Canada; and (C.N.) Charlottetown Research and Development Centre, AAFC, 440 University Avenue, Charlottetown, PE C1A 7M8, Canada

Increasing wireworm populations in agricultural fields are of concern to farmers in Atlantic Canada. Buckwheat (Fagopyrum esculentum Moench.) grown as a rotation crop before potatoes has been shown to reduce damage and increase marketable yield in wireworm-infested fields in Prince Edward Island; however, summer temperatures may be too cool for buckwheat to be as effective in Newfoundland. Buckwheat (cv. ‘Mancan’) grown in field trials at the St. John’s Research and Development Centre in 2014 and 2015 showed significant effects of seeding date on early bloom and full bloom dry matter yields, with a strong contrast between the two years due to differential July heat unit accumulation. The July 2015 average daily maximum temperatures were 9ºC cooler than in 2014 and resulted in much lower dry matter yields. In a second trial, nine Canadian buckwheat cultivars were planted at the same field location in late June in 2014 and 2015 after the risk of frost was below 10% probability. Dry matter yield differences were found between specific cultivars at early bloom and full bloom growth stage harvests; however, the most significant yield contrast was between the 2 years. The effects of these buckwheat treatments will be assessed by analysing the wireworm damage in potatoes from the 2016 production year.

Physiological races of wheat leaf rust (Puccinia triticina) in Canada in 2016. W. MCNABB, B. D. MCCALLUM, E. REIMER AND A. XUE. Morden Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 101 Route 100, Morden, MB R6M 1Y5, Canada; and (A.X.) Ottawa Research and Development Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Collections of 277 leaf rust (Puccinia triticina Eriks.) samples were obtained from spring and winter wheat cultivars grown in research plots and commercial fields throughout Manitoba, Saskatchewan and Ontario in 2016 to assess the virulence profile of the pathogen population. These samples produced 255 single pustule isolates which were inoculated onto a set of 16 differential isolines at the seedling stage. There was a high level of diversity with 72 virulence pathotypes identified. The most common pathotype was MNPS which comprised 15.7% of the isolates and was found more commonly on winter wheat than spring wheat cultivars. This pathotype was not detected from 2000–2014 and appeared at very low levels in 2015. The other common pathotypes were MBDS (14.5%) and MPPS (7.1%). A notable decline in virulence was seen on Lr2a and a slight decline in virulence on Lr9 and Lr21 in comparison with previous years. An increase of virulence was observed on Lr16, Lr17 and Lr24. A set of 79 isolates representing each of the virulence pathotypes was tested on an additional 12 wheat lines at the seedling stage and on five lines with adult plant resistance genes. On the expanded differential set no isolates were virulent on Lr19 and Lr52 and only one isolate overcame the resistance of Lr29. On adult plant differentials, no virulence was found for Lr22a and very few isolates were virulent on Lr35 which follows the trend from previous years.

A previously unrecognized Ustilago maydis APSES protein has a role in pathogenic development. J. MEADE, M. SEEGOBIN, M. E. DONALDSON AND B. J. SAVILLE. Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; and (B.J.S.) Forensic Science Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada

Ustilago maydis (DC.) Corda is a well-established model for investigating basidiomycete biotrophic pathogenesis. This fungus requires interaction with Zea mays for sexual reproduction and teliospore development. The resistant teliospores are critical for disease spread, and understanding the control of their development may reveal new means of disease management. We are investigating teliospore formation and germination by identifying genes expressed during these developmental transitions. In doing so, we identified a previously unrecognized APSES domain transcription factor UMAG_04778. The fungal specific APSES family of transcription factors contain a highly conserved helix-loop-helix DNA binding domain and are generally involved in controlling morphological transitions. There are five APSES proteins encoded in the U. maydis genome including Ust1, which was previously shown to regulate dimorphism, virulence and sporulation. However, only UMAG_04778 was found to have increased transcript levels during pathogenic development and in the teliospore, but undetected transcript levels in haploid cells. UMAG_04778 deletion did not inhibit plate mating or filamentous growth; however, it led to decreased leaf tumour formation, and virulence, as well as dramatically reduced teliospore formation during infections by both solopathogenic haploid and dikaryon strains. Constitutive expression of UMAG_04778 in solopathogenic strains led to the pigmentation of colonies grown on PDA and to the pigmentation, rounding, increased volume and rupture of cells grown in PDB. The gene expression pattern and mutant phenotypes led us to hypothesize that UMAG_04778 has a role in regulating morphological transitions leading to teliospore development in U. maydis. Data on characterization of this gene’s function was presented.

Virulence of isolates of Claviceps purpurea on eight different genotypes of wheat. J. G. MENZIES, H. W. KLEIN-GEBBINCK, A. GORDON AND D. M. O’SULLIVAN. Morden Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 101 Route 100, Morden, MB R6M 1Y5, Canada; (H.W.K.-G.) Lacombe Research and Development Centre, Beaverlodge Research Farm, AAFC, P.O. Box 29, Beaverlodge, AB T0H 0C0, Canada; (A.G.) National Institute of Agricultural Botany, Huntingdon Road, Cambridge CB3 0LE, UK; and (D.M.O’S.) School of Agriculture, Policy and Development, University of Reading, Whiteknights, Reading RG6 6AR, UK

Ergot of cereals, caused by Claviceps purpurea (Fr.) Tul., results in yield loss and downgrading of infested grain because of toxic alkaloids in the sclerotia. Resistant wheat genotypes are known, but their effectiveness against different C. purpurea isolates has not been studied. The objective of this study was to examine the pathogenic variability among isolates of C. purpurea on wheat lines differing in resistance. Forty-one single spore C. purpurea isolates were developed from western Canadian and UK collections and inoculated onto a set of wheat genotypes composed of durum wheat lines ‘Melita’, ‘Kyle’ and 9260B-173A, and hexaploid spring wheat lines ‘Cadillac’, ‘Vista’, ‘Kenya Farmer’, ‘Lee’ and HY630. Honeydew production and weight of sclerotia produced per spike were assessed. ANOVA indicated significant effects of the wheat lines, pathogen isolates and wheat line by pathogen isolate interactions for both honeydew and sclerotia weight production. This suggests a vertical resistance interaction (i.e. a gene for gene interaction). Correspondence analysis indicated the lowest honeydew and sclerotia weight production occurred on wheat line 9260B-173A, followed by ‘Kenya Farmer’. Pathogen isolates from the UK produced more honeydew and greater sclerotia weight than isolates from Alberta, which produced more than isolates from Saskatchewan and Manitoba. Isolates obtained from rye crops produced more honeydew and greater sclerotia weight than those from other host crops, with isolates from barley producing the least. Variability in virulence exists in populations of C. purpurea, and knowledge of virulence phenotypes is necessary to effectively breed for resistant commercial lines.

Effect of long-term phosphorus fertilizer management on phosphorus and cadmium concentration and yield of soybean. R. M. MOHR, C. A. GRANT (ret’d), G. R. BARDELLA AND D. N. FLATEN. Brandon Research and Development Centre, Agriculture and Agri-Food Canada, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; and (G.R.B., D.N.F.) Department of Soil Science, University of Manitoba, 13 Freedman Crescent, Winnipeg, MB R3T 2N2, Canada

Rapid expansion of soybean (Glycine max L.) production in Manitoba has generated a need for information regarding phosphorus (P) nutrition in this crop. Field studies were conducted at three locations in Manitoba from 2013 to 2015 to determine the effect of long-term P fertilizer management on P and cadmium (Cd) concentration in soybean. The residual effects of four rates of monoammonium phosphate fertilizer (0, 20, 40, 80 kg P ha⁻¹) and three fertilizer sources varying in Cd concentration (0.4 mg Cd kg⁻¹, 70 mg Cd kg⁻¹ and 210 mg Cd kg⁻¹), applied annually from 2002 to 2009, were evaluated. The long-term application of increasing rates of P fertilizer increased Olsen P concentration in surface soil, while DTPA-extractable Cd concentration increased as a function both of increasing P fertilizer rate together with increasing Cd concentration in the applied fertilizer. Midseason biomass P and seed P concentrations were positively related to soil P concentration, with Olsen P accounting for 40–78% of the variability in plant P. Increasing fertilizer rates and/or increasing Cd concentrations in applied fertilizer resulted in consistently higher plant tissue and seed Cd concentrations in soybean, and reflected differences in DTPA-extractable Cd levels in the soil. Seed yield of soybean did not increase with increasing Olsen P concentration, suggesting that soybean was generally able to effectively access sufficient soil P to optimize crop yield under the wide range of soil test P concentrations, ranging from 5 to 93 mg kg⁻¹, arising from previous P management practices.

Mitigation of stripe rust and leaf spot diseases in winter wheat in western Canada. K. NABETANI, J. M. LOBO, B. L. BERES, K. COLES, R. ABOUKHADDOUR, T. K. TURKINGTON, W. E. MAY AND H. R. KUTCHER. Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada; (B.L.B., K.C., R.A.) Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada (AAFC) 5403–1 Avenue South, Lethbridge, AB T1J 4B1, Canada; (T.K.T.) Lacombe Research and Development Centre, AAFC, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada; and (W.E.M.) Indian Head Research Farm, P.O. Box 760, R.R. #1 Government Road, Indian Head, SK S0G 2K0, Canada

Stripe rust disease of wheat, caused by Puccinia striiformis f. sp. tritici Eriks., is prevalent throughout western Canada. This study was conducted to evaluate disease impact on winter wheat at Lethbridge and Lacombe, AB and Saskatoon and Indian Head, SK. The effects of fungicide (combination of metconazole and pyraclostrobin) on stripe rust and leaf spot severity, and yield and quality of winter wheat were observed after fungicide application at three timings. Four cultivars varying in disease resistance, ‘AC Bellatrix’, ‘Moats’, ‘Radiant’ and ‘CDC Osprey’ were seeded in the 2015/2016 crop season. Fungicide was applied in the autumn, spring, or both autumn and spring to each cultivar and effects were compared with unsprayed checks. Under high stripe rust pressure, severity on susceptible cultivars, ‘AC Bellatrix’ and ‘CDC Osprey’, and severity of leaf spot on these cultivars and ‘Radiant’, were reduced by a single application in spring or applications in autumn and spring. Stripe rust severity was reduced from 78% to less than 5% on ‘AC Bellatrix’. Yield increased by nearly 30%, and quality was also improved in this cultivar. ‘Radiant’ was more susceptible to leaf spot than other cultivars, but had low stripe rust severity and the benefit of fungicide depended on location. ‘Moats’, which is highly resistant to stripe rust, did not benefit from fungicide application. Stripe rust and leaf spot susceptible cultivars were effectively controlled with spring fungicide application while autumn application alone appeared ineffective for disease control. The dual application in spring and autumn did not offer additional benefits.

