Pesticide Drift Management

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Pesticide Drift Management

• Dr. Eric P. Prostko
• Extension Weed Specialist
• University of Georgia

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Pesticide Drift ManagementTopics For Discussion

• definition
• types of drift
• factors affecting drift
• equipment
• management

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What is pesticide drift??

• the movement of the pesticide away from the
  target area.
• physical drift
• vapor drift

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Spray drift is undesirable!!

• inefficient use of equipment and time
• under-application/ineffective control
• litigation concerns
• unintentional contamination of foodstuffs
• air/water pollution
• livestock and human health/safety

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Corn and Grain Sorghum Yield Loss From Simulated
Staple Drift, College Station, 1994.
Applied 30 DAP
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Physical Drift

• movement of pesticide away from target during
  application
• droplet size
• boom height
• weather

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Studies have shown that equipment and its
operation are responsible for 68-90 of the
physical drift problems while weather accounts
for 10-32.
D. B. Smith et al., 1982
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Physical DriftDroplet Size

• measured in microns
• hair - 50 microns
• 20-370 micron range
• 200 micron average
• smaller drops increase drift potential (lt 100)

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Fall Rate of Various Size Droplets
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Relationship of Particle Size to Drift
Based upon 10 fall in 3 MPH winds
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Physical DriftDroplet Size

• nozzle selection
• Drift Guard Nozzles
• reduces volume of
• droplets below 200
• microns up to 65
• Raindrop Nozzles
• 0.7 - 200 microns
• or less

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Physical DriftSpray Boom Height
Spacing

Easy and inexpensive
Wide-angle nozzles can be placed lower to the
ground but also produce smaller droplets.
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Physical DriftWeather

• wind speed/direction
• most important
• temperature
• humidity
• inversions

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Physical DriftTemperature Inversions
Normal
Inversion
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Physical DriftOther Factors to Consider

• nozzle orientation
• spray pressure
• spray volume

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Physical DriftNozzle Orientation

• ground speeds gt 10 MPH
• 450 or more from perpendicular

30 lt 100 microns
88 lt 100 microns
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Influence of Spray Pressure on Droplet SizeFlat
Fan Nozzle - 0.6 GPM
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Physical DriftSpray Volume

• most effective means to increase spray volume is
  to increase nozzle orifice size
• i.e. 8002 vs. 8003 vs. 8004

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Vapor Drift

• the volatilization or evaporation of a pesticide
  from the soil or crop surface that occurs after
  application.
• Factors that influence vapor drift include
• vapor pressure/volatility
• temperature
• wind speed

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Vapor drift can occur even days after the
application
Wind
Drift
Vapor
Non-Target Sensitive Crop
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Vapor Pressure Values of Various Chemicals_at_ 770F
Note The higher the number the more volatile the
chemical.
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Pesticide Drift ManagementEquipment Modifications

• shielded spray boom
• covered boom
• hooded-sprayers
• air-assist systems
• electrostatic spraying

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Pesticide Drift ManagementDrift Control Agents

• thickeners
• increase droplet size of pesticide/water mixes
• 0.10-1.00/A
• 38F, Anchor, Array, Border, Chem-Trol, Corsair,
  Direct, Drifgon, Driftgard, Drop Zone, Get Down,
  Lo-Drift, More, Nalcotrol, Submerge, Sta-Put,
  Windfall

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Drift Fallout As Influenced By Pressure and
Nalcotrol
Source W. Bowers. 1975. Ohio State Univ.
Extension, Facts 1203.
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Top 10 Tips For Reducing Pesticide Drift

• nozzle selection
• reduce pressure
• lower boom height
• increase nozzle size
• avoid spraying when winds exceed 10 MPH

• lookout for inversions
• use additives
• calibrate sprayer
• keep records
• use common sense

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References used in the development of this slide
set include the following

• Reducing Spray Drift. Ohio State Univ.
  Extension Bulletin 816, H. Erdal Ozkan.
• Herbicide Application Management. Sandoz Crop
  Protection, 1993.