Infection occurs directly through root systems or stalks, resulting in weakened, discolored stalks.
Infection with some fungi begins within 30 days after planting. Infection with Fusarium spp. Stalk rot caused by Diplodia mavdis is usually brown to gray in color. Stalk rot caused by Helminthosporium rostratum will be brown to green in color. Fusarium stalk rot Stalk rot of corn, health stalk, charcoal stalk rot Charcoal stalk rot produces numerous black sclerotia which appear as tiny black dots on vascular strands and give a charred appearance.