Spray deposition in an artificial grapevine canopy as affected by spray angle regulation systems of radial airflow air-assisted sprayers

Abstract

As the most critical factor affecting pesticide application efficiency and drift risk, the airflow characteristics of air-assisted sprayers have been of great concern. This study compared seven assisted airflow angle regulation methods regarding within-canopy deposition quality and off-target losses to the ground and behind the target canopies, including a newly proposed airflow swing device, three types of directional housings, and airflow deflector settings. An artificial grapevine canopy and a multiple-tracer methodology were used to evaluate deposition. Results showed that airflow angle regulation methods caused significant differences in canopy deposition and off-target losses (p < 0.001). The sprayer equipped with 0° housing had the highest deposition on the canopy (122.27 μg cm−2), followed by the sprayer equipped with the −30° housing (99.26 μg cm−2). The sprayer equipped with both airflow swing devices and optimal deflectors had a deposition of 87.76 μg cm−2. The radial airflow air-assisted sprayer without any airflow interventions caused the highest off-target losses, reaching 31.95% of the total spraying volume. The optimal deflector setting was conducive to reducing ineffective losses, but it also deteriorated the deposition uniformity on the canopy. Significantly, the airflow swing device improved the deposition uniformity on the abaxial side of the leaves to 23.89%, which can provide a reference for future optimization of new air-assisted sprayers.