Dissipation of selected insecticides and fungicides applied during pre-harvest on mandarin and orange trees in Uruguay

Abstract

Abstract The dissipation of 4 commercial pre-harvest pesticides used in two Citrus species under field conditions is presented. The influence of agroecological region, the Citrus species and weather conditions on abamectin, spinosad, imidacloprid and difenoconazole dissipation rate on fruits were evaluated. A validated ethyl acetate method coupled to liquid chromatography-tandem mass spectrometry allowed the determination of pesticide residues having recoveries of 72–115%, relative standard deviations ≤16% and quantification limits below the international Maximum Residue Levels (MRLs). After 35–40 days from pesticides spraying, all residues were below the international required MRL. For each citrus species, the influence of the agroecological region on the pesticide dissipation was assessed. Film-protected fruits against direct radiation and rain showed higher residue levels of imidacloprid and spinosad than the non-protected ones. Either for orange or mandarin, abamectin residues were detectable only at the first day after application. These findings provide useful information to state safer pre harvest intervals and to ensure food safety and compliance with good agricultural practices.