Virulence Spectrum among Rhizoctonia solani f. sp. sasakii Isolates from Multi-Geographical Locations of India

Rhizoctonia solani f. sp. sasakii (RSS) is a highly devastating soil-borne fungal pathogen inciting banded leaf and sheath blight (BLSB) disease in maize. In India, annually one percent of the total maize yield is reduced by BLSB. Due to continuous occurrence and wide spread of disease, the present experiment was conducted to assess the pathogenic variability among different isolates obtained from multi-geographical locations of India. Pathogenic behaviour of each isolates was predicted through the comparable study of their incubation period, average disease score and disease intensity on the three maize hybrids (Normal maize- HM 8, QPM maize- QPM 9 and sweet corn- HSC I). The incubation period of all the R. solani isolates ranged from 3 to 7 days with average disease score ranged from 2.1 to 7.1depending upon the host and isolate interaction after artificial inoculation. Disease intensity of all the RSS isolates on maize hybrids varied from 8.1 to 52.1% while isolates RSS 29 (New Delhi) and RSS 1 (Karnal) were found highly virulent, in comparison to other forty nine RSS isolates. As these isolates were highly virulent on maize hybrids with average disease score ranged from 6.2 to 7.1, whereas the isolates RS 30 (Dholi) and RS 31 (Dhaula Kuan) were recorded as least virulent, showed resistant disease reaction with average disease score ranged from 1.5 to 2.4.