Optimization and Evaluation of Electrostatic Spraying Systems and Their Effects on Pesticide Deposition and Coverage Inside Dense Canopy Plants

Electrostatic spraying systems can improve the pesticide application efficiency by enhancing droplet deposition and coverage within crop canopies. This study evaluated the droplet size spectra and charge-to-mass ratio (CMR) of five electrostatically charged hollow-cone nozzles and one flat-fan nozzle paired with an electrode. Each nozzle was mounted on a moving boom in a wind tunnel and operated with the electrode and voltage that produced the highest CMR. Their effects on the spray coverage and deposition inside boxwood shrubs at wind speeds of 0 and 2.24 m s−1 were assessed. The nozzles operated with the optimized electrode had average improvements in the canopy deposition and canopy coverage of 1.33 µg cm−2 and 4.4% at a wind speed of 0 m s−1 and 0.26 µg cm−2 and 0.9% at a wind speed of 2.24 m s−1. The airborne drift measurements at various heights above the wind tunnel floor showed an average 0.50 µg cm−2 reduction in the drift at 0.1 m, variable results at 0.35 m, and minimal changes at heights of 0.7 m and above at a downwind distance of 2 m. These findings highlighted the potential of optimized electrostatic spraying systems to enhance pesticide deposition inside the crop canopy under various wind speeds while reducing the spray drift potential.