Southern rust was confirmed Aug. 3 on corn samples from Chesapeake and Suffolk in Virginia, according to a blog posting by Hillary Mehl, assistant professor of plant pathology at the Virginia Tech Tidewater Agricultural Research and Extension Center in Sufolk.
“Yield of corn at or near the dent stage is unlikely to be impacted by the disease, but less mature corn in the region may need to be protected with a fungicide application,” Mehl writes. “Strobilurins are good preventative fungicides whereas triazoles are recommended once sporulation is observed in a field due to their curative activity.”
Mehl says a combination fungicide is a good option as long as a strobilurin fungicide has not been applied previously. “Wet, warm weather favors disease development,” Mehl writes. “Once sporulation occurs, symptoms of rust are relatively obvious. Lesions start out as raised, blister-like pustules then break open to reveal orange spores."