Infection of smut of maize (Ustilago maydis) occurs during

Infection of smut of maize (Ustilago maydis) occurs during the Vegetative stage.
Corn smut is a plant disease caused by the pathogenic fungus Ustilago maydis that causes smut on maize and teosinte. The fungus forms galls on all above-ground parts of corn species.
The fungus infects all parts of the host plant by invading the ovaries of its host. The infection causes the corn kernels to swell up into tumor-like galls, whose tissues, texture, and developmental patterns are vegetative and mushroom-like.