By Andi Anderson
Illinois farmers are using cover crops to improve soil health, stop erosion, and protect water quality. But how do these crops affect soybean cyst nematode (SCN), a major pest in soybean fields?
SCN is found in over 80% of soybean fields in Illinois. To learn how cover crops impact SCN, scientists from Southern Illinois University, along with agronomist John Pike, led a study funded by the Illinois Soybean checkoff.
Researchers gathered about 3,000 soil samples from different farms across Illinois. These farms used several types of cover crops, such as cereal rye, annual ryegrass, clover, hairy vetch, and rapeseed. They took samples at four times—during cover crop planting in the fall, before soybean planting in spring, mid-season in August, and after harvest.
Early results show that cereal rye did not reduce SCN compared to no-cover plots. In areas with heavy SCN problems, some fields without cover crops even showed better SCN reduction, possibly due to drier soil in the cover crop areas. At the Henry White Farm site, SCN levels were similar across most cover crops and untreated plots.
However, one cover crop stood out—annual ryegrass. It showed a clear drop in SCN numbers compared to plots without cover crops.
The team is also studying how the timing of planting and killing the cover crops might affect SCN. These results could help farmers adjust their field plans.
Though the full study will end in 2025, the main lesson so far is that not all cover crops help with SCN. Moisture, crop type, and timing are important.
With resistance growing to the most common SCN-resistant soybean (PI88788), finding new ways like using the right cover crops may be key for farmers. Updates will be shared on the Field Advisor Research Hub.
Photo Credit: gettyimages-eugenesergeev
Categories: Illinois, Crops, Corn, Soybeans