The stalk rot phase of anthracnose generally first appears as narrow, vertical to oval, water-soaked lesions in the rind tissue. The black, blotchy areas on the stalk rind may extend through the rind and into the pith tissues. This separates anthracnose from secondary mold growth that occurs on stalk surfaces after plant death. Secondary molds can be scraped from the surface of the rind tissue. The black lesions of anthracnose cannot be scraped from the rind surfaces.
Anthracnose stalk rot causes a light tan to brown disintegration of the pith.
The diagnostic characteristic for anthracnose is the black, blotchy areas within the rind tissues. Anthracnose stalk rot generally causes lodging higher on the plant than is normal for the other stalk rot organisms. The anthracnose fungus overwinters in infected plant debris. It is a poor soil competitor and its population drops dramatically as infested residues disintegrate. Therefore, anthracnose is more severe where corn follows corn and infected residues are left on the soil surface.