Etiology and control of bacterial leaf blight of rice caused by Xanthomonas oryzae (Uyeda and Ishiyama) Dowson

Abstract

The bacterial leaf blight of rice, incited by Xanthomonas oryzae (Syeda and Ishiyama) Dowson is one of the most serious disease of economic importance in India and several other rice growing countries of the world. This disease was first reported in India by Sreenivasan et. al. (1959) from Maharashtra and a serious epiphytetic was reported by Srivastava and Rao (1963) from Bihar. In Kerala , eventhough severe epiphytotics of this disease have not been reported so far, the disease is endemic in the major rice growing areas of Kuttanad and Palghat. The pathogen was identified as Xanthomonas oryzae (Uyeda and Ishiyama) Dowson based on its morphological , cultural , physiological and biochemical characters together with its pathogenicity. For laboratory studies and mass culturing of the organism, Glucose Yeast extract Agar and Glucose Agar were found to be the best solid media and Glucose Yeast extract chalk broth and potato Sucrose Peptone broth were the best liquid media. The pathogen was found to survive in infected seeds for a period of 90 days , in infected debris in soil for a period of 28 days and in infected soil for less than a week indicating that the infected seeds and infected plant debris in soil play an important role in the epidemiology of the disease.