NEAR-ROW FATE OF AIR CURTAIN AND ORCHARD SPRAYER NURSERY CROP APPLICATIONS

Authors: Derksen, Richard; Krause, Charles; Fox, Robert; Brazee, Ross

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 7/12/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: In 1996, nursery and greenhouse crop receipts were nearly 11% of the total cash receipts for all U.S. farm crops. Crop management techniques, the variety in the size of nursery stock and the number of species can create unique pest management problems for nursery managers. The proximity of populated areas to nurseries also creates concerns for managers. Keeping in mind the desire of the nursery industry to reduce the number of passes through the blocks and to treat trees from one side only, the objective of this experiment was to compare the near-row fate of spray applications for conventional and prototype spray equipment using canopy spray deposits, spray coverage, and ground deposits as indicators of performance. A single row of hedge-pruned, Acer rubrum L, red maple trees in a commercial Ohio nursery were used as the experimental crop in this study. The two sprayers included a traditional orchard type sprayer and a prototype air curtain sprayer. Results of the tests indicate that the air curtain sprayer produced more uniform deposits vertically but not necessarily higher mean deposits overall than the traditional orchard type sprayer. The air curtain sprayer also produced somewhat higher ground deposits downwind of the treatment area. There were no statistically significant differences in spray coverage between sprayers. As operated, neither of the sprayers can be expected to produce uniform spray deposits around the nursery stock if treatments are made from one side of the row only. Nursery managers can use these results to adjust the operation of their equipment, such as reducing fan speed or changing spray distribution, to improve the efficiency, of and reduce the off-target impact of, their pesticide applications.

Technical Abstract: Commercial nurseries grow many plant varieties which can create a number of different kinds of pest management problems. Most nurseries can tolerate very little pest damage since cosmetic appearance of stock is strongly related to marketability. The variety of different crops and crop management techniques creates some unique planting systems which challenge conventional methods of spraying nursery trees. Two types of air-assist sprayer were used to treat a single row of hedge-pruned, Acer rubrum L, red maple trees in a commercial Ohio nursery, from one side only. A traditional orchard type sprayer and a prototype air curtain sprayer using cross-flow fans and hydraulic nozzles were evaluated for differences in canopy deposits, spray coverage, and downwind ground deposits. Food coloring and a commercial fungicide were used as tracers. Leaf targets were placed in several canopy locations and were sampled following each sprayer pass, as were plastic ground targets. Each target was later washed and the rinsate evaluated with a spectrophotometer. Electron Bean Analysis was used to evaluate spray coverage on sticky metal stubs that had been placed adjacent to each leaf target for each sprayer pass. Results of the tests indicate that the air curtain sprayer produced more uniform deposits vertically but not higher mean deposits than the traditional orchard type sprayer. The air curtain sprayer also produced somewhat higher ground deposits downwind of the treatment area. There were no differences in spray coverage between sprayers. Canopy and ground target deposits indicate that alternate row spraying will not necessarily produce uniform deposits across two tree rows as planted at the test site.