Southern rust of corn, caused by the fungus Puccinia polysora, was confirmed by the University of Kentucky Plant Disease Diagnostic Laboratory (PDDL) this week on samples from Caldwell County and Graves County. This is the first confirmation of southern rust in Kentucky in 2017, and the impact of this finding for Kentucky corn farmers will depend on current crop growth stage.
Fields that are between tasseling (VT) and milk (R3) growth stages may benefit from a fungicide application if southern rust is present. If fields have already received a fungicide application, they should be scouted to determine disease severity prior to a second application. More details on symptoms and signs of southern rust and recommendations for fungicide use can be found in a previous Kentucky Pest News (KPN) article that can be accessed here.
If you suspect you have southern rust in your field, work with local county Extension agents to submit samples to the PDDL for proper identification. Confirmations will be posted on the Integrated Pest Information Platform for Extension and Education (iPiPE) as discussed in a previous KPN article that can be accessed here. On the map, red counties/parishes indicate that southern rust has been confirmed by university/Extension personnel.
Carl Bradley, Extension Plant Pathologist and Kiersten Wise, Extension Plant Pathologist