Evaluation of Handgun and Broadcast Systems for Spray Deposition in Greenhouse Poinsettia Canopies
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Date
2010
Journal Title
Journal ISSN
Volume Title
Publisher
American Society of Agricultural and Biological Engineers
Abstract
Handgun applicators are popular, general‐purpose greenhouse sprayers. However, there are few
recommendations on how to use them to treat plant benches. Handgun applications made from one side can result in
significant differences in deposits between the side of the plant facing the spray stream and the opposite side. Broadcast
spraying over the top of the canopy may improve spray distribution across the canopy. The objective of this research was to
determine differences in performance between different sprayers used to treat mature poinsettias and differences in the fate
of the spray within the canopy with the aim to determine which techniques produced the highest spray retention on the abaxial
leaf surface. A benchtop trial was conducted using a mature poinsettia canopy in a greenhouse. Sprayer treatments were used
to apply tank mixes of pesticides and fluorescent tracer. Nylon screen targets were secured to the abaxial surfaces of leaves
in the upper and lower parts of the canopy. Benchtop trials revealed significant differences between the amount of spray found
on the upper and lower canopy target areas. Handgun nozzle pressure was a more significant factor in depositing material
on the abaxial surfaces of leaves than changing application rate. A TwinJet boom system using dual‐orifice nozzles did not
treat abaxial surfaces differently from the handgun applications. The air‐assist treatment with flat‐fan nozzles produced the highest mean deposits on abaxial surfaces in the lower canopy area, but overall there were no statistical differences in lower
canopy deposits between treatments. These results demonstrate the difficulty that ornamental producers have in targeting pesticide placement on abaxial leaf surfaces deeper in the canopy. The variability in spray deposits observed on foliage demonstrates the potential for significant variability in pest management.
Description
Keywords
Air‐assisted sprayers, Droplet, Greenhouse, Poinsettia, Spray deposition, Sprayers
Citation
R. C. Derksen et al, "Evaluation of Handgun and Broadcast Systems for Spray Deposition in Greenhouse Poinsettia Canopies," Transactions of the ASABE 53, no. 1 (2010)