Study on droplet drift and applicator exposure in rice flight prevention by multi-rotor plant protection UAV

Unmanned aerial vehicle (UAV) can produce droplet drift in pest control. This study investigated the difference in drift downwind by ISO22866 standard and pestcide exposure to applicators between spraying anisolecanazole and chlorantranilipprole by UAV and knapsack sprayer in rice fields. Data displayed that UAV had drifting deposits at 0-30 m from the boundary of the downwind zone when spraying in test conditions (4 m/s of flying speed and 1.8 m of flying height) , and the drift rate of chlorantraniliprole is 0.9% at distance of 30 m, while knapsack sprayer only has drifting deposits at 0-3 m to ground and drift rate no more than 0.6% in the area beyond 3 m. Meanwhile, the drift amount in the air when applied knapsack sprayer at 5 m and 10 m distance were all less than 0.001 μg/cm² , while UAV had more drift at 5 m than that at 10 m and has the most drift amount at 2 m height (the height UAV flys). The DV₅₀ of the knapsack sprayer was 149.4 μm and UAV was 115.3 μm. When combining the droplet size of these two application equipments, the results indicated that droplets of UAV had higher drift potential. In terms of pesticide exposure to applicators, it was discovered that the exposure of UAV application was almostly zero due to the separation of applictor and application machine, while knapsack sprayer application had whole body exposure to pesticide. Forearms and front legs were most severe, and the back of the right forearm even reached at 15.19 μg/cm². This work can be used as reference in the determination of the buffer zone range and human risk assessment.