DROPLET SIZE AND DRIFT POTENTIAL FROM MICRO-SPRAYER IRRIGATION EMITTERS

Aims: Determine the droplet size spectra of agricultural sprays as affected by herbicide formulations, spray nozzle designs, and operating pressures. Place and Duration of Study: This study was conducted in April 2014 at the United States Department of Agriculture Agricultural Research Service Aerial Application Technology Research Unit Facility in College Station, Texas. Methodology: The spray droplet size spectra of six herbicide formulations as well as water alone and water with nonionic surfactant were evaluated in a low-speed wind tunnel. These spray solutions were conducted with five different flat-fan spray nozzle designs, producing a wide range of spray droplet sizes. The wind tunnel was equipped with a laser diffraction sensor to analyze spray droplet size. All combinations of spray solution and nozzle were operated at 207 and 414 kPa and replicated three times. Results: Many differences in droplet size spectra were detected among the spray solutions, nozzle designs, and pressures tested. Solutions of Liberty 280 SL exhibited the smallest median droplet size and the greatest proportion of spray volume contained in droplets 100 µm or less in size. Solutions of Enlist Duo resulted in smaller median droplet size than many of the solutions tested, but also exhibited some of the smallest production of fine spray droplets. Median droplet size was found to vary greatly among nozzle designs, with the greatest droplet size and smallest drift-prone fine droplet production observed with air-inclusion designs utilizing a pre-orifice. Increasing the operating pressure from 207 to 414 kPa resulted in a decrease in median droplet size and an increase in the production of droplets 100 µm or less in size. Conclusion: Herbicide formulations and spray nozzle designs tested varied widely in droplet size spectra and thus the potential for spray drift. Increasing operating pressure resulted in decreased droplet size and an increase in the production of drift-prone droplets. Additionally, median droplet size alone should not be used to compare spray drift potential among spray solutions but should include relative span and V100 values to better predict the potential for spray drift due to drift-prone spray droplets.

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Meeting droplet size specifications for aerial herbicide application to control wilding conifers

New Zealand Plant Protection ◽

10.30843/nzpp.2020.73.11712 ◽

2020 ◽

Vol 73 ◽

pp. 13-23

Author(s):

Brian Richardson ◽

Carol Rolando ◽

Andrew Hewitt ◽

Mark Kimberley

Keyword(s):

Droplet Size ◽

Field Performance ◽

The Other ◽

Spray Drift ◽

Spray Application ◽

Herbicide Application ◽

Water Control ◽

Drift Potential ◽

Droplet Sizes ◽

Air Speed

Large areas of New Zealand are being aerially sprayed with herbicides to manage ‘wilding’ conifer spread. The purpose of the study was to obtain and analyse droplet spectra produced by nozzles commonly used for wilding conifer spraying to determine whether or not operational recommendations for a target droplet size class (~350 µm) are being met. Droplet spectra were measured in a wind tunnel for 27 nozzle x 3 operating condition (nozzle angle, air speed and pressure) combinations tested for each of three spray mixes. AGDISP, an aerial spray application simulation model, was used to quantify the field performance implications of changes to droplet spectra parameters. Only one nozzle, the CP-09, 0.078, 30°, met the target droplet size specification when used at 45° but not at 0°. However, under these conditions, this nozzle produced a large driftable fraction. All but one of the other scenarios tested produced much larger droplet sizes. Operational spray mixes tended to slightly increase the potential for spray drift compared with the water control. The CP-09, 0.078, 30° nozzle used at 45° met the operational droplet size specification but is more sensitive to changes to nozzle angle (0° versus 45°) than the other nozzles tested. None of the three Accu-FloTM nozzles tested met the target droplet size specification. However, the Accu-FloTM nozzles produced very few fine droplets making them good choices for reducing spray drift potential.

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Particle drift potential of glyphosate plus 2,4-D choline pre-mixture formulation in a low-speed wind tunnel

Weed Technology ◽

10.1017/wet.2020.15 ◽

2020 ◽

Vol 34 (4) ◽

pp. 520-527

Author(s):

Bruno C. Vieira ◽

Thomas R. Butts ◽

Andre O. Rodrigues ◽

Jerome J. Schleier ◽

Bradley K. Fritz ◽

...