Principal components analysis facilitates selection of breeding lines with optimum trait combinations. A. NAKHFOROOSH, C. MCCARTNEY, A. BEATTIE, S. KUMAR, A. BURT AND J. MITCHELL FETCH. Brandon Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; (C.M.) Morden Research and Development Centre, AAFC, 101 Route 100, Morden, MB R6M 1Y5, Canada; and (A.B.) Crop Development Centre, University of Saskatchewan, College of Agriculture and Bioresources, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

The primary goal of many plant breeding programmes is to develop new varieties with an optimized combination of traits. However, in many cases there is an inherent trade-off when combining traits (e.g. yield and β-glucan in oat). We assessed the suitability of using principal components analysis (PCA) to select the best lines carrying several desired traits when they do not combine well. A cross was made to incorporate the high β-glucan content from ‘CDC Morrison’ into the high-yielding ‘AC Morgan’ background. A population of 191 recombinant inbred lines (RILs, F6:F9), along with the parents and three check lines, was planted at Brandon, MB in 2016 in an alpha-lattice design with three replications. The agronomic traits (seed yield, plant height, maturity and lodging) were measured in the field, and the quality traits (β-glucan content, plumpness and test weight) were subsequently determined on RIL composites using standard methods. Agronomic traits varied significantly among investigated lines and checks. Seed yield and β-glucan were not correlated in analysis of trait averages across replications, however, a significant and negative correlation was observed between plumpness and β-glucan (r = −0.14, P = 0.052). Principal components analysis revealed how selection for yield and β-glucan leads to trade-offs. These results showed the usefulness of PCA by visualization of traits and lines in biplots in order to identify the best lines in a segregating population when traits are negatively associated.

Applications of soil-applied fungicides to manage phytophthora root rot on chili (Capsicum annuum) in Pakistan. K. NAWAZ, A. A. SHAHID, S. IFTIKHAR, W. ANWAR AND M. N. SUBHANI. Institute of Agricultural Sciences, University of the Punjab, 54590 Lahore, Pakistan; and (A.A.) Center of Excellence in Molecular Biology, University of the Punjab, 54590 Lahore, Pakistan

Chili (Capsicum annuum L.) is attacked by many fungal pathogens, including members of Oomycetes which are responsible for root rot worldwide. Fungal pathogens cause economic losses in different chili growing areas of Pakistan. Most of the plant tissues, including roots, crowns, fruit, and leaves, are vulnerable to Phytophthora capsici Leonian. It is very difficult to manage the phytophthora root rot of chili as different commercial varieties are extremely susceptible to P. capsici. The causal agent of the disease was isolated on corn meal agar (CMA), and identified on a morphological basis by using available taxonomic keys. The pathogen was also confirmed on a molecular basis through the internal transcribed spacer region. The BLASTN results showed 100% homology with already reported sequences of P. capsici in the NCBI database. Most of the farmers have conventionally relied on foliar fungicide applications to control phytophthora root rot in spite of their incomplete effectiveness. In this study, in vitro plate assay, seed soaking and foliar applications of six fungicides were evaluated against root rot of chili. In vitro assay revealed that significant inhibition of linear growth was obtained with triflumizole at 7.0%, followed by thiophanate methyl (8.9%), etridiazole (6.0%), propamocarb (5.9%) and 7.5% with mefenoxam and iprodione for P. capsici. The promising treatments of in vitro plate bioassay were evaluated in pot experiments under controlled conditions in the greenhouse. All fungicides were applied at 6-day intervals. Results of the pot experiment showed that all treatments considerably inhibited the percentage of P. capsici root rot incidence. In addition, application of seed soaking with all six fungicides combined with the foliar spray of the same components showed a significant reduction in root rot incidence. The combined treatments of all fungicides as in vitro bioassay, seed soaking followed by foliar spray are considered non-harmful control methods which have advantages and limitations. Hence, these applications proved effective and harmless for the management of soil-borne plant pathogens.

Pathogen growth inhibition and disease suppression on cucumber (Cucumis sativus) and canola (Brassica napus) plants with Active Flower, a foliar nutrient spray containing boron. L. NI AND Z. K. PUNJA. Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada

Greenhouse cucumber (Cucumis sativus L.) and canola (Brassica napus L.) are grown extensively in Canada and fungal diseases are a major limiting factor during commercial production of these crops. The effectiveness of Active Flower™ (AF), a fertilizer containing 3.0% boron (B) plus 8:4:12 of N:P:K in reducing the severity of several diseases was evaluated in this study. Six fungi were selected based on their importance as plant pathogens, and included Sclerotinia sclerotiorum (Lib.) de Bary, Botrytis cinerea Pers.:Fr., Pythium dissoticum Drechs., Fusarium oxysporum Schlecht. emend Snyder & Hans., Phoma lingam (Tode:Fr.) Desmaz. and Thielaviopsis basicola (Berk. & Broom) Ferraris. They were grown in potato dextrose broth (PDB) with four concentrations (0, 1, 3 and 5 mL L⁻¹) of AF. Growth inhibition was observed at rates of 1 and 3 mL L⁻¹, with the most pronounced effect seen at 3–5 mL L⁻¹. These concentrations were applied to cucumber ‘Tasty Green’ and canola ‘Westar’ grown under greenhouse conditions. Four applications were made at weekly intervals, and pathogen inoculation was made after the third application. Cucumber plants inoculated with Pythium and Fusarium and treated with AF had higher dry weights compared with the water control, with 3 mL L⁻¹ giving the greatest increase. The number of powdery mildew (Podosphaera xanthii (Castagne) Braun & Shishkoff) colonies on cucumber leaves was significantly reduced by AF at 3 and 5 mL L⁻¹ when applied at the onset of infection. On canola plants, AF at 1, 3 and 5 mL L⁻¹ increased dry weight and reduced disease development on leaves due to Sclerotinia and Phoma. Preliminary experiments showed that phenolic content, chlorophyll, B and N levels in foliage receiving AF were significantly increased.

High resolution DNA melting (HRM) assay for detection of Rx1 and Rx2 for rapid high-throughput selection for extreme resistance to Potato virus X in potato. X. NIE, V. DICKISON, S. BROOKS, M. SINGH AND A. MURPHY. Fredericton Research and Development Centre, Agriculture and Agri-Food Canada, 850 Lincoln Road, Fredericton, NB E3B 4Z7, Canada; (M.S.) Agricultural Certification Services, Fredericton, NB E3B 8B7, Canada; and (S.B.) Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada

Potato selections are regularly assessed for their response to Potato virus X (PVX) infection prior to their release by AAFC’s potato breeding programme. Extreme resistance (ER) to PVX has been detected in many potato breeding clones and advanced selections. Assessment of the existing PCR-gel electrophoresis based methods for detection of Rx1 and Rx2, the genes that independently control ER to PVX, indicated that the 5Rx1F/5Rx1R primer pair led to reliable detection of Rx1. However, the methodology is time consuming and it does not differentiate the absence of Rx1 from a failed PCR reaction. A newly designed primer pair that targets both Rx1 and rx1 produced an amplicon for both alleles. When the primer pair is combined with 5Rx1F/5Rx1R, respective amplicons, although not distinguishable in regular agarose gel electrophoresis, were produced. When subjected to a high resolution DNA melting (HRM) assay, two distinct melting profiles for Rx1 and Rx1/rx1, respectively, were detected. The efficacy of the HRM assay was validated in potato cultivars/clones with known phenotypes, indicating its potential for high-throughput selection of potato carrying Rx1. HRM assays of over 600 progeny from 12 crosses involving various parents correctly detected the presence or absence of Rx1 in each progeny, allowing accurate prediction of the phenotype. Progeny that tested positive for Rx1 by HRM exhibited ER to PVX whereas progeny that tested negative for Rx1 were susceptible to PVX infection. The genotype of each parent and the possible presence of Nx in two Rx1-possessing parents were discussed.

Identification of immunity-related LRR-containing genes in Cannabis sativa. N. PÉPIN AND D. L. JOLY. Université de Moncton, 18 avenue Antonine-Maillet, Moncton, NB E1A 3E9, Canada

Cannabis sativa L. is a multi-purpose plant that has been domesticated for its bast fibre in the stem, its seed of high nutritional value and its appealing medicinal properties. However, its cultivation faces important phytosanitary problems mainly due to diseases like powdery mildew (caused by various fungal species), gray mould (Botrytis cinerea Pers.) and white mould (Sclerotinia sclerotiorum (Lib.) de Bary). Here, we used genomic and transcriptomic data from C. sativa to search for proteins that encode conserved domains related to plant immunity, including: CC (Coiled-Coil), TIR (Toll/Interleukin-1 Receptor), NBS (Nucleotide-Binding Site), LRR (Leucine-Rich Repeat), etc. We identified several immunity-related gene candidates in C. sativa which have the typical architecture of Receptor-Like kinase (RLKs) and Receptor-Like Proteins (RLPs) candidates involved in PAMP-Triggered Immunity (PTI), or resistance gene (R genes) candidates involved in Effector-Triggered Immunity (ETI). Candidates were characterized based on conserved protein motifs, gene duplication events, chromosomal locations, phylogenetic relationships and gene expression analysis. Gene expression profiling using existing RNA-seq data revealed the expression of these genes in a wide range of tissues, and an additional RNA-seq dataset of C. sativa leaves infected with powdery mildew is currently being analysed. This study will provide insight into the evolution of immune receptors in the C. sativa genome, which may aid efforts to further characterize the function of these predicted genes and develop disease-resistant cultivars.

