Survey of dry bean fields for sclerotinia white mould. D. A. BURKE, G. C. DANIELS, C. A. PUGH, R. J. HOWARD AND M. W. HARDING. Crop Diversification Centre South, Alberta Agriculture and Forestry, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada; and (R.J.H.) RJH Ag Research Solutions, P.O. Box 1456, Brooks, AB T1R 1C, Canada
Annual surveys for white mould [Sclerotinia sclerotium Lib. de Bary] in commercial dry bean fields were performed in the 2011, 2013, 2014 and 2015 cropping seasons. Overall, disease incidences were 24%, 26%, 4% and 18% with severities measured on a 0–4 scale of 0.82, 0.4, 0.11 and 0.29, respectively. Survey results were visually compared with maps of accumulated precipitation in July of the corresponding years to examine if the low incidence and severity of white mould in 2014 could be explained. Accumulated precipitation levels in July did not directly correspond to white mould incidence or severity, indicating that the disease levels are determined by more factors than precipitation alone.
Response of soybean cultivars/lines to seedling blight and root rot [Rhizoctonia solani] under field conditions in southern Alberta. K. F. CHANG, S. F. HWANG, H. U. AHMED, S. E. STRELKOV, G. D. TURNBULL, D. A. BURKE AND M. W. HARDING. Crop Diversification Centre North, Alberta Agriculture and Forestry (AAF), Edmonton, AB T5Y 6H3, Canada; (S.E.S.) Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (D.A.B., M.W.H.) Crop Diversification Centre South, AAF, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada
Soybean (Glycine max L.) has great potential as an alternative crop in western Canada. In southern Alberta, the area seeded to soybeans has grown from a few hectares to about 4050 hectares in 2014, and this area is expected to continue to increase as early maturing and cold-resistant cultivars become available. Root rot is a common constraint to crop production, and the occurrence of root rot was documented in all 29 soybean fields surveyed in southern Alberta in 2014. Rhizoctonia solani Kühn caused seedling blight, including pre- and post-emergence damping-off and root rot of young and adult plants of soybean. The reactions of 22 soybean cultivars/lines to R. solani were assessed in inoculated field trials conducted at Brooks, Alberta, in 2014 and 2015. In all trials, R. solani-inoculated plots had lower emergence, nodulation and yield and higher disease severity compared with the non-inoculated plots. None of the lines were resistant to R. solani, however, the soybean cultivar/lines NSC Portage, TH29002RR, TH27005RR and LS 003R22 had the smallest reduction in stand establishment, and NSC MoosominRR2Y, NSC TilstonRR2Y, P001T34R and 23-60RY had the smallest reduction in seed yield. These cultivars/lines, when combined with seed treatments, may be effective in improving stand establishment and the seed yield of soybean in R. solani-infested soils.
An update on Aphanomyces euteiches research since its first detection in Alberta pea fields in 2013. S. CHATTERTON, T. WILLSEY, K. PINTO-LARSEN AND S. BANNIZA. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; and (S.B.) Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada
Aphanomyces root rot was first reported in Saskatchewan and Alberta pea fields in 2012 and 2013, respectively. Several research projects to understand disease development and potential seed treatment options have been initiated. Standard curves describing the relationship between oospore levels of Aphanomyces euteiches Drechs. and disease severity in soils from three soil zones (black, dark brown and brown) were developed in greenhouse trials. Peas grown in dark brown, autoclaved soils had higher disease severities compared with disease levels at the same inoculum densities in peas grown in brown and black soils. However, presence of Fusarium spp. in non-autoclaved soils significantly increased disease severity at all A. euteiches inoculum levels compared with autoclaved, inoculated soils. Seed treatments with a mixture of different active ingredients that included the newly registered product, ethaboxam, were effective in reducing Aphanomyces root rot of seedlings in greenhouse trials. The trials are being expanded to assess yield and disease response at naturally infested field sites throughout Alberta. Host range testing indicated that peas, lentils, alfalfa and cicer milkvetch are susceptible hosts, while dry beans, faba beans, chickpeas, soybeans, fenugreek and sainfoin are moderately resistant or non-hosts. Results to date suggest that dark brown soils, susceptible host crops and Fusarium spp. increase the risk of developing severe aphanomyces root rot.