Keyword(s):

Wind Tunnel ◽

Droplet Size ◽

Droplet Velocity ◽

Target Movement ◽

Spray Droplet ◽

Low Speed ◽

Particle Drift ◽

Drift Potential ◽

The Impact ◽

Low Speed Wind Tunnel

AbstractThe introduction of 2,4-D–resistant soybean and cotton provided growers a new POST active ingredient to include in weed management programs. The technology raises concerns regarding potential 2,4-D off-target movement to sensitive vegetation, and spray droplet size is the primary management factor focused on to reduce spray particle drift. The objective of this study was to investigate the droplet size distribution, droplet velocity, and particle drift potential of glyphosate plus 2,4-D choline pre-mixture (Enlist Duo®) applications with two commonly used venturi nozzles in a low-speed wind tunnel. Applications with the TDXL11004 nozzle had larger DV0.1 (291 µm), DV0.5 (544 µm), and DV0.9 (825 µm) values compared with the AIXR11004 nozzle (250, 464, and 709 µm, respectively), and slower average droplet velocity (8.1 m s−1) compared with the AIXR11004 nozzle (9.1 m s−1). Nozzle type had no influence on drift deposition (P = 0.65), drift coverage (P = 0.84), and soybean biomass reduction (P = 0.76). Although the TDXL11004 nozzle had larger spray droplet size, the slower spray droplet velocity could have influenced the nozzle particle drift potential. As a result, both TDXL11004 and AIXR11004 nozzles had similar spray drift potential. Further studies are necessary to understand the impact of droplet velocity on drift potential at field scale and test how different tank solutions, sprayer configurations, and environmental conditions could influence the droplet size and velocity dynamics and consequent drift potential in pesticide applications.

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Relative drift potential and droplet size spectra of aerially applied Propanil formulations

Crop Protection ◽

10.1016/s0261-2194(97)00064-1 ◽

1997 ◽

Vol 16 (8) ◽

pp. 717-721 ◽

Cited By ~ 14

Author(s):

R. Sanderson ◽

A.J. Hewitt ◽

E.W. Huddleston ◽

J.B. Ross

Keyword(s):

Droplet Size ◽

Size Spectra ◽

Drift Potential

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DROPLET SIZE SPECTRA, DRIFT POTENTIAL, AND GROUND DEPOSITION PATTERN OF HERBICIDE SPRAYS

Canadian Journal of Plant Science ◽

10.4141/cjps74-091 ◽

1974 ◽

Vol 54 (3) ◽

pp. 541-546 ◽

Cited By ~ 13

Author(s):

J. MAYBANK ◽

K. YOSHIDA ◽

R. GROVER

Keyword(s):

Droplet Size ◽

Field Experiments ◽

Control Technique ◽

Hydraulic Pressure ◽

Spray Drift ◽

Reduced Pressure ◽

Size Spectra ◽

Nozzle Height ◽

Drift Potential ◽

Ground Deposition

Droplet size spectra and quantity of spray drift were studied for two types of flat-fan nozzles. The large orifice flat-fan nozzles operated at reduced pressure produced less drift potential; however, the spectrum of droplets was coarse. The properties of the whirl jet cone nozzles suggest that these would also produce less drift-prone material. The spray fraction likely to drift was calculated to be approximately 3–8% of the total volume of spray with the flat-fan nozzles. This was confirmed in field experiments using labelled herbicides and a liquid scintillation counting technique. A realistic pattern of the distribution of ground deposition density over a swath (obtained by field experiments), and a factor of three in density fluctuation suggest that the generally accepted concept of uniformity of spray distribution in experimental plots should be modified. Recommendations of spray drift control technique were proposed regarding the hydraulic pressure, nozzle height and orientation, travelling speed/pressure, and the size of orifice.

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Comparison of Droplet Size, Coverage, andDrift Potential from UAV Application Methods and Ground Application Methods on Row Crops

Transactions of the ASABE ◽

10.13031/trans.14121 ◽

2021 ◽

Vol 64 (3) ◽

pp. 819-828

Author(s):

Jenna L. Gibbs ◽

Thomas M. Peters ◽

Lindsay P. Heck

Keyword(s):

