Assessment of Virulence Diversity of Rhizoctonia solani Causing Sheath Blight Disease in Rice from Eastern Up

Sheath blight of rice is an important and destructive disease caused by Rhizoctonia solani. Fifty rice sheath blight samples were collected from different parts of eastern UP and pathogenic variability was studied on different rice cultivars Viz.,Pusa Basmati-1(PB-1) susceptible rice cultivar and Tetep moderately resistant cultivar. The perusal of data indicated significant differences in the aggressiveness of isolates. The total of 50 isolates was grouped into four group as weakly virulent (WV), moderately virulent (MV), virulent (V) and highly virulent (HV), representing 30, 46, 20 and 4% of isolates, respectively. Majority of the isolates were moderately virulent on susceptible cultivar (PB-1), whereas in moderately resistant cultivar (Tetep) majority of isolates were weakly virulent representing (88%) followed by moderately virulent (8%) and virulent (2%).