A qualitative baiting technique for selective isolation and DNA diagnosis of Rhizoctonia spp., causal agents of rice sheath diseases, from soil

A baiting technique was evolved for selective isolation and DNA diagnosis of causal agents of rice sheath diseases by Rhizoctonia spp. from artificially inoculated and naturally infested soils using eleven plant stem segments and selective medium containing benomyl and metalaxyl. Rice, mat rush and wheat stem segments soaked in metalaxyl at 50 μg/ml were successfully used to isolate R. solani AG 1, R. solani AG 2, R. oryzae, R. oryzae-sativae and R. fumigate from artificially infested soils. Moreover, rice and wheat stem segments soused in metalaxyl at 100 μg/ml were successfully used to extract genomic DNA derived from all Rhizoctonia spp. Metalaxyl untreated stems were colonized in significantly higher numbers and contained in significantly higher concentration of DNA of these Rhizoctonia isolates than untreated stems. Untreated stems were also colonized isolates and extracted DNA derived from other common soil-inhabiting fungi.