Evaluation of Three Fungicides at Different Concentrations for In Vitro Control of Rhizoctonia solani Isolated from Broad Leaf Mustard

Rhizoctonia solani is a soil-borne phytopathogenic fungus with a broad host range and worldwide distribution. It causes damping off of seedlings and mature plant root rot, resulting in huge yield losses in numerous crops, including broad leaf mustard. The wide host range of Rhizoctonia solani, high survival rate of its sclerotia under diverse environmental conditions and lack of fully resistant cultivars, necessitate a shift in research focus toward chemical control approaches. The present investigation was conducted in central laboratory of IAAS, Lamjung campus, Nepal to test the efficacy of fungicides against Rhizoctonia solani pathogen. Three fungicides, namely Carbendazim, Mancozeb and Chlorothalonil at three concentrations 100, 150 and 200 ppm were tested in vitro using “Poisoned Food Technique”. The experiment was carried out in Completely Randomized Design with ten treatments and five replications where unamended potato dextrose agar media served as the negative control. A progressive increase in the percentage inhibition of radial growth in the fungus was noted as the concentration of the fungicides increased. Among the tested fungicides, Carbendazim at all concentrations and Mancozeb at 200 ppm were found to be most effective showing 100% growth inhibition whereas, Chlorothalonil at 100 ppm was found to be least effective exhibiting 56.23% growth inhibition over control on the last day of measurement. The results showed a highly significant difference at 5% significance level among the fungicides in their ability to inhibit the growth of Rhizoctonia solani. Future line of research should therefore focus on translating these findings into effective field-level management strategies. Integrating these fungicides with other management strategies including resistant cultivars, crop rotation and cultural methods should be explored to develop a more sustainable and holistic disease management approach.