|THISTLE, HAROLD - Forest Service (FS)
|BONDS, JANE A - Bonds Consulting Group
|KEES, G - Forest Service (FS)
|Fritz, Bradley - Brad
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2016
Publication Date: 2/2/2017
Citation: Thistle, H.W., Bonds, J.S., Kees, G.J., Fritz, B.K. 2017. Evaluation of spray drift from backpack and UTV spraying. Transactions of the ASABE. 60(1):41-50.
Interpretive Summary: Pesticide drift is a primary concern for any application scenario, in particular if these applications are made on federal lands, drift risks must be assessed and shown to conform the the National Environmental Policy Act. There is very little data in current literature documenting backpack and small boom sprayer spray movement patterns. As part of this study, several backpack and small boom sprayers were evaluated for spray deposition and downwind movement under typical application conditions. The results showed that no portion of the material sprayed moves to distances that would cause concern or adverse impact. These documented results support the use of the spray systems tested for federal land manager use as well as the development of a backpack and small boom sprayer spray movement model to guide other applicators.
Technical Abstract: The objective of these tests was to evaluate pesticide drift from ground applications using a standard manual pump backpack sprayer and a UTV-mounted boomless sprayer. Three deposition sampler types were deployed: Mylar cards, water-sensitive papers, and artificial foliage. This study indicates that drift of pesticide at 20 m downwind of backpack or UTV spraying was about 0.001 of the applied rate. This order of magnitude of drift was similar for both application methods. In the case of the backpack spraying, deposition decreased to about 0.01 of the applied rate just 1.5 m downwind of the swath edge. In the UTV trials, the closest off-swath measurement was 0.5 m downwind of the downwind swath edge, and deposition there ranged from about 0.5 of the applied rate down to less than 0.001. At 2.5 m downwind of the downwind swath edge, these values ranged from about 0.02 down to near 0.0001 of the applied rate. The study concludes that very small amounts of material were deposited at 20 m downwind, but drifted material was present. This conclusion is reached understanding that these trials were conservative by design, as there was almost no intervening vegetation between the release line and the collectors. The study also confirms the dependence of drift on wind speed in these applications.