using herbicides safely around woody plants off-site movement of herbicides 2013 washington state...

Using Herbicides Safely Using Herbicides Safely Around Woody PlantsAround Woody Plants

Off-site Movement of Herbicides

2013 Washington State Weed ConferenceBy: Paula Dinius, Urban Horticulturist

WSU Chelan County Extension

Fate of Herbicides after ApplicationFate of Herbicides after Application

Image source: http://pubs.usgs.gov/fs/2006/3028/pdf/fs2006-3028.pdf

Using Herbicides Around Using Herbicides Around Trees & ShrubsTrees & Shrubs

Mechanisms of Off-site Herbicide Movement Symptoms of Herbicide InjuryCase Studies

Using Herbicides Around Using Herbicides Around Trees & ShrubsTrees & Shrubs

Plant injury is usually caused by not following label directions.◦Using around sensitive plants◦Improper rate or method of application◦Spraying during adverse weather conditions◦Over/under irrigation

Using Herbicides Around Using Herbicides Around Trees &ShrubsTrees &Shrubs

Off-site movement is when any herbicide misses or moves from the intended treatment area.

Mechanisms of Off-Site MovementMechanisms of Off-Site Movement

Movement via air ◦Volatilization - vapor◦Drift – droplet and granule dust

Movement via soil water◦Leaching◦Run-off

Off-site Movement ~ VolatilizationOff-site Movement ~ Volatilization

High temperatures + low humidity = gas (vapor)

Fumes travel for long distances

Herbicide can volatilize right off plant or soil

Dependent on molecular weight of herbicide

Off-Site Movement Off-Site Movement Drift ~ DropletDrift ~ Droplet

Droplet drift is affected by

Weather conditions◦ Wind speed and direction◦ Temperature and humidity

Droplet size ◦ Nozzle type, size & height◦ Spray pressure

Carrier ◦ Type and volume

http://www.ent.iastate.edu/images/misc/spraynozzles.jpg

Influence of Droplet Size on Influence of Droplet Size on Potential Distance of DriftPotential Distance of Drift

Droplet Droplet Diameter Diameter (Microns)(Microns)

Type of DropletType of Droplet Time Time Required Required to Fall 10 to Fall 10 ft.ft.

Lateral Distance Lateral Distance Droplets Travel Droplets Travel Falling 10 ft. in 3 Falling 10 ft. in 3 mph windsmph winds

55 FogFog 66 66 min.min.

3 miles3 miles

2020 Very fine Very fine sprayspray

4.2 4.2 min.min.

1,100 ft.1,100 ft.

100100 Fine sprayFine spray 10 sec.10 sec. 44 ft.44 ft.

240240 Medium sprayMedium spray 6 sec.6 sec. 28 ft.28 ft.

400400 Coarse sprayCoarse spray 2 sec.2 sec. 8.5 ft.8.5 ft.

1,0001,000 Fine rainFine rain 1 sec.1 sec. 4.7 ft.4.7 ft.Source - University of North Dakota

Off-site Movement Off-site Movement Drift ~ Dust/GranularDrift ~ Dust/Granular

Dust and Granular Formulations◦ Dust can drift farther and for longer duration

than liquid.◦ Granular have less drift potential due to pellet

size/weight.

Image source: http://www.abc.net.au/news/image/997708-3x2-940x627.jpg

Wind Speed Indicators Wind Speed Indicators Drift Drift PotentialPotential

Field Observation Probable Wind Speed (mph)

Smoke rises, air motionless 0

Smoke drifts, air rises 1-3

Leaves quietly rustle 4-7

Leaves and twigs move 8-12

Branches move 13-18

Small trees sway 19-24

Large branches move 25-31

Whole trees move 32-38

Source: Herbicide Application Handbook. 2003. Monsanto

Chronic Exposure to Phenoxy Chronic Exposure to Phenoxy Herbicide DriftHerbicide Drift (Dicamba, 2,4-D, MCPP, etc.) (Dicamba, 2,4-D, MCPP, etc.)

Buffer StripBuffer Strip

Off-Site Movement ~ Soil WaterOff-Site Movement ~ Soil Water

Leaching◦Vertical

Run-off◦Horizontal

Off-site Movement ~ Off-site Movement ~ Leaching & Run-offLeaching & Run-off

Rainfall or irrigation water can move herbicides down through or off the soil.

