DATE: 9/20/2006

CONTACT: Dr. John Mueller, 803-284-3343, ext. 223; jmllr@clemson.edu

WRITER: Tom Lollis, 803-284-3343, ext. 241; tlollis@clemson.edu

Soybean rust warning system works in 2006

BLACKVILLE – The growing season for soybeans in South Carolina in 2006 has proved one thing – the monitoring plots established around the state as an early warning system for Asian soybean rust has worked.

“Yield losses will be at a minimum, despite the fact that rust showed up in August and September when it could have caused significant damage,” said John Mueller, Clemson University nematologist/ plant pathologist at Edisto Research and Education Center.

Soybean rust has been found in 13 counties in South Carolina and at least 100,000 of the state’s 435,000 acres of soybeans has been treated with one fungicide application at a cost of around $10 per acre, according to Mueller.

“Orangeburg, Calhoun, Sumter and Horry counties have had the highest levels of rust and the highest percentage of growers spraying for that and other diseases such as frogeye leaf spot, anthracnose and pod and stem blight,” he said.

The counties of Barnwell, Darlington and Edgefield were added this week to the previously reported list of Anderson, Calhoun, Colleton, Dorchester, Florence, Hampton, Horry, Lee, Orangeburg and Sumter.

Early in the year Clemson established 15 sentinel plots of early maturity soybeans around the state from the Coastal Plain to the Piedmont, putting every soybean grower in South Carolina within 50 miles of an early warning plot.

By the third week of September well over half the state’s soybean crop has reached growth stage R6, which means pods are filled with full size beans.

“They’ve made their crop, or will have within a week,” said Mueller. “In another week to 10 days after that they’ll start dropping leaves.” Early maturing Group 4 soybeans are either already harvested or in the process of being harvested.

Mueller estimates that a third to half the crop will wind up being sprayed once with fungicides.

“Two years ago we were afraid everybody would have to spray twice,” he said. “So, with the sentinel plots we have cut rust control costs in half.”

Left untreated, a severe rust infection can defoliate a soybean field within days.

END