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United States Department of Agriculture

Agricultural Research Service

Research Project: AERIAL APPLICATION RESEARCH FOR EFFICIENT CROP PRODUCTION Title: Evaluation of aerial spray technologies for adult mosquito control applications

Authors
item Hoffmann, Wesley
item Fritz, Bradley
item Farooq, Muhammad -
item Walker, Todd -
item Hornsby, Jonathan -
item Bond, J.A.S. -

Submitted to: Journal of Plant Protection Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 2013
Publication Date: September 13, 2013
Citation: Hoffmann, W.C., Fritz, B.K., Farooq, M., Walker, T., Hornsby, J., Bond, J. 2013. Evaluation of aerial spray technologies for adult mosquito control applications. Journal of Plant Protection Research. 53:222-29.

Interpretive Summary: Spray droplet size is a critical factor that impacts the efficacy of sprays used to control mosquitoes. Accordingly, accurate measurement of spray droplet size is important. Studies were conducted using three different, laser-based droplet size measurement systems to measure droplet size from three spray nozzles. There were differences in the distribution of droplet sizes produced by the three nozzles. For each nozzle type, the three droplet measurement systems quantified nearly identical droplet sizes. Results from this study will allow applicators to select the spray nozzle that meets their application needs and allow researchers to confidently compare distributions of droplet sizes measured using different instruments.

Technical Abstract: Spray droplet size has long been recognized as an important variable that applicators of vector control sprays must be aware of to make the most effective spray applications. Researchers and applicators have several different techniques available to assess spray droplet size from spray nozzles. The objective of this study was to compare the droplet size spectrum produced by three nozzles commonly used in vector control in a high-speed wind tunnel when characterized using three different laser-based droplet size measurement systems. Three droplet sizing systems (Malvern Spraytec laser diffraction, Sympatec Helos laser diffraction and TSI Phase Doppler Particle Analyzer (PDPA)) were simultaneously operated to measure the spray droplet size spectra for three spray nozzles under different operating conditions. The three spray nozzles (a Spray Systems 8001E flat fan, BETE PJ high pressure nozzle, and a Micronair AU5000 rotary nozzle) were evaluated in a high speed wind tunnel at airspeeds of 53 and 62 m/sec (120 and 140 mph). These tests are the first reported studies where direct comparisons of all three droplet sizing systems were conducted at the same time in a single wind tunnel for sprays targeting adult mosquitoes. There were significant differences in the droplet size spectra produced by the three nozzles. Within each nozzle type, the three droplet sizing systems measured nearly identical droplet sizes, particularly for the volume median diameters (DV0.5) values. For the 8001E flat fan nozzle, the Malvern system measured droplets 2-3 times larger for the 90th percentile based on spray droplet cumulative volume than the Sympatec or PDPA systems.

Last Modified: 4/20/2014