Efficacy of new fungicides against sheath blight disease management of rice caused by Rhizoctonia solani under field condition

Abstract

Rice (Oryza sativa L.) is second most important cereal and the staple food for more than half of the world’s population. Sheath blight is one major biotic constraints that affects rice production in India and is considered economically important disease of rice in the world The disease is caused by Rhizoctonia solani Kuhn (Teleomorph: Thanetophorus cucumeris (Frank) Donk), a fungal pathogen of both rice and soyabeans. The yield loss due to this disease is reported to range from 5.2-50 per cent depending on the environmental conditions, crop stages at which the disease occurs, cultivation practices and cultivars used. The disease has been named as “sheath blight” because of primary infection on leaf sheath. The fungus attack the crop from tillering to heading stage and leaf blade symptoms also observed. Initial symptoms are noticed on leaf sheath near water level. As the spot enlarge, the centre become grayish with irregular brown blackish border. The fungus Rhizoctonia solani produced usually long cells of septate mycelium which are hyaline within young, yellowish brown. It produced large number of globose sclerotia which initially turn white, late turn brown to purplish brown. Sclerotia as a major source of primary inoculum.In the study an experiment was laid out in the field condition during 2017-18 at experimental field of IGKV, Raipur to control the sheath blight disease of rice by application of different doses of chemical fungicide, the treatment of Propiconazole 13% + Difenconazole 13.9% SC (Tespa), Propiconazole 25% EC (Tilt), Tebuconazole 50% +Trifloxystrobin 25% WG (Nativo), Azoxystrobin 23% EC (Amistar), Validamycin 5% L (Vamcin), Captan 70% + Hexaconazole, WB (Takat), Hexaconazole 5% EC (Contaf), Carbendazin 50 WP (Bavestin) where tested in field under artificial condition. The Hexaconaxoke 5% EC found highly effective in reducing the Sheath blight disease severity (11.11%) and increase the grain yield (5566 kg/ha). The maximum disease severity (20.77%) and lowest grain yield (2600 kg/ha) was recorded under control condition.