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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Aerial Application Technology Research » Research » Publications at this Location » Publication #355787

Title: Evaluation of spray pattern uniformity using three unique analyses as impacted by nozzle, pressure, and pulse-width modulation duty cycle

item BUTTS, THOMAS - University Of Nebraska
item LUCK, JOE - University Of Nebraska
item Fritz, Bradley - Brad
item HOFFMANN, WESLEY - Former ARS Employee
item KRUGER, GREG - University Of Nebraska

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2018
Publication Date: 1/22/2019
Publication URL:
Citation: Butts, T., Luck, J., Fritz, B.K., Hoffmann, W.C., Kruger, G. 2019. Evaluation of spray pattern uniformity using three unique analyses as impacted by nozzle, pressure, and pulse-width modulation duty cycle. Pest Management Science. 75(7):1875-1886.

Interpretive Summary: The precise application of crop protection products is key to effective pest management and requires that spray delivery systems are setup and operated in a manner to provide uniform deposition of products to the intended target. The uniformity of the spray pattern across the full width of the spray system is potentially influenced by nozzle type, spray pressure, and in the case of pulse width modulation systems, the duty cycle. Using a spray patternator, which automates the measurement of spray deposit uniformity across multiple spray nozzles, the variability in spray patterns from multiple combinations of nozzle type, spray pressure and duty cycles were analyzed. Results showed that duty cycles greater than 40 percent for all nozzle types resulted in spray patterns that were sufficiently uniform to maintain product efficacy. Additionally, pairing air induction type nozzles operated at low spray pressures and low duty cycles was found to result in very poor spray patterns that would significantly impact product performance in the field. Through proper selection and operation of nozzle type and spray delivery system, spray pattern uniformity can be tuned to deliver precise, on-target deposition of pest control products across a given area ensuring effective control.

Technical Abstract: Most agricultural pesticide applications exclusively utilize hydraulic nozzles which form a spray pattern from the breakup of the spray solution liquid sheet. This spray pattern is critical to maintain an accurate overlap of spray to reduce crop injury potential while maximizing coverage on target pests to increase efficacy. The increasing popularity of pulse-width modulation (PWM) sprayers requires that application interaction effects on spray pattern uniformity be completely understood to maximize sprayer efficiency. The objective of this research was to determine the impacts of nozzle type (venturi vs. non-venturi), gauge application pressure, and PWM duty cycle on spray pattern uniformity. Research was conducted using an indoor spray patternator with automated data collection located at the University of Nebraska-Lincoln in Lincoln, NE USA. Coefficient of variation (CV), root mean square error (RMSE), and average percent error (APE) were used to characterize the spray pattern uniformity. Generally, across nozzles and pressures, duty cycle had minimal impact on the CV of spray patterns. However, across nozzles and duty cycles, increasing pressure decreased CV values resulting in more uniform spray patterns. The RMSE values typically increased as pressure and duty cycle increased across nozzles. This may be the result of a correlation between RMSE values and flow rate as RMSE values also increased as nozzle orifice size increased. Generally, APE increased as duty cycle decreased across nozzles and pressures with significant increases (40%) caused by the 20% duty cycle. Within non-venturi nozzles, increasing pressure reduced APE across duty cycles, while venturi nozzles followed no such trend. Overall, results suggest PWM duty cycles at or above 40% minimally impact spray pattern uniformity. Further, increased application pressures and the use of non-venturi nozzles on PWM sprayers increase the precision and uniformity of spray applications.