Degradation of Azoxystrobin, Lufenuron and Fenpyroximate Residues in/on Grape Fruits under Field Conditions.

Fungal infection and pests attack arevery serious problems that facing grapes growers in Egypt. Fungicide azoxystrobin, (Azostar® 25%SC), insecticide lufenuron, (Cymax® 5%EC) and acaricide fenpyroximate (Ortus super® 5%EC) are the most common pesticides used to control such pests (downy mildew, grape fruit worm Eudemis botrana and red spider mite, respectively) in Egypt. The present study was carried out to assess persistence Vs. degradation behavior of the mentioned pesticides when sprayed on foliage of grape plants under field conditions during fruiting stage at the recommended and double the recommended rates of application during the season of 2017 in Adam village, El-Nobaria district, El-Behaira Governorate, Egypt. Fruit samples were collected randomly, two hours (initial time) and 1, 3, 7, 14 and 21 days after application. Samples of treated and untreated (control) grape fruits were prepared, extracted, cleaned-up by QuEChERS analytical method before quantification by high performance liquid chromatography with diode array detector (HPLC-DAD) and gas chromatography extended by electron capture detector (GC). The corresponding values for dissipation of the mentioned pesticides initial deposits, degradation percentages of residues, Residual Lifetime 50% (RL50), Residual Lifetime 90% (RL90) and pre-harvest intervals (PHIs) of the tested pesticides were determined. Results revealed that grape fruits remained higher initial amounts by (2.93 and 3.97), (0.82 and 1.14) and (1.74 and 1.94) mg kg-1 azoxystrobin, lufenuron and fenpyroximate for both doses, respectively. As for RL50, RL90 andPHIs, values showed (3.22, 1.73, 1.85 days) and (9.71, 4.22 and 6.31 days) and (5, 6.89, 4.05 days) when the recommended doses were applied and also, (3.80, 10.4 and 6.85 days) and (1.91, 5.02 and 7.12 days) and (2.58, 6.09 and 5.24 days) at the double recommended rates of application, in/on grape, respectively. In general, azoxystrobin, lufenuron and fenpyroximate residue in/on grape fruits had low persistence. In addition, the grape fruits could be consumed safely after 5, 6.89, 4.05 days, respectively from treating by the recommended rate of azoxystrobin, lufenuron and fenpyroximate when compared by the Maximum Residue Limits (MRLs) of the Codex Alimentarius Commission or the European Union (2, 0.01 and 0.01 mg kg-1), respectively.