We have counted up to seventy sclerotia per rice plant. Sclerotia normally float on the water when rice is flooded and attach themselves to the sheath at the water line, germinate and infect the rice plant. Sclerotia need high humidity and temperatures to germinate. Horizontal movement does not usually occur until heading and progresses rapidly under favorable conditions. As rice plants mature, their stems become more compact, the encirclement of the leaf sheath becomes loose, and the plants become more susceptible to sheath blight.
Early varieties tend to be more susceptible than later varieties.
Short stature varieties tend to be more susceptible that taller varieties. However, varieties vary in their resistance and producers should consult with the Extension Service to obtain resistance information. The Sheath Blight fungus attacks 188 species of plants including soybeans, cotton, corn, and wheat. Proper nitrogen management reduces disease. Split nitrogen applications can reduce disease.