United State Department of Agriculture: Herbicide … · TEAM Leafy Spurge presents this...

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Leafy spurge is difficult tocontrol because it can grow inmany different environments.

If you have fought leafy spurge,you already know it is one of themost difficult invasive weeds tocontrol. Leafy spurge has beendescribed as the nearly perfectweed because it rapidlyinvades new areas andit has an arsenal ofdefenses that makecontrol and manage-ment difficult. A nativeof Europe and Asia,leafy spurge emergesearly in the spring andgets a head start onother vegetation in arace for space, sunlight,nutrients and water.

Prolific seed production and anextensive root system give theplant a huge competitive advantageand make consistent, long-termcontrol difficult.

All parts of the plantcontain a milky juicecalled latex, which pre-vents grazing by mostanimals and injuryfrom most insects.Latex can be toxic andwhen consumed bycattle causes scoursand weakness.

Leafy spurge willinvade a wide varietyof terrain from flood

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The latex in leafyspurge is a deterent tograzing by cattle andhorses.

plains to river banks, grasslands,ridges, and mountain slopes andgrows in diverse environments from

dry to subhumid and from subtropicto subarctic.

Leafy spurge will displace nativevegetation even in otherwise non-disturbed habitats. Leafy spurge isprimarily found in untilled, non-cropland habitats such as aban-doned cropland, pastures, range-land, woodland, roadsides, andwaste areas.

The extensive root system con-sists of numerous coarse and fineroots, occupying a large volume ofsoil. Roots are most abundant inthe upper foot of soil, but someroots extend to a depth of 15 feetor more. The roots are woody anddurable with numerous buds capa-ble of producing new shoots.

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An extensive root system, capableof storing nutrient reserves andproducing numerous shoots,makes leafy spurge extremelypersistent.

��pages 2-5• Leafy Spurge • Our Goal�� pages 6-9

• How Does It Work? • Timing• What Should I expect?!��pages 10-19

• Tordon • Banvel • Campaignor Landmaster • Plateau • Paramount

• 2,4-D • Glyphosate• Norosac or Casoron 4G• Control for small patches

• Control near water • Krenite S"��pages 22-25

• Sprayer calibration• Backpack sprayers or high-pressure guns

• Boom-buster or Boom-i-natorspray equipment

#��pages 26-29• Economics of using herbicides• What factors should I consider?

• Economic consideration when herbicidesare integrated with other control tools

• In Summary

�$%�pages 30-33• Integrated pest management

• Biological control • Multi-speciesgrazing • Burning • Reseeding

• Mapping a control strategy

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&'(��pages 35-36

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(Continued on next page)

These roots may be as large asone-half inch diameter in the upperfoot of soil and decrease to the sizeof a pencil lead with increasingdepth. The root system contains alarge nutrient reserve that can sus-tain the plant for years, allowing itto survive long periods of droughtand most methods used to manageand control the weed.

Herbage production can bedecreased by as much as 75%when leafy spurge infests pastureand rangeland. Infestations inWyoming, Montana and theDakotas alone are estimated tocost agricultural producers and tax-payers more than $144 million ayear in production losses, controlexpenses, and reduction in nativeplant and wildlife diversity.

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Herbicides are themost commonly usedleafy spurge manage-ment tool for containingand preventing thespread of existing infes-tations and for eradicat-ing new infestations.Presently, herbicidescan be used to controlleafy spurge in nearlyevery habitat it is found.Several traditional auxinherbicides and recentlyintroduced compoundsfrom other chemicalfamilies can be effective

as part of a long-term managementprogram. In addition, most experi-mental herbicides have beenscreened for leafy spurge controlsince the introduction of 2,4-D inthe 1940s.

Top-growth control and a gradualdecrease in the underground rootsystem are possible with a persist-ent herbicide program. The mosteconomical control methoddepends on the size and location ofthe infested area. Herbicides caneliminate small patches of leafyspurge with persistent treatments.Larger areas require additional(integrated) control measures,because long-term control isextremely difficult to achieve withany single control method. Thus,herbicides are an important compo-nent of any integrated pest man-agement (IPM) program focused onleafy spurge control.

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As leafy spurge density increases, grass produc-tion decreases. This is the cost of leafy spurge.

