Effect of pyrethroid insecticides on soybean and its pathogen Rhizoctonia solani Kuehn.

Laboratory tests were conducted to determine the phytotoxicity and fungitoxicity of five pyrethroid insecticides; cypermethrin, decamethrin, fenpropanate, fenvalerate and permethrin at different rates to soybean and its pathogen Rhizoctonia solani Kuehn. Fungitoxicities of the chemicals on pathogen were in the order of thiram greater than permethrin greater than cypermethrin greater than decamethrin greater than fenvalerate. Phytotoxicities on soybean seedlings were decamethrin greater than cypermethrin greater than fenpropanate greater than fenvalerate greater than permethrin greater than Arasan. A comparative study on both phytotoxic and fungitoxic effects indicated that the pyrethroids were less effective than Arasan for use in the control of this soil borne plant pathogen.