Corn growers in southern Florida should be wary that Southern corn leaf blight disease is on the rise, according to the South Florida Pest and Disease Hotline.
The disease is starting to appear in the Everglades Agricultural Area. Incidences are low but increasing in corn. Low levels of southern corn leaf blight were reported in a few fields in Southwest Florida. The disease is also increasing in corn in Homestead, Florida.
Disease symptoms usually occur on the leaves. Mature foliar lesions can be rounded on the sides but tend to be parallel-sided, often restricted by the veins. Lesions are light tan in the center with a reddish-brown border. A greenish growth near the lesion’s center may be noticed if spores are observed.
If the disease is severe, the lesions may become so numerous that they coalesce and turn the entire leaf necrotic. It is most prevalent during the fall growing season in South Florida. Warm to hot temperatures, typically 68 degrees Fahrenheit (F) to 90 degrees F, favors the disease, along with periods of extended leaf wetness.
Growers are reminded that Southern corn leaf blight is best controlled with resistant varieties. If resistance is unavailable, fungicide applications may be necessary, especially with corn grown in peninsular Florida. Fungicides should be applied early, particularly if the forecast calls for warm, humid weather.
Consult UF/IFAS recommendations in Chapter 17. Sweet Corn Production in the Vegetable Production Handbook of Florida for currently labeled products for control of southern corn leaf blight in Florida.