Evaluation of PWM technologies for pesticide spray applications in a two-year old apple orchard

Authors: SALCEDO, RAMON - The Ohio State University; Zhu, Heping; ZHANG, ZHIHONG - Kunming University Of Science And Technology; WEI, ZHIMING - Shandong Academy Of Agricultural Sciences; Chen, Liming; OZKAN, ERDAL - The Ohio State University

Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2020
Publication Date: 7/12/2020
Citation: Salcedo, R., Zhu, H., Zhang, Z., Wei, Z., Chen, L., Ozkan, E. 2020. Evaluation of PWM technologies for pesticide spray applications in a two-year old apple orchard. In:Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE), July 13-15, 2020, Virtual Meeting. ASABE Paper No. 2000079.

Interpretive Summary:

Technical Abstract: Utilization of pulse width modulation (PWM) controlled nozzles may mitigate the off-target losses generated during pesticide treatments. Assays in two-year old apple trees were conducted to evaluate spray quality in a single pass of three systems retrofitted in an airblast sprayer: 1) constant-rate with PWM nozzles controlled with a manual emission system; 2) variable-rate with PWM nozzles controlled automatically with a laser-guided intelligent spray system and 3) constant-rate without PWM controls. Stainless steel screens and water sensitive papers were selected as collectors for measuring the spray deposition and coverage on twelve trees randomly selected from four downstream rows. Plastic plates placed on the ground and nylon screens mounted at five heights on seven poles were used to assess ground and airborne drifts. Data showed that a single pass for each system provided adequate leaf deposits and coverage for the first two rows, but the disabled and manual PWM mode probably incurring over-spray problems. The variable-rate mode guaranteed a minimum number of droplets per unit area with a better relationship between deposition-coverage and the lower application rate. The automatic PWM control mode showed a better behavior in the ground and airborne drifts than the manually controlled PWM mode. Results suggested that a single spray pass from each of the three systems could provide adequate spray deposits and coverage in the first two rows, reducing economic costs, but the automatic PWM control could reduce more off-target losses, contributing more efficient spray applications than both conventional and manual PWM controlled constant-rate systems.