Long-distance dispersal of secondary sporidia probably can occur only during moist periods and under cloud cover at night. Plants are most susceptible to infection when spikes emerge from the boot, but infection can occur throughout the flowering period. Sporidia infect the ovaries, directly penetrating the glumes and ovary wall. Infection can move across all florets of a spikelet and to the spikelets above and below the initial infection site. Diseased kernels may be partially or completely displaced by masses of teliospores in cool, humid or wet weather.
Sporulation starts at the embryo end and moves along the suture of the grain.
The extent of kernel bunting depends on when infection occurs and how long favorable conditions last. Teliospores remain viable in the soil for up to 45 months. They survive longer when buried in dry soil than in moist, cropped soils or on the soil surface. Unlike other smut and bunt fungi, T. indica does not infect seedlings. This fungus must infect plants between the beginning of spike emergence and the end of flowering.