A virtual nozzle for modeling pesticide spray deposition in a plant canopy

Spray droplet dynamics have been studied, and many mathematical models have developed to simulate single droplet movement in air. However, most of these studies have been focused on “off-target” deposition (or drift). In this study, a complete spray pattern emitted from a flat fan nozzle was simulated, and the main goal was to develop a virtual nozzle with the same characteristics of an actual one. The virtual nozzle was used as a tool to study the “on-target” deposition of spray droplets in a soybean canopy. The results indicated that the virtual nozzle generated similar spray characteristics (droplet spectrum, VMD, NMD, and spray pattern) to those of an actual 8002 flat fan nozzle. Also 82–91% spray droplet spectra on individual simulated targets (in three-dimensional space) were recorded inside the 95% confidence intervals of that of those of the Kromekote cards sprayed by an actual 8002 flat fan nozzle. The Kromekote cards were attached to soybean leaves in different positions of the plant canopy. To convert spray droplet stains to spray droplet diameters a third-order “spread factor” was developed to match the spray characteristics of droplet stains to those of the droplets recorded by a laser detector.