Development of a smart sprayer for vineyards: first experimental results using PWM spray system

In the ambit of the OPTIMA H2020 Project (www.optima-h2020.eu), the use of a Pulse Width Modulation (PWM) system mounted on a vineyard air-assisted sprayer was assessed in the field to investigate its effects on variability of target spray coverage along the travel direction and at the different canopy heights. Water sensitive papers (WSP) positioned along the rows were sprayed with 12 different combinations of PWM duty cycle (DC = 30%, 50%, 70% and 100%) and forward speed (FS = 4, 6 and 8 km h-1). Using a dedicated software the WSP were analysed. The resulting spray coverage (SC) values indicated that both PWM duty cycle and sprayer forward speed affected the variability of spray coverage. Generally, the lower the duty cycle, the higher the variability of spray coverage. Nevertheless, the overall variability of SC due to the PWM on/off effect registered under field conditions was limited and it is therefore expected to be compatible with the use of such system for variable rate application treatments in vineyard.