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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 #320254
Title: The potential for cereal rye cover crops to host corn seedling pathogens

Author
item Bakker, Matthew
item ACHARYA, JYOTSNA - Iowa State University
item Moorman, Thomas
item ROBERTSON, ALISON - Iowa State University
item Kaspar, Thomas

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2016
Publication Date: 5/25/2016
Citation: Bakker, M.G., Acharya, J., Moorman, T.B., Robertson, A., Kaspar, T.C. 2016. The potential for cereal rye cover crops to host corn seedling pathogens. Phytopathology. 106:591-601.

Interpretive Summary: Cover cropping is an agricultural management practice that protects soil and water quality. However, there may also be down-sides to cover cropping under certain circumstances, and we need to understand these in order to avoid them. One potential problem is that if cover crops are closely related to the following grain crop, they may make disease more likely on the following crop. We demonstrate that microorganisms growing in roots of cereal rye cover crops are able to cause corn seedling disease. As a result, we argue that cover crop management should specifically consider disease risk on the subsequent grain crop.

Technical Abstract: Cover cropping is a prevalent conservation practice that offers substantial benefits to soil health and water quality. However, winter cereal cover crops preceding corn may diminish beneficial rotation effects by growing two grass species in succession. Here, we show that rye cover crops host pathogens capable of causing corn seedling disease. We isolated Fusarium graminearum, Fusarium oxysporum, Pythium sylvaticum and Pythium torulosum from roots of rye and demonstrate their pathogenicity on corn seedlings. We quantified the densities of these organisms in rye roots from several field experiments and at various intervals of time after rye cover crops were terminated. Fusarium oxysporum was detected in 90.4% of rye root samples. Corresponding values for P. sylvaticum, P. torulosum, and F. graminearum were 74.3%, 41.2% and 23.5%, respectively. Each of the four species increased in density over time on roots of herbicide-terminated rye in at least one field site. We confirmed this ability to increase in density on dead rye tissue for F. graminearum in a controlled environment experiment. Pathogen load in rye roots differed among fields. There is potential for elevated disease pressure in corn planted following rye cover crops, although this risk will likely vary among fields and depends on environmental conditions.