Genetic diversity of blackleg (Leptosphaeria spp.) isolates in Alberta. E. PEREZ-LARA, R. FREDUA-AGEYMAN, S. F. HWANG AND S. E. STRELKOV. Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (R.F.-A., S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17 507 Fort Road NW, Edmonton, AB T5Y 6H3, Canada

Blackleg can be a devastating disease of Brassica napus L. (rapeseed/canola) and occurs in most countries where this crop is grown. The disease is caused by the Leptosphaeria maculans (Desmaz.) Ces. & De Not.–Leptosphaeria biglobosa Shoemaker & Brun complex. In Alberta, blackleg disease has been reported in more than 70% of fields surveyed. The objective of this study was to evaluate the extent of genetic diversity in L. maculans and L. biglobosa populations in the province. Canola stem tissues showing symptoms of blackleg were collected from 110 fields visited in 2016. Single-spore isolation was carried out on samples from each field and one isolate per field was randomly selected for DNA extraction. PCR amplification with L. maculans and L. biglobosa-specific DNA markers and with inter-simple sequence repeat (ISSR) markers suggested that all of the isolates analysed from the 110 fields were L. maculans, with no isolates of L. biglobosa identified in 2016. Significant genetic diversity existed among the L. maculans isolates, indicating the potential for different virulence phenotypes on host plants.

Meeting the challenges of carrot crown rot in Prince Edward Island. R. D. PETERS, M. M. MACDONALD, H. LU, A. RYAN, S. ADAMS, J. DRISCOLL, A. MACPHAIL, D. GREGORY, B. CRANE, G. DYKERMAN, L. HALE AND G. WANG-PRUSKI. Charlottetown Research and Development Centre, Agriculture and Agri-Food Canada, 440 University Avenue, Charlottetown, PE C1A 4N6, Canada; (M.M.M., B.C., L.H.) University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3, Canada; (H.L., G.W.-P.) Department of Plant, Food, and Environmental Sciences, Dalhousie University, P.O. Box 550, Truro, NS B2N 5E3, Canada; (A.R., S.A., J.D.) Prince Edward Island Horticultural Association, P.O. Box 2232, Charlottetown, PE C1A 8B9, Canada; and (G.D.) Brookfield Gardens, 1067 Millboro Road, Brookfield, PE C0A 1Y0, Canada

Fusarium crown rot has caused economic losses in Prince Edward Island (PEI), Canada in recent years. Crown lesions on carrots have resulted in rejection rates as high as 60–70% in some seasons. Isolates collected from symptomatic carrot crowns from 2010–2016 have been predominantly identified as Fusarium avenaceum (Fr.) Sacc. or F. oxysporum Schlechtend:Fr. Studies to determine isolate pathogenicity revealed that isolates of F. avenaceum were highly aggressive on carrot tissue, whereas isolates of F. oxysporum were only weakly pathogenic. Based on both disease incidence and severity parameters, therefore, F. avenaceum is the major carrot crown rot pathogen causing crop loss in PEI. A collection of isolates obtained from 2010–2016 from diverse regions of PEI were tested for fungicide sensitivity in amended agar assays, using concentrations of technical grade difenoconazole, fludioxonil or thiabendazole. The growth of all isolates of F. avenaceum was suppressed by the three fungicides in vitro, however, isolates were somewhat more sensitive to fludioxonil and thiabendazole (EC₅₀ < 1 mg L⁻¹) as compared to difenoconazole (EC₅₀ < 10 mg L⁻¹). These data were used as the basis for the establishment of field trials from 2012–2016 to test various chemical programmes for efficacy against fusarium crown rot. To date, no foliar or soil-applied chemical programmes have been shown to provide efficacy against this disease. In the absence of chemical control, best management practices to control fusarium crown rot of carrot in PEI will rely on the prevention of crown injury to limit pathogen infection and the choice of less susceptible cultivars.

Foliar and root pathogens of Cannabis sativa (marijuana) in British Columbia. Z. K. PUNJA AND G. RODRIGUEZ. Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada; and (G.R.) Agrima Botanicals Corporation, 260–22529 Lougheed Highway, Maple Ridge, BC V2X 0T5, Canada

An increase in the cultivation of Cannabis sativa L. (marijuana) plants in Canada is associated with increased incidence and severity of various diseases, many of which have not been previously reported. In this study, hydroponically grown C. sativa were sampled over a 4-year period (2013–2017) to determine the prevalence of foliar and root pathogens. Following isolation, pathogenicity studies were conducted to establish the extent of disease symptoms caused by the recovered microbes. Browning and rotting of roots was shown to be caused by Pythium dissotocum Drechsler and P. myriotylum Drechsler. In addition, Fusarium oxysporum Schlecht. emend. Snyder & Hansen and F. solani (Mart.) Sacc. were also isolated from symptomatic roots, which upon reinoculation onto healthy plants, caused stunting, yellowing and wilting. The potential for spread of F. oxysporum through the hydroponic system was confirmed by its detection in the recirculating nutrient solution. A rot of the flower buds was associated with Botrytis cinerea Pers., which caused Botrytis bud rot. In addition, the pathogenicity of Penicillium olsonii Bainer & Sartory, and to a lesser extent, P. copticola Houbraken, Frisvad & Samson, which were also recovered from diseased flower buds, is reported for the first time, causing penicillium bud rot. These species were also present on dried flower buds destined for sale. Powdery mildew was found to be caused by Golovinomyces (Erysiphe) cichoracearum sensu Salmon. The pathogen was detected on vegetatively propagated cuttings. The management of these pathogens on C. sativa will require the implementation of sanitation methods, biological control agents, and chemical products adopted from greenhouse vegetable production, as well as the use of pathogen-free propagation materials. Breeding for disease resistance should also become a priority.

Identification and screening of durable rust resistance-related metabolites in various wheat cultivars. N. RAJAGOPALAN, Y. LU, W. ZHANG, K. BOYLE, B. MCCALLUM, C. HIEBERT, E. REIMER, W. MCNABB, P. FOBERT, M. CUPERLOVICH-CULF AND M. C. LOEWEN. Aquatic and Crop Resources Development, National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK S7N 0W9, Canada; (B.M., C.H., E.R., W.M.) Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada; (P.F., M.C.L.) Aquatic and Crop Resources Development, National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada; and (M.C.-C.) Information and Communication Technology, National Research Council of Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6, Canada

For almost a century, the gene Lr34 has conferred durable resistance against fungal rust diseases, making it one of the most important resistance genes in wheat. Recently, we showed that the LR34Sus homologue of the protein (which does not provide disease resistance) may be an importer of chlorophyll catabolite compounds, while others have shown that close relatives of these compounds accumulate in the flag leaves of Lr34-containing plants. We are expanding on these findings toward a broader evaluation of metabolites linked to resistance. Toward this we report here a comparative study of the metabolite makeup of the flag leaves of a collection of germplasm, using LC-MS technology. Wheat lines including Thatcher and Thatcher Lr34 as well as a variety of other near-isogenic lines with various resistance genes presented individually or stacked with each other, as well as select sister pairs (± Lr34) arising from a Sumai3 × Thatcher cross. From these data we have identified a single unique novel metabolite (P6) that uniquely accumulates to higher levels in plants carrying Lr34 and see some preliminary evidence of additional metabolic separation in broader metabolomics analyses.

Characterization of flax genotypes for resistance to Oidium lini. K.Y. RASHID. Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada

Powdery mildew caused by the fungus Oidium lini Skoric, is a major disease affecting flax (Linum usitatissimum L) worldwide. This disease was first identified in Canada in 1997, and the incidence and severity have been on the rise in Canada, causing major reductions in yield and quality of the seed and fibre. This research aimed at characterizing the resistance in flax. Commercial flax cultivars and hundreds of flax genotypes including the flax core collection and improved breeding lines have been tested under natural inoculum pressure in the field, and to a local isolate of powdery mildew under controlled growth cabinet conditions. Results showed a moderate level of resistance in most Canadian flax cultivars, a wide range of reactions in the core collection and breeding lines, and high level of resistance in some breeding lines with a high correlation between the field and the controlled indoor testing. Resistant breeding lines are potentially useful in breeding higher levels of resistance in future flax cultivars for mitigating the risk from this disease.

Structural organization and haplotypes of rust resistance genes in flax. S. RAVICHANDRAN, F. M. YOU, K. Y. RASHID, L. YOUNG, H. M. BOOKER AND S. CLOUTIER. Ottawa Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (F.M.Y., K.Y.R.) Morden Research and Development Centre, AAFC, 101 Route 100, Morden, MB R6M 1Y5, Canada; and (L.Y., H.M.B.) Crop Development Centre, Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

Flax (Linum usitatissimum L.) and flax rust, caused by the fungal pathogen Melampsora lini (Ehrenb.) Lév., were the basis of the pathosystem studied by Dr H. Flor when he hypothesized the gene-for-gene concept in the 1950s. Since then, five rust resistance loci named K, L, M, N and P have been identified to contain race-specific rust resistance genes. The L locus harbours a single gene with at least 12 alleles while M, N and P have tandemly duplicated genes, in addition to multiple allelic forms. With the exception of locus K, DNA sequences for some allelic forms have been defined but a comprehensive understanding of all loci and their genetic diversity are still lacking. First, we performed a structural analysis of the four known loci to illustrate their evolution through duplication mechanisms. Second, a set of 30 differential lines each containing different alleles of the five genes was sequenced using Illumina short reads to a coverage of ~28×. Reads homologous to each of the rust resistance genes were extracted and de novo assembled. Here, we report on the L allelic series which is highly polymorphic, displaying multiple indels and single nucleotide polymorphisms. Comparisons with previously published sequences indicated several discrepancies in DNA sequence. The present analysis will clarify sequence identity and enhance our knowledge of the diversity and functionality of flax rust resistance genes.