Potential depends on:◦Solubility of herbicide◦Adsorption to soil

particles◦Persistence of herbicide◦Soil texture and structure ◦Amount and frequency of

rainfall/irrigation

Herbicide Movement Herbicide Movement in Soilin Soil

Herbicide Characteristics

◦ Solubility: Highly soluble herbicides are more likely to run-off or leach

Image source: http://www.elmhurst.edu/~chm/vchembook/171solublesalts.html

Herbicide Water SolubilityHerbicide Water SolubilityPesticide Solubility (mg/l)

Dichlobenil (Casoron)Dichlobenil (Casoron) 21.221.2

Benefin (Balan)Benefin (Balan) 0.10.1

Glyphosate (Round-up)Glyphosate (Round-up) 900,000900,000

2,4 - D dimethyamine2,4 - D dimethyamine 796,000796,000

Pendimethalin (Prowl)Pendimethalin (Prowl) 0.2750.275

Dicamba salt (Banvel)Dicamba salt (Banvel) 400,000400,000

Oryzalin (Surflan)Oryzalin (Surflan) 0.70.7

Trifluralin (Treflan)Trifluralin (Treflan) 0.30.3

Isoxaben (Gallery)Isoxaben (Gallery) 1.01.0

Picloram (Tordon)Picloram (Tordon) 200,000200,000

Source: OSU Extension Pesticide Properties Database

No endorsement of products intended, used for example purpose only.

Herbicide Movement Herbicide Movement in Soilin Soil


Absorbency – vegetation uptake

Adsorbency – binding of a chemical to soil particles

Herbicide Movement in SoilHerbicide Movement in Soil


◦ Persistence = resistance to breakdown in soil. (Half-life of herbicide in the soil)

Degradation occurs mainly in O & A Horizon

Factors influencing degradation: ◦Microbes◦Soil chemical reactions◦Sunlight/temperature

Image source: http://jupiter.plymouth.edu/~sci_ed/Turski/Courses/Earth_Science/soil_profile_diag.jpg

Persistence in SoilPersistence in SoilChemical Half-life in Months Half-life in DaysDicamba (Banvel) 2 – 6 60 - 120

Dichlobenil (Casoron) 4 – 12 120 - 360

Glyphosate (Roundup) 1 30

Pendimethalin (Prowl) 3 – 6 90 - 180

Picloram (Tordon) 6 - 18 180 - 540

Trifluralin (Treflan) 6 - 12 180 - 360

2,4-D (Weedar 64) 1 30

Oryzalin (Surflan) <1 20

Benefin (Balan) 1.5 40

Isoxaben (Gallery) 2 - 3 60 - 90

Source: http://npic.orst.edu/ingred/ppdmove.htm

No endorsement of products intended, used for example purpose only.

Herbicide Movement in Soil Herbicide Movement in Soil

Soil ProfileHerbicide Characteristics

•(Ad)Sorption Coefficient:

Image source: http://turfgrass.cas.psu.edu/education/turgeon/Modules/11_WeedManagement/Herbicide_Fate/Content/HF16.html

Herbicide Movement in SoilHerbicide Movement in Soil Soil

Characteristics

Soil texture: Sandy soils much

more prone to leaching.

Compacted clay soils are prone to runoff.

Well aggregated loamy soils reduce herbicide movement.

Image source: www.nj.nrcs.usda.gov/


Soil Characteristics

Organic matter: Soils high in OM have: Increased microbial activity Greater water holding capacity Greater adsorption capacity

Image source: http://echezabalperiod2.wikispaces.com/file/view/Euplotespha-Ciliate_Protozoa-by_Ralf_Schmode.jpg; & http://www.teachengineering.org/view_activity.php?url=collection/nyu_/activities/nyu_permeability/nyu_permeability_activity1.xml


Site Characteristics

Slope: Greater the slope, greater potential of herbicide movement

Awareness of Root SystemsAwareness of Root Systems


National Pesticide Information Center◦OSU Extension Pesticide Properties Database◦Based on Solubility, Koc, and Half-life ◦Pesticide Movement Rating

Very high – Very low

http://npic.orst.edu/ingred/ppdmove.htm

National Pesticide Information Center◦Pesticide Movement Rating

◦Pendimethalin (Prowl) = Very low◦Dichlobenil (Casoron) = Moderate◦Oryzalin (Surflan) = Low◦2,4 –D amine (Weedar 64) = Moderate◦Isoxaben (Gallery) = Low◦Dicamba (Banvel) = Very high◦Picloram (Tordon) = Very high◦Glyphosate (Roundup) = Extremely low◦Benefin (Balan) = Extremely low


Source http://npic.orst.edu/ingred/ppdmove.htm

Herbicide Injury Herbicide Injury SymptomsSymptoms

Seedling Growth Inhibitor Seedling Growth Inhibitor Herbicides Herbicides Root & Shoot ~ Stunting & DistortionRoot & Shoot ~ Stunting & Distortion

Newly planted woody plants◦ Root tips enlarge into rounded

structures and shoots can swell and be stunted.

Established woody plants◦ Stems enlarge and become brittle

http://extension.agron.iastate.edu/soybean/documents/herbicideinjury_05.pdf

Seedling Growth Inhibitor Seedling Growth Inhibitor HerbicidesHerbicides

Root & Shoot Inhibitors◦Benefin – Balan ◦Pendimethalin –

Pendulum, Prowl◦Trifluralin – Treflan◦Oryzalin – Surflan◦Isoxaben – Gallery◦Prodiamine –

Barricade

Trifluralin damage to spruce

Growth Regulator HerbicidesGrowth Regulator HerbicidesMalformed or Distorted ~ Leaves or ShootsMalformed or Distorted ~ Leaves or Shoots

Systemic herbicides

Symptoms usually on new growth

Leaf cupping, twisting or strapping of leaves, splitting or cracking of bark

Prone to drift and can move with leading edge of soil water.

