Safety of nine pesticides commonly applied to peach tree in the late growth stage

To evaluate the safety of pesticides used on peach trees at the late growth stage, the early-ripening peach cultivar ‘Jinlinghuanglu’ was used to investigate changes of pesticide residues in the peaches. The distributions of different pesticides in peach twig, leaf, peel, and flesh samples after the application of nine pre-mixed pesticide formulations at 1- and 2-fold of the maximum recommended doses, including four insecticides (abamectin, chlorantraniliprole, lambda-cyhalothrin, and imidacloprid) and five fungicides (difenoconazole, fenbuconazole, azoxystrobin, thiophanate-methyl, and carbendazim) were also investigated 7 and 14 days before the harvest. In addition, the usefulness of bagging for the control of pesticide residues at the late growth stage was evaluated. The results showed that the residual amounts of three fungicides (difenoconazole, fenbuconazole, and azoxystrobin) and four insecticides (abamectin, chlorantraniliprole, lambda-cyhalothrin, and imidacloprid) were always below the maximum residue limits (MRLs) set by China for whole peaches, even treated with 2-fold of the maximum recommended daily doses 7 days before the harvest. However, carbendazim residue was significantly higher than the MRL value in whole peaches after the excessive application of carbendazim and thiophanate-methyl. Furthermore, the potential risk of carbendazim migration from peach peels, leaves, and twigs to peach flesh may increase over time. The residual amounts of carbendazim in whole peaches with bagging treatments were significantly lower than the MRL value. Bagging also dramatically decreased the residues of eight other pesticides in whole peaches. The results also revealed that the distributions of nine pesticides in different peach-tree tissues were similar, which followed in the order: peach peels > whole peaches > peach leaves ≥ peach flesh ≥ peach twigs. The results indicated that the breakdown mechanisms of different pesticides in peaches varied at the late growth stage. The excessive application of carbendazim and thiophanate-methyl increased the risk of carbendazim residues in peaches. Bagging is an effective way to reduce pesticide residues in peaches. The results will contribute to the removal of pesticide residues in peaches and reducing the risk of dietary intake.