Asiatic Soybean Rust was confirmed yesterday and today in South Carolina commercial soybean fields in Calhoun, Colleton, and Hampton Counties, SC. Although soybean rust has now been found in 7 SC Counties, all are below the lakes in South Carolina. This still does not put rust close enough to warrant a recommendation from us to spray for the disease. The closest confirmed rust on soybeans to our North Carolina soybeans is now approximately 115 miles from Charlotte, 310 miles from Elizabeth City, 140 miles from Fayetteville, 115 miles from Murphy, 195 miles from Raleigh, 250 miles from Washington, 160 miles from Wilmington, and 175 miles from Winston-Salem, NC. (The mileages in red are changes from our previous update.)
Rust has now been confirmed this year on soybeans in 39 counties/parishes in seven states (LA, FL, AL, MS, GA, SC & AR).
Rust has progressed at a faster rate this year than in years past. With a late soybean crop, the odds on needing to apply fungicides is increased. Now is the time to check spray equipment and be sure to have the proper nozzles for applying fungicides.
We do not recommend spraying soybeans that have not started blooming with a fungicide to control Asiatic soybean rust. Such pre-bloom applications have seldom improved yields. Once soybeans start blooming, we would recommend spraying if rust has been confirmed within 100 miles of the field.
Article by Steve Koenning, NCSU Extension Plant Pathologist and Jim Dunphy, NCSU Extension Crop Scientist