Anthracnose stalk rot
Area of impact: Stalk
Description: The outer stalk will have shiny black blotches on it; the inner stalk might also be black or it might show no signs of infection. Internodes on the stalk might be rotted and easily crushed with fingers.
Pathogen involved: Colletotrichum graminicola (a fungus)
Timing/Conditions: Occurs after pollination and symptoms are most visible just before plant maturity.
Contributing factors: Corn residue left on the ground, insect injury and environmental stress. Overwinters in corn residue. This is the same fungus that causes Anthracnose leaf blight.
Management practices: Plant resistant hybrids maintain balanced fertility, keep plant stress to a minimum and control insect damage.