Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 30, 1997
Publication Date: N/A
Technical Abstract: Ground-level and airborne spray samples were collected downwind of a semi-dwarf apple orchard in a series of drift experiments. Two sprayers were used to successively spray the downwind row of trees on two days during each year. Sprayers used in these studies were: two air- curtain, cross-flow fan units, an adjustable air boom, an axial-flow fan and a proposed ASAE 'standard' sprayer. Different fluorescent tracers wer used in each sprayer and downwind collectors were changed after each sprayer completed a pass. Data from studies conducted for four years were combined, based on wind velocity during each spray pass. Wind velocity classes were: less than 3, between 3 and 4.5, and greater than 4.5 m/s. Collectors were located at distances up to 132 m downwind from the tree row; with airborne spray samples collected from 0.5 to 10 m elevations. Experiments were included in the analysis only if wind direction assured that the spray plume covered the sample stations. Deposits at downwind distances beyond 50 m were greater for sprays applied when wind velocity was greater than 4.5 m/s than when wind speeds were less than 3 m/s. Ground deposits decreased at a greater rate with increased downwind distance than did airborne spray concentrations.