Managing Pesticide Drift Mary Beth Henry

Aquatic Weed Short Course Coral Springs Marriott

• The use of trade names in this presentation is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition.

• Pesticide users must review and comply with all conditions set forth in the pesticide label.

Disclaimer:

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.

Types of Drift

• Vapor Drift - associated with volatilization, gases, fumes

• Particle Drift - movement of spray particles

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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 Drift Applying pesticides in a manner that

allows drift to occur is a label violation

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

8

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

9

Factors Affecting Drift

• Chemical

• Formulation

• Additives

• Drop size

• Evaporation

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Factors Affecting Drift

• Environmental Factors –Wind speed and direction

–Temperature and humidity

–Air stability/inversions

–Topography

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Factors Affecting Drift

• Equipment & Application

–Nozzle type

–Nozzle size

–Nozzle orientation

–Nozzle pressure

–Height of release

–Technology

UF/IFAS PIO

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 size Droplet diameter is measured in microns

(μm) 1 μm = 0.001 mm = 0.0001 cm

Type of droplet Diameter (μm) Smoke <1

Fog 15 Mist 50

Grain of salt 100 Rain 500

0 50 100 150 200 250 300 350 Drift distance (feet)

200 μm droplet 100 μm droplet 50 μm droplet 20 μm droplet

3 mph wind D

ropl

et re

leas

e: 3

ft. a

bove

gro

und

Small droplets

Large droplets

Droplet size Droplet size is influenced by nozzle

orifice size and spray pressure At a given pressure, droplet size

decreases as nozzle orifice size decreases

At a given nozzle orifice size, droplet size decreases as spray pressure increases

What is the target minimum droplet size to reduce drift:

a. 50 µm

b. 100 µm

c. 200 µm

d. 350 µm

18

What is the target minimum droplet size to reduce drift:

a. 50 µm

b. 100 µm

c. 200 µm

d. 350 µm

19

Labels and Droplet Size

CDMS

Droplet size Nozzle orifice size and spray pressure

should maximize droplet size but still provide adequate coverage

Droplets too big: Poor coverage

Good droplet size: Adequate coverage

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 code Very fine (VF) Red Fine (F) Orange Medium (M) Yellow Coarse (C) Blue Very coarse (VC) Green Extremely coarse (XC) White

ASABE Spray Quality Categories

Very fine

Fine Medium Coarse Very coarse

Extr. coarse

Increasing pressure Increasing

orifice size

Droplet size Use nozzles with the largest orifice size

that is appropriate for the application

Use 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

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

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

29

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

30

Wind

Kansas State University

Drift potential is lowest at wind speeds between 3 and 10 miles per hour

Evaporation of Droplets Humidity effects on droplet size

70% RH 30% RH

Wind

Factors Affecting Drift

• Temperature inversions

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Radiant cooling of the ground

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

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: Drift Reduction Additives

• Polyvinyl

• Polyacrylamide

• Linear alkyl epoxide

• Polymide copolymers

UF/IFAS PIO

Strategies to Reduce Drift: Buffer Zones

CDMS

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%

45

Why All the Interest?

33%

33%

24%

8% 2%

Drift

Improper tank mix

Application Equipment

Off label application

Causes of the Drift

13%

26%

38%

23%

NozzleApplicatorPhysicalOtherApplicator

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 Agronomy University of Florida/IFAS Copyright 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 mbhenry@ufl.edu