Diseases of garlic and onion in Alberta in 2015. G. C. DANIELS, R. C. J. SPENCER, J. S. BROATCH, J. FENG, S. L. I. LISOWSKI, R. J. HOWARD, J. M. NIELSON AND M. W. HARDING. Crop Diversification Centre South, Alberta Agriculture and Forestry (AAF), 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada; (R.C.J.S.) Alberta Ag-Info Centre, AAF, Provincial Building, Bag 600, Stettler, AB T0C 2L0, Canada; (J.S.B.) AAF, Lacombe Research and Development Centre, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada; (J.F.) Alberta Plant Health Lab, AAF, 17507 Fort Road, Edmonton, AB T5Y 6H3, Canada; and (R.J.H.) RJH Ag Research Solutions, P.O. Box 1456, Brooks, AB T1R 1C, Canada
Plant and soil samples were collected from five garlic and 10 onion fields in Alberta in 2015. In total, seven garlic and 21 onion plants were evaluated. Symptoms of disease and signs of fungal pathogens were evaluated visually upon receipt. Samples were then incubated in humid chambers to encourage additional growth of pathogens. Fungi were identified by spore or hyphal morphology observed by phase contrast microscope at 400×. Presence of the aster yellows phytoplasma was detected by nested PCR. Nine fungal genera were observed on symptomatic plants, including Fusarium, Embellisia, Penicillium, Botrytis, Alternaria, Rhizoctonia, Arthrobotrys, Stemphyllium and Sclerotium. The most prevalent fungal genera were Penicillium, Fusarium and Rhizoctonia which were found in more than 60% of samples. The aster yellows phytoplasma was detected in four of the 28 samples. Bacterial soft rot was noted in 33.3% of fields sampled, but causal agents were not identified.
Management of cucumber green mottle mosaic virus in Alberta greenhouses through surveillance and varietal screening trials. W. ELLOUZE, V. MISHRA, R. J. HOWARD, K.-S. LING AND W. ZHANG. Crop Diversification Centre South, Alberta Agriculture and Forestry, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada; (R.H.) RJH Ag Research Solutions, P.O. Box 1456, Brooks, AB T1R 1C, Canada; and (K.S.L.) USDA-ARS, U.S. Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC 29414, USA
Cucumber green mottle mosaic virus (CGMMV) is an increasing threat to greenhouse cucumber crops worldwide. Our analysis of symptomatic samples from commercial greenhouses in Alberta revealed that an Asian genotype of CGMMV was predominantly responsible for the disease. Growing resistant cucumber varieties that prevent infection, replication and symptom development is the most practical approach to controlling the virus. Currently, no high-yielding cucumber variety with CGMMV resistance is commercially available. Six Mini and nine Long English (LE) cucumber varieties were screened for resistance to CGMMV and effects of infection on productivity. Among Mini varieties, Sunniwell was the most sensitive (infection rates (IR) of 100%), but had the highest fruit yield. Katrina was the most resistant (IR: 79%), but was intermediate in yield compared with Sunniwell. Among nine varieties of LE screened for resistance to CGMMV, Bonbon was highly sensitive (IR: 83%) without compromising yield, which was highest. The most sensitive LE variety was DR4879CE (IR: 90%), while Verdon, the most widely grown cultivar in Alberta, was intermediate (IR: 55%) in its resistance. In yield comparisons, DR4879CE and Verdon were poor performers. This trial revealed the relative suitability of commercial cucumber varieties for use in greenhouses at risk from CGMMV infection and where minimizing production losses is a key consideration.
