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Kansas Turfgrass Conference

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Title: Kansas Turfgrass Conference


1
Understanding Spray Drift
Robert E. Wolf Extension Specialist Application
Technology
2
Why Interest in Drift?
  • Spotty pest control
  • Wasted chemicals
  • Off-target damage
  • Litigious Society ????
  • Result - higher costs -
  • Windy?? (Timing)
  • Environmental impact (Water and Air Quality)

3
Misapplication Facts
4
Facts about drift
5
Why is the Nozzle Important?
  • Amount of spray applied
  • Uniformity of the spray
  • Coverage on the target
  • Amount of off-target drift

6
Technical Aspects of Spray Drift
7
Definition of Drift
  • Movement of spray particles and vapors
    off-target causing less effective control and
    possible injury to susceptible vegetation,
    wildlife, and people.
  • Adapted from National Coalition on Drift
    Minimization 1997 as adopted from the AAPCO
    Pesticide Drift Enforcement Policy - March 1991

8
Types of Drift
  • Vapor Drift - associated with volatilization
    (gas, fumes)
  • Particle Drift - movement of spray particles
    during or after the spray application

9
Factors Affecting Drift
  • Spray Characteristics
  • chemical
  • formulation
  • drop size
  • evaporation
  • Equipment Application
  • nozzle type
  • nozzle size
  • nozzle pressure
  • height of release
  • Weather
  • air movement (direction and velocity)
  • temperature and humidity
  • air stability/inversions
  • topography

10
Wind Direction
  • Wind direction is very important
  • Know the location of sensitive areas - consider
    safe buffer zones.
  • Do not spray at any wind speed if it is blowing
    towards sensitive areas - all nozzles can drift.
  • Spray when breeze is gentle, steady, and blowing
    away from sensitive areas.
  • Dead calm conditions are never recommended.

11
Wind Meters and Compass
Prices for Wind Meters taken from Gemplers 2000
Master Catalog Plastimo Airguide Inc., 1110
Lake Cook Road, Buffalo Grove, IL
60089(708-215-7888)
12
Inversions
Under normal conditions air tends to rise and mix
with the air above. Droplets will disperse and
will usually not cause problems.
13
Temperature Inversions
Under these conditions the temperature increases
as you move upward. This prevents air from
mixing with the air above it. This causes small
suspended droplets to form a concentrated cloud
which can move in unpredictable directions.
14
Recognizing Inversions
  • Under clear to partly cloudy skies and light
    winds, a surface inversion can form as the sun
    sets.
  • Under these conditions, a surface inversion will
    continue into the morning until the sun begins to
    heat the ground.

15
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16
Precautions for Inversions
  • Surface inversions are common .
  • Be especially careful near sunset and an hour or
    so after sunrise, unless
  • There is low heavy cloud cover
  • The wind speed is greater than 5-6 mph at ground
    level
  • 5 degree temp rise after sun-up
  • Use of a smoke bomb or smoke
  • generator is recommended to
  • identify inversion conditions.

17
Wind Patterns Near Treelines
Adapted from Survey of Climatology Griffiths and
Driscoll, Texas AM University, 1982
18
Wind Patterns Around Buildings
Ground
Diagram of wind around a building. Adapted from
Farm Structures
H.J. Barre and L.L. Sammet, Farm Structures
(Wiley, 1959)
19
Spray Droplet Size
20
Drift Dropsize Relationship
  • Particle drift will result from the smaller drops
    created during the spray process. The size of
    the droplets created is critical.
  • Dropsizes are measured in microns using laser
    beams.

21
Dropsize Facts
  • One micron 1/25,000 inch
  • Expressed as (VMD)
  • Volume Median Diameter
  • Example - VMD 500 microns

22
Comparison of Micron Sizes for Various Items
(approximate values)
  • pencil lead 2000 (?m)
  • paper clip 850 (?m)
  • staple 420 (?m)
  • toothbrush bristle 300 (?m)
  • sewing thread 150 (?m)
  • human hair 100 (?m)

150
23
Raindrop compared to a Turbo Turf Flood
5.0 MPH wind at 40 psi
Raindrop Drop
Turbo Turf Flood
24
1/2 of spray volume smaller droplets
VMD
1/2 of spray volume larger droplets
25
Cutting Droplet Size in HalfResults in Eight
Times the Number of Droplets
250 Microns
250 Microns
500 Microns
250 Microns
250 Microns
250 Microns
250 Microns
250 Microns
250 Microns
26
Important Droplet Statistics
VMD (50)
VD0.9 (90)
Operational Area
VD0.1 (10)
27
Evaporation of Droplets
High Relative Humidity Low Temperature
Low Relative Humidity High Temperature
Fall Distance
Wind
28
Strategies to Reduce Drift
  • Select nozzle to increase drop size
  • Increase flow rates - higher application volumes
  • Use lower pressures
  • Use lower spray (boom) heights
  • Avoid adverse weather conditions
  • Consider using buffer zones
  • Consider using new technologies
  • drift reduction nozzles
  • drift reduction additives
  • shields

29
Drift Reduction Additives
  • Many available!
  • Not EPA regulated
  • Long chain polymers
  • New-soluble powders
  • 50 - 80 reduction in off-target movement
  • Pump shear problems

30
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31
EPA Requested Changes Coming!!!!
  • New Label language-EPA Reviewing Public Comments
  • Public Listening Sessions planned
  • Sometime in 2003??
  • Match the crop protection product to the target
  • Adhere to label guidelines based on an industry
    standard
  • ASAE S-572
  • Buffer Zones or No Spray Zones
  • Maximize Efficacy
  • Minimize Drift

VMD
32
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33
For more information contact
rewolf_at_ksu.edu
www.bae.ksu.edu/rewolf/
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