Coinciding with the release of the Vulnerable Species Pilot project and Herbicide Strategy drafts (see stories below), EPA also published a technical document that provides scientific background and justifications for the proposed mitigation measures in the two drafts. The technical document contains several key points about aerial applications and drift mitigation that NAAA has been making to EPA for years, and their inclusion in the technical document is a major victory for aerial applicators. The first is that drift only moves downwind, hence upwind buffer zones are not necessary. While this seems obvious, it is likely that EPA, the Fish and Wildlife Service, and National Marine Fisheries Service have had reservations that aerial applicators can accurately measure wind direction throughout an application. NAAA has commented numerous times about how onboard smokers or an meteorological measurement systems can accurately measure wind direction.

 

EPA also acknowledged that a standing crop, over which most aerial applications are made, reduces the amount of drift from aerial application compared to bare ground alone. NAAA has repeatedly informed EPA that performing all registration risk assessments with the assumption that every aerial application is over bare ground is unrealistic. The technical paper also discusses NAAA’s proposal to move away from the inaccurate Tier 1 model and its assumptions in AgDRIFT and instead utilize the Tier 3 AgDRIFT model with parameters set to reflect modern aerial applications. While the technical document still uses Tier 1, it states that EPA “continues to consider those [NAAA’s] comments and may update its input parameters and spray drift modeling prior to implementing spray drift buffers calculated using AgDRIFT® described in this document.” NAAA is pleased with these developments and will continue to promote more accurate modeling of aerial applications.