Effect of monocrotophos and quinalphos on soil algae

Abstract

The effect of monocrotophos and quinalphos, applied at rates ranging from 0·5 to 5 kg ha⁻¹, on algal populations was determined in a soil by following the mean probable number (MPN) method. Single or two successive additions of monocrotrophos to the soil had no inhibitory effect on the algal flora. Only two successive additions of quinalphos, even at close to field application rates (0·5 to 2 kg ha⁻¹), were significantly toxic to the algae, but not a single application.