Black Sheath Rot Symptoms on Rice
Black Sheath Rot (fungus - Gaeumannomyces graminis var. graminis): Black sheath rot or crown rot was considered a minor disease of rice in Texas for
several decades, but has become increasing important with increasing intensive
production systems. The fungus attacks the crown, lower leaf sheaths, and roots
of the rice plant causing a dark brown to black discoloration of the leaf sheaths from the crown to
considerably above the water line. As the discolored, infected sheaths decay,
tiny, black, fungal reproductive structures (perithecia) form within the tissue
and can be seen with a hand lens. The disease is usually observed late in the main
crop season and may cause reduced tillering, poor grain fill, and lodging. Crop
rotation with non-grass crops and thorough discing and maintenance of a clean
fallow field from the summer prior to planting rice will help control the disease
by destroying plant residue and weed host upon which the pathogen survives.
February, 1996
