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The recognition of agricultural pesticide application complexity has increased in recent years due to pesticide drift concerns and increasingly difficult-to-control pests. Spray application optimization is necessary to maximize pesticide efficacy while reducing environmental impact. Pulse-width modulation (PWM) spray application systems can be a vital precision agricultural tool by providing quick and accurate variable rate application changes and creating an opportunity for a site-specific pest management strategy. Research was conducted to identify the impact of PWM duty cycle, nozzle type, application pressure, and spray solution on spray droplet velocity to develop potential PWM optimization practices. Spray droplet velocity increased as pressure and duty cycle increased across nozzles. Greater variability in droplet velocities was observed across nozzles when pulsed at a 20 % duty cycle. Venturi nozzles created greater reductions in droplet velocity as duty cycle decreased and had greater variability in droplet velocity measurements than non-venturi nozzles. Based on present research, if PWM sprayers are to be used in site-specific pest management strategies, it is recommended that non-venturi nozzles coupled with greater than 40 % duty cycle be used to reduce spray droplet velocity variability, mitigate changes in drift potential, and assist pesticide applicators in optimizing site-specific pest management strategies.

The amenability of electrostatic-charged sprays to a wide array of pesticides with different chemistries should be a useful tool in combating insect resistance. Results reported here suggest that the potential exists for obtaining increased efficacy against whiteflies using an electrostatic spray charging system, and that additional research will be required to improve charge-to-mass (Q/M) ratio in order to increase deposition of pest control materials to the lower surfaces of cotton leaves where the whiteflies reside.

a b s t r a c tPrevious work sought to compare the results from imaging software for characterising droplet coverage, but none exists examining these five software programs: Droplet Scan Ò , Swath Kit Ò , Deposit Scan, Image J, and Drop Vision Ò -Ag. Additionally, a freely available smartphone application (App), SnapCard was developed to provide an extension tool for in-field analysis of spray collectors, but nothing has been published regarding its comparison to other imaging software systems. The present study was conducted to compare five existing imaging software types against the new App, SnapCard. Six nozzles producing different spray qualities were selected to spray a water + Brilliant Blue Dye solution over two artificial collector types (water sensitive paper and Kromekote Ò ). Each collector was assessed for percent coverage using the five imaging systems and SnapCard. Objectives of this study were: 1. To establish a baseline dataset using the sprayed cards and five commonly used imaging systems, and compare the coverage results from each. 2. Use the baseline data from Objective 1 as a measurement of precision to judge the results from SnapCard. 3. Make an assessment of SnapCard against the other imaging software type data in the study.Results showed that SnapCard has similar measured coverage means compared to other image analysis systems. For both collector types, SnapCard measured coverage within one standard deviation of the means across nozzle types. SnapCard is able to provide an immediate answer without expensive software or needing a laboratory to measure sprayed collector coverage with precise results, which further underscores its value. The other software types were not all similar for coverage, but the data followed the same trends for droplet size. Increasing the droplet size consistently decreased the coverage, across both collector types. Droplet Scan reported the highest coverage while Drop Vision-Ag and Swath Kit gave lower coverage values on water sensitive paper and Kromekote Ò collectors, respectively.