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This manual provides informa-tion concerning the use of herbi-cides and their integration withother weed control technologies.TEAM Leafy Spurge presentsthis information ONLY as a guidefor potential leafy spurge man-agement programs. You mustALWAYS read and follow the labelinstructions for registered uses ofherbicides which are given on con-tainer labels. The label is the finalguide and should be strictly fol-lowed. The information presentedin this manual was current at thetime of publication, but herbicidelabel requirements change as dic-tated by law and research results.Consult the current label for safetyprecautions including necessaryprotective clothing, reentry require-ments, and grazing restrictions.It is up to you, the end user, toalways read and follow labeldirections for proper use of her-bicides in the many environ-ments leafy spurge grows.

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The goal of this manual is sim-ple: We want to provide you, therancher, landowner or land manag-er, the information you need toevaluate the various herbicidesavailable and determine how theycan best be integrated into yourmanagement program.

We’ll start by providing somebasic information about herbicides,potential benefits and the kinds ofresults that can be expected. We’ll

then move into more detailed infor-mation about timing, control in dif-ferent habitats, the cost-benefit ofusing herbicides and integratingherbicides with other control tech-niques.

The key is STARTING.Herbicides are not a cure-all or anovernight solution; however, theyare another tool that can contributeto a sustainable long-term leafyspurge management program.Control requires a well-plannedprogram with consistent and carefulfollow-through. Herbicides won’twork unless you use them, and thesooner you start, the sooner theycan start working for you.

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When working with any herbicide,always read and follow labeldirections.

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No herbicide is labeled exclusively forrangeland weed control. All have beenadopted for rangeland use from herbicidestargeting weeds in croplands.

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None of the herbicides used tocontrol leafy spurge were devel-oped specifically for controllinginvasive weeds on rangeland andwildlands. It costs too much for acompany to develop and label acompound solely for the control ofnoxious weeds that only impactnon-cropland acreage with limitedeconomic return. Thus, all herbi-cides presently labeled for leafyspurge control were selected fromcropland chemicals and labeled for

use on rangelands and grasslands.For example, Tordon (picloram)was labeled in the mid 1960s forweed control in wheat. Banvel(dicamba) is a corn herbicide, andthe newly labeled leafy spurge her-bicides Plateau (imazapic) andParamount (quinclorac) were devel-oped for weed control in peanutsand rice, respectively.

All herbicides used for leafyspurge control are safe for usearound domestic animals andwildlife when applied as directed by

Plateau was developed for use onpeanuts.

Paramount was developed foruse on rice.

the herbicide label. The auxin orauxin-like herbicides such asTordon, Banvel, and 2,4-D controlmany broadleaf weeds but notgrasses. Plateau controls a limitednumber of broadleaf plants, is safeto use under many shrubs andtrees, but can injure certain grass-es, especially when used at higherrates. Paramount controls a verylimited number of broadleaf plants,but it is safe to use around virtuallyall trees, shrubs, and grasses. Incontrast, Roundup (glyphosate) andits generic equivalents are non-selective and will injure nearly allplants.

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A rule of thumb is for every yearleafy spurge has been establishedin a location, two years of treat-ment will be needed for completecontrol.

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Small patches of leafy spurge are the easiest to control, and are ideal targetsfor herbicide use.

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Leafy spurge is persistent andland managers must be even morepersistent and proactive in theirmanagement efforts to successfullycontrol this weed. It is important toget an initial idea of how muchleafy spurge you have and the sizeof the areas you wish to treat.Controlling leafy spurge is muchlike fighting a range fire. Smallpatches should be treated first toprevent spread. The edge of largerstands should be treated to preventfurther spread and gradually reducethe size of the infestation.

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Proper timing of herbicide appli-cations is essential for good leafy

spurge control. Leafy spurge ismost susceptible to 2,4-D, Banvelor Tordon applications when theplant is in the true flowering andseed production stage from mid- tolate June, or in early to mid-September after the stems havedeveloped new fall regrowth.Glyphosate plus 2,4-D (Campaignor Landmaster BW) provides goodleafy spurge control when appliedduring seed set in late June orearly July. Glyphosate plus 2,4-Dmay slightly injure grasses whenapplied in early summer. Herbicidesapplied during the hot and dryweeks of summer, when leafyspurge is somewhat dormant, areless effective. Fall-applied Plateau

FLEA BEETLE LIFE CYCLEFLEA BEETLE LIFE CYCLE

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Table 1. Longevity of leafy spurge control if an infestation is not retreated.

Years without retreatmentControl 12 monthsafter last treatment 1 2 3

----------------------------------------------- percent control -----------------------------------------------

95 or more 85 70 <2080 60 <20 070 <30 0 - -60 20 0 - -

and Paramount provide better long-term control than applications madeearlier in the growing season. Inthe case of Plateau, fall applica-tions also cause less grass injury.