Fusarium graminearum mutant screening towards identification of pathogen-associated molecular patterns in the fusarium head blight–wheat interaction. A. ERANTHODI, R. SUBRAMANIAM, T. OUELLET, C. RAMPITSCH, E. A. SCHULTZ AND N. A. FOROUD. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; (R.S., T.O.) Ottawa Research and Development Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (C.R.) Morden Research and Development Centre, AAFC, 101 Route 100, Unit 100 Morden, MB R6M 1Y5, Canada; and (A.E., E.S.) Department of Biological Sciences, University of Lethbridge, 4401 University Drive West, Lethbridge, AB T1K 6T5, Canada
Fusarium head blight (FHB), caused primarily by Fusarium graminearum Schwabe, is a destructive disease of wheat and related cereals, responsible for substantial reduction in yield and quality of grains. With the objective of screening candidate pathogen-associated molecular patterns (PAMPs), we selected seven proteins (PAMP1–PAMP7) from the F. graminearum secretome based on their sequence homology to proteins with pathogenicity roles in other plant–pathogen interactions. Knockout (KO) and overexpression (OX) mutants of F. graminearum were generated for the genes that encode these proteins. The KO and OX cassettes were prepared and the plasmids were electroporated into Agrobacterium tumefaciens. Mutants were generated by homologous recombination between a modified T-DNA of Agrobacterium and the F. graminearum genome during Agrobacterium-mediated transformation. Two wheat lines, Superb and GS-1-EM0040 (‘CIMMYT 11ʹ/‘Superb’*2), were point-inoculated with mutants PAMP1-OX, PAMP2-KO or PAMP2-OX and screened against wild-type inoculated wheat lines. The number of infected spikelets was significantly lower for wheat lines inoculated with PAMP1-OX or PAMP2-OX than for those inoculated with wild-type strain. Likewise, PAMP2-OX inoculated wheat lines had significantly fewer infected spikelets than PAMP2-KO inoculated wheat lines. Based on these preliminary results, we postulate that PAMP1 and PAMP2 activate receptors in wheat leading to the basal immune response known as PAMP-triggered immunity. Analysis of the remaining five genes is currently underway.
Identity and host specificity of root rot pathogens colonizing standing pea stubble from the Canadian Prairies. A. ESMAEILI TAHERI, S. CHATTERTON, N. A. FOROUD, B. D. GOSSEN AND D. L. MCLAREN. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; (B.D.G.) Saskatoon Research and Development Centre, AAFC, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; and (D.L.M.) Brandon Research and Development Centre, AAFC, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada
The composition and host specificity of pathogenic fungal communities colonizing pea residues from Alberta and Manitoba was studied. Standing pea stubble was sampled from diseased and healthy patches of 16 commercial fields in 2013–2015 after harvest and in the following year prior to crop seeding. Canola, wheat and pea were grown in pots filled with ground pea stubble mixed with sterile Cornell potting mix. Root rot severity of the hosts was evaluated and sections from diseased roots were plated on agar media. Fungal communities isolated from roots were characterized using characteristics in culture and PCR-based identification. Approximately 2700 fungal isolates, belonging to some 50 species, were identified. Fusarium avenaceum (Fr.) Sacc. and Fusarium culmorum Sacc. were most prevalent in wheat, F. avenaceum, Fusarium solani (Mart.) Sacc. and Fusarium oxysporum Schlecht. emend Snyder & Hans. were most abundant in pea, and F. avenaceum was most abundant on canola. Aphanomyces euteiches Drechs. was isolated only from one Manitoba field, and only on pea. Fungal communities of healthy and diseased patches of fields were similar, but the fungi isolated from post-harvest stubble were different from that of pre-plant stage. Root rot incidence and severity were lower on canola than on pea or wheat, which indicates that canola is less susceptible to the fungal root pathogens of pea than either pea or wheat.
MAP kinases and defence signalling for disease resistance in wheat. R. GOYAL, C. WEST, L. HUI, J. CHIU, M. FRICK, N. CHOMISTEK, B. E. ELLIS, D. TULPAN, A. LAROCHE AND N. A. FOROUD. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; (B.E.E.) Michael Smith Laboratories, University of British Columbia, #301-2185 East Mall, Vancouver, BC V6T 1Z4, Canada; and (D.T.) National Research Council of Canada, 100 des Aboiteaux Street, Moncton, NB E1A 7R1, Canada
Plants have a well-developed mechanism of abiotic/biotic stress perception, which is relayed through an intricate network of signalling to mount a defence response. MAP kinases form an important component of the defence signalling cascade. There exists a large repertoire of MAP kinases in plants; some of them have been implicated in disease resistance in plants. Among monocots, with the exception of rice and Brachypodium, the information on MAP kinases is limited and not well organized, especially in wheat and related cereals. We constructed full length sequences of wheat MAP kinases by sequencing the cDNA amplicons and analysing the contigs in publicly available databases using bioinformatics tools. The MAP kinases belonging to families of MAPKs, MAPKKs and MAPKKKs were annotated following Arabidopsis nomenclature. Using yeast two-hybrid assays the mutual MAP kinase interactions were studied at protein level. The positive interactions identified suggest a preserved architecture of MAP kinase signalling in plants. Studies are underway to identify specific MAP kinases associated with Fusarium head blight defence signalling.
