D.A. Ball, R. Parker, J. Colquhoun, and I. Dami

PREVENTING HERBICIDE DRIFT ANDINJURY TO GRAPES

EM 8860 • March 2004 • $4.00

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog

2

During the past several years,grape acreages have increasedsignificantly in Washington andOregon (17 percent and 23 percent,respectively, from 1999 to 2002).Unfortunately, herbicide drift canpose a major threat to the growthand success of commercial grapeproduction adjacent to areas ofsmall grain, hay, grass seed, or cornproduction.

Grapes are especially sensitive toseveral herbicides used in agro-nomic crops, pasture, rangeland,forestry, and noncrop areas. Whenapplied to nearby crops, herbicidescan drift to vineyards and causesignificant injury to grapevines.

Drift is defined as the movementof herbicides off the site where theywere applied. Drift can occur eitherduring herbicide application(particle spray drift) or after appli-cation to plants and soil when theherbicide volatilizes (vapor drift).

Herbicide drift can injure foliage,shoots, flowers, and fruits. If injuryis severe enough, or occurs repeat-edly, it can cause reduced yield,poor fruit quality, and, occasionally,vine death. Drift injury can result ina substantial economic loss. Inaddition, drift to grapes frommisapplication of pesticides couldresult in illegal residues on theexposed crop.

Preventing Herbicide Drift andInjury to Grapes

Daniel A. Ball, weed scientist, Colum-bia Basin Agricultural ResearchCenter, Oregon State University;Robert Parker, Extension weedscientist, Washington State University,Prosser; Jed Colquhoun, Extensionweed specialist, Oregon State Univer-sity; and Imed Dami, viticulturist, OhioState University.

Herbicide injuryto grapevines canlast several yearsafter the occurrenceof the drift; it mayreduce vigor,increase suscepti-bility to diseases,reduce yield andfruit quality, andshorten the life ofthe vineyard.

Growth-regulatorherbicides such as2,4-D and dicambaare the herbicides most likely toinjure grapes. Growth-regulatorherbicides mimic auxins, which areplant hormones that regulate growthand development. Grapes are manytimes more sensitive to growth-regulator herbicides than are cornand wheat. Herbicide concentra-tions of 100 times below therecommended label rate have beenreported to cause injury to grapes.Field observations indicate that driftfrom growth-regulator herbicidescan injure grapes half a mile ormore from the application site.

Growth-regulator herbicides arewidely used for control of emergedbroadleaf weeds (postemergence) ingrowing wheat, pasture, rangeland,grass seed, and corn. They also arecommonly used in turf and by

railroads, utilities, highway depart-ments, and municipalities to controlunwanted woody plants and broad-leaf vegetation on rights-of-way. Apartial list of common growth-regulator herbicides and otherherbicides that can injure grapes isfound in Table 1.

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog

3

Types of herbicidesmost harmfulto grapes

The herbicides of most concernfor grape injury are discussed inthis publication. Other herbicideswith different modes of action alsocan drift and injure grapes, so careis needed during all herbicideapplications.

Growth regulatorsThe most common growth-

regulator herbicides used in thePacific Northwest are 2,4-D anddicamba. The potential for vapordrift from 2,4-D and dicambadepends on the specific herbicideformulation. For example, vaporfrom the ester formulations of2,4-D (e.g., Salvo, Weedone) ismore likely to drift than that

from the amine formulations(e.g., Weedar 64). Ester formula-tions of 2,4-D are widely usedbecause of their lower cost, greaterabsorption by plant tissues, andeffectiveness in weed control. Thegreater drift potential of esterformulations has led to restrictionson their use in certain areas ofOregon and Washington.

GlyphosateGlyphosate is the active ingredi-

ent in Roundup and similar prod-ucts. Glyphosate can drift andinjure grapes but usually is less of aproblem than growth regulatorsbecause it is not volatile and grapesare not as sensitive to these herbi-cides. Nevertheless, glyphosate candrift in windy conditions and,because it is systemic, cantranslocate within grapevines andkill the growing points.

Glyphosate is applied prior toplanting wheat, after harvest, andfor maintenance of summer fallow.In addition, it is labeled for use invineyards. Usually, injury invineyards results when glyphosateapplied under grapevines contactsgreen tissues of the vines.Glyphosate mist from sprayers alsohas been implicated in damageresembling that caused by growth-regulator herbicides.

ALS inhibitorsAcetolactate synthase (ALS)

inhibitors are systemic and maycause injury similar to thatcaused by glyphosate. The ALSinhibitors include the sulfonylureas(e.g., Amber, Finesse, HarmonyExtra, Peak, Express, Ally) andimidazolinones (e.g., Pursuit,Raptor, Beyond, Arsenal, andPlateau). ALS inhibitors are widely

Table 1. Herbicides that have potential to injure grapes.

