Full TGIF Record # 75966
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Publication Type:
Content Type:Abstract or Summary only
Author(s):Wolf, Robert E.; Minihan, Cathy L.; Peterson, Dallas E.
Author Affiliation:Wolf: Extension Specialist, Biological and Agricultural Engineering; Minihan: Graduate Research Assistant; and Peterson: Professor, Department of Agronomy, Kansas State University, Manhattan, KS
Title:Influence of spray droplet size on paraquat and glyphosate efficacy
Section:Equipment and application methods
Other records with the "Equipment and application methods" Section
Meeting Info.:Columbus, OH: December 14-16, 1999
Source:Proceedings of the North Central Weed Science Society. Vol. 55, December 2000, p. 116-117.
# of Pages:2
Publishing Information:Champaign, IL: North Central Weed Science Society
Keywords:TIC Keywords: Spraying; Paraquat; Glyphosate; Postemergence herbicides; Nozzles
Abstract/Contents:"Application of postemergence herbicides is becoming an ever-increasing complex phase of crop production. Recent nozzle technology is placing an increased emphasis on achieving optimum efficacy while keeping the drift potential at a minimum. New nozzles are being designed that will reduce the variability of the drop size spectrum for a given nozzle size and pressure. Less driftable fines are being created when used correctly. The most recent development is the venturi nozzle. This study was designed to measure the droplet characteristics of a venturi nozzle (AI flat-fan) in comparison to two popular flat-fan nozzles, the extended range flat-fan (XR) and the turbo flat-fan (TT), while evaluating efficacy in cultivated oats. Two products, gromoxone and glyphosate (trimesium salt), were applied at 19, 38, and 76 L/ha at an operating pressure of 276 kPa. The applications were made with a tractor plot sprayer equipped with a 3 m rear mounted boom. Nozzles were spaced at 76 cm and located 51 cm above the target. The nozzle angle and orifice sizes used were 110015, 11003, and 11006 for each nozzle type. Water sensitive cards were placed under the spray boom to collect the droplet data. Four replications were summarized. The volume median diameter (VMD, 50%) was measured for each application scenario. In general, as spray volume increased the VMD also increased with the venturi tips producing larger droplets than the turbo flat-fan tips, which produced larger droplets than the extended range flat-fan tips. Another droplet statistic measured was volume diameter 0.1 (VD 0.1, 10%). This statistic represents the micron size of the droplets that are in the lower 10 percent of the spray volume. The lower this number the more potential for off-target drift to occur wtih 200 microns and lower being considered highly driftable. The extended range flat-fan had the smallest micron size across each volume with 19L/ha being the lowest. The VD 0.1 for the turbo flat-fans was next smallest with the same trend across volume. The venturi nozzles gave the largest VD 0.1. A more important statistic for indicating drift potential is the number of droplets that are 200 microns or less in size. At 19L/ha the extended range flat-fan tips nearly tripled the venturi flat-fans for number of droplets created under 200 microns. At 38 L/ha the extended range flat-fan tips more than doubled both the turbo and venturi flat-fan tips for number of droplets created under 200 microns[.] These data indicate the extended range flat-fan tips have significantly more droplets that are considered highly driftable than either the turbo or venturi flat-fans. Efficacy data collected with this study indicate that the venturi and turbo flat-fan tips performed equally well or better than the extended range flat-fan tips regardless of herbicide and application timing. As evidenced in this study, pesticide applicators can achieve good weed control while minimizing water requirements by utilizing low spray volumes using venturi and turbo flat-fan tips risking less chance for drift."
Note:This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Wolf, R. E., C. L. Minihan, and D. E. Peterson. 2000. Influence of spray droplet size on paraquat and glyphosate efficacy. Proc. North Cent. Weed Sci. Soc. 55:p. 116-117.
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