Drop Nozzle from a Remotely Piloted Aerial Application System Reduces Spray Displacement

Weeds remain as one of the major limiting factors affecting agricultural production and crop productivity and cause significant yield loss globally. Alternate to traditional control of weeds with broadcast application of herbicides, spot spraying of weeds is commensurate with patchy spatial distribution of weeds. But the displacement of spray caused by wind and rotor wash remains a major concern, which can lead to inefficient coverage and unintended environmental loading. To mitigate this issue, drop nozzles have been developed to direct the spray closer to the target, thereby reducing drift and enhancing spray efficacy. A remotely piloted aerial application system (RPAAS) was outfitted with a 60 cm drop nozzle comprised of a straight stream and a 30° full cone nozzle to increase spray accuracy by reducing the effect of wind on spray displacement. Wind speed averaged 5.63 ± 0.40 m/s and varied from 2.23 to 8.94 m/s. A fluorescent spray solution was applied on 13 Kromekote cards placed in a grid configuration. The center of deposition for each of the spray applications was determined using Python software. Spray displacement was calculated as the distance between the center target site and the center of deposition for each of the spray applications. Regardless of nozzle angle, the drop nozzle produced significantly less spray displacement compared to the no drop nozzle, which should increase herbicide efficacy of targeted applications.