Dissipation of quinalphos residues on cauliflower (Brassica oleracea L. var.capitata)

The dissipation of quinalphos on the main and spring crops of cauliflower sprayed at a rate of 250 g a.i./ha was studied. The residues of the insecticide were estimated in the samples taken at various intervals by using gas-liquid chromatography and the TLC-enzyme inhibition technique. Quinalphos residues took about 7 and 4 days to reach a level lower than 0.25 ppm on the curds of the main and spring crops, respectively. The oxygen analog of quinalphos was also detectable, in negligible amounts. About 95% of the insecticide degraded on the cauliflower within 8 days. Repeated applications of the insecticide did not result in any build-up of the residues.