ETIOLOGY, INOCULATION METHODS AND. EVALUATION OF BOTANICALS AGAINST SHEATH ROT COMPLEX.OF MCE

摘要

Several organisms, namely, Sarocladium oryzae, Drechslera oryzae, Fusarium moniliforme, F. pallidoroseum, Cephalosporium strictum, Phoma sorghina and Curvularia lunata were isolated from sheath rot infected plants of different rice genotypes grown atfarmers' field and research stations in Haryana. Amongst these, 5. oryzae, D. oryzae, F. moniliforme, F. pallidoroseum and C. strictum were found pathogenic. The frequency of occurrence of F. moniliforme from naturally infected plants was highest (47.6%)followed by S. oryzae (19.1%), F. pallidoroseum (14.3%), D. oryzae and C. strictum (9.5% each). Association of D. oryzae, F. pallidoroseum and C. strictum with sheath rot is the first report. On mean basis, insertion of single rice stem piece culture proved best for inducing sheath rot caused by different organisms. However, for S. oryzae single rice grain inoculation method produced maximum disease (60.6%). Spraying and injecting spore suspension at boot stage and keeping Typha piece cultures in the hills did not cause disease. Amongst various botanicals tested during kharif 1998-2000, amarbel (Cuscuta gronovii) and neem (Azadirachta indica) leaf extracts were, found better over other treatments and provided about 40% disease control closely followedby belpathar (Aegle marmelos) and gulbansa (Mirabilis jalapa) leaf extracts. However, a significant increase in grain yield was recorded in neem and gulbansa treatments during kharif 1999 and 2000.