Common smut (Boil smut, Blister smut)

Caused by: Ustilago zeae
Problem Category: Fungal Disease
Symptoms: Tumor-like galls on plant tissues which are initially green-white or silvery white in color; interior of galls darken and turn into masses of powdery dark brown or black spores (with the exception of galls on leaves which remain greenish in color); galls may reach up to 15 cm in diameter and are common on ears, tassels, shoots or midrib of leaves; galls on leaves remain small and do not burst open.
Comments: Fungus overwinters on crop debris or in the soil and can survive for several years; fungus usually enters the plant through wounds; application of nitrogen fertilizer increases incidence of disease, while application of phosphorous fertilizer decreases infection.
Management: Although many practices may be recommended for the control of common smut, the only method that is completely effective is to grow resistant corn hybrids.
Control: