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

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

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

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

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

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

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

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.

Physical Drift Droplet Size Measured in microns 20-370 micron range 200 micron average Smaller drops increase drift potential (< 100)

Fall Rate of Various Size Droplets

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

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.

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

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

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

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

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

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

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

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/plantsci/weeds/a657w.htm Reducing Spray Drift. Ohio State Univ. Extension Bulletin 816, H. Erdal Ozkan. Herbicide Application Management. Sandoz Crop Protection, 1993.