Commercial Pesticide

This publication provides information on pulse width modulation (PWM) technology including its working principle, components, benefits, and best management practices for its optimal utilization on agricultural sprayers. Agricultural sprayers are commonly used for pesticide applications and come in various design types and sizes, including three-point hitch, pull-behind, and self-propelled. During pesticide applications, maintaining a target application rate across the whole field is important for effective pest management. On sprayers with traditional flow-based control systems, the liquid flow rate is regulated to account for ground speed variations by adjusting the spray pressure. However, this becomes an issue when spray pressure reaches outside the narrow operating range of the selected nozzle and results in non-uniform droplet size and pattern. Higher spray pressures at faster travel speeds produce finer droplets which are more prone to spray drift; applications at lower pressures produce coarser spray droplets and reduce spray fan angle. Pulse width modulation technology was developed to overcome this pressure variation issue; pulse width modulation does not rely on spray pressure to regulate system flow rate with changes in ground speed. In pulse width modulation systems, the flow rate is varied by changing the intermittent cycling of the electronically actuated solenoid valves while the system pressure remains constant throughout the boom.