Dave Nanda is telling farmers to keep an eye out for foliar diseases in corn. He's particularly concerned about northern corn leaf blight, which likes wetter-than-normal and cooler-than-normal weather. Gray leaf spot is also a concern, depending on weather patterns. The gray leaf spot fungus tends to prefer warmer temperatures, but also wet or high-moisture conditions.

Nanda, Genetics and Technology Consultant for Seed Consultants, Inc. says that infections in some fields likely started in early July. Some reports from farmers indicated they had seen lesions. Others reported that their fields seemed clean.

Stay alert! Northern corn leaf blight is one disease that could affect corn if weather patterns remain cool and wet. (Photo courtesy of Kiersten Wise, Purdue University)

Hybrids differ in susceptibility to these diseases. It's a good time to check with your seedsman about each hybrid, so you know where to concentrate your scouting efforts.

Related: Spraying Foliar Fungicide Can Aid Corn Health

Plant breeders have improved resistance to many diseases, including northern corn leaf blight and gray leaf spot, Nanda says. However some hybrids have more resistance than others. And how much any hybrid might be affected may depend upon how sever the outbreak of the disease becomes.

The key is keeping the disease from infecting the ear leaf, Nanda says. If significant disease pressure develops, a fungicide application may be warranted. Consult with your dealer, and check labels carefully so you know when to apply various products. In early planted fields the window for effective applications may be closing soon.

In fields that were planted early, check labels on products to make sure you don't apply fungicides too soon. Certain fungicides carry a risk of producing some ear abnormalities if applied before the stage of growth for the corn specified on the fungicide label.

Whether either of these diseases or any other foliar disease in corn has an impact this year will ultimately depend on weather patterns the rest of the season, Nanda says. Stay alert and keep scouting, he concludes.