1. Pesticide Drift Management
Curtis Rainbolt, Les Baucum, and Ron Rice

2. Pesticide Drift Management Topics For Discussion
Definition
Types of drift
Factors affecting drift
Management

3. What is Pesticide Drift?
Drift- movement of spray particles beyond the designated target
Two types:
physical drift
vapor drift

4. 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

5. 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

6. Physical Drift
Movement of pesticide away from target during application
Influenced by:
Droplet size
Boom height
Weather

7. Physical Drift Weather
Wind speed/direction
* most important
Soil moisture
Temperature
Humidity
Inversions

8. 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
When winds are light and variable it usually means that the direction they are blowing is unpredictable. This is a disaster waiting to happen in most application scenarios. As an applicator you would rather have a wind blowing strong enough to have a set direction. Then you can make better judgments regarding a particular application in reference to downwind sensitive areas. Such as not spraying, leaving a buffer and coming back when wind changes direction, etc.

9. Physical Drift Droplet Size
Measured in microns
micron range
200 micron average
Smaller drops increase drift potential (< 100)

10. Fall Rate of Various Size Droplets

11. Relationship of Particle Size to Drift
Based upon 10’ fall in 3 MPH winds

12. Physical Drift Ideal Spray Boom Height
Spacing
Easy and inexpensive
Wide-angle nozzles can be placed lower to the target, but also produce smaller droplets.

13. Physical Drift Other Factors to Consider
Nozzle selection
Spray pressure
Spray volume

14. 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

15. Influence of Spray Pressure on Droplet Size Flat Fan Nozzle - 0.6 GPM

16. Pesticide Drift Management Drift Control Agents
“thickeners”
increase droplet size of pesticide/water mixes

17. 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

18. Vapor drift can occur even days after the application
Wind
Drift
Vapor
Non-Target
Sensitive Crop

19. Six Ways to Reduce Drift
Check the wind speed and direction
Read the pesticide label
Use nozzles that produce large droplets
Lower your application pressures
Lower your boom height
Be aware of your surroundings

20. References used in the development of this slide set include :
Strategies for reducing herbicide drift, Iowa State University, Brent Pringnitz,
Kansas State University's Application Technology Project website
Pesticide Drift Management, University of Georgia, Eric Prostko
Herbicide Spray Drift, North Dakota State University,
Reducing Spray Drift. Ohio State Univ. Extension Bulletin 816, H. Erdal Ozkan.
Herbicide Application Management. Sandoz Crop Protection, 1993.