A complex interaction of controllable and uncontrollable factors is involved in aerial application of crop production\r\nand protection materials. Although it is difficult to completely characterize spray deposition and drift, these important factors\r\ncan be estimated with appropriate sampling protocol and analysis. Application height is an important variable influencing\r\noff-target spray drift, but this variable has not been easily measured or logged. A custom-configured aircraft-mounted laser with\r\nlogging capabilities makes this possible. This study was designed to investigate droplet size and deposition characteristics of a\r\nlow drift CP flat-fan nozzle at application altitudes 3.7 m, 4.9 m, and 6.1 m. In the study, CP flat-fan nozzles were set to a\r\ndownward angle of 30 degrees applying a mixture of water, Syl-Tac�® adjuvant, and Rubidium Chloride (RbCl) tracer at a\r\n28.5 L/ha application rate. Spray droplets were collected using water sensitive paper (WSP) cards placed in the spray swath.\r\nMylar sheets were also placed in the swath and downwind for drift sampling. Statistical analysis indicated that median droplet\r\ndiameter as determined by WSP in the spray swath was not significantly influenced by spray application height. Similarly,\r\nstatistical analysis also indicated that concentration of RbCl tracer from Mylar samplers in the spray swath was not significantly\r\ninfluenced by application height. Application height had a significant effect on spray deposition from drift samplers, along\r\nwith wind direction and relative humidity. Final results for drift samplers may have been influenced by shifts in wind\r\ndirection that altered the relationship between orientation of samplers and wind.
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