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Posted 24 August 2009. PMN Crop News.

Extension Resources Available to Better Diagnose Corn Ear Abnormalities

Source: Ohio State University Press Release.

Columbus, Ohio (August 18, 2009)–Corn ear abnormalities, caused by a variety of conditions from weather stress to diseases to insects, can be major limiting factors of yield and grain quality. Knowing what disorders affect the ear can lead to better management and greatly improve crop production.


Ohio State University Extension's Agronomics Crop Team has developed a Web site and supporting materials to aid growers in diagnosing abnormal corn ear disorders and other related conditions.

“Ear abnormalities or disorders are perennial problems occurring somewhere in Ohio every year. Temperature extremes, water stress, chemical injury, diseases, insects and nutrient deficiencies can all play a role depending on the particular disorder,” said Peter Thomison, an OSU Extension corn agronomist and a member of the OSU Extension Agronomics Crop Team. “Environment is probably the major factor, so in some cases, there's little a grower can do. Hybrids vary in their sensitivity to certain ear anomalies like 'blunt ear syndrome,' also known as 'beer can ears.' Moreover, there are interactions between environmental conditions and certain cultural practices that can exacerbate problems, and growers can take steps to identify those problems and apply the right management practices.”

Thomison, who also holds an appointment with the Ohio Agricultural Research and Development Center, and Allen Geyer, research associate in the Department of Horticulture and Crop Science, have developed an “Abnormal Corn Ears” poster that highlights various corn ear abnormality symptoms and causes, complete with color photos and detailed text.

The poster covers the following corn ear abnormalities: ear pinching, blunt ear syndrome, multiple ear syndrome, drought damaged ears, Diplodia ear rot, poor pollination at the ear tip, poor or incomplete kernel set, tip dieback, chaffy ears, bird damage, Western bean cutworm ear injury, tassel ears, zipper ears and kernel red streak.

Thomison and Geyer have also established a Web site, “Troubleshooting Abnormal Corn Ears and Related Disorders” at The Web site supplements the poster with information on management practices for avoiding or minimizing ear abnormalities, in addition to more detailed information on abnormal ear development, reduced kernel development, ear molds and disease, feeding injury, and miscellaneous ear problems, such as hail and flooding damage, arrested ears, hollow husk and genetic ear oddities.

“The purpose of both the Web site and the poster is to assist corn growers and agricultural professionals in diagnosing various ear disorders, and adjust management of the crop accordingly,” said Thomison.

A 26- x 33-inch copy of the poster is available for $10 plus shipping. The poster is printed on plasticized-coated paper for durability. To order a poster, log on to, or contact the Ohio State University Communications and Technology Media Distribution office at (614) 292-1607 or e-mail Ask for “Abnormal Corn Ears” poster ACE-1.

An 11- x 14-inch version of the “Abnormal Corn Ears” poster is available online at

Peter Thomison
OSU Extension, OARDC