Goss’s bacterial wilt and leaf blight on corn in Alberta in 2015. M. W. HARDING, G. C. DANIELS, A. GILL, C. J. HILL AND R. J. HOWARD. Crop Diversification Centre South, Alberta Agriculture and Forestry, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada; and (R.J.H.) RJH Ag Research Solutions, P.O. Box 1456, Brooks, AB T1R 1C, Canada
Clavibacter michiganensis subsp. nebraskensis (Vidaver and Mandel) Davies et al., the causal agent of Goss’s bacterial wilt and leaf blight on corn, recently expanded its geographic range to a number of new regions in North America. For example, it was first reported in Alberta in 2013 and while it has not caused serious economic consequences, the potential for spread and increased severity is a concern for Alberta corn producers. A survey for Goss’s wilt and leaf blight symptoms in Alberta in 2015 included 55 corn fields in 10 counties. Symptoms were found in 20 of 55 fields surveyed (prevalence = 36%). The incidence of leaf blight ranged from trace levels to 50%. Only one field had signs and symptoms of vascular wilt. Seventeen of the 20 positive fields were reported in southern Alberta, from Census Agricultural Regions 1 and 2. The remaining three symptomatic fields were found in central Alberta (Census Agricultural Region 5).
Survey for blackleg on canola in southern Alberta in 2015. T. B. HILL, C. J. HILL, G. C. DANIELS, D. A. BURKE, C. A. PUGH AND M. W. HARDING. Crop Diversification Centre South, Alberta Agriculture and Forestry, 301 Horticultural Station Road East, Brooks, AB T1R 1E6, Canada
Blackleg is a disease on canola caused by the phytopathogenic fungus Leptosphaeria maculans (Desmaz.) Ces. & de Not., which attacks all above-ground parts of the host plant. Infected plants often form dry, sunken cankers at the stem base. The results of infection can be reduced yield and quality, often due to premature senescence and lodging. A survey for blackleg was performed in southern Alberta in 2015. A total of 83 canola fields in 16 municipalities were surveyed. Surveyors walked a W-shaped pattern, stopping at five locations that were at least 20-m apart. At each location, 20 stems were evaluated for blackleg for a total of 100 stems/field. All stems were cut in cross-section at the soil line and then visually rated for blackleg symptoms. Symptoms included vascular discolouration at the cut surface and/or the presence of basal stem cankers. Blackleg prevalence was calculated as the percentage of fields with symptoms present. Incidence was calculated as the percentage of plants with blackleg symptoms, and severity was estimated using a 0–5 scale for rating vascular discolouration. The prevalence of blackleg was 79.5%, the incidence was 21.59% and the severity was 0.39. The most recent previous survey for blackleg in Alberta was done in 2012. In that year, the prevalence, incidence and severity were 99%, 21% and 1.26, respectively.
Characterization of populations of Plasmodiophora brassicae by genotyping-by-sequencing. M. D. HOLTZ, S. F. HWANG, J. ZANTINGE AND S. E. STRELKOV. Field Crop Development Centre, Alberta Agriculture and Forestry (AAF), 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada; (S.F.H.) Crop Diversification Centre North, AAF, 17507 Fort Road, 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 obligate soilborne pathogen that causes clubroot disease in canola and other cruciferous crops. Recently, new aggressive populations of the pathogen, virulent on clubroot resistant canola (Brassica napus L.) cultivars, have been found in Alberta, Canada. In order to determine the relationship of members of these aggressive populations to other P. brassicae populations present in Alberta a next-generation genotyping-by-sequencing (GBS) method was employed. Twenty-one populations or single-spore isolates were analysed. DNA was extracted from spores purified from infected roots and used for GBS. Over 10 million sequences were generated and thousands of variable nucleotides were identified. The new aggressive populations could be easily distinguished from other P. brassicae populations using the data generated. Additionally, the sequence information produced should allow for the development of markers and assays for the detection of resistance-defeating P. brassicae populations.