Growth regulators ALS inhibitors

2,4-D Dicamba Others Glyphosate Sulfonylurea Imidazolinone Others

Amine 4 Banvel Bronate* Roundup Ally Arsenal GramoxoneBarrage Clarity Crossbow* Rodeo Ally Extra Assert AimEsteron 99 Rave* Curtail* Roundup Ultra Amber Beyond BoaFormula 40 Landmaster* Roundup Canvas PursuitHi Dep MCPA UltraMax Cimarron RaptorLV-4 RT Master Roundup Express PlateauLV-6 Starane WeatherMax FinesseSaber Tordon Landmaster* GleanSalvo Turflon Glyphos Harmony ExtraSavage Trimec Glypro Harmony GTTricep RT Master OustWeedar 64 Touchdown PeakWeed-B-Gon Rave*WeedmasterWeedone

This list is not all-inclusive; other herbicides also may injure grapes.*A prepackage mixture containing a growth-regulator herbicide as at least one active ingredient.

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog

4

used in alfalfa, pea, and wheatproduction, and for noncroplandweed control. They are applied bothbefore planting (preemergence) andpostemergence at extremely lowrates. The high biological activity ofALS inhibitors increases thelikelihood of drift injury to grapes,especially if temperature inversions

allow small spray particles toremain suspended in the air forextended periods. However,because of the low volatility ofALS-inhibitor herbicides, injury tograpes from this type of herbicidegenerally occurs only from nearbyapplications.

Herbicide drift injurySpring applications of the herbi-

cides described above oftenaccumulate in the growing points ofgrapes, where injury symptomsappear first. Fall applications mayaccumulate in roots. The type andseverity of injury to grapes dependson the concentration of theherbicide, time of exposure andcorresponding vine growth stage,and grape variety.

Time of exposure is important, asinjury is much more severe duringperiods of rapid grape growth. Thepotential for injury can be reducedconsiderably if potentially injuriousherbicides are applied in earlyspring when grapes are still dor-mant (prior to grape bud break).Bud break generally occurs aroundearly to mid-April.

If exposure occurs between budbreak and bloom, during the periodof rapid shoot growth, grape injurycan be severe. Field observationshave indicated that herbicide driftexposure prior to bloom but afterbud break can cause flower abor-tion, curling of shoot tips, cessationof shoot growth, and regrowth ofdeformed leaves after exposure.

Mid- and late-season exposureusually causes minor leaf deforma-tion since most shoots are fullygrown and few developing leavesare present to respond to theherbicide. However, exposure ofdeveloping berries to herbicidesmay greatly delay or even preventripening.

The sensitivity of grapevines toherbicide drift also depends on thegrape cultivar. Nonetheless, withsevere and repeated exposure toherbicide drift, all cultivars arevulnerable.

Figure 1.—2,4-D drift injury symptoms.

Fan-shaped leaves with small puckered spots between veins and sharppoints (enations) at leaf margins (photo by I. Dami).

Zigzag shoot growth with shortened internodes (photo by I. Dami).

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog

5

Figure 2.—Dicamba drift injury symptoms.

Leaf cupping upward (photo by I. Dami).

Leaf cupping downward (photo by I. Dami).

Growth regulatorinjury symptoms

Injury from growth-regulatorherbicides usually appears within2 days of the drift incident. Symp-toms of 2,4-D injury includecharacteristic fan-shaped leaveswith sharp points at leaf margins,epinasty (downward bending ofleaves), leaf strapping with deepsinuses, and leaf puckering withconstricted veins that may beslightly chlorotic (Figure 1).Research in Washington withConcord grapes has found that2,4-D affects fruit quality, includingfruit color, sugar levels, and acidcontent. Dicamba injury usuallycauses leaf cupping and a distinctmarginal band of restricted growth(Figure 2).

Shoot tips seldom resume growthafter injury by growth-regulatorherbicides, but laterals continue togrow. The result is a very bushyvine with a shade canopy and poorfruit exposure. Growth regulatorinjury is particularly severe whenmultiple incidents occur to the samegrape planting over a period ofyears.

Symptoms of fanleaf degenera-tion, a viral disease, often resemblethose caused by growth regulators.

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog

6

Glyphosate and ALSinhibitor injury symptoms

Symptoms vary, depending on thetime of application. During thegrowing season, grape injury fromglyphosate and ALS inhibitorsusually takes a couple of weeks toappear. The first symptom usually isyellowing of the growing points,followed by necrosis and death ofthe growing points (Figure 3). As aresult, apical dominance may bebroken, resulting in growth ofnumerous lateral shoots (bushygrowth). Other symptoms includearrow-shaped, cupped, and upward-curled leaves, shortened internodes,and occasionally interveinal chloro-sis (Figures 3 and 4).

Fall uptake of glyphosate mayresult in symptoms the followingyear, including stunting of earlyshoot growth, leaf chlorosis anddistortion, very short internodes,abundant lateral shoots, and abortedflowers. These early-spring symp-toms may be confused with viral orfungal diseases (e.g., Eutypadieback).

Grape root injury can occur fromeither glyphosate or ALS inhibitors,although we are uncertain of thepotential amount of root injury andits long-term implications. Itgenerally is believed that root injuryis more likely from ALS-inhibitingherbicides than from glyphosate.

