3.7.7
SPRAY DEPOSITION AND COVERAGE ON RED MAPLE IN A NURSERY

CR KRAUSE, RC DERKSEN, RD FOX and RD BRAZEE

US Department of Agriculture, Agricultural Research Service, Application Technology Research Unit, Department of Plant Pathology, OARDC, Ohio State University, Wooster, OH 44691, USA

Background and objectives
Thorough knowledge of the delivery, dispersal, and fate of fungicides is crucial to ensure accurate fungicide distribution [1] with minimal offtarget contamination, enhanced retention of active ingredients on targeted surfaces, and drift reduction that lead to more effective disease management [2].

Material and methods
Tracers (Cu(OH)2 and blue food dye) were sprayed onto four year-old, multi-stem Acer rubrum in a commercial nursery with two types of air-assist sprayers. A conventional axial flow orchard sprayer and a prototype air curtain sprayer using cross-flow fans were evaluated for tree canopy penetration and downwind ground deposits. Electron beam analysis and spectrophotometry were used to measure tracer leaf deposits and coverage on inert microscope stubs.

Results and conclusions
The air curtain sprayer produced more uniform deposits through the canopy but not higher mean deposits or greater coverage than the conventional orchard sprayer. Downwind ground deposits and coverage were greater from the air curtain sprayer than those from the conventional orchard sprayer. Reduction of pesticide applications and improved fungicide efficacy will help safeguard environmental quality and enhance producer profitability.

References
1. Krause CR, Brazee RD, Derksen RC, Zhu H, Fox RD, 1997. Phytopathology 87, S54.
2.Tappan C, Krause CR, Powell CC, 1997, J. Environ. Hort. 15, 19-22.