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Research Highlights
Cover Crops May Help to Reduce SCN Populations

Cover crops are being investigated to reduce soybean cyst nematode (SCN) populations in North Dakota. The faba bean cover crop is one of many that can be considered a non-host plant for SCN. Photo: Guiping Yan

By Carol Brown

Cover crops have numerous benefits for farm fields including reducing soil erosion, increasing soil organic matter, improved soil drainage, weed suppression and more. Guiping Yan, a plant pathology associate professor at North Dakota State University, is hoping to add “reducing soybean cyst nematode (SCN)” to the benefit list.

“Soybean cyst nematode is an important disease in North Dakota, the United States and the world,” says the nematologist. “After planting soybeans year after year, SCN resistance has declined. A new SCN population has developed and resistance to some soybean cultivars is not as effective as before.”

Crop rotation is a good place to begin to control SCN reproduction as wheat and corn are known as non-hosts. Cover crops could add another layer of protection. Yan is exploring which cover crops are most effective in helping to reduce SCN populations through a research project supported by the North Dakota Soybean Council.

“We’ve screened a total of 38 cover crop species/cultivars,” Yan says. “We’ve included cover crops currently being used in North Dakota and some that could potentially be used. That means the cover crops found to be successful at reducing SCN here in North Dakota could also be used in other states.”

Yan and her team have been testing various species annually since 2017 in growth chambers and microplots. They have added new sets of cover crops or changed the species studied as results emerge.

“We have found there are a lot of cover crops that are considered non-SCN hosts,” she says. “We have tested alfalfa (cv. Bullseye), brown mustard (Kodiak), camelina (Bison, Joelle), faba bean, daikon radish, Sunn hemp, triticale (Winter 336), red clover (Arlington), oilseed radish and winter rye (ND Dylan). They are all non-hosts for SCN. In general, they can be used in growers’ fields, but some may be better than others in terms of SCN population reduction.”

Cover crops can reduce SCN populations basically in three ways. Non-hosts are cover crops that SCN juveniles won’t eat. There are also certain species, like white mustard, that produce biochemical compounds toxic to nematodes. And some species act as a trap crop, which enhances SCN egg hatching and penetration, but the hatched juveniles are unable to adequately feed due to poor nutrition and then either die or do not reproduce, Yan says.

According to Yan’s research, over the years she has found that certain turnip and lupine cover crops showed some SCN population reproduction in the soil, suggesting that they could be considered poor or suitable hosts. But overall, many of the cover crop species tested showed declines in SCN reproduction, showing promise that usage of a cover crop can be used to fight this soybean pest.

“The combination of different field managements — host resistance, crop rotations, seed treatments and cover crops all working together will be a good way for sustainable farm management and good soybean production,” comments Yan. “There are so many benefits to using cover crops. When you plant cover crops, you may increase production.”

Yan and her team members have published several research articles documenting this work:

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.