Evaluation of weather-based forecasting models and cultivar resistance to manage leaf curl (Colletotrichum fioriniae) on celery crops in Ontario. S. REYNOLDS, M. J. CELETTI, K. JORDAN AND M. R. MCDONALD. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; and (M.J.C.) Ontario Ministry of Agriculture, Food and Rural Affairs, 1 Stone Road West, Guelph, ON N1G 4Y2, Canada

Colletotrichum fioriniae (Marcelino & Gouli) Shivas & Tan causes leaf curl on celery in Ontario. The disease renders the crop unmarketable when lesions develop along the stalk and when crown rot develops. The objectives of this study were to: (i) evaluate disease forecasting programmes to reduce the number of fungicide sprays while maintaining disease control, and (ii) to screen for cultivar resistance. For the forecasting trial, the fungicide Quadris Flowable (azoxystrobin 25%) was alternated with Switch 62.5WG (cyprodinil 37.5% and fludioxonil 25.0%) and were applied on cv. ‘TZ 6200‘. Spray timings were determined using TOMCAST with a threshold of 15 disease severity value, and BOTCAST at a cumulative disease severity index of 21. A weekly calendar spray and a no-spray control were included. Disease management was achieved using TOMCAST, with five fungicide applications compared with the seven sprays applied on a calendar spray basis. BOTCAST prompted only one spray and disease severity was equivalent to that of the no-spray control. The per cent of marketable weight was >98% for TOMCAST and the calendar spray, while BOTCAST and the no-spray control had <70%. For the cultivar trial, 12 cultivars were evaluated for resistance to C. fioriniae. Cultivars ‘TZ 9075', ‘TZ 6010', ‘Hadrian’ and ‘Merengo’ were the least susceptible with a per cent marketable yield greater than 70%, while ‘TZ 9779ʹ was the most susceptible with per cent marketable yield less than 20%. Cultivar selection and TOMCAST can be incorporated into the integrated pest management programme to manage celery leaf curl in Ontario.

Effector triggered immunity versus non-host resistance against potato cyst nematodes – a transcriptomic analysis. M. SABEH, E. LORD, M. ST-ARNAUD AND B. MIMEE. Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 boulevard Gouin, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada; and (M.S., M.S.-A.) Biodiversity Centre, University of Montreal and Montreal Botanical Garden, 4101 Sherbrooke East, Montreal, QC H1X 2B2, Canada

The potato cyst nematodes Globodera rostochiensis (Woll.) Behrens and Globodera pallida (Stone) Behrens, are major plant parasitic nematodes affecting Solanaceous spp. including potato, tomato and eggplant. They are quarantine organisms in Canada and many other countries. These nematode species have developed specialized proteins called effectors to outwit plant defences. Some plants as a result evolved resistance based on the recognition of these effectors, which was again overcome by virulent nematode pathotypes. RNA sequencing of different Globodera spp. and pathotypes at the parasitic stage was used to identify sequence variations and differentially expressed genes. Globodera rostochiensis and G. pallida were directly compared to Globodera tabacum (Lownsbery & Lownsbery) Behrens and Globodera mexicana (Campos-Vela) Subbotin et al. because of the difference in their primary host and genetic similarities. Pathotypes of G. rostochiensis were also compared to understand their ability to parasitize different potato genotypes. These analyses revealed 22 genes unique to potato infecting species, G. rostochiensis and G. pallida, including 10 that have a signal peptide but no transmembrane domain suggesting they are secreted and potentially implicated in pathogenicity. These analyses also highlighted genes, including the RBP-1 and RBP-4 effector genes, as being significantly more expressed as well as having sequence variation which show very strong evidence of being associated with pathogenicity in the same two species. Globodera rostochiensis pathotype analysis showed members of the SPRYSEC effector family strongly associated with avirulence to the H1 resistance gene, deployed in commercially available resistant potato.

Determining the risk of fusarium root rot on field pea by greenhouse soil bioassay and qPCR analysis. S. SAFARI, L. HALL AND S. CHATTERTON. Faculty of Agricultural, Life & Environmental Sciences, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (S.S., S.C.) Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403–1 Avenue South, Lethbridge, AB T1J 4B1, Canada

Field avoidance is one of the most recommended management options to minimize impact of pea root rot pathogens. Field indexing tools commonly used to quantify pathogens in fields are real time PCR (qPCR) for pathogen quantification or greenhouse bioassays. The objective of this study was to determine the efficiency of these tools for predicting fusarium root rot risk. Field surveys were conducted in 14 commercial pea fields across Alberta to collect soil and root samples. Overall, 140 soil and root samples were collected from 10 sites in each field. Root samples were rated for severity and used for PCR analysis to determine causal organisms. To determine minimum inoculum potential, field soils were serially diluted, planted to peas in a greenhouse, and root rot severity measured by visual assessment. Significant difference in disease severity was observed when the proportion of field soils was below 10% but there was no significant difference between plants grown in soil collected from symptomatic and asymptomatic sites in a field. Results showed low correlation between DNA quantities of Fusarium avenaceum (Fr.) Sacc. or Fusarium solani (Mart.) Sacc. in the soil and disease severity. This could be due to low pathogen DNA recovery from soil samples and/or presence of PCR inhibitors in soil DNA extracts. To improve the accuracy of estimation, soil DNA will tested using droplet digital PCR which is not affected by PCR inhibitors. The results obtained from the disease severity assessments of the fields soil and quantification of F. avenaceum and F. solani DNA from soil will be compared to determine the efficiency of these methods in predicting disease risk in pea fields.

Comparative performance of annual and perennial forage legumes for forage production in north-western Ontario. T. S. SAHOTA. Thunder Bay Agricultural Research Station, 435 James Street South, Thunder Bay, ON P7E 6S7, Canada

Alternate forage legumes could compensate production losses due to winter kill of alfalfa. An experiment in completely randomized block design with 15 treatments (alfalfa, berseem clover, at standard seed rates, fenugreek at 15, 30 and 45 kg ha⁻¹, galega at 25, 35 and 45 kg ha⁻¹, galega/and alfalfa mixtures with berseem at 6.5 and 13 kg ha⁻¹, and alfalfa red clover mixture), replicated four times, was initiated at Thunder Bay in 2011. Results, averaged over 2012–14, indicated that galega seeded at 25 kg ha⁻¹ produced the highest dry matter yield of 5.6 Mg ha⁻¹ year⁻¹ (~20% higher than alfalfa). Increasing seed rate of galega from 25 to 45 kg ha⁻¹ didn’t help in increasing its yield. First cut protein content in galega at 25 kg seed ha⁻¹ (26.1%) was higher than that in alfalfa (22%). In the second cut, protein content in galega at different seed rates was either similar or somewhat better than alfalfa. Galega had higher RFV than alfalfa. Calcium, sodium and boron seemed to be lower, but copper, zinc, iron and manganese were higher in galega than that in alfalfa. Intercropping alfalfa and galega with berseem improved the forage dry matter yield in the initial years only. Fenugreek yield was significantly lower than other legumes. In 2016, galega at 35 kg ha⁻¹ recorded 2.02 Mg ha⁻¹ higher yield than its seeding at 25 kg kg ha⁻¹ and 3.07 Mg ha⁻¹ higher yield than alfalfa. Fifteen farmers in Ontario would be seeding galega for the first time in 2017 in 1000 acres.

Effect of autumn and spring applied urea and ESN on spring wheat production in north-western Ontario. T. S. SAHOTA. Thunder Bay Agricultural Research Station, 435 James Street South, Thunder Bay, ON P7E 6S7, Canada

Spring wheat is an important cash crop in NWO with short growing season. Autumn application of N could help seeding early in spring. Autumn applied urea may lead to high N losses. ESN could be an alternative to urea; though in cold springs it may be too slow to release N. Part substitution of N from urea with ESN could be better than urea alone. A field experiment, with nine treatments (a no N check, and N at 80 kg ha⁻¹ from urea, ESN and urea + ESN (3:1/and 1:1 on N basis) – applied in the autumn and spring), was conducted in completely randomized block design, replicated four times, during 2014–16 at Thunder Bay, Ontario. Application of N irrespective of its source and time of application significantly improved the grain and straw yield and grain protein content. Results from N treatments varied with the years. In 2016, when 209 mm rainfall occurred in June, spring applied ESN gave 1.24 Mg ha⁻¹ extra grain and 0.92 Mg ha⁻¹ higher straw yield than urea. Pooled analysis over 3 years, indicated that highest grain (4.46 Mg ha⁻¹; 14.6% protein) and straw (5.52 Mg ha⁻¹) yields were obtained with spring application of urea + ESN (3:1on N basis) at 80 kg N ha⁻¹. Overall, grain yields from spring and autumn applied N were similar. Grain protein content was highest (15.3%) with spring applied ESN at 80 kg N ha⁻¹.

Evaluation of western spring wheat varieties for their production potential in north-western Ontario. T. S. SAHOTA. Thunder Bay Agricultural Research Station, 435 James Street South, Thunder Bay, ON P7E 6S7, Canada

Compared to southern Ontario and Quebec, climatic conditions at Thunder Bay are closer to Manitoba and parts of western Canada. Eleven spring wheat varieties, including Sable as a check (AAC Bailey, AAC Iceberg, AAC Innova, AAC Proclaim, AAC Redwater, BW 931, BW 932, Enchant VB, HY 1312, Sable and Whitehawk), were evaluated at Thunder Bay during 2013–15 in completely randomized block design replicated four times. WR859CL was added in 2014 and 2015. All varieties were grown with recommended management practices. Averaged over years, Hy1312, AAC Innova and WR859CL produced the highest grain yield (5.47 Mg ha⁻¹ to 5.56 Mg ha⁻¹), which was 0.85–0.94 Mg ha⁻¹ higher than Sable. AAC Proclaim was the only other variety that recorded >5.10 Mg ha⁻¹ grain yield. AAC Innova registered the highest straw yield (7.54 Mg ha⁻¹; ~1.10 Mg ha⁻¹ higher than Sable). Varieties that gave 6.50 Mg ha⁻¹ or more straw yield were AAC Iceberg, AAC Proclaim, Enchant VB and WR859CL. Producers in north-western Ontario would prefer varieties that are good for both grain and straw production; for which AAC Innova was the best fit. No lodging or serious disease infestation was observed in any of the varieties.

