Smut manifests as the destruction of plant tissues, which are replaced by a powdery mass of teliospores. In the case of loose smut, the entire ear is affected, becoming dusty, while its rachis often remains bare. Covered smut is characterized by the preservation of the grain coat, inside which the mycelium develops; when crushed, a specific "herring" odor is detected.
The development of the disease depends on the biological characteristics of the pathogen and environmental conditions. Loose smut infects the plant during the flowering phase under high humidity and temperatures from +22 to +27 °C, overwintering inside the grain. Covered smut infects the plant during the seed germination period from inoculum present on the surface of the caryopsis or in the soil.
Varietal resistance is provided by genetic mechanisms that prevent the pathogen from penetrating the ovary or block the development of mycelium in the seedling. In the variety testing system, the degree of infection is assessed visually at the full maturity stage, and varieties demonstrating a minimal percentage of infected ears compared to the standards receive higher ratings.