Effect of plant protection chemicals on bradyrhizobwm in cowpea (Vigna unguiculata (L) walp)

Abstract

Effect of selected plant protection chemicals were tested on Bradyrhizobium both in the laboratory and in the field. The fungicides Thiram, Bordeaux mixture and Fytolan showed inhibition of the bacteria under in vitro conditions. These fungicides caused an initial reduction in rhizosphere population of Bradyrhizobium in the field. But later a gradual increase in the bacterial count was noticed. The fungicide Carbendazim and insecticides Carbofuran, Phorate and HCH showed no inhibition of Bradyrhizobium under laboratory and field conditions. Combinations of all the three insecticides with Thiram, Bordeaux mixture and Fytolan showed inhibition of the bacteria in in vitro. The rhizosphere bacterial population showed an initial reduction when these were applied in the soil.