Pathogen(s) causing disease:

Aureobasidium zeae

Location:

Northern Midwest US states, Ontario, Quebec, Europe and South America

Symptoms:

Affected leaves are covered with numerous small round spots. Spots are ~ 1/8 inch in diameter, oval to circular and appear water-soaked. The center of the spot dies, leaving a tan colored center surrounded by a brown/purple border. This border is often circled by a yellow halo. This resembles an eye, hence the name 'eye spot'.

Conditions:

 Infection favored by prolonged periods of cool, wet weather. Some yield loss if severe infections occur within three to four weeks of silking

Management:

Plant resistant/partial resistant hybrids. Conventional tillage/moldboard plow (if possible) to bury corn residues. Crop rotation away from continuous corn. Foliar fungicides offer effective control.

Sources:

Bloomberg, Jim. Bayer CropScience Corn Disease Identification Guide PowerPoint. 2009.
Iowa State University