Air-Assisted Spray Transfer under Different Operating Conditions in Coffee Trees

Operational optimization of spraying in coffee cultivation can enhance application effi-ciency and control effectiveness. However, no studies have specifically assessed droplet deposition on leaves adjacent to the application band—a phenomenon referred to as ‘transfer’ in this study. This study aimed to quantify the deposition and transfer resulting from different application rates and jet types in coffee trees. Three application rates (200, 400, and 600 Lha-1) and two jet types (conical and standard flat) were tested. Evaluations were conducted for both sides of the sprayer (left and right), across three sections of the plant (upper, middle, and lower), and for two positions on the plagiotropic branch (inner and outer). Data were analysed using a linear mixed model. The results showed higher deposition using the flat spray tip; however, deposition was uneven across thirds of the plants and varied with application rates, being lower at the inner branch position. Trans-fer rates were consistent between application sides, with lower values observed for the in-ner branch position when using the conical spray tip at the 200 Lha⁻¹ rate. Overall, the re-sults indicated that a 200 Lha⁻¹ rate using cone-jet tips is an effective strategy for increas-ing deposition on the reference tramline, while minimizing carry-over. In contrast, main-taining this dosage with flat spray tips resulted in higher deposition on the reference tramline but also caused a greater increase in carry-over.