Given the increasing disease risks to soybean in Manitoba, it is essential to help producers better plan their crop rotations, i.e., by determining the pathogens affecting production. Our objectives were to assess the effect of soybean frequency in crop rotations on soybean disease status, and to develop tools for better disease risk assessment in this crop. Using four cropping patterns involving canola, corn, wheat, and soybean, we sampled both soil and plant tissues to determine the nature of pathogens and observed diseases. Using valuable data gathered from this project, we published six manuscripts in peer-reviewed journals, in addition to three magazine articles and several conference papers. In summary, we characterized several pathogens involved in soybean disease under different rotation regimes. Many were described for the first time on soybean or in Western Canada. Continuous soybean cropping consistently resulted in the highest soybean root rot severity, and Fusarium species were the major pathogens isolated from diseased samples. This work was the first to report: (i) Fusarium cerealis causing root rot on soybean [1], (ii) Fusarium sporotrichioides causing soybean root rot in Canada [2], (iii) Diaporthe longicolla causing pod and stem blight and seed decay on soybean in Western Canada [3], and (iv) Diaporthe caulivora causing Northern stem canker on soybean in Western Canada [4]. We developed a molecular tool to specifically differentiate Fusarium graminearum sensu stricto from other F. graminearum species in the F. graminearum species complex that causes both root rots in soybean and fusarium head blight in cereals [5]. We found Fusarium species that can cause both Fusarium head blight (FHB) on wheat and Fusarium root rot (FRR) on soybean. We revealed that these Fusarium species interestingly also produce trichothecenes when causing root rot in soybean [6]. Luckily, no toxins were found in the seeds. We published all of the designed primers from our papers and deposited all sequences in the GenBank for public use.

[1] Abdelmagid et al. 2018. First Report of Fusarium cerealis causing root rot on soybean. Plant Disease 102:2638-2639.

[2] Abdelmagid et al. 2021. First report of Fusarium sporotrichioides causing root rot of soybean in Canada and detection of the pathogen in host tissues by PCR. Canadian Journal of Plant Pathology 43:527-536.

[3] Abdelmagid et al. 2022. First Report of Pod and Stem Blight and Seed Decay caused by Diaporthe longicolla on Soybean in Western Canada. Plant Disease 106:1061.

[4] Abdelmagid et al. 2019. First Report of Northern Stem Canker Caused by Diaporthe caulivora on Soybean in Western Canada. Plant Disease 103:372.

[5] Hafez et al., 2020. Specific detection and identification of Fusarium graminearum sensu stricto using a PCR-RFLP tool and specific primers targeting the translational elongation factor 1 alpha gene. Plant Disease 104:1076-1086.