10/19/01

Contacts:
Wayne Pedersen, University of Illinois, (217) 333-3847
Tracy Petersen, Iowa State University Agriculture Communications, (515) 294-0706

VIGILANCE TO DISEASE SHOULD BE KEY STRATEGY FOR SOYBEAN GROWERS

URBANA, Ill. -- Vigilance should be the watchword for soybean growers who suspect their fields contain the diseases soybean cyst nematode or Rhizoctonia root rot, according to a University of Illinois plant pathologist.

Wayne Pedersen is one of the researchers in the Yields Project, a multistate effort to understand factors limiting soybean yields. The project also involves Iowa State University, the University of Wisconsin and Southern Illinois University.

Pedersen said his research has reinforced the recommendation that producers should switch to disease-resistant varieties in fields infested with soybean cyst nematode (SCN). "SCN is our number-one disease problem, and it can be dramatically managed by resistant varieties," he said.

"We've found that newer SCN-resistant varieties don't suffer much yield drag, and they also don't appear to be as affected by post-emergent herbicides as SCN-susceptible varieties," Pedersen said.

On the other hand, Pedersen said herbicides may play a role in the presence of Rhizoctonia root rot. He recommended that growers who've had problems with Rhizoctonia should look for the disease's dark red lesions on plant roots below the soil surface. If the disease is present, farmers should in future years select varieties with the best resistance and use "kinder, gentler herbicides," he said.

If the disease isn't present, herbicide injury may predispose the soybean plant to infection by Rhizoctonia, he said. However, more than 800 varieties have been screened for resistance. More information is available on the Varietal Information Program for Soybeans website at http://web.aces.uiuc.edu/VIPS.

Yields Project research indicates there are complex relationships among seed treatments, herbicides, disease and other factors. Pedersen said it also has shown the progress that seed companies have made. "My hope has been that the Yields Project identify where we need to spend our resources in breeding programs. So far, it's done exactly that. In the last year we've added a lot more varieties. So the project is feeding the breeding program."

Pedersen's current work examines how sudden death syndrome affects the whole growing system. He is completing a study on the interaction between SCN and herbicide injury.

One area of his research is exploring potential interactions between seed treatments and herbicides. Pedersen has suggested that soybean growers who plan to plant no-till before May 1 should consider using fungicide seed treatments. "This interaction may turn out to be one of the most important questions addressed by the Yields Project," he said. "Because growers want the most effective, economical herbicide program they can find."

Pedersen's research is part of the Yields Project, a multistate research program funded by Iowa and Illinois checkoff dollars through the Soybean Research and Development Council (SRDC). The Yields Project is one of the largest soybean research projects ever undertaken to understand factors that limit soybean yields.

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