Effect of benomyl and thiophanate-methyl on metabolic activities of Rhizoctonia solani Kühn.

Effect of benomyl and thiophanate-methyl on various metabolic activities of Rhizoctonia solani was investigated. Both fungitoxicants strongly reduced endogenous whole cell and mitochondrial respiration by inhibiting one or the other key enzymes of electron transport chain; the activity of cytochrome oxidase being most markedly inhibited. Incorporation of 3II-thymidine was reduced by both while there was little or no inhibition in the rate of incorporation of 14C-uracil and 14C-leucine. Cell permeability was not affected to any appreciable extent and there was a little release of cellular components from the treated cells only at prolonged incubation. It is concluded that benomyl and thiophanate-methyl have a similar mode of action which primarily involves inhibition of respiratory activities, and as a consequence the biosynthesis of DNA is reduced.