عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Bacterial sheath rot is one of the serious diseases of rice in several countries, especially prevalent in Asian tropical regions. The disease causes grain sterility and serious yield loss in upland grown rice. In survey made during 2002- 2004 symptoms resembling those of bacterial sheath rot were observed in paddy fields of several areas of Mazandaran province. The disease was characterized by brown and elongate spots on the sheaths. In severe infection cases, the entire flag leaf sheath became dry and sterility of panicle occurred. Based on physiological and biochemical characteristics and pathogenicity tests, one bacterial species was found associated with the sheath rot and grain discoloration diseases. The predominant bacterial species was Pseudomonas syringae. A pathogenic bacterium was isolated from 19% of the diseased samples. The disease incidence was low in 2002- 2003, the highest being recorded on cv. Hashemi Tarom (7%) in 2003 and the lowest (3%) on cvs. Nemat and Mahalli Tarom . On the whole the incidence was higher on the local cultivars. However, in pathogenicity tests, the improved varieties were more susceptible than the local ones. This is the first report of the occurrence and distribution of bacterial sheath rot of rice in Mazandaran Province.