Survey of Rice Sheath Blight Disease in Kuttanad and Effect of Biocontrol Agents and Fungicides against Rhizoctonia solani

Abstract

Aims: Rice is an important crop cultivated worldwide, whose production is influenced by numerous factors like pest, disease, weather parameters. In India, diseases accounts for 35 per cent in yield reduction, with sheath blight being significant. This disease is notably prevalent in Kuttanad region of Kerala. This study involves a survey conducted in Kuttanad to assess the extent of the disease and in vitro management using biocontrol agents and fungicides. Study Design:  Study was outlined in Completely Randomised Design (CRD) to evaluate the in vitro efficacy of bioagents. Place and Duration of Study: Department of Plant Pathology, College of Agriculture, Vellayani and M.S. Swaminathan Rice Research Station, Moncompu, between 2022 and 2023 Methodology: Survey was conducted in forty locations of Kuttanad in which the disease incidence was recorded and samples were collected. The isolates obtained were tested for pathogenicity by artificial inoculation on rice variety, Uma. Cultural characteristics of isolates were studied. The virulent culture obtained was further advanced for the in vitro studies with biocontrol agents and fungicides. The inhibition of fungal growth was also recorded. Results: Forty isolates of sheath blight pathogen (Rhizoctonia solani) were obtained. The virulent isolate among these was identified on the basis of number of days taken for symptom development by artificial inoculation and this was further advanced for the in vitro studies. Bacillus amyloliquefaciens was found to be more effective with an inhibition percentage of 68.64. Among the tested fungicides, Kresoxim methyl 40% + Hexaconazole 8% WG showed cent per cent growth inhibition of pathogen at 500 and 1000 ppm concentrations which was on par with Azoxystrobin 18.2% + Difenoconazole 11.4% SC at 1000 ppm. Conclusion: From this study, it can be concluded that, that these biocontrol agents and fungicides are very effective in the management of the pathogen and hence can be used for further field-level studies in management of the disease.