BLACKVILLE  –  Soybean rust was detected on samples in Dorchester County Sept. 9, the second and third cases in South Carolina this year.

The latest cases were found on four leaves out of 100 in a sentinel site near Reevesville. Rust also was found on one out of 100 leaves in an adjacent site. In both sites, pustules were actively producing spores.

The first case was found on one leaf out of 50 collected Sept. 1 from a sentinel plot near Carnes Crossroads, an area between Moncks Corner and Summerville in Berkeley County.

With dry weather predicted for at least the next week, rust may have a difficult time spreading unless fields are irrigated, said John Mueller, Clemson University extension soybean pathologist at the Edisto Research and Education Center.

Farmers do not need to consider spraying a fungicide unless committed to spray for insects, Mueller said. The exception would be fields with seeds in the growth stage with good moisture and yield potential that have not received a fungicide spray.  

Soybean rust – yellowish in appearance on plant leaves – is a disease that causes premature defoliation, early maturation and severe loss of yield and decreased seed weight.

Rust is now active on soybeans throughout the Southeast and has recently become more active in Georgia. The disease recently was detected in Effingham County, Ga., which sits across the Savannah River from Hampton County.