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The use of aerial application with electrostatic charge is an alternative to improve the quality of insecticide applications in soybean crop. The objective of this study was to evaluate the drift and chemical control of the caterpillar and stink bug complex promoted by aerial applications of insecticide in the soybean crop, using electrostatic spray system and rotary atomizers. The insecticide Thiamethoxam + Lambda cyhalothrin was applied with a Cessna 188 Ag Truck agricultural aircraft in two treatments: SPE ® electrostatic system, with 54 SPE-5 nozzles and 10 L ha-1 application rate, and Travicar model ® 05165 rotary atomizer, with 55° angle blades and application rate of 20 L ha-1. Drift was evaluated through quantification of active ingredient, by means of liquid chromatography, on nylon strings set 20, 40, 80, 160 and 320 m downwind from the applied area. Control efficiency was measured by counting caterpillars and stink bugs found five days after application. The droplet spectrum was also evaluated through water sensitive papers placed in the target area. It was verified that the hydraulic nozzles, associated with the electrostatic system, generated lower drift, but there was no difference in pest control efficiency, in relation to the rotary atomizers.

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 applications in soybean crops. Hydraulic nozzles and rotary atomizers, regulated to a wide spectrum of droplet sizes, sprayed thiamethoxam plus 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 strings set 20, 40, 80, 160 and 320 m downwind from the applied area. Control efficiency was measured by counting caterpillars and stinkbugs found five days after spray. Rotary atomizers produced lesser 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.

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