Glyphosate (Roundup, variousothers) applied for leafy spurgecontrol follows a different patternthan glyphosate plus 2,4-D.Glyphosate is most effective forleafy spurge control when appliedeither after seed filling, in mid-sum-mer, or after fall regrowth hasbegun. Glyphosate applied in earlyspring or after a killing frost gener-ally provides poor long-term con-trol. Consult your local ExtensionService for the most recent infor-mation concerning leafy spurgecontrol with herbicides.

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The control of well-establishedleafy spurge stands must be con-sidered a long-term managementprogram. A landowner must devel-op a persistent annual program thatwill prevent the spread of larger

stands, eliminate smaller infesta-tions, and prevent the spread ofleafy spurge to uninfested areas.The extensive leafy spurge rootsystem allows the plant to regrowfrom depths of 15 feet or more forseveral years. No single treatmentwill eradicate this weed. A consis-tent annual treatment program canprovide long-term control. Do notskip a year until you have con-trolled at least 90 percent of theleafy spurge in an area. Leafyspurge reinfests rapidly (Table 1)and in a very short time you willhave lost any benefits from previ-ous treatments. This is a commonand costly mistake. Once you haveachieved a high level of control,remaining isolated patches can bespot-treated, resulting in a lesscostly control program. Be vigilantin your spray program. Environ-mental conditions that favor leafyspurge can result in a resurgenceof the weed and require you toresume a more aggressive controlapproach.

Table 2. Leafy spurge control in pastures and rangeland with herbicides applied atoptimal timings for the specific herbicide.

Months afterYear 1 Years 2-4 as needed initial treatment

Herbicide Rate Herbicide Rate 12 24 36 48

(Product) (Product) ------ (% control) ------

Tordon 1 qt Tordon 1 qt 65 70 75 90Tordon 2 qt --- --- 75 20 0 --Banvel 2 qt Banvel 2 qt 55 85 95 --Banvel 8 qt --- --- 80 35 -- --2,4-Da 1 qt + 1 qt 2,4-Da 1 qt + 1 qt 20 30 35 20Tordon 1 pt Tordon 1 pt 40 50 40 50Tordon+2,4-D 1 pt + 1 pt Tordon+2,4-D 1 pt + 1 pt 50 65 75 85Tordon+2,4-D 1 qt + 1 qt Tordon+2,4-D 1 qt + 1 qt 70 75 80 95Glyphosate+2,4-Db 54 fl oz Glyphosate+2,4-Db 54 fl oz 60 65 85 --Glyphosate+2,4-Db 54 fl oz Tordon+2,4-Db 1 pt + 1 pt 75 80 90 --Glyphosate 2 pt --- --- 80 10 -- --Plateau+MSOc 8 oz + 1 qt Plateau+MSO 8 oz + 1 qt 85 90 95 --Paramount+MSOc 1.3 lb + 1 qt Paramount+MSO 1.3 lb + qt 55 75 95 --a 2,4-D at 1 qt/A applied twice per year in the fall.b Applied during the seed-set growth stage in late June to early July. Glyphosate + 2,4-D is a com-mercial mixture available as Landmaster BW or Campaign and was applied in years 1 and 3.c MSO = methylated seed oil.

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Tordon (picloram) historically hasbeen the most effective herbicidefor controlling leafy spurge. Tordonapplied at 2 quarts per acre cangive 75 percent or more leafyspurge control the first year aftertreatment (Table 2). This is anexpensive treatment and is gener-ally used to control leafy spurge insmall or isolated patches. Tordon

applied at 2 quarts per acre everyother year can provide good leafyspurge control and significantlyreduce annual application costs.

Research at North Dakota StateUniversity demonstrated the effec-tiveness of a less expensive optionfor leafy spurge control. Repeatedannual treatments of Tordon at 1 to2 pints per acre plus 2,4-D at 1quart (4-pound-per gallon concen-trate) applied in June, during flow-

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ering, can be quite effective. Theresearch demonstrated that a mix-ture of Tordon at 1 pint and 2,4-Dat 1 quart per acre could provide 85percent leafy spurge control afterfour annual applications (Table 2).This combination was the mostcost-effective treatment evaluated,when averaged across severallocations (Table 3). Some landmanagers prefer to start a programusing Tordon at 1 quart per acreplus 2,4-D the first year and thenreduce the Tordon rate to 1 pint peracre in subsequent years.

