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Peggy Sellers, Master Gardener State Coordinator, Purdue University
Anthracnose of corn, caused by the fungus Colletotrichum graminicola, is a disease that affects leaves and stalks. Symptoms appear initially on lower leaves as small, oval water-soaked lesions that enlarge and turn tan to brown with yellow to reddish-brown borders. Lesions may coalesce and blight entire leaves. Older lesions will turn gray in the center with small black specks. These fungal structures (acervuli) look like black spines when viewed with a hand lens. Anthracnose leaf blight may be followed by top kill and stalk rot. The leaf blight rarely causes large yield losses; the stalk rot phase is most important.
Symptoms on stalks appear as water-soaked areas on the surface of the lower internodes, that later develop into brownish linear streaks. These streaks turn black later in the season. Larger, oval, black areas may also develop. Pith of infected stalks disintegrates and is gray to dark brown. Severely infected stalks are likely to lodge.
This disease is favored by cool to warm, wet, humid weather, reduced tillage, and stresses that result in early senescence. The fungus overwinters in infected crop residue (leaves, leaf sheaths and stalks) and spores are spread by splashing rain and wind.
Management of this disease is based on the use of resistant hybrids, crop rotation, plowing under infected residue, and balanced soil fertility.
For more information please refer to:
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Anthracnose Leaf Blight on Corn (Photo by Greg Shaner)
|Seedling Anthracnose on Corn (Photo by Greg Shaner)|
|Stalk Rot Caused by Anthracnose on Corn (Photo by Greg Shaner)||Close-up of Rotted Corn Stalk (Photo by Greg Shaner)|
Plant and Pest Digital Library and Digitally Assisted Diagnosis, Purdue University, West Lafayette, Indiana.