Most corn growers in the Carolinas and Virginia have a big corn crop in the ground, much of it already sold for more than $7 a bushel, but there is one more weather-related hurdle to jump before the crop is in the bin.

Southern rust is a devastating disease to corn and soybeans, but it is an infrequent visitor to the Carolinas and Virginia. This year it started showing up in south Georgia in mid-June, and that is reason for alarm says veteran North Carolina State University Corn Specialist Ron Heiniger.

“We have a really good corn crop in the ground in North Carolina. The weather has been nearly perfect, growers got the crop in the ground right on schedule, and they have been able to take care of it. To finish this crop off they have to keep an eye on the weather and on the development of Southern rust,” Heiniger says.

He explains that tropical weather fronts, similar to the one that came up the Georgia Coastline and on into the Carolinas and Virginia a few weeks back, can move the spores that cause Southern rust long distances in a short period of time.

“What we don’t need is for one of these tropical storms to move through the Southeast in the second or third week of July — that could really put a damper on what looks to be close to a record corn crop in North Carolina,” Heiniger adds.

He explains that waiting until they see distinctive yellow, circular spots in their corn fields — symptoms of Southern rust —is too late to treat. 

“If tropical storms look certain to hit in our area, growers would be wise to go ahead and spray with a strobilurin fungicide. These fungicides may not completely protect corn from the disease, but they will usually provide 2-3 weeks of protection and hopefully a change in weather conditions that could help reduce the occurrence of Southern rust, he says.

“I’m stressing to our growers to keep an eye on weather forecasts and to stay in touch with their Extension agents, and to have a plan of action if the weather conditions are right for Southern rust to form.

“They don’t need to panic and spray if the disease isn’t likely to form, but they do need to be ready if weather conditions are right for Southern rust,” Heiniger adds.