Field Scale Evaluation of Spray Drift Reduction Technologies from Ground and Aerial Application Systems

Abstract

The objective of this work is to evaluate a proposed test plan for the validation testing of pesticide spray drift reduction technologies (DRTs) 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 an air-induction version of the reference nozzle. The aerial system DRT 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 m downwind was measured. There were a number of confounding issues with the measured data including poor recovery of deposits and non-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 agricultural dispersion model. A number of additional improvements and checks are suggested prior to further field evaluations.