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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #347781
Title: Disease risks associated with cover crops in corn and soybean production

Author
item ROBERTSON, A. - Iowa State University
item Kaspar, Thomas
item ACHARYA, J. - Iowa State University
item MUELLER, D. - Iowa State University
item LEANDRO, L. - Iowa State University

Submitted to: Integrated Crop Management Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/29/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cover crops have numerous environmental and soil health benefits and are being more widely used by farmers in Iowa. Still some farmers are reluctant to use cover crops because of increased risks to crop yields in part because of increased disease potential. The goal of our research is to understand how cover crops may affect disease potential in the following cash crop and thereby recommend actions that may be taken to mitigate disease risk. Our research showed that a rye cover crop terminated shortly before corn planting can increase the incidence of corn seedling root diseases, but this risk is lessened by terminating the cereal rye cover crop 10 or more days before planting corn. Alternatively, corn following a cereal rye cover crop had less stalk rot than corn that did not follow a cover crop. For soybean, some cover crop species (pea, crimson clover, hairy vetch, alfalfa) were found to be hosts to the fungus that causes sudden death syndrome, whereas other cover crops (oat, cereal rye, triticale, wheat, false flax, millet, mustard) were non-hosts. Greenhouse experiments showed that some cover crops may also increase incidence of seedling root diseases of soybean, but field trials did not show any increase in seedling diseases following cover crops. Thus, cover crops in Iowa can have positive and negative benefits on corn and soybean seedling establishment and growth. Terminating a cover crop 10 or more days before planting corn would help to reduce the risk. Also, when selecting a cover crop species the cash crop following it should be considered and cover crops likely to be hosts of likely pathogens should be avoided.

Technical Abstract: Cover crops have numerous environmental and soil health benefits and are being more widely used by farmers in Iowa. Still some farmers are reluctant to use cover crops because of increased risks to crop yields in part because of increased disease potential. The goal of our research is to understand how cover crops may affect disease potential in the following cash crop and thereby recommend actions that may be taken to mitigate disease risk. Our research showed that a rye cover crop terminated shortly before corn planting can increase the incidence of corn seedling root diseases, but this risk is lessened by terminating the cereal rye cover crop 10 or more days before planting corn. Alternatively, corn following a cereal rye cover crop had less stalk rot than corn that did not follow a cover crop. For soybean, some cover crop species (pea, crimson clover, hairy vetch, alfalfa) were found to be hosts to the fungus that causes sudden death syndrome, whereas other cover crops (oat, cereal rye, triticale, wheat, false flax, millet, mustard) were non-hosts. Greenhouse experiments showed that some cover crops may also increase incidence of seedling root diseases of soybean, but field trials did not show any increase in seedling diseases following cover crops. Thus, cover crops in Iowa can have positive and negative benefits on corn and soybean seedling establishment and growth. Terminating a cover crop 10 or more days before planting corn would help to reduce the risk. Also, when selecting a cover crop species the cash crop following it should be considered and cover crops likely to be hosts of likely pathogens should be avoided.