Corn Crop Could Be Hurt By Leaf Blight

Early-season infection of northern corn leaf blight on corn leaf in Southwest NY (2019). Image by the Cornell Cooperative Extension.

SOUTHERN TIER — As much as one-half of the local corn crop could be lost if northern corn leaf blight hits this year like it did last year, according to Cornell Cooperative Extension. 

In 2019, northern corn leaf blight (NCLB) appeared throughout the Southwest New York region. This year, farmers might be faced with this disease yet again. Normally, NCLB is more of an issue in fields that have been planted with corn for more than one year in a row. However, this year has been especially challenging due to the consistent temperatures of 65-85 degrees, high humidity, and sporadic rainfall. These conditions all contribute to NCLB in corn production, officials warned.

Identifying corn diseases can be difficult. Early NCLB symptoms appear as long, narrow, tan lesions that form on the leaf surface of a corn plant. As the disease progresses, the lesions become longer, more oblong, or “cigar-shaped” and can appear grayish in color. These lesions can range from 1-8 inches long with multiple lesions forming dense, irregular areas of dead tissue on the corn leaves. Once this happens, the plant can no longer develop to its fullest potential, which may reduce crop yields.

Research shows there can be a 20 to 50 percent decrease in corn yields if lesions are present prior to or at tasseling, which is the start of ear development. Fields that have been planted to corn for multiple years in a row are at a much higher risk of NCLB because the disease survives the winter on infected corn stubble at the soil surface.

As temperatures rise in the spring and early summer, the bacteria that cause NCLB can be splashed or wind-blown onto leaves of the new corn crop. Tilling in old corn stalk residue after the corn is harvested, choosing disease-resistant corn hybrids, and strategic use of fungicides are ways to reduce potential yield loss from NCLB, officials said.

The Southwest NY Diary, Livestock and Field Crops Program is working with Cornell University faculty and staff to help producers properly manage this pest. For more information about corn diseases, disease management, or if one suspects their crop has NCLB, contact Field Crops Specialist Josh Putman at 716-490-5572 or


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