In-vitro evaluation of fungicides and biocontrol agents against R. solani causing root rot of cotton in Rajasthan

Abstract

Root rot pathogens (R. solani) were isolated in majority from diseased cotton plants showing root rot symptoms collected from farmer’s field during survey. The pathogenicity of recovered isolates of R. solani were separately confirmed by Koch’s postulates by growing susceptible cotton cultivar “Jai BG-II” in pathogen inoculated pots also observed incidence and typical symptoms by respective isolates.. In view of increasing disease incidence in cotton growing areas, attempts were made to evaluate six (systemic and non-systemic) fungicides viz., Carbendazim, Vitavax power, Azoxistrobin, Rhizolex, Tebuconazole and Thiram at 50, 100, 250 and 500 ppm concentrations against R. solani in vitro. Sensitivity of Carbendazim, Vitavax power and Tebuconazole was found more pronounced against R. solani, whereas Carbendazim was highly effective against R. solani at all the concentrations with 100 per cent inhibition of mycelial growth. In vitro studies for evaluating comparative efficacy of four Trichoderma isolates. The efficacy of the T. viride isolates (T-5 and T-3) found to be highly effective against R. solani pathogens in vitro. However, T. aureoviride was found to be less effective than T. viride.