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Anthracnose
leaf blight is caused by the fungus Colletotrichum
graminicola, and it is usually one of the first leaf diseases to appear. It
can also cause lesions on the stems of seedlings, especially if they have been
hail-damaged. The fungus survives in crop residue and is splashed onto the
leaves. Anthracnose is definitely more severe where corn follows corn. Symptoms
are brown, oval, or elliptical spots (up to approximately 1/2 inch in length)
with a dark brown or purplish border, often surrounded by a yellowed zone (see
photo). There may be black speckles within the dead tissue. Sometimes the
symptoms are limited to the leaf margins. Anthracnose can cause significant
damage to very young plants and contribute to postemergence stand loss, but this
disease requires warmer weather than what we have experienced so far. As the
temperature goes up, look for this disease in your fields.
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