Heavy rain over the last two weeks has accelerated Southern rust, and with about a third of the fields untreated, Arkansas’ corn growers have been urged to scout fields for the disease.

“Based on the number of calls that I’ve received this week, there are a large number of late-planted corn acres that have not been scouted or treated,” said Scott Monfort, Extension plant pathologist for the University of Arkansas Division of Agriculture.

Southern rust is a fungus that can reduce yields. The fungus spores typically cannot survive winter in temperate climates, but can be blown into Arkansas by weather systems.

“Southern rust can now be found in almost every county close to and north of I-40,” he said. “Incidence and severity of the disease has increased from light to moderate levels over the last two weeks.”

While there are recommended applications for certain stages of growth, Monfort said spraying shouldn’t be automatic.

Growers should “scout their fields for disease, determine growth stage and yield potential before applying a fungicide,” he said.

Since the beginning of July, more than 9 inches of rain have fallen at North Little Rock, according to the National Weather Service. Other rainfall amounts since July 1: Pine Bluff, 6.41 inches; Jonesboro, 6.1 inches.

For more information on Southern rust symptoms and effects, go to www.aragriculture.org/diseases/Corn/ or in Corn Production Handbook.