Pesticide Drift Management

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Pesticide Drift Management

• Curtis Rainbolt, Les Baucum, and Ron Rice

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Pesticide Drift ManagementTopics For Discussion

• Definition
• Types of drift
• Factors affecting drift
• Management

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What is Pesticide Drift?

• Drift- movement of spray particles beyond the
  designated target
• Two types
• physical drift
• vapor drift

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Drift (continued)

• All movement to off label crops is illegal
• Chemical drift is an unavoidable part of
  pesticide application
• Managing spray drift is the responsibility of the
  applicator

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Spray drift is undesirable!

• Inefficient use of equipment and time
• Under-application/ineffective control
• Crop damage and litigation concerns
• Unintentional contamination
• Air/water pollution
• Environmental and human health/safety

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Physical Drift

• Movement of pesticide away from target during
  application
• Influenced by
• Droplet size
• Boom height
• Weather

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Physical DriftWeather

• Wind speed/direction
• most important
• Soil moisture
• Temperature
• Humidity
• Inversions

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Drift Potential May be High at Low Wind Speeds

• Because
• Light winds (0-3 mph) tend to be
• unpredictable and variable in direction
• Calm and low wind conditions may indicate
  presence of a temperature inversion
• Drift potential is lowest at wind speeds between
  3 and 10 mph (gentle but steady breeze) blowing
  in a safe direction

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Physical DriftDroplet Size

• Measured in 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 DriftIdeal Spray Boom Height
Spacing

• Easy and inexpensive

• Wide-angle nozzles can be placed lower to the
  target, but also produce smaller droplets.

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Physical DriftOther Factors to Consider

• Nozzle selection
• Spray pressure
• Spray volume

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Turbulence-Chamber and Air-Assist Nozzles

• Allow air into a mixing chamber creating a vacuum
  that mixes the air and spray solution
• Forms large bubbles that do not drift as far

Turbo TeeJet
Greenleaf, TurboDrop
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Influence of Spray Pressure on Droplet SizeFlat
Fan Nozzle - 0.6 GPM
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Pesticide Drift ManagementDrift Control Agents

• thickeners
• increase droplet size of pesticide/water mixes

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Vapor Drift

• The volatilization or evaporation of a pesticide
  from the soil or crop surface that occurs after
  application
• Vapor drift is influenced by
• 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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Six Ways to Reduce Drift

1. Check the wind speed and direction
2. Read the pesticide label
3. Use nozzles that produce large droplets
4. Lower your application pressures
5. Lower your boom height
6. Be aware of your surroundings

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References used in the development of this slide
set include

• Strategies for reducing herbicide drift, Iowa
  State University, Brent Pringnitz,
  http//www.weeds.iastate.edu/mgmt/qtr99-1/nozzles.
  htm
• Kansas State University's Application Technology
  Project website http//www.bae.ksu.edu/rewolf/
• Pesticide Drift Management, University of
  Georgia, Eric Prostko http//www.cropsoil.uga.edu/
  weedsci/slides/drift/
• Herbicide Spray Drift, North Dakota State
  University, http//www.ext.nodak.edu/extpubs/plant
  sci/weeds/a657w.htm
• Reducing Spray Drift. Ohio State Univ. Extension
  Bulletin 816, H. Erdal Ozkan.
• Herbicide Application Management. Sandoz Crop
  Protection, 1993.