Response of indigenous field populations of Fusarium graminearum to fungicide application in Manitoba. S. ALLEN, H. DERKSEN, M. SACHS, A. BRÛLE-BABEL AND T. GRÄFENHAN. (S.A., M.S., A.B., T.G.) Department of Plant Science, 222 Agriculture Building, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; (S.A., T.G.) Canadian Grain Commission, 196 Innovation Drive, Winnipeg, MB R3T 6C5, Canada; and (H.D.) Manitoba Agriculture, 65 3rd Avenue NE, Carman, MB R0G 0J0, Canada
Fusarium head blight (FHB) is an important disease of wheat in Canada, causing yield loss and downgrading of grain. Application of synthetic fungicides is part of an integrated pest management strategy; however field efficacies have been variable. The main causal agent of FHB in Canada, Fusarium graminearum, has multiple characteristics that can drive rapid adaptation to the environment. The high genetic diversity observed in field populations of F. graminearum may be a contributing factor to variation in fungicide efficacy. This study assesses the response of indigenous field populations of F. graminearum on spring wheat to fungicide application in Manitoba. Field trials at two farm locations with four replicated plots of untreated control and fungicide treatments at two application timings were sampled for infected wheat spikes in 2017. An Amplified Fragment Length Polymorphism (AFLP) approach was used to assess the genetic response of F. graminearum field populations to fungicide treatment. Fungicide treatment was shown not to be a significant source of genetic variation, however, minor genetic variation among fungicide treatments was observed for isolates of the 15-acetyldeoxynivalenol trichothecene genotype. The genetic data will be complemented with in vitro fungicide sensitivity testing. This research will increase our understanding of the within-field variability of F. graminearum and the population response to fungicide application.
Cross-pathogenicity of Fusarium graminearum between soybean and wheat. N. GARMA, Y. GHARBI, L. R. ADAM, M. HAFEZ, A. ABDELMAGID AND F. DAAYF. Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
Fusarium species cause disease in several economic crops in Manitoba and Canada, including root rot in soybean and fusarium head blight (FHB) in cereals. Root rot caused by Fusarium species pose a significant challenge to soybean growers in Manitoba, and so does FHB in cereals. In the field, soybean and wheat are usually used in rotation with each other. In wheat, FHB is caused by some Fusarium species, especially F. graminearum. In soybean, Fusarium species are also involved in root rots, but more than one species may be involved. Recent scouting and sample collection in Manitoba fields indicated the presence of F. graminearum in soybean tissues and soil, which is also supported by previous literature from other soybean-growing regions, i.e., Argentina. Such observations raise several questions, such as whether FHB in wheat contributes to root rots in soybean through F. graminearum and the impact of F. graminearum from soybean on wheat and other cereals. The objectives of this study are to: (1) Evaluate the cross pathogenicity of F. graminearum isolates recovered from wheat on soybean and vice-versa, (2) Determine whether serial passages of F. graminearum on soybean can affect the fitness of the pathogen in term of gain or loss of pathogenicity on either host, and (3) Determination of the diversity of F. graminearum on soybean plant. We tested the pathogenicity of selected F. graminearum isolates, collected from wheat, barley and oat, on soybean and wheat, under greenhouse conditions. These experiments revealed that all the isolates from wheat, barley and oat are able to cause root rot disease on soybean and also that isolates from soybean were able to cause FHB on wheat. Work is ongoing to complete the other objectives. This study will provide Manitoba growers with valuable information for better disease management of soybean root rots and cereal FHB.
Two-year in-depth studies to identify Fusarium species causing root rot of soybean (Glycine max L.) in Manitoba. Y. M. KIM, M. A. HENRIQUEZ, D. L. MCLAREN, R. L. CONNER, S. F. HWANG, K. F. CHANG 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, Unit 100 Morden, MB R6M 1Y5, Canada; (S.F.H., K.F.C.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17507 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
Manitoba is the second largest soybean producer in Canada comprising 29% of total production with 926,700 ha seeded in 2017. Fusarium root rot of soybean is an economically important disease worldwide and has been the major root disease of commercial soybean fields in Manitoba since 2012. In order to examine Fusarium spp. diversity and population structure as well as to monitor changes in pathogen populations over time, multi-year in-depth studies on root rot pathogens were conducted. The research was carried out each year for two years (2012 and 2017) in three different commercial soybean crops from the major production areas in Manitoba. A total of 1868 single spore isolates were obtained in two separate years. The pathogen species were sub-grouped and identified based on their morphological characteristics on selection media and through microscopic examination. Identification of Fusarium spp. was confirmed by DNA sequencing of the ribosomal intergenic spacer, the internal transcribed spacer regions, and the translation elongation factor 1 alpha gene. In addition, the frequency and diversity of Fusarium spp. associated with soybean root rot were determined. Findings from these in-depth studies will support the development of improved management strategies for root rot disease associated with different Fusarium spp. in soybean in Manitoba and across Canada.
Phytophthora sojae in Manitoba soybean crops: distribution and pathotype identification. D. L. McLAREN, Y. M. KIM, M. A. HENRIQUEZ, R. L. CONNER, S. F. HWANG, K. F. CHANG, S. E. STRELKOV, B. D. GOSSEN, T. L. HENDERSON, T. J. KERLEY AND W. C. PENNER. 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., W.C.P.) Morden Research and Development Centre, AAFC, 101 Route 100, Unit 100 Morden, MB R6M 1Y5, Canada; (S.F.H., K.F.C.) Crop Diversification Centre North, Alberta Agriculture and Forestry, 17507 Fort Road NW, 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.) Saskatoon Research and Development Centre, AAFC, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
In Manitoba, the soybean industry has grown rapidly with consecutive increases in seeded hectares from 87 000 ha in 2007 to 926 700 ha in 2017. Phytophthora stem and root rot, caused by Phytophthora sojae Kaufm. & Gerd., is one of the most damaging diseases of soybean (Glycine max (L.) Merr.) worldwide. This pathogen was discovered in Manitoba in 2011. The common races and virulence profiles of P. sojae were characterized following a survey in 2014. Isolates of P. sojae from infected soybean plants were assessed for pathotype identification using a differential set of soybean lines, each containing one resistance gene to P. sojae (Rps1a, 1b, 1c, 1d, 1k, 3a, 6 or 7) and a universal susceptible line (rps). This first in-depth study of the race structure of P. sojae indicated the presence of four pathotypes, with ‘1a, 1c, 7ʹ being present in most commercial fields. Since then, the pathotype diversity has increased as has the spread of P. sojae within the Manitoba soybean production areas. The identification of the pathotypes causing this disease is an important step for effective management through selection of cultivars carrying gene(s) resistant to the predominant pathotypes. Improved disease control will ultimately result in increased profits by increasing yields, reducing risk and enhancing opportunities for soybean producers.