Design and prototype manufacturing of a hydraulic system with a rotating head for pesticide application in citrus trees at high application volumes

In this study, a "Hydraulic Rotary-Head Sprayer Prototype" was manufactured to spray citrus trees at high application volumes and compared with a vertical boom oscillating motion sprayer commonly used by citrus farmers under orchard conditions. The manufactured prototype spraying system consists of 2 rotary-heads, each with 3 nozzles, placed vertically on one side (right side) of an existing mounted -type sprayer. In the study, the sprayer of the prototype manufactured was operated at 81 and 68 rpm rotation speeds of rotary spray head to investigate the effect of rotation speed on the covarege and deposit amounts on the tree. The prototype sprayer was operated at three different application volumes (839, 998 and 1520 L/ha) and the vertical boom oscillating motion sprayer selected as the comparison sprayer was operated at only 1520 L/ha application volume and comparisons were made by measuring the coverage, droplet depositions and ground loss of spray on W. Murcott citrus trees (crown height 3 m). In the orchard experiments, sampling was carried out on each tree at 0⸰, 45⸰ and 90⸰ azimuth positions according to the direction of tractor progress, in the lower, middle and upper regions of the vertical plane, including the inner and outer parts of the tree crown. Water-sensitive papers were used as sampling surfaces and amounts of the coverage rate and droplet deposition on the target surfaces were calculated with the Image J image processing program using the droplet data on these papers. According to the obtained data; the rotation speed of the hydraulic rotary spray head was effective on the amount of the coverage rate and droplet deposition on the tree crown and ground loss of spray droplets. The increase in rotation speed (81 rpm) increased the coverage and droplet deposition while decreasing the droplet losses on ground. At the same application volume, the rotary head system provided less coverage inside the tree crown and more coverage outside the tree crown compared to the vertical rod oscillating system. Although the rotary head system provided more debris than the vertical rod oscillating system at the same application volume, the rotary head system produced less drug (droplet) losses.