Reducing ground and airborne drift losses in young apple orchards with PWM-controlled spray systems

Pulse Width Modulated (PWM) solenoid valves can be used to control nozzle flow rates for precision spray applications reduce pesticide use, thereby reducing environmental risk and production cost. Field tests in a two-year-old young apple orchard were conducted investigate losses the ground air an air-blast sprayer equipped with three systems: 1) manually controlled constant-rate system enabled PWM (Manual-PWM), 2) laser-guided variable-rate (Laser-PWM); 3) conventional disabled (Disabled-PWM). Artificial targets (plastic plates water sensitive papers) placed under twelve trees randomly selected from four rows of collect ground. Airborne determined by using nylon screens, mounted at five heights on each seven poles distributed different distances first sprayed row. Laser-PWM Manual-PWM produced significantly lower airborne drift inside outside than Disabled-PWM, these decreased as distance away row increased. reduced total 90.3% loss 85.0% compared Disabled-PWM whereas same 84.1% 7.9%, respectively. detectable that reached 88.4 m where was operated. Thus, either automatic or manual would have great potentials improve application efficiency significant reductions both consumption orchards, off-target environment.