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Anthracnose: Kentucky Corn IPM

Anthracnose


Symptoms

Anthracnose, caused by the fungus Colletotrichum graminicola, is often the first disease that shows up on corn. Small, round to irregular, water-soaked spots first appear on lower leaves. Spots later turn yellow and then brown with reddish-brown borders. Yellow zones often develop around the leaf spots (see figure at right). Numerous spots can cause leaf tips or entire leaves to turn yellow. With the aid of a hand lens, black spines can be seen arising from the center of the spots. The leaf-spotting phase of the disease generally doesn't occur past the knee-high stage of corn growth.

Anthracnose

Cause

Anthracnose
Anthracnose Rot

The fungal pathogen Colletotrichum graminicola is the causal agent of anthracnose in corn. Anthracnose is common early in the season in fields where debris from the previous year was left on the soil. This early season disease phase is generally more severe in fields where continuous no-till corn has been grown. It causes a leaf spot disease when corn is in the seedling stage. The pathogen is disseminated by wind and rain splash.

Plants become somewhat resistant to the leaf-spotting phase as the crop develops. If weather conditions are favorable for continued development of the disease (high moisture and moderate temperatures), plants become susceptible to the "top-dieback" and stalk rot disease phases later in the season.

Detection of anthracnose at the seedling stage should alert scouts to watch for the disease later in the season. The fungus also affects a number of grass species. The presence of infected grasses in or near corn fields could represent a continuing source of new infection.

IPM Techniques

References and Additional Information

  • IPM-2 Kentucky IPM Manual for Corn

  • PPA-10a Kentucky Plant Disease Management Guide for Corn and Sorghum, P. Vincelli and D.E. Hershman, Extension Plant Pathology, University of Kentucky

  • Compendium of Corn Diseases.M.C. Shurtleff. The Amer. Phytopathol. Soc. 1980.

This site was created and is maintained by Pat Dillon, Department of Entomology, University of Kentucky, S-225 Agricultural Science Ctr North, Lexington, KY USA  40546-0091 (phone: 859/257-3571). Please send questions or suggestions to: pdillon@uky.edu