July 22, 2004

Early signs of SDS suggest soybean crop is at risk

by K.C. Jaehnig

CARBONDALE, Ill. -- Symptoms of soybean Sudden Death Syndrome, or SDS, have shown up early this year, say experts from Southern Illinois University Carbondale's College of Agricultural Sciences, and this could affect the state's bean crop.

"If we should get a cool spell with rain, we could see a lot more of it.""Because we saw it so early, that tells us that the potential yield loss is much greater than it's been in recent years," said researcher Catherine A. Schmidt from the Department of Plant, Soil and Agricultural Systems.

SDS, an incurable fungal disease, infects plant roots early in the growing season. By the time a farmer notices the damaged leaves, it is too late to take any precautionary measures. Being a fungus, the disease does well in cool weather, and it seems to hit hardest those beans planted early.

"Farmers planted early this year because of the dryer spring," Schmidt said. "We saw our first symptoms (in research plots in Carbondale, Carmi, Paris, Pontiac and Valmeyer) at the end of May. Symptoms were mild to pretty moderate."

Since then, SIUC researchers have been keeping a sharp eye on the weather, which, though it may feel summery, is not as hot as usual.

"On average, we're quite a bit cooler than normal," Schmidt said.

SDS symptoms usually crop up around mid-August, making hot, dry weather for the next three weeks crucial for farmers concerned about SDS.

Cool temperatures and rain in the next three weeks won't necessarily doom all soybeans, Schmidt said."There are farmers for whom a late August cold snap could be devastating, but most growers -- especially in Southern Illinois -- will have dodged the bullet (if cooler, wetter weather hits the region then)," Schmidt said.

"When we say the disease potential is greater than it has been, we have to emphasize the word 'potential,'" she noted.

"It's a spotty disease. It won't hit an entire 2,000-acre field -- it will just hit splotches. And even if a farmer gets hit with severe SDS, he will still have a yield. It just may not be enough to make his payments."

At this point, there's not a lot farmers can do to ward off the disease.

"They either planted resistant varieties -- and when I say 'resistant,' I mean 'partially resistant,' because there are no truly 100 percent-immune varieties -- or they didn't," Schmidt says. "And no one can control the weather."

As for the future, Schmidt recommends buying the most resistant varieties on the market.

"When you order your beans in October or November, that's the only time you can improve your odds for beating SDS," she said.

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