Using Lidar to Compute a Above Canopy Mass Balance of Aerially Applied Sprays

Aerial spraying with pesticides is a common approach to weed, insect pest, and disease control in a range of settings, including pest eradication in populated environments. With such a wide range of application scenarios, there is need to quantify the likely level of spray drift in order to assess risks to the environment and/or public health. Additionally, more accurate quantification will allow for improved predictions and better policy relevant decisions to be made for mitigation efforts (e.g., instigate buffer zones around sensitive areas or to change the application method). Therefore it is desirable to optimize aerial applications to reduce risks while maintaining efficacy. Aerosol lidar offers the ability to extend point sampled concentrations of spray to a spatial picture to compute a full mass balance of the applied spray. Since, current models do not completely account for the turbulence conditions above aerodynamically rough surfaces, there is a need to further understand mass fate and transport in this area. We report on a field study designed to test the implications of canopy roughness on spray drift. A combined lidar and ground sampling study is reported on. This paper will present the results of efforts to do a full mass accountancy of spray, as well as discuss the observed relationships between drift and canopy-generated turbulence.