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Managing Pesticide DriftMary Beth Henry
Aquatic Weed Short CourseMay 5, 2010, Coral Springs Marriott
Learning Objectives
• What spray drift is
• How environmental factors affect drift
• The effects of droplet size
• How your decisions can affect spray drift
UF/IFAS PIO
What is Drift?
Unknown Photo Source
The physical movement of pesticide through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target site.
What isn’t Drift?
• Pesticides moved by:
– Erosion
– Migration
– Volatility
– Windblown soil particles
Unknown Photo Source
Types of Drift
• Vapor Drift - associated with volatilization, gases, fumes
• Particle Drift - movement of spray particles
Unknown Photo Source
Why All the Interest in Drift?
• Spotty pest control
• Wasted chemicals
• Off-target damage
• Environmental impact
– Water and Air Quality
• Public more aware of pesticide concerns
• Spraying in more populated areas
Unknown Photo Source
Why All the Interest in Drift?
• Because drift can cause injury to:– Adjoining crops– Livestock– Wildlife– Humans
• Because drift costs money:– Restitution for damaged crops– Reduced control of intended target pest(s)– Increased regulations because of drift problems
Detrimental effects of driftReduced application rate on target pestApplying pesticides in a manner that allows drift to occur is a label violation
Recent EPA Activity
a. Draft label changes regarding drift
b. Comment period closed 3/5/10
c. 935 submissions
9
What are the major factors in managing drift?
a. Droplet size
b. Wind speed and direction
c. Chemical and formulation
d. All of the above
10
What are the major factors in managing drift?
a. Droplet size
b. Wind speed and direction
c. Chemical and formulation
d. All of the above
11
Factors Affecting Drift
• Chemical
• Formulation
• Additives
• Drop size
• Evaporation
Unknown Photo Source
Factors Affecting Drift
• Environmental Factors– Wind speed and direction
– Temperature and humidity
– Air stability/inversions
– Topography
Unknown Photo Source
Factors Affecting Drift
• Equipment & Application
–Nozzle type
–Nozzle size
–Nozzle orientation
–Nozzle pressure
–Height of release
–Technology
UF/IFAS PIO
What is the target minimum droplet size to reduce drift:
a. 50 μm
b. 100 μm
c. 200 μm
d. 350 μm
15
What is the target minimum droplet size to reduce drift:
a. 50 μm
b. 100 μm
c. 200 μm
d. 350 μm
16
Droplet Size• Large droplets have less potential to drift because
they:– Fall more quickly– Evaporate more slowly– Are less affected by wind
• Small droplets often result from:– High spray pressure– Small nozzle tips– Wind shear across the nozzles
UF/IFAS PIO
Droplet sizeDroplet diameter is measured in microns (μm)
1 μm = 0.001 mm = 0.0001 cm
Type of droplet Diameter (μm)Smoke <1
Fog 15Mist 50
Grain of salt 100Rain 500
Comparison of Micron Sizes for Various Items (approximate)
• 2000 μm
• 850 μm
• 420 μm
• 300 μm
• 150 μm
• 100 μm
#2 Pencil lead
paper clip
staple
toothbrush bristle
sewing thread
human hair
150
One micron (μm) =1/25,000 inch
Relationship of Drift to Drop Size
Volume Median Diameter (VMD)
Spraying Systems Co.
3 mph windD
ropl
et re
leas
e: 3
ft. a
bove
gro
und
Small droplets
Large droplets
Droplet sizeDroplet size is influenced by nozzle orifice size and spray pressure
At a given pressure, droplet size decreases as nozzle orifice size decreasesAt a given nozzle orifice size, droplet size decreases as spray pressure increases
Labels and Droplet Size
CDMS
Droplet spectrum1
Contact insecticide & fungicide
Systemic insecticide & fungicide
Contact foliar herbicide
Systemic foliar herbicide
Soil-applied herbicide
Incorpor-ated soil-applied herbicide
Very fine (VF)
Fine (F) X
Medium (M)
X X X X
Coarse (C) X X X X
Very coarse (VC)
X X X
Extremely coarse (XC)
X
1Based on Volume Mean Diameter (VMD) designation.
Category (symbol) Color codeVery fine (VF) RedFine (F) OrangeMedium (M) YellowCoarse (C) BlueVery coarse (VC) GreenExtremely coarse (XC) White
ASABE Spray Quality Categories
Spraying Systems Co.
Very fine
Fine Medium Coarse Very coarse
Extr.coarse
Increasing pressureIncreasing
orifice size
Droplet sizeUse nozzles with the largest orifice size that is appropriate for the applicationUse a spray pressure near the middle of the range for a given nozzle
Low Drift Nozzle Types
UF/IFAS PIO
Which Size is Best?
