Abstract
Pesticide drift is an issue in modern farming, mainly for crops under constant spraying as soybeans. This study aimed at assessing drift and pest control for aerial application on soybean crops. Hydraulic nozzles and rotary atomizers, regulated to a wide spectrum of droplet sizes, sprayed thiamethoxam and lambda-cyhalothrin using an agricultural aircraft Ipanema 202A at volume rate of 20 L ha-1. Treatments consisted of testing two devices: a rotary cage atomizer (Micronair AU 5000) with blade angles of 65° for larger droplets, and with angle of 55° for smaller ones; and a set of adjustable nozzles (Stol model) with deflector angle of 90° for smaller droplets, and with angle of 30° for larger ones. Drift was evaluated through quantification of active ingredient, by means of liquid chromatography, on nylon strands set 20, 40, 80, 160 and 320 m away from target area, following wind displacement. Control efficiency was measured by counting caterpillars and stinkbugs found five days after spray. Rotary atomizers produced less drift compared to adjustable nozzles at the designed setting. Furthermore, drift can be reduced through a suitable regulation of the devices, keeping an effective pest control.
Highlights
Atomizers achieved lower values of drift compared to hydraulic nozzles, without differing from one to another, and showing mean drift index of 0.062 (91.5% reduction with regards to the worst case)
Rotary atomizers showed the lowest levels of drift with high efficiency to control caterpillars and stinkbugs in soybeans, whether compared to the hydraulic adjustable nozzles
Further studies are required to broaden the number techniques to be used for drift reduction
Summary
Major losses of yield are expected (AITA et al, 2015). In this sense, most attention is given to which chemical to be used rather than to the way it is applied (BUENO et al, 2011). For the operation to succeed, a proper spraying should be mastered, ensuring product reach to the target efficiently, lowering losses and environmental contamination. Part of the applied product can be lost, especially if application techniques are being wrongly used, constituting one of the largest challenges to be overcome in modern agriculture (NUYTTENS et al, 2011; ZHAO et al, 2014)
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