Molecular phylogeny of Rhynchosporium commune from central Alberta. M. D. HOLTZ, J. ZANTINGE, K. XI AND T. K. TURKINGTON. Field Crop Development Centre, Alberta Agriculture and Forestry, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada; and (T.K.T.) Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, 6000C & E Trail, Lacombe, AB T4L 1W1, Canada
Rhynchosporium commune Zaffarano, McDonald, and Linde sp. nov. (formerly: R. secalis (Oudem.) J.J. Davis) is the causal agent of the foliar disease scald of barley. Recent evidence has shown that R. commune originated in northern Europe then proceeded to disperse into barley producing areas around the world. Phylogenetic analysis was undertaken to determine the relatedness of R. commune from central Alberta to populations in other regions. Multilocus sequence analysis was performed using the housekeeping gene β-tubulin, the mating-type genes MAT1-1-3 and MAT1-2-1, and two non-coding RFLP loci, pRS6 and pRS52. The resulting sequence information was then compared with publicly available R. commune sequences from five continents. The degree of relatedness to other populations varied with the locus and isolate examined. Most sequence haplotypes found were either present in R. commune populations on multiple continents or they have not been reported previously. However, sequences previously detected only in Scandinavia, Australia or the Middle East were present in Albertan isolates. Results show the R. commune population in central Alberta is diverse and that previously undocumented gene flow has occurred between Alberta and other continents.
Effects of post-application land treatment on the efficacy of Vapam to control clubroot [Plasmodiophora brassicae] of canola. S. F. HWANG, H. U. AHMED, Q. ZHOU, S. E. STRELKOV, B. D. GOSSEN, G. PENG AND G. D. TURNBULL. Alberta Agriculture and Forestry, Crop Diversification Centre North, 17507 Fort Road N.W., Edmonton, AB T5Y 6H3, Canada; (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (B.D.G., G.P.) Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, SK S7N 0X2, Canada
Clubroot, caused by Plasmodiophora brassicae Woronin, has become a serious threat to canola (Brassica napus L.) production in western Canada. The efficacy of Vapam (metam sodium) for the control of clubroot in Brassica vegetable crops has been variable, reflecting different application methods and post-fumigation land treatment. Experiments were carried out to evaluate the effects of the amount of watering, soil incorporation and tarping on the efficacy of Vapam fumigant in reducing clubroot severity in P. brassicae-infested soils. Vapam fumigation consistently improved seedling emergence, plant growth, plant biomass, pod number and seed yield, and reduced gall weight and clubroot severity compared with the non-treated control. Post-application incorporation of Vapam into the soil improved plant biomass and seed yield, and reduced clubroot severity compared with a non-incorporated control. Covering the treated soil with a construction-grade plastic tarp after Vapam fumigation significantly improved seedling emergence, plant vigour and reduced gall weight and clubroot severity compared with non-treated plots covered with plastic. A 12-day duration of covering increased emergence and yield compared with a 7- or 16-day covering duration. The volume of water applied for drench applications or watering + plastic tarping did not affect the efficacy of Vapam. In summary, soil incorporation and tarping of the land after application increased the effectiveness of Vapam in reducing clubroot.
Effect of irrigation and plant canopy architecture on white mould development in dry bean. K. A. KADER, P. M. BALASUBRAMANIAN AND S. CHATTERTON. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada
Dry bean (Phaseolus vulgaris L.) is the most profitable pulse crop grown under irrigation in southern Alberta. White mould (WM) caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary is a major constraint to dry bean production. Field studies were conducted at AAFC-Lethbridge in 2015. Three levels of irrigation (high, medium and low) and five cultivars with different canopy architecture (semi-upright bush, upright bush and prostrate) were arranged in a split-plot design and plots were evaluated for WM incidence and severity, flower infection, yield and thousand seed weight (TSW). Microclimate variables were monitored using data loggers and sensors. WM incidence, severity and flower infection observed were significantly higher in high irrigation plots compared with medium and low irrigation plots. Higher water content within the top 5-cm of soil, prolonged leaf wetness and cooler canopy temperatures were maintained in high irrigation plots compared with medium and low irrigation plots. Plots grown under medium and low irrigation had similar WM levels, but yield and TSW were reduced under low irrigation. WM development in AAC Burdett and I9365-31, lines with partial resistance, were not affected by irrigation regime. Thus, irrigation schedule and choice of cultivars can be effective tools for WM management in Alberta. This trial will be conducted for 2 more years.