Western Crop Protection Association
Droplet sizeNozzle orifice size and spray pressure should maximize droplet size but still provide adequate coverageDroplets too big:Poor coverage
Good droplet size:Adequate coverage
Factors You Can’t Control• Weather
– Wind(speed & direction)
– Temperature
– Humidity
• Susceptible crops or other non-target areas of concern near your application site
Western Crop Protection Association
Wind
UF/IFAS PIO
The range of wind speed to avoid drift is:
a. 0-3 mph
b. 2-5 mph
c. 3-10 mph
d. 6-12 mph
35
The range of wind speed to avoid drift is:
a. 0-3 mph
b. 2-5 mph
c. 3-10 mph
d. 6-12 mph
36
Wind
Kansas State University
Drift potential is lowest at wind speeds between 3 and 10 miles per hour
Wind
Kansas State University
Temperature and Humidity
The faster they evaporate the more likely they are to reach a driftable size before reaching the target
Spraying Systems Co.
Evaporation of DropletsHumidity effects on droplet size
70% RH 30% RH
Wind
Factors Affecting Drift
• Temperature inversions
Unknown Photo Source
Radiant cooling of the ground
Western Crop Protection Association
Drift Potential vs Inversions
Western Crop Protection Association
Factors the Applicator can Control
• You can control…– The selection of the applicator/operator
– Equipment selection and setup
– Field conditions
– The choice of the product
UF/IFAS PIO
Equipment Selection and Setup
UF/IFAS PIO
Strategies to Reduce Drift: Equipment Setup
• Select nozzle to increase drop size• Increase flow rates - higher application volumes• Use lower pressures• Use lower spray (boom) heights• Drift reduction nozzles
UF/IFAS PIO
Strategies to Reduce Drift: Equipment Setup
UF/IFAS PIO
Strategies to Reduce Drift: Equipment Setup
UF/IFAS PIO
Strategies to Reduce Drift: Equipment Setup
Unshielded boom
Wil-Richshield
Wind Cones
AE shield
18’Vertical
2.47 1.51 1.43 1.51
100’Horizontal
4.19 1.57 1.93 1.56
TOTAL 6.66 3.08 3.36 3.07
Avg. wind speed
8.7 8.0 10.4 10.1
Strategies to Reduce Drift: Equipment Setup
UF/IFAS PIO
Strategies to Reduce Drift: Electrostatic Sprayers
Kansas State University
Strategies to Reduce Drift: Electrostatic Sprayers
Kansas State University
Strategies to Reduce Drift: Sensor-Controlled Sprayers
UF/IFAS Doc. HS-872
Strategies to Reduce Drift: Drift Reduction Additives
• Polyvinyl
• Polyacrylamide
• Linear alkyl epoxide
• Polymide copolymers
UF/IFAS PIO
Strategies to Reduce Drift: Drift Reduction Additives
Nozzle type Droplet size (micron)
Visible injury (meters)
Turbo TeeJet 250b 6.2a
Turbo FloodJet 261b 5.5a
Turbo Air Induction 284a 5.7a
XR Flat Fan (40 psi) 240c 8.1b
XR Flat Fan (20 psi) 222c 8.0b
University of Nebraska
Strategies to Reduce Drift: Drift Reduction Additives
University of Nebraska
Strategies to Reduce Drift: Drift Reduction Additives
UF/IFAS PIO
Strategies to Reduce Drift: Buffer Zones
CDMS
Product Selection
UF/IFAS PIO
Drift and the Law
Drift and the Law
• 2,4-D
• MCPA
• 2,4-DP
• MCPP
• MCPB
• Dicamba
• Triclopyr
UF/IFAS PIO
Drift and the Law
UF/IFAS Agronomy
Drift and the Law
UF/IFAS PIO
FDACS-13345
FDACS-13345
FDACS-13328
http://www.doacs.state.fl.us/onestop/forms/13328.pdf
A major ag insurance company categorized 1996 payouts due to misapplication. What percentage were due to drift?:
a. 33%
b. 48%
c. 17%
d. 68%
67
A major ag insurance company categorized 1996 payouts due to misapplication. What percentage were due to drift?:
a. 33%
b. 48%
c. 17%
d. 68%
68
Why All the Interest?
33%
33%
24%
8% 2%
Drift
Improper tank mix
Application Equipment
Off label application
Whoops
wrong field!
70
What percentage of drift incidences may be attributed to applicator judgment?:
a. 16%
b. 38%
c. 50%
d. 78%
71
What percentage of drift incidences may be attributed to applicator judgment?:
a. 16%
b. 38%
c. 50%
d. 78%
Why All the Interest in Drift?
13%
26%
38%
23%
NozzleApplicatorPhysicalOther
Photo/Diagram Credits• Many slides from Fred Fishel “Pesticide Drift-Keeping it on Target “ (included slides from)• University of Florida/IFAS• Florida Depart. of Agriculture and Consumer Services• Kansas State University• University of Nebraska• US EPA• CDMS• National Coalition on Drift Minimization• Spraying Systems Co.• Western Crop Protection Association
• Additional Slides from Brandon Fast “Pesticide Drift "University of Florida,
Fred Fishel, Ph.D.Department of AgronomyUniversity of Florida/IFASCopyright 2009 University of Florida
Mention of trade names in this presentation is solely for providing specific information. It is not a guarantee or warranty of the products named, and does not signify that they are approved to the exclusion of others of suitable composition. Use pesticides safely. Read and follow directions on the manufacturer’s label.
Thanks!Mary Beth Henry