Evaluation of fungicides against sheath blight of rice caused by Rhizoctonia solani (Kuhn.)

Fixed plot survey for sheath blight disease conducted in some major rice growing areas of Cuddalore district, Tamil Nadu indicated that the per cent disease index (PDI) varied with low to high level. The maximum PDI of 36.5% was recorded in Naduthittu followed by Vadakkumangudi (32.4%), Vallampadugai (26.5%), Muttlur (21.4%) and the least level of incidence was noticed in Ramapuram (10.5%). Four different inoculation methods were tested in the field. Among the four methods of artificial inoculation, sheath inoculum was found to be the best in plant infection. Out of different fungicides screened against the pathogen under in vitro condition, the new chemical ICF 310 at 1000 ppm concentration completely inhibited the growth of Rhizoctonia solani Kuhn, causing sheath blight disease. In pot culture different methods of treatment were applied by using ICF 310 against R. solani, where the fungicide ICF-310 at different levels showed significant influence on the incidence sheath blight of rice. Among the various treatments, combined application of ICF 310 as ST @ 2 g/kg of seeds + ICF- 310 @ 0.1% as seedling root dip + ICF- 310 @ 0.1% as foliar spray at 30 DAT and 45 DAT recorded the minimum sheath blight incidence (8.99%) at harvest. This was followed by combined application of ICF-310 as seed treatment @ 2g/kg of seeds + ICF- 310 @ 0.1% as foliar spray at 30 DAT+ 45 DAT which recorded the sheath blight incidence of 9.45% and the maximum sheath blight disease incidence was observed in untreated control.