Spray Volume Influence and Adjuvants on Droplet Deposition in Disease Control in Coffee Growing

The effective development of coffee production depends directly on the ability to control phytopathogenic diseases, which reduce crop quality and productivity. Uniform pesticide application remains an operational challenge due to new formulations, reduced spray volumes, and structural characteristics of coffee plants. This study evaluated the efficiency of adjuvants associated with reduced spray volumes for controlling brown eye spot (Cercospora coffeicola) and coffee leaf rust (Hemileia vastatrix). A randomized complete block design with 11 treatments and five replicates was used. Spray volumes of 650, 333, and 250 L ha−1 were combined with vegetable oil (VO; 1 L ha−1), sodium lauryl ether sulfate plus a natural compound-based adjuvant (LESS; 0.35 L ha−1), or LESS combined with vegetable oil (0.5 L ha−1). An additional farm-standard treatment consisted of 800 L ha−1 with 1.0 L ha−1 VO. The experiment was conducted on the Icatu 42 cultivar, and spray deposition, droplet spectrum and disease control efficacy were evaluated. LESS increased droplet coverage, spreading, wetted area, and spray retention. Reduced vegetable oil rates associated with adjuvants improved spray application parameters and disease control. The 250 L ha−1 spray volume provided greater deposition throughout the canopy, while higher volumes increased runoff, soil losses and spray drift. The combination of LESS with 250 L ha−1 achieved the highest deposition efficiency and the greatest reduction in coffee leaf rust and brown eye spot incidence, whereas 333 L ha−1 + LESS provided the best control of brown eye spot. These results demonstrate that reduced spray volumes combined with high-performance adjuvants can optimize coffee disease management.