A simple in vitro assay to measure enhanced ‘pathogenesis-related’ enzyme expression during scald barley interaction. K. KUMAR, J. ZANTINGE, K. XI, S. WATERMAN AND P. JUSKIW. Field Crop Development Centre, Alberta Agriculture and Forestry, 5030-50 Street, Lacombe, AB T4L 1W8, Canada
Leaf scald, caused by Rhynchosporium commune Zaffarano et al., is a major barley disease in central Alberta and around the world. Yield losses from severe leaf scald infection have been estimated as much as 20–36% in Alberta. The objective of the present study was to develop an in vitro assay to screen barley germplasm for scald pathogen recognition and pathogenesis-related (PR) protein expression of β 1–3 glucanase. Sterile barley seeds were inoculated by soaking in a scald spore suspension or mock inoculated with sterilized water. Inoculated seeds were placed on culture media containing a base layer of 0.5% water agar, and a second thin assay layer containing 0.2% dye linked (AZCL- β-Glucan). In the presence of β 1–3 glucanase activity, water soluble blue dye was released from the AZCL- β-Glucan substrate into the assay media. Blue colour was measured visually, by diffusion area (mm) and optical density (OD, 595 nm). Blue colouration present in the media directly correlated with enzyme activity and resistant cultivar-scald interaction. However, some lines showed variation in both the lab and field, and this variation emphasized the complex nature of the pathogen–plant relationship. There is a need for more research to determine the experimental conditions for the measured parameters that potentially caused inconsistent or variable results observed in this investigation.
Seasonal dynamics of Botrytis cinerea and Sclerotinia sclerotiorum in seed alfalfa fields of southern Alberta. J. REICH, D. JOHNSON AND S. CHATTERTON. Department of Geography, University of Lethbridge, 4401 University Drive West, Lethbridge, AB T1K 3M4, Canada; and (J.R., S.C.) Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada
Blossom blight of seed alfalfa (Medicago sativa L.) is caused by the fungal pathogens Botrytis cinerea Pers.:Fr. (Bc) and Sclerotinia sclerotiorum (Lib.) de Bary (Ss). Nineteen commercial seed alfalfa fields in southern Alberta were surveyed over three growing seasons (2013–2015) to determine the seasonal occurrence of Bc and Ss. Each field was surveyed four times during July and August in each year. Disease incidence and severity ratings were assigned in the field, and floret and pod samples were plated on semi-selective media in the lab. In 2014 and 2015, aerosol samples were collected by three spore samplers installed in three fields. Aerosol samples were analysed in a real-time quantitative polymerase chain reaction (qPCR) assay to quantify the daily spore concentrations of Bc and Ss. In all 3 years, blossom blight symptoms were present at trace levels. Plated samples revealed greater variability in pathogen incidence among fields, although seasonal trends were similar between years despite considerable differences in macroclimatic variables. Spore discharge for both pathogens did not follow the same seasonal trends as plated samples. Overall, these results suggest that management and microclimatic factors (e.g. irrigation) may play a more important role than macroclimatic factors in the development of blossom blight of alfalfa in southern Alberta.
Production of double haploids with resistance to Fusarium mycotoxins. D. RYABOVA, H. S. RANDHAWA, L. BIHARI, F. EUDES, D. SPANER, P. HUCL, R. J. GRAF, J. PRUS, E. AMUNDSEN AND N. A. FOROUD. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; (D.S.) Agricultural, Food and Nutritional Science, Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (P.H.) Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada
Fusarium graminearum Schwabe, the causal agent of fusarium head blight (FHB), is known to produce mycotoxins that contaminate cereal grain crops. The most effective way of controlling FHB is to grow cultivars with resistance to FHB. An in vitro selection procedure was previously developed for common wheat Triticum aestivum L. to produce double haploids (DHs) with resistance to trichothecenes. The procedure involves microspore culture in the presence of Fusarium mycotoxins (DON, 3-ADON, 15-ADON, NIV, T-2). Microspores possessing mechanisms of resistance or tolerance to mycotoxins will develop into embryos, while susceptible genotypes are screened out. The objective of this study is to produce double haploid lines resistant to Fusarium mycotoxins. Fourteen crosses were used for microspore culture and 569 double haploids were generated. The addition of mycotoxins to culture media decreased viability of microspores, embryo formation, as well as regeneration of embryos into plantlets. Mycotoxin treatments resulted in a 5–35% reduction in embryo germination relative to the control. Winter wheat had a spontaneous doubling rate of 84–85%, whereas spring wheat plantlets, which are expected to have low spontaneous doubling, were treated with colchicine to produce double haploids. Double haploids generated in this study will be used in breeding programmes towards germplasm development.
