In-vitro evaluation of some commercial fungicides on linear growth of Rhizoctonia solani

摘要

Rhizoctonia solani is a soil borne plant pathogen having a wide host range including vegetables, cereals, legumes and ornamental crops (Garcia et al., 2006). R.solani primarily attacks underground plant parts like the seeds, hypocotyls and roots of the plants but also capable of infecting above ground plant parts (e.g. pods, fruits, leaves and stems). R. solani has often been associated with root rot, yield decline in field crops. The pathogen is predominantly a plant pathogenic and soil inhabiting in nature (Carling and Leiner, 1990). R. solani, damages crops during whole growing season and attacks almost all plants. Through cross pathogenicity of R. solani, isolates of R. solani are collected from wheat, rice, maize and cotton, it was observed that there is no evidence of virulence to cotton (Yan et al., 1984). R. solani is a basidiomycetes fungus which does not produce asexual spore. The pathogen produces dark brown colour sclerotia which can persist in soils for long periods of time (Agrios 2005). Disease symptoms include canker on roots and stems (Banville and Carling, 2001). Above ground symptoms of the disease are, plant stunting, chlorosis, puckering of leaves and formation of Rhizoctonia, patches (Banville and Carling 2001). Early seasoninfection can result in delayed emergence of seedlings. Previously many scientists have reported that some commercial fungicides completely inhibited the growth of pathogen. Gupta (2002) reported that carbendazim inhibited 95-100 per cent radial growth of R. solani. Tiwari et al. (2002) reported that propiconazole and hexaconazole at 1000 ppm concentration completely inhibited the radial growth of R. solani. In the present investigation, an in-vitro experiment was carried out for testing the efficacy ofsome commercial fungicides against R. solani.