Tordon at one quart per acre plus2,4-D can provide greater controland does not need to be retreatedas frequently, but the higher rate isinitially more expensive than thelower rate Tordon at 1 pint per acreplus 2,4-D (Table 2). Tordon shouldbe applied at one quart per acre inthe fall because the one pint rate isineffective. Spring or fall applica-tions of Tordon at 2 quarts per acreor more achieved similar results;

however, Tordon plus 2,4-D is moreeffective when applied in thespring. The optimum time for theannual application of Tordon plus2,4-D will be slightly later each yearbecause the herbicide stressdelays flowering.

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• Tordon is a restricted useherbicide because it isphytotoxic to most broadleafplants, has a relatively long soilresidual, and is water solublewith the potential to move intounderground water.

• Do not use Tordon on a sandyporous surface or substrataoverlaying groundwater 10 feetor less below the surface.

• Do not contaminate streams,ponds or irrigation ditches.

• Do not use on flood or sub-irrigated land.

• Do not use Tordon at the ratesrequired for leafy spurge controlon cultivated land.

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Table 3. Comparison of forage production versus cost of several leafy spurgetreatment programs.

Year 1 Years 2 and 3 Forage Total

Herbicide Rate Herbicide Rate Yield Cost

(Product) (Product) (% of check) ($/A)

Tordon+2,4-D 1 pt + 1 pt Tordon+2,4-D 1 pt + 1 pt 161 392,4-D 2 qt 2,4-D 1 qt 138 9Banvel 2 qt Banvel 2 qt 143 120Glyphosate+2,4-D 54 fl oz Glyphosate+2,4-D 54 fl oz 133 27Glyphosate+2,4-D 54 fl oz Tordon+2,4-Da 1 pt + 1 qt 161 31Plateau+MSO 8 oz + 1 qt Plateau+MSO 8 oz + 1 qt 104 60a Glyphosate+2,4-D was applied in years 1 and 3.

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Added notes:• Do not transfer livestock from

treated grass areas on tosensitive broadleaf crop areasfor 12 months after application(or until Tordon has disappearedfrom the soil) without firstgrazing seven days on anuntreated grass pasture.Otherwise, urine may containenough herbicide to cause injuryto sensitive broadleaf plants.

• Do not use Tordon near trees orother desirable broadleafvegetation. Also carefulapplication is necessary toprevent spray drift.

• Tordon is rainfast in 6 to 8hours.

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Banvel (dicamba) will provideintermediate levels of leafy spurgecontrol in pastures and rangelandbut treatments with Banvel are gen-erally not cost-effective. Banvelapplied at 1.5 to 2 gallons per acrewill give good leafy spurge control

for one year (Table 2), but controlusually decreases rapidly the sec-ond year after treatment. Banvel isabsorbed into the plant by theleaves and roots. The best resultsshould be obtained with Banvelwhen applied to leafy spurgefoliage in mid-June or earlySeptember. A follow-up treatmentof 2,4-D at 1 quart per acre (fourpound-per gallon concentrate) willbe needed to prevent reinfestationby seedlings or root buds.

Banvel can provide 95 percentleafy spurge control after threeapplications, when applied annuallyat 2 pounds per acre (Table 2). Thereduction in leafy spurge increasedforage production by 143 percent(Table 3). However, annual Banveltreatments were not cost-effectivebecause of the relatively high costof the herbicide.

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• When using Banvel near water,precautions similar to Tordonshould be observed. Note: Thewaiting period after treatment forgrazing dairy animals variesfrom seven to 90 days, depend-ing on the rate applied. Checkthe label for details before using.No waiting period is requiredbetween treatment and grazingfor non-dairy animals whenBanvel is used alone. Meatanimals should be moved fromtreated areas 30 days prior toslaughter.

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Typical auxin injury to leafy spurgeone and two weeks aftertreatment.

1 week 2 weeks

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• Banvel is rainfast in 6 to 8hours.

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Campaign or Landmaster BW(glyphosate + 2,4-D) can provideseason-long, leafy spurge control,but there is a risk of grass injury,especially when applied in the fall.Glyphosate + 2,4-D at 3.38 pintsapplied once during early seed-setcan provide 75 percent or betterleafy spurge control (Table 2).Grass injury can range from 0 to 10percent from this treatment.Glyphosate + 2,4-D costs approxi-mately 40 percent less than 1 pintof Tordon plus 1 quart of 2,4-D peracre, and it provides better controlthe first year.

