Biofumigation to Manage Soilborne Row Crop Diseases in the North Central Region

Commodities

Practices

Soilborne diseases, such those caused by Sclerotinia sclerotiorum and pathogen complexes that target seedlings, limit the productivity of dry beans and sunflowers across Minnesota and North Dakota. These crops lack the same research base of chemical, genetic, non-chemical tools available for major commodities. Brassicaceous cover crops used for biofumigation have the potential to suppress soilborne pathogens while providing numerous agroecosystem services including retaining nutrients, reducing soil erosion and improving water infiltration, increasing organic matter, providing pollinator resources, and weed and disease suppression. Yet little research exists on how to optimize these systems under northern temperatures and soil conditions.

This project will evaluate brassica cover crop species, termination methods, and decomposition-enhancing practices to determine how biofumigation influences disease dynamics and agronomics in dry bean and sunflower. Field trials at the University of Minnesota and North Dakota State University will assess crop biomass, pathogen suppression, crop agronomics, and changes in soil nutrients. Crop, disease, and microbial outcomes of standard practices, non-cover cropped plots and rye cover cropped treatments, will be compared with brassicaceous cover crops, and readily available farm equipment will be used for residue management. Laboratory assays will measure pathogen sensitivity to isothiocyanates and assess impacts on beneficial microbial populations to clarify both functional mechanisms and tradeoffs.

A key component of this project is farmer collaboration. In year three, the most effective practices from research-farm trials will be implemented in on-farm demonstrations in Minnesota and North Dakota. These farmer-led trials, along with feedback from our grower and agronomic advisory panel, will evaluate operational feasibility and ensure recommendations reflect real production systems.

Learning outcomes include region-specific guidelines for establishing, terminating, and incorporating brassica cover crops; identification of brassica species suited to cold conditions; and improved understanding of microbial responses to biofumigation. Action outcomes include adoption of validated practices, improved disease management, more consistent yields, and enhanced confidence in integrating cover crops into cropping systems.

Objective 1 will evaluate brassicaceous cover crops, termination methods, and decomposition accelerators for pathogen suppression, producing learning outcomes on best practices for termination, incorporation, and cold-tolerant cover crop options and action outcomes that advance adoption of cover crops and non-chemical disease management.

Objective 2 will assess agronomic impacts, generating learning outcomes on cover crop contributions to biomass, soil nutrients, and yields and action outcomes that support informed farmer decisions through on-farm validation.

Objective 3 will determine biofumigation effects on beneficial microbes, with learning outcomes on microbial shifts and action outcomes that guide cover crop use for soil and plant health.