Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 28, 2011
Publication Date: May 3, 2011
Citation: Fritz, B.K., Hoffmann, W.C., Bagley, W.E., Hewitt, A. 2011. Field scale evaluation of spray drift reduction technologies from ground and aerial application systems. Journal of ASTM International. 8(5):JAI103457. Interpretive Summary: Drift associated with spray application of crop production and protection products is a continual concern for the potential detrimental effects to the environment and neighboring cropland. With an increasing number of drift-reducing technologies being developed and marketed for use with agricultural chemicals, there is a need to scientifically quantify and rate the effectiveness of these products. A series of field trials comparing conventional and drift-reducing spray systems were conducted following protocols established as part of the Environmental Protection Agency’s Drift Reduction Technology Program. Reductions from drift reduction systems were on the order of 60% and were similar to reductions determined using drift models. As a result of this work, a number of improvements to the established testing methodologies were suggested to provide a science-based program that appropriately credits applicators for reduced drift with the use of effective technologies.
Technical Abstract: The objective of this work is to evaluate a proposed Test Plan for the validation testing of pesticide spray drift reduction technologies for row and field crops, focusing on the testing of ground and aerial application systems under full-scale field evaluations. The measure of performance for a given DRT tested under field conditions is the downwind deposition as measured on horizontal fallout collectors. Ground and aerial application equipment were evaluated for in-swath and downwind deposition of sprays as applied by both a reference system and a drift reducing technology. For this study, the reference system was defined as a spray boom outfitted with the ASABE Fine/Medium boundary reference nozzles. For the ground system, the drift reducing system tested was a ground sprayer outfitted with and air-induction version of the reference nozzle. The aerial system drift reduction technology was a flat fan nozzle specifically designed for aerial application usage. Downwind deposition was measured from the edge of the swath out to 100 m downwind. Additionally, the airborne portion of the spray remaining suspended in the air at 50 meters downwind was measured. There were a number of confounding issues with the measured data including poor recovery of deposits and no-ideal wind directions during specific replications. Even with these issues, the drift reduction between the reference and DRT system measured in the field for the aerial trials was similar to that estimated using the AGDISP model. A number of additional improvements and checks are suggested prior to further field evaluations.