Severe grass injury can occur ifglyphosate plus 2,4-D is applied tothe same area in two consecutiveyears. Grass injury of 30 percentor more can result from fall applica-tions of glyphosate plus 2,4-D eventhough the treatment can result inleafy spurge control of 60 to 70 per-cent. One approach that is typical-ly affordable and less damaging tograsses is to apply glyphosate plus2,4-D during leafy spurge seed-set,in late June, followed the next yearby applications of Tordon plus2,4-D during the true-flower growthstage of leafy spurge. Alternatingthe use of these two products canprovide up to 95 percent leafyspurge control in three years (Table2).

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• Spray coverage with glyphosateplus 2,4-D must be uniform.Grass injury can be minimized ifthe product is not sprayed to thepoint where runoff occurs.

• Glyphosate plus 2,4-D is notlabeled for use in areas grazedby livestock. Treated areascannot be grazed or hayed untileight weeks after the treatment.As always, read and followlabeled instructions.

• Campaign or Landmaster arerainfast in 6 to 12 hours.

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Plateau applied in the fall at 8 to12 ounces per acre can provide upto 90 percent leafy spurge controlone year after treatment (Table 2).The label recommends applicationfrom late-August to mid-October,but prior to a killing frost. Researchin North Dakota found that the bestleafy spurge control resulted fromPlateau applications in mid-September. Plateau should beapplied with a methylated seed oil,(MSO), at 1 quart per acre. Theaddition of 28 percent UAN liquidfertilizer to Plateau plus the MSOhas occasionally increased long-term leafy spurge control. Plateaucan reduce both warm and coolseason grass production, butgrasses will recover the season fol-lowing treatment especially ifPlateau is applied at 8 ounces or

less per acre. Plateau applied inthe spring is generally much lesseffective for controlling leafy spurgethan fall applications.

Plateau is safe to use near andaround a variety of trees. Checkthe label for the specific plants youare concerned about. Conifer trees,especially young growth candles,can show temporary yellowing ofstem tips. However, these injuriesare generally not permanent andusually clear up without any long-term injury to the tree. Plateauapplied in the fall can severelyinjure or kill lilac.

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• Do not use on turf being grownfor sale or other commercialuse.

• Do not apply to the foliage ofdesirable trees or ornamentalplants.

• Do not exceed 12 ounces ofPlateau per acre in one year.

• The use of this chemical inareas where soils are perme-able, particularly when the watertable is shallow, may result ingroundwater contamination.Check the label to ensure theproper use of the herbicide andcompliance with Federal law.

• Plateau is rainfast after onehour.

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Paramount (quinclorac) is anauxin-type herbicide with moderatesoil residual that will control bothannual grasses and somebroadleaf weeds, especially fieldbindweed and leafy spurge.Research has found that 1 to 1.33pounds of Paramount (75% dryflowable) applied with an MSO willprovide 90 percent or better leafyspurge control after two annualapplications, without grass injury(Table 2). However, the currentlabeled application rate is only 8

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Plateau can temporarily injureevergreen species.

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Leafy spurge plant two weeksafter treatment with Plateau.

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ounces (0.5 pounds) per acre,which will suppress leafy spurgebut will not provide long-term con-trol.

The manufacturer is currentlyworking to increase the maximum-labeled application rate. CombiningParamount with Distinct, a combi-nation of Banvel plus diflufenzopyrcan increase long-term leafyspurge control. Diflufenzopyr is ananti-auxin compound that whenadded to Paramount can doubleleafy spurge control. Currently,diflufenzopyr is only available incombination with Banvel (Distinct).The maximum application rate forParamount plus Distinct is 8ounces of Paramount (DF) plus 6ounces of Distinct per acre (70%water dispersible granule).Paramount or Paramount combinedwith Distinct has a wide window ofapplication and can be applied toleafy spurge in the fall any timeprior to a killing frost (September -October), or during the true-flowergrowth stage of leafy spurge (mid-to late June).

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• Use this product only inaccordance with its labeling andworker protection standards.

• Do not enter treated areasprior to the restricted entryinterval of 12 hours. Paramountis labeled for leafy spurgecontrol only in non-cropland,industrial sites, and roadsides

that are not hayed or grazed.The use of this chemical wheresoils are permeable, particularlywhere the water table is shallow,may result in groundwatercontamination.

• Do not apply using aerialequipment unless permitted bythe special local need provision.

• Paramount is rainfast 6 hoursafter application.