Evaluation of Ontario and Manitoba winter wheat varieties for their production potential in north-western Ontario. T. S. SAHOTA. Thunder Bay Agricultural Research Station, 435 James Street South, Thunder Bay, ON P7E 6S7, Canada

Winter wheat acts as a cover crop in autumn/winter, and could be a good option for grain and straw production and for spreading field operations in areas with short growing seasons. Seven Ontario and 12 Manitoba winter wheat varieties were evaluated for their production potential in two experiments in completely randomized block design replicated four times at Thunder Bay, Ontario, during 2012–15. CDC Falcon was the common check in the two experiments. All varieties were grown with recommended management practices. Averaged over years, it was found that none of the Ontario varieties (AC Morley, Keldin, Priesley, Princeton, Standard and Whitebear) gave higher grain or straw yield than CDC Falcon (6.00 Mg ha⁻¹ grain and 11.24 Mg ha⁻¹ straw yield). Whitebear (hard white) gave the lowest grain (3.63 Mg ha⁻¹) and straw (7.55 Mg ha⁻¹) yields. Only three out of 11 Manitoba winter wheat varieties (Swainson 7.58 Mg ha⁻¹, Moats 6.76 Mg ha⁻¹ and AAC Gateway 6.57 Mg ha⁻¹) recorded significantly higher grain yield than CDC Falcon. Aforesaid three varieties also produced the highest straw yields (15.5–16.4 Mg ha⁻¹); Swainson topped in the straw yield and was the best dual purpose variety. No lodging or serious disease infestation was observed in any of the varieties.

QTL mapping of seed hardness trait in common bean (Phaseolus vulgaris). K. S. SANDHU, F. M. YOU, R. L. CONNER, P. M. BALASUBRAMANIAN AND A. HOU. Morden Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 101 Route 100, Morden, MB R6M 1Y5, Canada; and (P.M.B.) Lethbridge Research and Development Centre, AAFC, 5403 1 Avenue South, Lethbridge, AB T1J 4B1, Canada

The seed hardness trait has a profound negative impact on cooking time and canning quality in dry beans. This study aims to identify the genetic factors associated with this trait, and develop associated molecular markers to better understand and tag this trait. A recombinant inbred line (RIL) population was derived from a cross between hard- and soft-seeded black bean parents H68-4 and BK04-001, respectively. Ninety-two RILs and parents were grown at two locations in southern Manitoba during the years 2014–16, and under greenhouse conditions. Seeds from both the field and greenhouse grown RIL populations were tested for seed hardness traits. The hydration coefficient and stone seed count were estimated by soaking the seeds overnight at room temperature. For mapping of genomic regions contributing to the trait, the RIL population was also genotyped using genotype by sequencing (GBS) approach. The QTL mapping revealed that in addition to the major QTL on chromosome 7 at a genomic location previously reported to affect the trait, novel QTLs with significant effects were also detected on chromosome 1 and 2. This study demonstrated that multiple genetic factors are involved in the control of this complex trait.

Use of KASP assays for the analysis of rpg4/Rpg5 gene complex for marker-assisted selection for Ug99 stem rust resistance in barley. J. SANGHA, J. R. TUCKER, W. G. LEGGE AND A. BADEA. Brandon Research and Development Centre, Agriculture and Agri-Food Canada, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada

The highly virulent stem rust Puccinia graminis f. sp. tritici Pers.:Pers./Eriks. & Henn. race TTKSK (aka isolate Ug99) has emerged as a potentially serious threat to global wheat and barley production. Sources of resistance in barley are limited and only a few cultivated and wild barley accessions have been found resistant to TTKSK. Three of these resistant lines were developed at Agriculture and Agri-Food Canada’s Brandon Research and Development Centre, Brandon, Manitoba. One of these lines, TR02272, is derived from the backcross (BC-6) of ‘AC Metcalfe’ cultivar with Q21861 as the donor parent of rpg4/Rpg5 gene complex. This line is being used to introgress stem rust resistance into barley germplasm along with a few other lines through molecular marker-assisted backcrosses and doubled haploid production. Several molecular markers for Kompetitive Allele Specific PCR (KASP) assays linked to this gene complex were designed based on the information reported by Arora et al. (2013) and publicly available sequences at NCBI. The assays target the single nucleotide polymorphisms (SNPs) corresponding to the amino acids at 205, 217 and 1287. This approach increased the accuracy and automated the screening process by eliminating the time-consuming analysis of PCR products by gel electrophoresis or the need to sequence the rare mutations. These KASP assays combined with a simplified and economical DNA extraction protocol provide barley researchers a rapid, cost-efficient, and reliable method of screening for Ug99 stem rust resistance.

Indian cup plant (Silphium perfoliatum): promising results of a possible forage for the Canadian prairies. M. P. SCHELLENBERG. Swift Current Research and Development Centre, Agriculture and Agri-Food Canada, P.O. Box 1030, Swift Current, SK S9H 3X2, Canada

Indian cup plant (Silphium perfoliatum L.) has been suggested as a plant with potential as a forage or biogas feedstock. This is a perennial species native to the Eastern USA and Canada with an ability to spread rapidly. The plant can attain a plant height of up to 2 m. Presently, no work is noted for material grown in semiarid regions of North America. A study was undertaken at Swift Current Research and Development Centre, Agriculture and Agri-Food Canada to examine the plants’ potential as a forage. A randomized complete block design was utilized to examine five populations in a field nursery. Plants were harvested 20 July 2016 at the bud stage removing all material 15 cm above the soil surface after being planted in May 2015. Biomass was greatest for the ‘A’ population (682 g per plant) with NDF (35% to 21%), ADF (35% to 21%) and crude protein (22% to 8%) being highly variable. These initial results do indicate the potential of the Indian cup plant as a forage in western Canada but one must also consider 2016 received well above the normal amount of precipitation. Additional research is required to determine the potential of this plant under more normal precipitation patterns. The high degree of variability in ADF, NDF and crude protein also indicates the potential for selection to improve the forage nutritional value.

The effect of selected mycorrhizae fungi on clubroot of canola. A. SEDAGHATKISH, F. AL-DAOUD, S. H. LEE, J. J. ZWIAZEK, B. D. GOSSEN AND M. R. MCDONALD. Department of Plant Agriculture, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada; (S.L., J.J.Z.) Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2E3, Canada; and (B.D.G.) Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

In previous studies with commercial biocontrol agents, clubroot (caused by Plasmodiophora brassicae Woronin) severity was reduced under controlled conditions, but only occasionally reduced in the field. The current study investigated suppression of clubroot symptoms on canola (Brassica napus L.) using the mycorrhizae fungi Piriformospora indica Verma, Glomus intraradices Schenk and Smith (AGTIV, Premier Tech), or a mixture of endo and ectomycorrhizal species in a commercial formulation (Root Rescue) in growth room studies that were replicated and repeated. Brassicae spp. rarely develop mycorrhizal associations, but the research was initiated because it was known that P. indica can colonize the roots of some Brassica crops and promote growth and stress tolerance, and that P. indica can induce disease resistance in other plants. Microscopic observation showed that canola roots were colonized by P. indica and some of the fungi in Root Rescue, but not by G. intraradices. Clubroot severity index (DSI) was slightly reduced in canola plants treated with P. indica (60% DSI as compared with 79% DSI in the untreated check) when plants were inoculated with 5 × 10⁵ resting spores mL⁻¹, but not in plants inoculated with 5 × 10⁴ or 5 × 10⁶ resting spores mL⁻¹. There were no differences among treatments in shoot fresh and dry weights. The reason that symptoms were not reduced at the lowest inoculum concentration for P. brassicae is not known. Colonization by P. indica may protect roots from infection, stimulate root growth, or induce resistance to clubroot by modifying plant metabolism.

Comprehensive investigation of gene transcript level change during teliospore germination in Ustilago maydis. A. M. SETO, M. E. DONALDSON AND B. J. SAVILLE. Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9L 0G2, Canada; and (B.J.S.) Forensic Science Program, Trent University, 1600 West Bank Drive, DNA Building, Peterborough, ON K9L 0G2, Canada

The fungal plant pathogen Ustilago maydis (DC.) Corda is dispersed as thick-walled teliospores, which are dispersed, germinate, complete meiosis, and initiate new rounds of infection. Teliospore germination is asynchronous and this is a challenge when identifying changes in gene expression. This challenge was overcome by performing RNA-seq on dormant U. maydis teliospores and teliospores induced to germinate for 9 and 18 h. RNAs in the teliospore may be at a higher or lower level than in the haploid or dikaryon cultures. Starting from either of these two levels, nine distinct patterns in transcript level change were identified during teliospore germination. The existence of these 18 patterns suggested transcriptional and post-transcriptional control of gene expression during teliospore development and germination. Gene ontology (GO) term enrichment analyses were performed to identify the biological categories that are represented in each pattern. This provided insight into the biological processes that are changing during teliospore germination. Reverse transcriptase quantitative PCR (RT-qPCR) was performed, to assess the existence of the transcript level changes indicated by RNA-seq, in a biological replicate of teliospores that have been induced to germinate. The results of RNA-seq, RT-qPCR and GO enrichment analysis will be presented, and summarized in a model of gene expression/biological function control during teliospore development and germination. This model can be used to direct future investigations into the biological processes associated with teliospore germination in the smut fungi.

