Variability in Rhizoctonia solani causing sheath blight of rice and its chemical management

Abstract

Rhizoctonia solani is infamous fungus for its highly destructive pathogenic effect that can result in extensive damage of rice crop. To know the variability among the Indian isolates of R. solani inciting sheath blight in rice, four isolates were isolated from diseased samples of Uttar Pradesh, Uttrakhand, Gujarat and Karnataka states of India. Variability in isolates was observed with respect to the cultural, morphological and pathogenic level. Evaluation of toxicity of various fungicides against R. solani under in vitro condition showed the maximum sensitivity of R. solani by carbendazim even at 1 ppm concentration followed by Tebuconazole + trifoxystrobin and Hexaconazole. R. solani showed good tolerance to Kresoxim methyl even at 100 mg kg-1 concentration. All tested fungicides namely Propiconazole, Hexaconazole, Kresoxim-methyl, Tebuconazole 50% + Trifloxystrobin 25%, Tricyclazole and Carbendazim caused complete inhibition of colony growth of R.solani at 1000 ppm. Foliar spray of Carbendazim @ 0.1% was found highly effective for the management of sheath blight in field condition with highest per cent reduction in disease (86.29%) followed by Tebuconazole + Trifloxystrobin (83.30%), Hexaconazole (74.20%) and Propiconazole (45.28%). Plots treated with Tricyclazole and Kresoxim Methyl had only 29.15 and 12.24 per cent reduction over control, respectively.