DATE: 8/21/2006

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

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

First sign of soybean rust in S.C. for 2006 is found

BLACKVILLE – The first sign of Asian soybean rust has been found in an early-warning monitoring plot in Calhoun County.

"South Carolina soybean growers need not panic, though,” said John Mueller, Clemson University nematologist /plant pathologist at Edisto Research and Education Center. Last week he examined almost 1,400 leaves from 43 soybean fields or sentinel plots. Just one leaf out of 25 leaves pulled from one field showed one lesion containing three very young pustules that had just begun producing disease spores.

The samples were from a field of maturity group 5 soybeans near the intersection of State Road 22 and Interstate 26. The plants were in growth stage R-5, meaning they contained full-sized pods with developing beans.

No rust was found in a field of maturity group 4 soybeans right next to the field where the disease organism was detected.

Mueller said that growers who have soybeans with good yield potential -- between 40 and 50 bushels an acre -- and developing pods, could consider spraying with a strobilurin fungicide.

“That will offer protection from rust and other more common diseases such as frogeye leaf spot, target spot, pod and stem blight and anthracnose,” he said.

“Levels of rust are extremely low in South Carolina right now. However, we are predicted to have slightly cooler temperatures and a fairly good chance of thunderstorms through Friday in South Carolina,” Mueller said. “These weather conditions could be conducive to the development of rust and other pod, stem and leaf diseases.”

He reminded growers that soybeans which have not flowered do not need to be sprayed. Soybeans which are at or past late growth stage R5 should not be sprayed.

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