Experts from the University of Kentucky are weighing in on this season’s southern rust on corn. According to a sample taken in Graves County on July 17, southern rust is present on, and it has been evident in several other Western Kentucky counties as well.
Carl Bradley, UK extension plant pathologist with the College of Agriculture, Food and Environment, believes that the occurrence of the disease could potentially impact yields.
“The disease risk is relative to the corn’s growth stage,” Bradley says. “Late-planted corn is definitely at a risk for yield loss.”
Southern rust is typically caused by Puccinia polysora, and the majority of corn hybrids are susceptible to it. Depending on the winter, the pathogen’s arrival in Kentucky may vary. In 2016, it caused yield losses for some producers in the state.
Kiersten Wise, UK extension plant pathologist, says that proper disease identification is “critical” because southern rust can be commonly confused with common rust. In some instances, the outcome of common rust may not be large yield loss.
If southern rust is present, some corn between the tasseling to the milk stage may receive protection from foliar fungicide. The benefits of foliar fungicide naturally decrease as plants reach the R4 stage.
Agricultural producers can keep track of the southern rust and how it is moving across Kentucky by visiting the Integrated Pest Information Platform for Extension and Education website at http://ext.ipipe.org/.