Defence gene expression and metabolites accumulation in corn (Zea mays) in response to Clavibacter michiganensis subsp. nebraskensis, the causal agent of Goss’s wilt. A. B. SHUMILAK, A. SOLIMAN, L. R. ADAM, J. T. TAMBONG, L. M. REID AND F. DAAYF. Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada; (J.T.T., L.M.R.) Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (A.S.)Department of Genetics, Faculty of Agriculture, University of Tanta, Egypt

Goss’s wilt is a growing concern for corn (Zea mays L.) growers in Manitoba, Canada. Little is known about the genetic interaction between corn and the bacterial pathogen, Clavibacter michiganensis subsp. nebraskensis (Vidaver & Mandel) Davies et al. (Cmn). The objective of this study is to understand at the molecular level, how corn can defend against Cmn. Two lines of corn screened as susceptible (CO447) and tolerant (CO450) to Goss’s wilt, respectively, were inoculated with Cmn isolates that possess different aggressiveness levels. The highly aggressive Cmn isolate (CMN14–5–1) produced severe symptoms on CO447, which quickly developed water soaked lesions, and then rapidly developed into necrotic lesions. However, symptoms on CO450 exhibited chlorosis, freckling, and necrosis that did not progress beyond the initial 6 days after inoculation, with the same isolates. Similar results were observed with the less aggressive Cmn isolate (DOAB232), though symptoms were less severe. Area under disease progress curve values were estimated for both lesion length and disease severity, which yielded significant differences amongst treatments. Analysis of the expression of 31 genes associated with plant defence was performed on plants challenged with each Cmn isolate. Three genes, respiratory burst oxidase homolog protein D (rbohD), ras-related protein 7 (Rab7) and 1-deoxy-D-xylulose-5-phosphate synthase (DXS) were upregulated only in CO450. One gene, jasmonate-zim-domain protein 20 (jaz20), was upregulated only in CO447. The results of phenolic extractions from corn leaves inoculated with Cmn, and analysed using HPLC equipped with UV-PDA and fluorescent detectors, will be discussed. There is potential of developing cultivars with higher resistance to Cmn, and this research can be a foundation for it.

Optimization of a TaqMan real-time PCR for detection of Goss’s wilt pathogen in corn seeds. A. SIDIBÉ, R. XU, F. DAAYF, A. SOLIMAN, L. ADAM, L. M. REID, T. BARASUBIYE AND J. T. TAMBONG. Ottawa Research and Development Centre, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (F.D., A.S., L.A.) Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

Clavibacter michiganensis subsp. nebraskensis (Vidaver & Mandel) Davies et al. (Cmn) is the causal agent of Goss’s wilt and blight of corn. During severe epidemics, losses could be as high as 50% from systemic infections of the xylem. Even though seed transmission rates are very low, this risk leads to potential phytosanitary challenges for export countries. Recently, we published a TaqMan assay for accurate detection of Cmn in pure cultures and leaf samples. There is no publicly available assay for detection of Cmn in corn seeds. The aim of this study was to optimize our previously developed TaqMan assay for Cmn detection in corn seeds. The number of colony forming units (cfu) in cultures of strain DOAB 397 was determined. One-tenth serial dilutions were performed to obtain Cmn suspensions of 1.70 × 10⁸ to 17.0 cfu. The bacterial suspensions (200 µL) were added to different amounts (50, 100 and 200 mg) of autoclaved or un-autoclaved cornmeal and TaqMan assay performed after total DNA extraction. The different amounts of the cornmeal did not impact the detection limit. Significant differences, however, were observed between un-autoclaved and autoclaved cornmeal with a very high detection limit (10⁶ cfu) for the former. This suggests that one or more unknown biologically active factors in un-autoclaved cornmeal have a negative impact on either the Cmn colonies added or the DNA. Using autoclaved cornmeal, the detection limit was 170 cfu with the celB probe. The assay will be validated with greenhouse-infected seeds. This assay could be an invaluable tool in certifying corn seeds destined for export.

Assessing existing information about greenhouse potting media organic content and microbial profile. S. SIVAKUMAR. Van Luyk Greenhouses and Garden Centre, 1728 Gore Road, London, ON N5W 5L5, Canada

In the greenhouse industry, various types of growing media are used for growing and maintaining plants in containers or in the ground. Growing media components can have a significant impact on plant health and pest problems. Disease management in the greenhouse is challenged by the source of plant material, the greenhouse environment and the options available to effectively deal with pest management. Fertilizer and pesticide usage in the greenhouse could be better managed through optimizing growing media properties and handling. This has the added economic benefit of reducing input costs through potential savings in crop inputs while contributing to less potential waste. Growing media or soil is a dynamic, complex mixture of diverse physical, chemical and biological properties that influences plant health, pest problems and thus forms the basis for sustainable agriculture. Vast majority of organic and inorganic growing media properties are still not well described, despite being extensively used in the industry. Growing media characteristics (physical components such as peat or bark and chemical composition such as the pH) can have a significant impact on plant production and are influenced by external input (e.g. irrigation and fertilizer application) and environmental conditions (e.g. storing temperature). Farmers would be better able to manipulate the properties of their growing media to carry out sustainable greenhouse production if these properties were known in advance. Optimal handling practices for growing media in the greenhouse industry are not well described. This fundamental information about growing media will assist greenhouse operators in maintaining their farming operations environmentally friendly.

Management of injury by Striacosta albicosta (Lepidoptera: Noctuidae) and deoxynivalenol content in maize. J. L. SMITH, V. LIMAY-RIOS, D. C. HOOKER AND A. W. SCHAAFSMA. Department of Plant Agriculture, University of Guelph, Ridgetown Campus, University of Guelph, 120 Main Street East, Ridgetown, ON N0P 2C0, Canada

Western bean cutworm, Striacosta albicosta Smith (Lepidoptera, Noctuidae) has become a key ear-feeding maize pest in Ontario, Canada that is challenging to control due to tolerance to commonly used transgenic Bacillus thuringiensis (Bt) events. Infection by Fusarium graminearum Schwabe frequently occurs in Ontario resulting in mycotoxin contamination of maize grain, particularly deoxynivalenol (DON). The objectives of this study were to evaluate the impact of injury by S. albicosta on mycotoxin accumulation and to evaluate Bt-maize events, alone, or in combination with insecticides and fungicides for control of S. albicosta injury and DON accumulation. A positive response was found between DON, injury and risk of F. graminearum infection during the silking period. The Vip3A event provided superior protection from S. albicosta injury over insecticide treatment of non-Bt or Cry1F hybrids. Injury reduction was similar among pyrethroid and diamide insecticides, applied alone or pre-mixed at early VT or R1 stages. Lower DON concentrations were observed with chlorantraniliprole tank-mixed with prothioconazole during VT/R1 or with chlorantraniliprole + £-cyhalothrin at early VT followed by prothiconazole at R1. A combined insecticide/fungicide treatment applied at silk emergence is the most effective management approach in regions with frequent incidence of this pest complex in the absence of F. graminearum-tolerant maize hybrids expressing high-dose insecticidal proteins against S. albicosta.

Secretome analysis of Clavibacter michiganensis subsp. nebraskensis; the Goss’s wilt bacterial pathogen of corn under induction with xylem sap. A. SOLIMAN, C. RAMPITSCHAND AND F. DAAYF. Department of Genetics, Faculty of Agriculture, University of Tanta, Egypt; (C.R.) Morden Research and Development Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5, Canada; and (F.D.) Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

The host specificity of Clavibacter michiganensis subspecies is still not fully understood, as different subspecies may colonize different hosts without developing disease. Our goal in this research was to investigate changes in the secretome profile of Clavibacter michiganensis subsp. nebraskensis (Vidaver & Mandel) Davies et al. (Cmn) under induction with corn (host) or tomato (non-host) xylem sap. Two Cmn isolates, Cmn14–5–1 and DOAB232, that possess high and low level of aggressiveness, respectively were induced with xylem sap of corn (CXS) or tomato (TXS). Secreted proteins in the supernatant were extracted and digested with trypsin. Tryptic peptides were injected into LC-ESI- MS/MS, and then MS spectra were searched on the Mascot engine against Cmn and maize databases. In CXS, the highly aggressive Cmn isolate, Cmn 14-5–1 produced higher levels of cell wall degrading enzymes such as cellulase (CelA), endoglucanase and numerous hydrolases. High levels of protein degrading enzymes, such as serine peptidase, aminopeptidase, and metallopeptidase that can suppress plant defence proteins were also produced by Cmn 14-5–1. Catalase and carbonic anhydrase proteins, ROS scavengers, showed high abundance in the Cmn14-5-1 isolate in comparison to DOAB232 which may provide some protection against plant ROS during the interaction. Generally, DOAB232 had a weak response to CXS and even weaker to TXS induction. Protein abundance of Cmn14-5-1 secretome under induction with TXS was higher than those of DOAB232. The secretome of the CXS with either isolate showed unique proteins that facilitate molecule transport and signalling such as peptidyle ABC transporters and other hydrolases proteins. The study shed some light on the possible pathogenicity factors of Cmn in corn.

Assessment of strategies to enhance resistance against new clubroot pathogens using current resources. T. SONG, K. HORNADAY, N. TONU, F. YU AND G. PENG. Saskatoon Research and Development Centre, Agriculture and Agri Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Clubroot disease is one of the most severe threats to canola production in Canada. In Alberta, more than 2000 commercial fields have been confirmed with clubroot infestation and the disease tends to spread into Saskatchewan and Manitoba. So far, host resistance is the most effective and practical approach to control clubroot disease in canola production. However, the emergence of new clubroot pathotypes that knocked down the commercial clubroot resistance (CR) cultivars raises a potential challenge to researchers and breeders to develop new CR cultivars to prevent the potential outbreak of disease due to these virulent clubroot pathogens, thereby minimizing the economic loss for the entire industry. In this project collaborating with a commercial seed company, we performed assessment of the strength and durability of CR cultivars by pyramiding multiple CR genes against the P3 and other pathotypes. Currently, we found that canola with different combinations of CR genes showed various levels of responses against the virulent pathotypes from Alberta. Interestingly, reciprocal crosses of particular CR genes possessed distinct responses. The results suggested that pyramiding current CR genes with proper configuration of crossing is promising to develop CR cultivars against the newly identified virulent clubroot pathotypes. To achieve this purpose, it is indispensable to understand the molecular mechanisms of the CR genes used in the market, which will be the target of our ongoing study. Moreover, we are also determining the risk of resistance breakdown under low levels of inoculum in order to better employ CR resources in Saskatchewan and Manitoba.

