Spray deposition on coffee leaves from airblast sprayers with and without electrostatic charge

Abstract

Studies on the quality of applications of plant protection products on coffee crops are lacking. Thus, we studied spray deposition on coffee leaves and losses to the soil from hydropneumatic spraying at different spray volumes and with and without an electrostatic charge. The experiment was set up using randomized blocks in a factorial design (4 x 2 + 1). Spray deposition on the upper, middle and lower parts of the canopy and losses to the soil were evaluated using Brilliant Blue tracer. Applications were made at 200, 300, 400 and 500 L ha^-1 with a conventional airblast sprayer (axial fan type) and an airblast sprayer with directed air jets. Applications were also made with an electrostatic sprayer at 130 L ha^-1. Electrostatic spraying resulted in greater spray deposition on the lower part of the coffee canopy compared to non-electrostatic spraying. On the lower and middle parts of the plants, the sprayer equipped with directed air ducts performed better than the sprayer with nozzles arranged along the lateral arcs (axial). The spray volume of the airblast sprayers without electrostatic charge (200 to 500 L ha^-1) did not influence spray deposition on the plant leaves and losses to the soil, which were lower with the electrostatic sprayer.