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New research funded by the Illinois Soybean Association (ISA) checkoff program is looking at cover crops, including winter wheat, as potential aids in the battle against soybean cyst nematode (SCN). The study builds on previous trials in Illinois and Kentucky that showed promise for use of cover crops to reduce SCN egg populations.

In the mid-1990s, a University of Kentucky study indicated no-tilling soybeans into wheat stubble suppressed SCN egg production and reduced counts. Research by former University of Illinois Extension educator Mike Plumer also documented SCN egg reductions following grass cover crops.

“These were limited trials, but if we can repeat these findings, we’ll help show that adding wheat or grass covers to the rotation before soybeans can provide another tool for managing SCN,” says Dan Davidson, Ph.D., ISA research technical coordinator.

Leading the new ISA checkoff-funded study is Jason Bond, professor of plant soil and agricultural systems at Southern Illinois University Carbondale.

“SCN remains the number one cause of yield loss in soybeans, taking as much as 30 percent of soybean yield potential even if there are no visual symptoms,” notes Bond.

SCN populations reinforce need to test

The research team has already gained significant knowledge after collecting SCN samples last fall to establish baseline counts. Tests of the samples showed egg counts ranging from 0 to 37,600 eggs per 100 cc of soil (about a half cup.) An egg count of more than 2,000 is considered cause for concern. More than half the samples—14 of 22—showed counts above this threshold.

 “In 17 years of in-field trials, I’ve never seen such wide swings in sample counts,” says Bond. “Counts of 2,000 or above, from about a half cup of soil, require increased management. And this range in egg counts reinforces how important it is to test for SCN every couple of years.”

 Researchers will compare the fall baseline counts with spring SCN populations to determine the effect of grass and wheat cover crops.

Keep managing SCN

Meanwhile, experts recommend farmers work with trusted advisers to develop an SCN management plan. Consider these practices:

• Test your fields to confirm SCN numbers.
• Rotate to non-host crops between soybeans.
• Consider a seed treatment nematicide.
• Rotate resistant varieties. SCN can adapt to individual varieties, so rotating—even to another PI 88788 resistant variety—may help reduce SCN populations.

“Managing resistant populations will require multiple strategies, including resistant traits, rotation and chemical controls. ISA hopes this research gives growers another possible tool to consider for managing this pervasive pest,” Davidson says.

The Illinois Soybean Association (ISA) checkoff and membership programs represent more than 43,000 soybean farmers in Illinois. The checkoff funds market development, soybean production and profitability research, promotion, issues management and analysis, communications and education. Membership and advocacy efforts support Illinois soybean farmer interests in local areas, Springfield and Washington, D.C. ISA programs are designed to ensure Illinois soy is the highest quality, most dependable, sustainable and competitive in the global marketplace. For more information, visit the website ilsoy.org.