Early-Season Corn Diseases: Northern Corn Leaf Blight

SOUTHWEST, NEW YORK (July 23, 2020) – Cornell Cooperative Extension’s SWNY Dairy, Livestock and Field Crops Program provides agricultural producers with timely information to manage diseases in their fields. 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 65-85oF, high humidity, and sporadic rainfall. These conditions all contribute to NCLB in corn production.

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 has shown that there can be a 20-50% 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.

The Southwest NY Diary, Livestock and Field Crops Program is working closely with Cornell University faculty and staff to help producers properly manage this pest. For more information about corn diseases, disease management, or if you suspect you might have NCLB, contact Field Crops Specialist Josh Putman at 716-490-5572 or jap473@cornell.edu.

Cornell Cooperative Extension’s Southwest New York Dairy, Livestock, and Field Crops Program specialists are here to help provide research-based resources and support during this challenging time. Their team of four specialists includes Katelyn Walley-Stoll, Farm Business Management (716-640-0522 or kaw249@cornell.edu); Joshua Putman, Field Crops (716-490-5572 or jap472@cornell.edu); Alycia Drwencke, Dairy Management (517-416-0386 or amd453@cornell.edu); and Amy Barkley, Livestock Management (716-640-0844 or amb544@cornell.edu). While specialists are working remotely at this time, they are still offering consultations via phone, text, email, videoconferencing, and mail along with socially distanced site visits. They are also providing weekly updates with timely resources and connections via email and hardcopy and virtual programming. For more information, or to be added to their notification list, contact Katelyn Walley-Stoll, Team Leader, at 716-640-0522, kaw249@cornell.edu or visit their website swnydlfc.cornell.edu.

The Southwest New York Dairy, Livestock, and Field Crops Program is the newest Cornell Cooperative Extension regional program and covers Allegany, Cattaraugus, Chautauqua, Erie, and Steuben Counties. The Southwest New York Dairy, Livestock, and Field Crops regional specialists work with Cornell faculty and Extension educators to address the issues that influence the agricultural industry in New York by offering educational programming and research based information to agricultural producers, growers, and agribusinesses in the Southwestern New York Region. Cornell Cooperative Extension is an employer and educator recognized for valuing AA/EEO, Protected Veterans, and Individuals with Disabilities and provides equal program and employment opportunities.

Photo Captions: Early-season infection of northern corn leaf blight on corn leaf in Southwest NY (2019).

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If you would like more information about this topic, please call Josh Putman at 716-490-5572 or email jap473@cornell.edu. For more information about Cornell Cooperative Extension, contact your county’s Association Executive Director. Allegany County – Laura Hunsberger, lkh47@cornell.edu or 585-268-7644. Cattaraugus County – Dick Rivers, rer263@cornell.edu or 716-699-2377. Chautauqua County – Emily Reynolds, eck47@cornell.edu or 716-664-9502. Erie County – Diane Held, dbh24@cornell.edu or 716-652-5400. Steuben County – Tess McKinley, tsm223@cornell.edu, or 607-664-2301. 

Last updated July 24, 2020