Effect of reduced application rates of dicofol and pirimiphos-methyl on strawberries and common beans on their residue content and crop production

Residues of dicofol and pirimiphos-methyl applied at different rates on strawberry and common beans, respectively, were monitored at different intervals. The rate of crop production of each rate was also studied. High-performance liquid chromatography was employed to detect both compounds and gas chromatography/mass spectrometry analysis was conducted for further confirmation. All tested rates produced residue levels below the respective maximum residue limits (MRL) of dicofol and pirimiphos-methyl. The highest two rates of dicofol (185 and 139 g of active ingredient/feddan) and of pirimiphos-methyl (750 and 562 g of active ingredient/feddan) produced comparable production rates of strawberry and common beans, respectively. Dicofol residues were 0.230 and 0.105 mg/kg, 1 and 2 weeks, respectively, after the application of the highest rate. The highest rate of pirimiphos-methyl produced a residue level of 0.399 mg/kg, 1 week after application.