Droplet Size ◽

Geometric Mean ◽

List Type ◽

Row Crops ◽

Strong Potential ◽

Drift Potential ◽

Mean Diameter ◽

Pesticide Drift ◽

Aerial Vehicle ◽

Application Methods

HighlightsDroplet size, coverage, and drift potential of pesticide spray in corn with UAV application methods were compared with ground methods.Measured droplets were smaller in UAV trials (102 to 182 µm geometric mean diameter) than in ground trials (265 to 432 µm geometric mean diameter).UAV methods (particularly those without a boom) achieved high coverage in the middle swath of the field (>60 droplets cm-2) compared to ground methods (10 to 40 droplets cm-2).Real-time particle monitors indicated potential for downwind spray drift during ground trials but not UAV trials.The findings indicate a strong potential for “spot” or “band” spray coverage using UAV methods.Abstract. Worldwide, the use of uncrewed aerial vehicles (UAVs) for pesticide application has grown tremendously in the past decade. Their adoption has been slower for Midwestern row crops. This study compared droplet size, coverage, and drift potential of sprays from UAV application methods to those from ground (implement) sprayer methods on corn in the Midwest. Droplet sizes measured during UAV spray trials [geometric mean diameters of 179 and 112 µm for UAV (boom) and UAV (no boom), respectively] were substantially smaller than those deposited during implement spray trials [mean diameters of 303 and 423 µm for implement (regular) and implement (pulse)]. Droplet coverage was high and localized in the middle swath of the field for the UAV with boom (10 to 30 droplets cm-2) and with no boom (60 droplets cm-2). Droplet coverage was broader, covering the entire field width for the implement methods (10 to 40 droplets cm-2). Vertical coverage of droplets was more uniform for UAV methods than implement methods. Although the UAVs produced smaller droplets than the implement methods, we still observed greater potential for downwind pesticide drift during the implement spray trials. Because localized application may be beneficial for pest control and drift reduction, the findings indicate a strong potential for “spot” or “band” spray coverage using UAV methods. This is likely due to the smaller size, reduced spray volumes, and increased agility of UAVs as compared to more conventional methods. Keywords: Agriculture, Application, Corn, Coverage, Drift, Droplet, Implement, Particles, Pesticides, Pesticide drift, Precision agriculture, Row crops, Spray trial, Uncrewed aerial vehicle (UAV), Unmanned aerial vehicle (UAV).

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Droplet Size Impact on Efficacy of a Dicamba-plus-Glyphosate Mixture

Weed Technology ◽

10.1017/wet.2018.118 ◽

2019 ◽

Vol 33 (1) ◽

pp. 66-74 ◽

Cited By ~ 5

Author(s):

Thomas R. Butts ◽

Chase A. Samples ◽

Lucas X. Franca ◽

Darrin M. Dodds ◽

Daniel B. Reynolds ◽

...

Keyword(s):

Droplet Size ◽

Herbicide Resistance ◽

Weed Management ◽

Integrated Weed Management ◽

Weed Species ◽

Application Process ◽

Biological Efficacy ◽

Particle Drift ◽

Drift Potential ◽

Droplet Sizes

AbstractChemical weed control remains a widely used component of integrated weed management strategies because of its cost-effectiveness and rapid removal of crop pests. Additionally, dicamba-plus-glyphosate mixtures are a commonly recommended herbicide combination to combat herbicide resistance, specifically in recently commercially released dicamba-tolerant soybean and cotton. However, increased spray drift concerns and antagonistic interactions require that the application process be optimized to maximize biological efficacy while minimizing environmental contamination potential. Field research was conducted in 2016, 2017, and 2018 across three locations (Mississippi, Nebraska, and North Dakota) for a total of six site-years. The objectives were to characterize the efficacy of a range of droplet sizes [150 µm (Fine) to 900 µm (Ultra Coarse)] using a dicamba-plus-glyphosate mixture and to create novel weed management recommendations utilizing pulse-width modulation (PWM) sprayer technology. Results across pooled site-years indicated that a droplet size of 395 µm (Coarse) maximized weed mortality from a dicamba-plus-glyphosate mixture at 94 L ha–1. However, droplet size could be increased to 620 µm (Extremely Coarse) to maintain 90% of the maximum weed mortality while further mitigating particle drift potential. Although generalized droplet size recommendations could be created across site-years, optimum droplet sizes within each site-year varied considerably and may be dependent on weed species, geographic location, weather conditions, and herbicide resistance(s) present in the field. The precise, site-specific application of a dicamba-plus-glyphosate mixture using the results of this research will allow applicators to more effectively utilize PWM sprayers, reduce particle drift potential, maintain biological efficacy, and reduce the selection pressure for the evolution of herbicide-resistant weeds.

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