Spray drift-based pesticide residues on untreated edible crops grown near agricultural areas

Abstract

We aimed to quantify spray drift-based exposure of fruits and vegetables grown in gardens or allotments next to agricultural areas to plant protection products (PPP). The amount of spray drift transported into gardens during the treatment of tall growing crops or field crops was simulated. Two different test systems in an outdoor wind tunnel were used, approximating conditions for the application to both crop types. For the experiments, strawberries, tomatoes and lettuce were used representing non-target food crops in gardens. After spraying, distance-related residues of the tracer pyranine were measured on the three food crops positioned 1–15 m downwind in the non-target area. Additionally, petri dishes were placed in front of the food crops to measure the ground deposition concurrently. For both scenarios, good correlation of residues on the non-target food crops and the ground deposition was found (linear regression model, R2 = 0.88–0.97). But unlike the field crops scenario, the experimental setup of the tall growing crops shows large deviations from the field situation, not allowing the transfer of the results to the field situation. The results of the wind tunnel experiments and of field trials on ground deposition were used to estimate the amount of PPP residues on food crops cultivated near agricultural fields. For example, application of a pesticide (1.3 kg active ingredient per ha−1) to field crops was estimated to result in residue levels of 0.39 mg kg−1 on lettuce, 0.32 mg kg−1 on strawberries, and 0.06 mg kg−1 on tomatoes cultivated 5 m from the field, thus indicating an exceedance of the default maximum residue level (MRL) (0.01 mg kg−1). Therefore, further in-depth studies are required to broaden the range of non-target crops and to refine the tall growing crop scenario to allow estimations of spray drift-based residues.