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United States Department of Agriculture

Agricultural Research Service

Research Project: Pesticide Application Technologies for Spray-drift Management, Maximizing In-field Deposition, and Targeted Spraying

Location: Crop Production Systems Research Unit

Title: Reducing pesticide drift by considering propeller rotation effects from aerial application and near buffer zones

Authors
item Thomson, Steven
item Womac, Alvin -
item Mulrooney, Joseph -

Submitted to: Sustainable Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 2013
Publication Date: April 21, 2013
Citation: Thomson, S.J., Womac, A., Mulrooney, J. 2013. Reducing pesticide drift by considering propeller rotation effects from aerial application and near buffer zones. Sustainable Agriculture. 2(3):41-51.

Interpretive Summary: Drift from aerial application can be minimized by use and proper setup of low drift nozzles and atomizers, attention to weather conditions for spraying, and proper height of application. One factor not considered much for aerial application is the direction of the propeller rotation on the aircraft. Propeller wash turbulence carries droplets from nozzles to the right of the fuselage and deposits them beneath or to the left of the fuselage. Sometimes when nearing the end of a spray run, the aerial applicator may turn off one boom to spray an incomplete swath. The question then becomes whether flight direction influences drift potential. Scientists and Engineers with the USDA ARS Crop Production Systems Research Unit, Stoneville MS USA in collaboration with engineers at the University of Tennessee acquired data to assess the influence of which direction the propeller is turning on off-target drift of applied chemical. New data showed that, indeed, flying in a direction where the propeller wash direction is upwind (such as east to west flight for a southern cross-wind) can reduce the potential for off-target drift. This information can be used by agricultural pilots to determine which direction a pilot should fly in relation to a crosswind to minimize drift while spraying with a single boom near buffer zones.

Technical Abstract: Off-target drift of chemical from agricultural spraying can damage sensitive crops, destroy beneficial insects, and intrude on human and domestic animal habitats, threatening environmental quality. Reduction of drift from aerial application can be facilitated at the edge of a field by offsetting spray ½ or 1 boom width from the field edge or by switching off one boom. For single boom application (and especially when spraying in a cross wind), there is some question whether off-target drift of sprayed crop protection agent is influenced by which boom is spraying and if direction of propeller rotation has any effect. An experiment was conducted to determine the effect of propeller wash rotation on aerial spray drift from turbine-powered aircraft. Spray samplers were placed at three sample lines to collect drift fallout and air-entrained particles 104, 134, 195, and 317 meters downwind, perpendicular to the flight path. An aqueous mixture of malathion was applied from the aircraft through fifty hollow cone nozzles. Five total replications were conducted over two days. Each replication had four treatment combinations of actively spraying boom and airplane direction. Results showed that neither active boom nor boom location (upwind or downwind) was statistically significant for either sampling method at the 0.05 level. Blocking the study to account for weather differences increased statistical precision. Thus when analysis was limited to the second day of testing, propeller wash direction was significant at the 0.10 level for the fallout sheets (P = 0.0773), and at the 0.05 level for high volume (Hi-Vol) air samplers (P = 0.0200). Higher concentrations occurred when propeller wash spiraled downwind. Based on results of this study, recommendations for pilots spraying with a single boom near a boundary is to spray so that propeller wash rotation occurs upwind.

Last Modified: 9/23/2014
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