Nitrogen application improves photosynthetic productivity, leaf chlorophyll efficiency, and yields of contrasting oat genotypes under salinity conditions. X. D. SONG, W. WU, B. L. MA, W. K. YAN AND G. S. ZHOU. Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (X.D.S., G.S.Z.) Key Lab of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, 12 East of Wenhui Road Yangzhou, Jiangsu Province, China

Salinity is one of the major environmental stresses that adversely affect plant growth and metabolism. Agronomic practices such as nitrogen (N) management have been considered as a critical strategy to alleviate this stress and increase crop production. This study aims to determine the role of various N applications in crop yield formation and its associated physiological mechanisms under two saline conditions. Two oat genotypes, 6-SA120097 (salt tolerance) and 153-ND121147 (salt sensitive), subjected to medium saline (100 Mm) in comparison with non-saline conditions under four levels of N (0, 0.5, 1.5 and 2.5 g/pot), were grown under the controlled greenhouse conditions. The N treatments were applied as basal fertilizer (30% of N), and at tillering (30% of N), booting (20% of N) and flowering (20% of N) stages. Photosynthetic gas exchange rate, photosystem II (PSII) photochemistry, chlorophyll readings, electrolyte leakage of flag leaves during the grain-filling stage, as well as yield and yield components were determined. Under the non-saline conditions, N application increased (P < 0.05) leaf net photosynthetic rate, maximum photochemical quantum yield and effective photochemical quantum yield of PSII. High rates of N treatment also ameliorated the inhibition effect of saline stress on leaf photosynthetic parameters. Irrespective of N treatments and saline conditions, the salt-tolerant genotype displayed a higher net photosynthetic rate, maximum photochemical quantum yield, and effective photochemical quantum yield of PSII with low electrolyte leakage, as compared to those of the salt-sensitive genotypes. This study implies that use of salt-tolerant cultivars with appropriate N management can be recommended as a promising strategy for alleviating the adverse effects of salt stress on crop physiological parameters and crop yield.

Assessing infection in wheat seeds by Fusarium graminearum using Biospeckle Laser Analysis, a novel application of the biospeckle technique. D. B. SUTTON AND Z. K. PUNJA. Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada

Fusarium head blight is a major fungal disease on cereal grains worldwide, reducing crop yields and contaminating harvested grains with mycotoxins. Infection is frequently latent and scab symptoms may be non-apparent in diseased seeds. In this study, Fusarium graminearum Schwabe infection in red spring wheat seeds was studied using Biospeckle Laser Analysis, a laser light technique that measures the light scattering activity, known as biospeckle activity (BA), on the specimen surface. Each measurement produces a biospeckle pattern (BP) that is an image representing the BA in the field of view. Dissected seeds were inoculated with a spore suspension of F. graminearum, placed in a humid chamber, and BA was measured sequentially over 48 h using a prototype sensor and compared with the uninoculated control. Results indicated that the germ BA of inoculated seeds was significantly reduced over time compared with healthy control seeds. Infection of whole seeds was then studied using mycelium of F. graminearum as inoculum. Observations over 48 h indicated that while the BA from healthy seeds increased with time, reflecting biological activity, the BA in infected seeds peaked at 36 h. When the mycotoxin deoxynivalenol (DON) was added to seeds at 20 µg mL⁻¹, the BA was suppressed compared with healthy control seeds. These results indicate that Biospeckle Laser Analysis may be a promising method to monitor seed response to infection by measuring cellular activity via light scattering activity on the seed surface. In addition, moderately resistant and moderately susceptible breeding lines were compared to susceptible red spring wheat. Significantly lower disease indices, computed from BA time-response curves, were observed in moderately resistant seeds and moderately susceptible seeds compared with susceptible seeds (P < 0.05).

Marker assisted wheat breeding for the Canadian prairies. J. TOTH, S. PANDURANGAN, A. BURT, J. MITCHELL FETCH AND S. KUMAR. Cereal Genomics, Brandon Research and Development Centre, Agriculture and Agri-Food Canada, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada

Bread wheat (Triticum aestivum L.) is an important crop and export commodity for Canada. Increased global population, demand for quality grains, and rapidly evolving pathogens have necessitated the need to breed high yielding disease resistant wheat cultivars. Significant gains in breeding efficiency can be made through advances in wheat genetics and genomics. Identification of genes and quantitative trait loci for economically important traits and associated molecular markers have the potential to improve selection efficiency in breeding programmes. Marker assisted selection enriches desirable allelic frequency, complements phenotypic data, and allows gene stacking. An important class of molecular markers for high-throughput marker assisted selection are Kompetitive Allele Specific Polymerase chain reaction (KASP) markers, based on single nucleotide polymorphisms. KASP markers have been developed for various genes and quantitative trait loci that confer resistance to leaf rust, stripe rust, stem rust, fusarium head blight, loose smut, common bunt, leaf spot, wheat blossom midge and wheat stem sawfly. KASP markers are also available for wheat grain and flour protein content and characteristics. Agronomic traits such as vernalization, day length sensitivity and height can also be selected based on KASP markers. We present a list of validated KASP markers to improve selection efficiency in Canadian breading programmes.

Future direction for breeding quantitative disease resistance in barley at the Agriculture and Agri-Food Canada, Brandon Research and Development Centre. J. R. TUCKER, A. BADEA, C. W. HIEBERT, W. G. LEGGE, C. A. MCCARTNEY AND W. G. D. FERNANDO. Brandon Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; (C.W.H., C.A.M.) Morden Research and Development Centre, AAFC, 101 Route 100, Morden, MB R6M 1Y5, Canada; and (J.R.T., W.G.D.F.) Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada

Development of resistance to pathogens is a major objective for plant breeders. While quantitative resistance (polygenic) is generally considered to be more durable than major gene resistance, breeding for quantitative traits is considerably more challenging. Traditional breeding has involved discovery proceeded by incremental incorporation of multiple quantitative trait loci (QTL) over time. Additive accumulation of QTLs can result in a high level of resistance; however the process is slow and laborious due to the requirements of phenotypic testing. New genotyping technologies are now available that could hasten the breeding process. Currently, a 50K Illumina Infinium® iSelect® HTS custom genotyping assay (developed by the James Hutton Institute, Scotland, UK with single nucleotide polymorphisms (SNPs) identified using a diverse collection of international barley germplasm) is being evaluated for generating genomic estimated breeding values (GEBVs) for prediction of fusarium head blight and deoxynivalenol content in two-row barley. If successful, this breeding method could also be employed for developing adult-plant resistance for other important diseases in barley such as stem rust and spot blotch. Preliminary results indicate that 50K SNP markers are generally applicable to Canadian barley germplasm, and this technology should be useful for high-throughput genotyping. Future testing will evaluate applicability for use in genomic selection in the AAFC-BRDC barley breeding programme. This research represents a new collaboration and common effort among AAFC-Brandon, AAFC-Morden and the University of Manitoba.

Survey of Pratylenchus neglectus in fields in Prairie Canada. P. WENYIKA, F. GOUVEA-PEREIRA AND M. TENUTA. Department of Soil Science, University of Manitoba, 13 Freedman Crescent, Winnipeg, MB R3T 2N2, Canada

Root lesion nematode species are among the most important plant parasitic nematodes of crop plants in Canada. Among the economically important species of this genus is Pratylenchus neglectus (Rensch) Filipjev et al. which is shown in other countries to infest wheat, canola, chickpea and oat. In a survey for plant parasitic nematodes of fields sown to pulses that we conducted in 2014 and 2015, Pratylenchus occurred in 19% of the 93 fields sampled. The mean densities in positive fields were 1170 and 3552 for yellow pea and lentil, respectively. Maximum densities of 6297 and 9009 nematodes kg⁻¹ soil were obtained for yellow pea and lentil fields, respectively. The mean densities are at or above that for which root lesion nematodes cause yield reductions of pulses and other field crops in other countries. Sequencing and species-specific PCR analyses indicated the species of root lesion nematode to be P. neglectus. However, some sequencing results had low reliable matching to P. neglectus. The results indicate P. neglectus is widely distributed in fields in Prairie Canada. However, studies continue to resolve remaining uncertainties such as the possible presence of other root lesion species, the preferred host(s) of P. neglectus, and yield losses caused.

Biopesticides successfully suppress bacterial spot disease caused by Xanthomonas gardneri in tomato. M. A. K. WIJESINGHE, T. DUMONCEAUX AND S. M. BOYETCHKO. Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada

Bacterial spot disease is a serious problem worldwide in tomato cultivation without successful control measures to date. A series of growth chamber experiments were conducted to assess the efficacy of a formulated biopesticide Neo-Boost and a biological control agent Bacillus amyloliquefaciens against Xanthomonas gardneri (ex Sutic) Jones et al. The disease incidence was lowered by 65.6% and 70.9% due to the application of Neo-Boost and B. amyloliquefaciens, respectively. Quantitative PCR showed a reduction of X. gardneri gene copy number due to application of the biopesticides at 2 days after challenging the plants. In addition, the biopesticides increased plant biomass, nutrient absorption and induced flowering in tomato plants. A strong positive correlation was observed between X. gardneri gene copy number and disease severity. Negative correlations were seen between disease severity, plant dry weight, plant nutrient absorption and number of flowers at 50% flowering. Application of biopesticides increased the production of plant defence enzymes peroxidase, superoxide dismutase and polyphenol oxidase. Neo-Boost and B. amyloliquefaciens were proven to be efficient in controlling tomato bacterial spot disease and inducing systemic resistance in tomato plants.

