By Blake Jackson
Frequent rainfall throughout Kentucky has raised concerns about foliar diseases in corn, but one of the most significant threats Southern rust has not yet been detected in the state, according to Dr. Kiersten Wise, UK Extension Plant Pathologist.
Southern rust generally reaches Kentucky around mid-July, and the need for fungicide applications depends largely on the crop’s growth stage when the disease appears. Corn remains most responsive to fungicide treatments through the milk (R3) stage.
Fields that already received a fungicide application at the VT/R1 stage are less likely to require another treatment if Southern rust develops later.
Growers can monitor the spread of the disease through the Crop Protection Network’s tracking map, where confirmed cases reported by university and Extension specialists are highlighted in red. This year, the disease has progressed slowly in southern states, delaying its movement into Kentucky. As a result, much of the corn in western Kentucky is expected to reach R3 or later before Southern rust arrives.
Another disease of concern, Tar spot, was confirmed in Daviess County on July 14. Similar to Southern rust, fungicide applications may still provide benefits through the R3 stage if the disease is present and the field has not previously been treated at VT/R1.
However, many Kentucky corn fields have already passed the stage where fungicide applications are economically beneficial, making continued scouting and field-specific management decisions important.
Curvularia leaf spot has also become increasingly common across Kentucky this season. Caused by the fungus Curvularia lunata, the disease produces small tan to pale-yellow lesions surrounded by brown or tan halos.
Although it has been associated with yield reductions in some locations, including Kentucky, widespread economic losses have not been reported, and growers are encouraged to continue monitoring fields throughout the season.
Photo Credit: gettyimages-klosfoto
Categories: Kentucky, Crops, Corn