- Southern Corn Rust can cause severe yield loss and the disease can spread rapidly.
- It is very aggressive and takes just five to 10 days to go from the first signs of rust on the leaves to complete leaf loss.
The symptoms of Southern Corn Rust are orange to brown masses of spores (urediospores) that erupt through the upper leaf surface.
Southern Corn Rust has been found in Lenoir and Wayne counties in eastern North Carolina and farmers need to scout their fields and be prepared to make a fungicide application, according to researchers at North Carolina State University.
Southern Rust can cause severe yield loss and can spread rapidly. It is very aggressive and takes just five to 10 days to go from the first signs of rust on the leaves to complete leaf loss. It is a fungal disease of corn that is well adapted to warm, humid or wet environments.
Ordinarily, Southern Rust is not a problem for North Carolina corn farmers because spores arrive so late in the season that little or no impact on yield occurs. However, this year early warm weather and moist conditions have helped set the stage for an early infestation in North Carolina. The movement of the disease was also aided by Hurricane Arthur.
Dr. Steve Koenning, Plant Pathology Extension Corn Specialist and Dr. Ronnie Heiniger, Crop Science Extension Corn Specialist of North Carolina State University have prepared a publication, Alert: Potential for Southern Rust on Corn in North Carolina to advise corn growers on how to manage Southern Corn Rust.
“Southern Rust can be recognized by the bright orange or golden brown, circular to oval pustules that give leaves a rusty appearance. The pustules are about the size of a pin head and are filled with powdery masses of orange spores that are readily dislodged and blown in the wind,” Koenning and Heiniger write. “Thanks to these spores, Southern Rust can spread quickly.”
If growers see Southern Rust in their field or nearby fields they should IMMEDIATELY arrange to spray corn with a strobilurin fungicide, Koenning and Heiniger advise. If Southern Rust does get into a field prior to the dent stage growers should treat aggressively with the best fungicides available at the highest rates.