Abstract: AgDisp is a "first principles" science-based model that predicts spray drift from application sites. It was developed by the USDA Forest Service and was designed to optimize agricultural spraying operations and has detailed algorithms for characterizing the release, dispersion and deposition over and downwind of the application area (quoted from the EPA website). The model, as "AgDrift", was validated by the Spray Drift Taskforce for low-level, large droplet agricultural spraying operations, with limits placed on the maximum altitude, computational time, downwind drift distance and minimum droplet size. However, AgDisp (with the AgDrift limitations relaxed) is now the model of choice for EPA's Risk Assessments of mosquito aerial adulticiding applications, which are applied at higher altitudes with smaller droplet sizes in a complex environment with many obstructions and vegetative filters. The "open field" assumptions modeled by EPA overestimate real world drift and deposit levels from aerial adulticiding. This presentation will introduce the audience to AgDisp modeling and discuss some of these issues.
