Disease suppressive ability of certain society cover crop soils on barley and soybean root disease


Aiyer, H., Caldwell, C., & Foster, A. (2020). Disease suppressive ability of certain society cover crop soils on barley and soybean root disease. Presented at the Canadian Phytopathological Society Atlantic regional meeting, 2020. Abstract submitted to be published in Canadian Journal of Plant Pathology

Plain language summary

Graduate student Harini Balasundaram (Now Harini Aiyer) gave a presentation of her research on cover crop effects on the soil microbiome with a focus on 2020 Field pathology data. She found that cover crops influence the abundance of important fungal pathogens that cause disease to the roots of both barley and soybean plants. Root disease was lowest in both the crops when planted after sorghum-sudan grass, buckwheat, and phacelia and in a study of the microbiome these cover crops had some significantly effect the overall diversity of fungi and bacteria. It was suspected that the changes in diversity may allow the soil to suppress the ability of root pathogens to cause disease in barley and soybean. This hypothesis is being tested in an ongoing greenhouse trial where plants we under controlled disease pressure and the methods of the trial were discussed.


Cover crops are important components of cropping systems, grown to improve soil fertility and prevent erosion. Their ability to improve soil health can be associated through interactions with microorganisms in the soil and this may effect on disease in future cropping years. The effects of cover crops on soil fungal and bacterial communities and the influence of these microbial communities on root disease in barley and soybean planted in the subsequent year was examined. Two field trials were planted with spring cover crops in the first year and split to barley or soybean in the subsequent year. Root disease ratings and pathogen isolation from barley and soybean was conducted. Amplicon sequencing was performed on soil and residue DNA targeting bacteria and fungi. This data was analyzed for changes in alpha and beta diversity and relative abundance of individual microorganisms. Fusarium oxysporum was identified as a causal agent of root disease in both barley and soybean. Reduced root disease severity was observed in both crops planted after sorghum-sudan grass, buckwheat, and phacelia. The relative abundance of F. oxysporum and other Fusarium spp. amplicons were also significantly influenced by cover crops. Studies to determine the Fusarium root disease suppressive ability of soil following cover cropping are ongoing. This research will improve the understanding of cover crop effects on the soil microbiome and how these relationships influence disease in future cropping seasons.

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