Figure 3.—Glyphosate injury symptoms.

Distorted leaves.

Lateral shoot growth with unusual burst of latent buds on nodes,short internodes, and distorted leaves (photo by I. Dami).

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog

7

Protection fromherbicide drift injury

Both grape growers and nearbygrowers of other crops can takesteps to reduce the risk of herbicidedrift injury to grapevines.

Avoid making herbicide appli-cations during sensitive periods ofgrape growth and development.All users of potentially injuriousherbicide products should knowwhere grapes are being grown intheir vicinity and when grapes arein sensitive developmental stages.

Consider using products with areduced potential for injury tooff-target plants (see Table 2).These herbicides either affectemerging seedlings or causecontact injury to plants and are nottranslocated in grapes to growingpoints or fruit.

Maintain good relations withneighbors. Grape producers shouldmake sure that neighbors inapproximately a half-mile radiusaround the vineyard are aware thatvines are very sensitive to herbi-cides. Communicate the presence ofthe vineyard to state and countyhighway departments, utilities, andother agencies that might sprayrights-of-way or roadsides. If theseareas run through your property,keep them free of weeds so they areless likely to be sprayed. Work withyour neighbors by encouragingthem to use drift-reduction spraynozzles that produce large dropletsand to select herbicides that are lesslikely to injure grapes (Table 2).

Figure 4.—ALS inhibitor injury symptoms fromsulfonylurea herbicide spray drift.

Chlorosis of leaf veins and change in leaf appearance from smooth tocrinkled (photo by I. Dami).

Table 2. Alternative herbicides for wheatless likely to injure grapes.

AchieveAvengeBuctrilDiscover

EverestHoelonMaverickKarmex or Diuron

ParamountPumaSencor

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog

8

Minimize drift injury fromherbicides used in the vineyard.Glyphosate is registered for use ingrapes; however, if not appliedproperly, severe damage can occur.To avoid injury, grape growersshould observe the followingguidelines.• Avoid glyphosate contact with

any green parts of the vine orby drift.

• If possible, avoid summer andfall application when grapes aremost susceptible to injury.

• Avoid glyphosate applicationswhen shoots begin to trail,especially with downwardshoot-training systems such asSingle High Wire, GenevaDouble Curtain, Smart-Dyson,and Scott Henry.

• Use a shield mounted to a wandfor a backpack sprayer applica-tion or a commercial shieldedsprayer such as a dome sprayer.

• Avoid spraying in windyconditions or during totallycalm, temperature inversionconditions.

• Use drift-reduction nozzles(e.g., turbo flat-fan and air-atomizing types) that operate atlower pressure (15–30 psi) andproduce large droplets, thusreducing the chance of drift.

• Use vine grow tubes to protectfirst-year vines from herbicidecontact with green shoots.

• If chemical weed control ispracticed in the vineyard, beginthe weed management programwith preemergence herbicides(check your local pesticidespray guide) and follow up withpostemergence herbicidesbefore bud break.

• In midseason, use a contactherbicide (not systemic) to treatweed escapes.

• If using 2,4-D in your vineyard,apply it before active shootgrowth occurs, use low spraypressures, and be extremelycareful to avoid treatment whenweather conditions favor drift,such as during high tempera-tures, breezy conditions, andtemperature inversions.

Additional herbicidedrift resources

For more information aboutherbicide drift, see the followingpublications or Web sites.• Washington Association of

Wine Grape Growers DriftMonitoring information(http://www.wawgg.org/index.php?page_id=29)

• Kansas State University DriftQuestions & Answers(http://www.oznet.ksu.edu/library/hort2/MF2588.pdf)

• Oregon State UniversityExtension publicationEM 8737, Preventing PhenoxyHerbicide Damageto Grape Vineyards(http://eesc.oregonstate.edu/agcomwebfile/edmat/html/em/em8737/em8737.html)

The Oregon Department ofAgriculture (503-986-4653) andWashington Pesticide ManagementDivision (Washington Departmentof Agriculture, 509-225-2647,toll-free 1-877-301-4555) directinvestigations on suspected driftincidents in their respective states.

© 2004 Oregon State University.

This publication was produced and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Extension work is acooperative program of Oregon State University, the U.S. Department of Agriculture, and Oregon counties. Oregon State UniversityExtension Service offers educational programs, activities, and materials—without discrimination based on race, color, religion, sex, sexualorientation, national origin, age, marital status, disability, or disabled veteran or Vietnam-era veteran status. Oregon State UniversityExtension Service is an Equal Opportunity Employer.

Trade-name products are mentioned as illustrations only. This does not mean that the Oregon State University Extension Service eitherendorses these products or intends to discriminate against products not mentioned.

Published March 2004.

THIS P

UBLICATIO

N IS O

UT OF D

ATE.

For mos

t curr

ent in

formati

on:

http:/

/exten

sion.o

regon

state.

edu/c

atalog