Interactions between biocontrol agents and soil microbes: impact on pathogen growth and disease suppression. A. C. WYLIE AND Z. K. PUNJA. Simon Fraser University, Department of Biological Sciences, 8888 University Drive, Burnaby, BC V5A 1S6, Canada

Biological control of plant diseases is of particular importance in intensive organic greenhouse vegetable production where pesticides are not permitted. In these production systems, growers use microbially diverse substrates including composts as a medium for plant growth. The impact of a microbially rich substrate on the efficacy of an inundatively applied biocontrol agent has not been previously studied, i.e. is it additive, neutral or negative with respect to disease suppression? Using several different vermicomposts incorporated into sterilized substrate, we assessed pathogen suppression in vitro and disease suppression on cucumber plants. In addition, the effects of two biocontrol agents – Bacillus subtilis strain QST 713 (Rhapsody) and Clonostachys rosea f. catenulata (Gliocladium catenulatum) strain J1446 (Prestop), against the pathogens Fusarium oxysporum f. sp. radicis-cucumerinum Vakal. (Forc), and Rhizoctonia solani Kühn on cucumber and radish, respectively, were evaluated. We found a range of synergistic and antagonistic responses, depending on the host, pathogen and biocontrol agent. For example, C. rosea alone provided better control of Forc growth in vitro and more consistent disease suppression in cucumber growth experiments compared with vermicompost alone, and when combined they showed a synergistic effect. Neutral to negative effects were found for B. subtilis alone and combined with vermicompost in this Forc system. Vermicompost microbes had neutral to synergistic effects with C. rosea in growth trials using the radish/R. solani model. The methods developed herein could be used as a preliminary screen for biological control organisms for their efficacy in microbially rich environments.

Development of high throughput protocols for automated nucleic acid extraction and molecular detection of potato viral, fungal and bacterial pathogens on large scale. H. XU, L. WARD, X. LI, J. NIE, S. CODY AND M. ANNETT. Canadian Food Inspection Agency, Charlottetown Laboratory, 93 Mount Edward Road, Charlottetown, PE C1A 5T1, Canada

Numerous fungi, bacteria and viruses can infect potato and cause various diseases, many of which are regulated in Canada for protecting potato production. Potato nuclear stock and seed tubers must be indexed for regulated pests and certified for use in Canada and for export. Imported potato germplasm and other types of potatoes must be subjected to quarantine and surveillance testing, respectively. Disease surveys are often conducted for understanding pest status in Canada for appropriate phytosanitary actions. In order to perform these tests, the diagnostic laboratories have to develop and implement reliable and cost-effective diagnostic procedures with the capacity to screen massive samples within a short period of time. Here we report the development of a high throughput testing process for automated nucleic acid (NA) extraction based on the use of magnetic beads, automated liquid dispensation, PCR/RT-PCR (multiplex, 96-well plate based) and capillary analysis of PCR amplicons. Potato viral, bacterial and fungal species were used in the evaluation. Standard procedures were developed, validated and employed for screening over 3000 field samples (leaves, tubers). Over 30% of the test samples were verified using conventional testing procedures including NA extraction based on organic solvent, PCR, RT-PCR and agarose gel electrophoresis. In comparison with the conventional molecular procedures, the high throughput testing retained the same level of sensitivity and specificity and improved the repeatability and reproducibility. The high throughput testing procedures significantly reduced the hand-on testing time and overall turnaround testing time that is extremely important for seed potato trade and for taking regulatory and phytosanitary actions.

The regulation of intrinsic signalling in Brassica napus defending against Leptosphaeria maculans. C. YANG AND W. G. D. FERNANDO. Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

Gene-for-gene interaction is triggered by the recognition between R proteins from host and Avr effectors from pathogen. The interaction between host R proteins and pathogenic effectors initiates a set of localized and rapid signalling cascades called hypersensitive response (HR). This response subsequently induces several signalling pathways including oxidative burst, hormonal biosynthesis/signalling and programmed cell death (PCD). In this study, the general objective is to explore the crucial factors in Brassica napus L. – Leptosphaeria maculans (Desmaz.) Ces. & De Not. pathosystem. The cv. ‘Surpass400' and ‘01–23-2-1' exhibited the HR phenotype while the cv. ‘Westar’ showed susceptibility. RT-qPCR results suggest that the early activation (3 dpi) of salicylic acid (SA) signalling was related to the initiation of the processes resulting to HR. The abundance of ethylene (ET) responsive genes coincides with SA signalling, suggesting co-expression between SA and ET signalling in the resistant cultivars. Histological staining showed that the cultivars with HR induced the localized oxidative burst to hinder early hyphal development (3 dpi to 5 dpi). This was supported by hydrogen peroxide accumulation, lignification and localized cell death. Moreover, the co-inoculation between L. maculans/Leptosphaeria biglobosa Shoemaker & Brun mixed inoculum and the aminotriazole (AT) treatment (a catalase inhibitor) exhibited smaller leaf lesions in the susceptible ‘Westar’. These results agree with the findings that the early induction of cellular signalling in basal defence is the key to induce HR.

Genome-wide association study for fusarium wilt resistance in flax (Linum usitatissimum). F. M. YOU, K. Y. RASHID, Z. YAO AND S. CLOUTIER. Morden Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 101 Route 100, Morden, MB R6M 1Y5, Canada; and (S.C.) Ottawa Research and Development Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Fusarium wilt is a disease of flax (Linum usitatissimum L.) that is caused by the fungus Fusarium oxysporum f. sp. lini (Bolley) Snyd. & Hans. The fungus infects the roots and blocks the vascular system causing wilt and death that result in severe yield loss. To identify genes and markers associated with wilt resistance, the core collection of 407 flax accessions was re-sequenced with the Illumina platform and evaluated for wilt resistance in the flax wilt nursery at Morden, Manitoba between 2011 and 2014. A total of 1 773 632 SNPs were identified. A genome-wide associated study was performed using the general linear model with TASSEL. Based on the data from three years, 49 putative quantitative trait loci (QTL) were located near resistance gene analogues (RGAs) on all 15 chromosomes. Thirty-seven QTL were located within a distance of 1.5 MB to NBS-coding genes and nine QTL were as close as within 0.1 Mb. One QTL was validated by a previously identified SSR marker. These QTL explained 7–12% of phenotypic variation of wilt resistance and were additive. The results provide useful resources for genomics-assisted breeding in flax.

Relationship between rhizosphere soil acid phosphatase activities and forage production in silage corn and soybean intercropping in cool climate. M. ZAEEM, M. NADEEM, W. ASHIQ, W. ALI, S. M. GILLANI, H. PHAM, V. KAVANAGH, S. ELAVARTHI, M. A. CHEEMA, L. GALAGEDARA AND R. THOMAS. School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland, 20 University Drive, Corner Brook, NL A2H 5G4, Canada; (M.N.) Department of Environmental Sciences, COMSATS Institute of Information Technology, Vehari, 61 100, Pakistan; (V.K.) Department of Fisheries, and Land Resources, P.O. Box 340, Pasadena, NL A0L 1K0, Canada; and (S.E.) Department of Agriculture and Natural Resources, Delaware State University, 1200 N Dupont Highway, Dover, DE 19 901, USA

Cereal-legume intercropping systems can enhance agroecosystem efficiencies through increased soil enzyme activities, mineralization and bioavailability of nutrients in root rhizosphere. These can lead to higher nutrient uptake, improved agronomic performance and higher forage productivity. A field experiment was conducted to evaluate the production potential of silage corn (Yukon R and DKC26-28RIB) intercropped with forage soybean genotypes (Big Fellow RR, Game Keeper RR and Kester’s Bob White) in cool climatic production systems. Also, the relationship between rhizosphere soil acid phosphatase activities (RS-APase) and forage production was assessed. The plants were grown in monocrop (control) and intercrop (corn and soybean) systems. Intercropping produced significantly (P < 0.001) higher forage biomass than the monocropping. Significantly higher forage production i.e. 16.96 Mg ha⁻¹ was recorded in the Yukon R and the Big Fellow RR under the intercropping system, whereas lowest biomass i.e. 2.15 Mg ha⁻¹ was recorded in the Kester’s Bob White soybean monocropping. RS-APase were also increased significantly (P < 0.001) in all the intercropping systems. Maximum RS-APase was recorded in the DKC26-28 RIB-Game Keeper RR intercropping (22.485 µmole pNP g⁻¹ min⁻³⁰), whereas minimum was recorded in the DKC26-28 RIB monocropping (16.07 µmole pNP g⁻¹ min⁻³⁰). A significant positive correlation was recorded between RS-APase and forage production in the intercropping (r = 0.40*) while a significant negative correlation was recorded in the monocropping (r = −0.66***). Study findings suggested that intercropping might be an appropriate approach to enhance forage production due to improved soil health under cool climatic production systems.

Assessing thermal indices for modelling grain corn phenological development on the Prairies. J. ZHANDA, P. R. BULLOCK, F. ZVOMUYA, Y. LAWLEY, L. M. REID AND D. FLATEN. University of Manitoba, Faculty of Agricultural and Food Sciences, Winnipeg, MB R3T 2N2,Canada; and (L.M.R.) Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Grain corn (Zea mays) production on the Canadian Prairies is delayed by limited seasonal heat unit accumulation. However, agroclimatic studies have shown some positive trends in heat unit accumulation in recent decades, increasing the feasibility of corn grain production in cooler regions such as the Prairies. A 2 year study was initiated in 2015 at six sites in Manitoba and two sites in Alberta to quantify heat unit requirements of five corn hybrids with different maturity ratings and to identify a thermal index with a consistent accumulated value from planting to maturity. The indices assessed included the corn heat unit (CHU), growing degree days with a base temperature of 10°C, modified growing degree days with a base temperature of 10°C and maximum temperature of 30°C, general thermal index (GTI) and days after planting. Corn phenology from emergence to silking was monitored by time-lapse cameras. Physiological maturity (R6) was defined by the presence of a black layer at the tip of the corn kernels. Automated weather stations recorded hourly and daily weather conditions including air temperature. There were no significant differences in heat unit accumulation among the five hybrids, despite their differences in CHU rating and regardless of the index used. There was an inverse relationship between cold nights and CHU. Overall, the hybrids required more CHU to reach R6 than their rated values. The cumulative heat at R6 for all thermal indices across all locations had a coefficient of variation <10%, with GTI having the lowest (<5%) regardless of the hybrid. Although not statistically significant, the GTI was the most consistent and accurate heat unit especially at the R6 stage. Cold overnight temperatures on the Canadian Prairies are speculated to slow corn phenological development on subsequent days and thus increase the amount of heat required for corn to reach R6. However, in this study, an increased number of cold nights decreased the amount of CHU accumulated by all hybrids from planting to maturity.