Dicamba damage on Linden

Growth Regulator HerbicidesGrowth Regulator Herbicides

2,4-D, MCPP, MCPA

DicambaTriclopyr,

picloram, clopyralid

Dicamba/2,4-D Damage on Pin Oak

Phenoxy Damage on ConifersPhenoxy Damage on Conifers

2,4-D damage to pine & fir

Invasive.org, Minnesota Department of Natural Resources Archive,

Phenoxy Growth Phenoxy Growth Regulator Regulator HerbicideHerbicide

◦Irregular contours herbicide damage on honey locust trunk

(2,4-D, Dicamba, MCPP, etc.)

Herbicide Injury SymptomsHerbicide Injury SymptomsLeaf Chlorosis or NecrosisLeaf Chlorosis or Necrosis

Inhibition of photosynthesis causes various patterns of chlorosis.

Pre-emergence systemic herbicides absorbed by roots translocated to leaves.

Post emergent systemic Symptoms more severe on

side of herbicide placement.

Glyphosate damage

Leaf Chlorosis or Necrosis Leaf Chlorosis or Necrosis HerbicideHerbicide

At high rates, necrosis can occur without chlorosis.

Symptoms may persist for more than a year.

Symptoms may be confused with salt burn, drought, or freeze damage.

Picloram damage to maple

Diuron = KarmexDiruon + bromacil

= Krovar Imazapyr = ArsenalDiquat and

paraquat = Ortho Diquat, Reward

Oxyfluorfen = Goal

Paraquat Damage on Pecan; Krovar damage on Zelkova

http://www.caes.uga.edu/commodities/fruits/pecan/media/images/paraquatdamage2.JPG

Leaf Chlorosis or Necrosis Leaf Chlorosis or Necrosis HerbicidesHerbicides

Distorted Growth and ChlorosisDistorted Growth and Chlorosis

Glyphosate damage (sublethal dose)◦Chlorosis to necrosis◦Shortened internodes◦Stunted growth◦Witches broom effect◦Loss of apical

dominance◦Branch dieback

Glyphosate Damage on Rose

Case StudiesCase StudiesDichlobenil

PicloramTrifluralin

Dichlobenil Dichlobenil (Casoron) (Casoron) and the Flowering Cherry Treesand the Flowering Cherry Trees

Flowering Cherry Tree Casoron DamageFlowering Cherry Tree Casoron Damage

Picloram andPicloram andthe Curb the Curb CleanerCleaner

Trifluralin and the Conifer ConundrumTrifluralin and the Conifer Conundrum

SummarySummaryAlways Thoroughly Read & Follow All Pesticide Always Thoroughly Read & Follow All Pesticide

Label DirectionsLabel Directions

Study present & future weather conditions◦ Temperature◦ Wind speed & direction◦ Humidity◦ Rainfall

Study plants found in surrounding area◦ Identify species◦ Tree and shrub root zone

area◦ Slope

Choose herbicide to fit site conditions with considerations of potential movement

SourcesSources Washington State University. 2002. Turf & Ornamental Weed Management Principles.

MISC0170 Washington & Oregon State University & University of Idaho. 2005. Pacific Northwest

Weed Management Handbook. Starbuck, Chris. 1998. Turfgrass Research & Information Report. University of

Missouri-Columbia Turfgrass Research. http://agebb.missouri.edu/pdc/turf/report98/sesen.htm

Cornell University. 1983. Dicamba (Banvel) Herbicide Profile 10/83. http://pmep.cce.cornell.edu/profiles/herb-growthreg/

Dexter A.G. 1993. Herbicide Spray Drift A-657 (Revised). North Dakota State University & University of Minnesota http://www.ext.nodak.edu/extpubs/plantsci/weeds/a657w.htm

Ohio State University. Newsletter. Do “Drift Retardant” Chemicals Really Work? C.O.R.N. 2000 – 14. http://netc2000.tamu.edu/abstracts/tx009/paper/~corn/archive/2000/may00/00-15.html#linkg

Costello, Perry, Matheny, Henry, & Geisel. 2003. University of California. Abiotic Disorders of Landscape Plants A diagnostic Guide. Publ. 3420.

Sinclair, Lyon. & Johnson.1987. Cornell University. Diseases of Trees and Shrubs Voge, Derle, and Jenkins. 1994. Oregon State University Extension. OSU Extension

Pesticide properties Database. National Pesticide Information Center. http://npic.orst.edu/ingred/ppdmove.htm

using herbicides safely around woody plants off-site movement of herbicides 2013 washington state...

Documents

soil herbicide movement

offsite movement drift

soil degradation

herbicide misses

halflife of herbicide

weedmanageme slide

monsanto slide

soil dependent