Evaluation of host range of Fusarium spp. from pea fields in Alberta. S. SAFARIESKANDARI, S. CHATTERTON AND L. HALL. Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; and (L.H.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
Fusarium root rot is one of the most important diseases of pea, as it can cause severe yield losses. Previous studies demonstrated that F. avenaceaum (Fr.) Sacc. and F. solani (Mart.) Sacc. are commonly associated with root rot symptoms on pea in Canada. The objective of this study was to determine the host range of these Fusarium spp. Isolates used in the study were obtained from pea root samples collected during field surveys in Alberta and have different levels of virulence on pea as determined by pathogenicity tests. Pathogenicity to pea, lentil, faba bean, chickpea, wheat, canola, dry bean, soybean and barley was assessed using a seed inoculation method in the greenhouse. Root rot severity was determined approximately 4 weeks after planting. Fusarium avenaceum caused significantly greater disease severity on pea, dry bean, chickpea, red lentil and faba bean. All other crops had root rot ratings not statistically different from control plants. For F. solani, disease severity was not significantly different among tested plants except for pea, chickpea and faba bean which had significantly greater disease severity compared with control plants. Results indicate that F. avenaceum isolates have a broad host range on pulse crops which can influence crop rotation decisions to manage impact and persistence of fusarium root rot.
The impact of crop rotation and fungicide application on wheat leaf disease severity and crop productivity. T. K. TURKINGTON, K. XI, G. PENG AND D. PAGEAU. Lacombe/Beaverlodge Research Centre, Agriculture and Agri-Food Canada (AAFC), 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada; (K.X.) Field Crop Development Centre, Alberta Agriculture and Forestry, 5030-50 Street, Lacombe, AB T4L 1W8, Canada; (G.P.) Saskatoon Research Centre, AAFC, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; and (D.P.) Québec Research and Development Centre, AAFC, 1468 St-Cyrille Street, Normandin, QC G8M 4K3, Canada
The impact of previous crop and fungicide application on leaf disease and productivity of wheat was assessed at Lacombe, AB, Melfort, SK and Normandin, QC in 2014. Moderate disease occurred at Lacombe and Melfort, where Prosario® application at anthesis significantly reduced flag leaf disease severity. Although disease was lower at Normandin, where the rotation sequence did not include flax, fungicide resulted in a small, but significant reduction in disease, while rotation had no effect. Rotation and its interaction with fungicide had no effects on leaf disease severity at Lacombe and Melfort.G Although the interaction was significant at Normandin, differences in disease were too small to show substantial biological significance. The fungicide treatment resulted in a significant increase in yield at Lacombe and Melfort, but not Normandin. Previous crops affected yields at Lacombe and Melfort, and were highest when planted into field pea or flax stubble and lowest when planted into barley or canola, although at Normandin yields were highest and similar for field pea and barley stubble. At Melfort there was an interaction of fungicide and rotation; yield differences among previous crops were not significant for no-fungicide treatments. However, when a fungicide was applied, yield was highest for field pea stubble, while the remaining stubble types produced lower and similar yields.
Effect of seed dressing fungicide and inoculum density on aphanomyces root rot of field pea in Alberta. L. F. WU, K. F. CHANG, S. F. HWANG, S. E. STRELKOV, R. L. CONNER, B. D. GOSSEN AND G. D. TURNBULL. Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; (K.F.C., S.F.H., G.D.T.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17507 Fort Road N.W., Edmonton, AB T5Y 6H3, Canada; (R.L.C.) Morden Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), Unit 100-101, Route 100, Morden, MB R6M 1Y5, Canada; and (B.D.G.) Saskatoon Research and Development Centre, AAFC, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
Field pea (Pisum sativum L.) is an important commercial crop in Alberta with high protein content and the ability to improve the nitrogen content in soil. Root rot caused by soilborne pathogens is common in field pea crops in Alberta. Recently, root rot caused by Aphanomyces euteiches Drechs. produced substantial stand and yield losses where above-normal spring rainfall occurred. Experiments were conducted to determine the effect of seed treatment and inoculum density on aphanomyces root rot of field pea under greenhouse and field conditions. Five seed-treatment fungicides, including Apron Advance, Intego Solo, BAS 516F, BAS 720F and BAS 516F + BAS 720F (1:3), were evaluated in 2015. Except for Apron Advance, all of the treatments reduced root rot severity. BAS 516F, BAS 720F and Intego Solo also improved plant vigour compared with the control treatment under greenhouse conditions. Under field conditions, the seed treatments were generally not effective. In an inoculum density study, increasing inoculum density reduced seedling emergence and plant vigour, and increased root rot severity under both field and greenhouse conditions. The field experiments will be repeated in 2016.