Transcript Kansas Turfgrass Conference

Understanding Spray Drift
Robert E. Wolf
Extension Specialist
Application Technology
Why Interest in Drift?
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Spotty pest control
Wasted chemicals
Off-target damage
Litigious Society ????
Result - higher costs - $$$
Windy?? (Timing)
Environmental impact (Water and Air Quality)
Misapplication Facts:
2%
33%
8%
24%
33%
Equipment
Drift
Tank Mix
Wrong Field
Off Label
Facts about drift:
23%
13%
26%
38%
Nozzle
Applicator
Physical
Other
Why is the Nozzle Important?
 Amount
of spray applied
 Uniformity of the spray
 Coverage on the target
 Amount of off-target drift
Technical
Aspects of Spray
Drift
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
Types of Drift:
Vapor Drift - associated with
volatilization (gas, fumes)
Particle Drift - movement of spray
particles during or after the spray
application
Factors Affecting Drift:
Spray Characteristics
Equipment &
 chemical
Application
 formulation
 nozzle type
 drop size
 nozzle size
 evaporation
nozzle pressure
Weather
 height of release
 air movement (direction and velocity)
 temperature and humidity
 air stability/inversions
 topography
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Wind Direction:
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Wind direction is very important
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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.
Wind Meters and Compass
Name
Features
Cost*
Dwyer
Floating Ball
15.50
Wind Wizard
Mechanical
39.50
Turbo Meter
Wind speed - knots, feet/min, meters/sec, mph
135.00
Kestrel 1000
Maximum, average, current wind speed
- knots, feet/min, meters/sec, mph
89.00
Kestrel 2000
Maximum, average, current wind speed, temp,
wind chill- knots, feet/min, meters/sec, mph
119.00
Kestrel 3000
All wind speed features plus temp, wind chill, dew
point, heat index, relative humidity
159.00
Plastimo Iris 50**
Compass
89.00
*Prices for Wind Meters taken from Gempler’s 2000 Master Catalog
**Plastimo Airguide Inc., 1110 Lake Cook Road, Buffalo Grove, IL 60089(708-215-7888)
Inversions:
Under normal
conditions air
tends to rise and
mix with the air
above. Droplets
will disperse and
will usually not
cause problems.
Normal Temperature Profile
Cooler
Temperature decreases
with height
Altitude
Warmer
Increasing Temperature
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.
Temperature Inversion
Temperature increases
with height
Altitude
Cool Air
Increasing Temperature
Warm Air
Recognizing Inversions:
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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.
105 foot tem perature m onitoring tow er
105’ 38 °F
C loud of 5 -25 u oil
droplets generated under
unstable conditions
64’
40 °F
32’
40 °F
16’
41 °F
8’
41 °F
C lo u d is d isp ersin g
2 .5 m p h w in d
1 0 5 ’ 3 8 °F
.5 m p h w in d
S h allo w su rface in v ersio n
S T A B L E co n d itio n s u p to 6 4 ’
N E U T R A L co n d itio n s at 1 0 5 ’
64’
32’
16’
3 8 °F
3 7 °F
3 6 °F
8’
3 3 °F
Precautions for Inversions:
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Surface inversions are common .
Be especially careful near sunset
and an hour or so after sunrise,
unless…
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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.
Wind Patterns Near Treelines:
Adapted from Survey of Climatology:
Griffiths and Driscoll,
Texas A&M University, 1982
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)
Spray Droplet Size
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.
Dropsize Facts:
 One
micron = 1/25,000 inch
 Expressed as (VMD)
Volume Median Diameter
 Example - VMD = 500 microns
Comparison of Micron Sizes for
Various Items: (approximate values)
 pencil
lead
 paper
clip
2000 (m)
150
850 (m)
 toothbrush
bristle
 sewing thread
420 (m)
300 (m)
150 (m)
 human
100 (m)
 staple
hair
Raindrop compared to a
Turbo Turf Flood
5.0 MPH wind at 40 psi
Turbo Turf Flood
Raindrop Drop
1/2 of spray volume = smaller droplets
VMD
1/2 of spray volume = larger droplets
Cutting Droplet Size in Half
Results in Eight Times the Number of Droplets
250
Microns
250
Microns
500
Microns
250
Microns
250
Microns
250
250
250
250
Microns Microns Microns Microns
Important Droplet Statistics:
Operational
Area
Evaporation of Droplets
High Relative Humidity
Low Temperature
Wind
Low Relative Humidity
High Temperature
Strategies to Reduce Drift:
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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:
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drift reduction nozzles
drift reduction additives
shields
Drift Reduction Additives:
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Many available!
Not EPA regulated
Long chain polymers
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New-soluble powders
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50 - 80% reduction in
off-target movement
Pump shear problems
EPA Requested Changes Coming!!!!
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ASAE S-572
Buffer Zones or No
Spray Zones
Maximize Efficacy
Minimize Drift
E
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Example Reference Graph
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coarse/
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very coarse/ extremely coarse
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Drop Size (microns)
New Label languageEPA 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
DropSize(microns)
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M
3
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300
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Cumulative Volume Fraction
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9
0.9
For more information contact:
[email protected]
www.bae.ksu.edu/rewolf/