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2,4-D in the form of a low volatileester, water soluble amine, or watersoluble powder (applied at a rate of1 quart per acre, 4-pound-per-gal-lon concentrate) gives short termcontrol of leafy spurge top growthbut has little effect on overall standreduction (Table 2). The productionof desirable forage can beincreased when 2,4-D is applied inthe spring (Table 3). Applying 2,4-Dat rates even up to 1.25 gallons peracre generally provides less than40 percent control after one year.Applying 2,4-D annually (spring orfall) or biannually (spring and fall)does not result in long-term leafyspurge control. The amine andester formulations of 2,4-D providesimilar leafy spurge control regard-less of the application date or rate.The amine formulation is preferredover the ester formulation becauseit is less volatile and more econom-ical.

Tordon and Banvel at high ratesmay provide acceptable control for

two or more years, but the cost ishigh except for treatment of smallpatches. The 2,4-D, Tordon +2,4-D, and 2,4-D + glyphosate(Landmaster BW or Campaign)treatments are less expensive thanBanvel and Tordon common userates, but must be applied annually.Consider herbicide and applicationcosts with the timeliness of a treat-ment when selecting a herbicide ora treatment program for leafyspurge control.

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• Amine formulations of 2,4-D at 1quart per acre (4-pound-per-gallon concentrate) may be usedto control leafy spurge topgrowth among trees. Avoidcontacting tree foliage with directspray or spray drift, because2,4-D can injure trees: 2,4-Dmust not contact the green barkof young trees. Check the labelto ensure the proper use of theherbicide and compliance withFederal law.

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Glyphosate (e.g. Roundup)applied at a rate of 1 quart per acrefrom mid-July to mid-Septembercan result in 80 to 90 percent con-trol of leafy spurge. Applicationsmade prior to mid-June will notadequately control leafy spurge. Afollow-up treatment with 2,4-D at 1pint (4 pound-per gallon concen-

trate) the following year (mid-Juneto mid-July) is necessary to preventseedling reinfestation.

Glyphosate plus 2,4-D(Campaign or Landmaster BW) canbe applied instead of glyphosate toincrease leafy spurge control anddecrease grass injury. Both formu-lations are safe for leafy spurgecontrol under trees. Glyphosateplus 2,4-D can be applied two tofour weeks earlier (early seed-setstage) than glyphosate alone and itcan produce good leafy spurgecontrol.

Glyphosate (Rodeo and similarformulations only) can safely beused on leafy spurge infestationsnear water. Rodeo applied at 1.5pints per acre will provide 80 to 90percent leafy spurge control whenapplied from mid-July to mid-September. A nonionic surfactantapproved for aquatic sites must beadded to the solution for best

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Glyphosate (Rodeo or Roundup)injury one week after treatment.

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results. Consult the manufactureror dealer for approved surfactantsfor safe use near water.

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• Glyphosate is a water solubleand non-selective herbicide andit will kill grasses and otherdesirable plants. This productdoes not provide residual weedcontrol. Direct spray or spraydrift will cause injury to treefoliage and young trees withgreen bark.

• Do not treat weeds under poorgrowing conditions, such as,drought stress, disease or insectdamage, as reduced weedcontrol may result. For bestresults, spray coverage shouldbe uniform and complete.

• Do not spray weed foliage to thepoint of runoff.

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Norosac, or Casoron 4G(dichlobenil) is a preemergenceherbicide that will suppress leafyspurge for about one season.Dichlobenil 10G should be appliedat 60 to 80 pounds per acre beforeleafy spurge emerges. Research inNorth Dakota indicates thatdichlobenil applied in November at80 pounds per acre can provide 80percent suppression of leafy spurgethe following June. However, con-trol rapidly declines to around 20percent by the end of the growing

season. Dichlobenil applied at 60 to80 pounds per acre is an expensivetreatment but is safe under trees. Itmay be a useful treatment in smallshelterbelts or under trees, nearbuildings, etc.

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• Do not plant sensitive plants (fir,hemlock, pine, spruce) thefollowing spring if the 8-poundrate is used.

• Do not apply directly to water.

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When leafy spurge is confined tosmall, well-defined areas, herbicidetreatments should be used to pre-vent the spread of the stand. Don’tjust treat the leafy spurge plants.Treat an extra 10 to 15 feet aroundeach patch to control spreadingroots and seedlings. Biological con-trol and grazing should not be usedto manage small patches.

The most important thing toremember with small stands is todo everything possible to preventseed production and spreadingroots. Grazing and herbicide controlcan be used together to achievethis goal. Small stands of leafyspurge can be eradicated with her-bicides when the right products areused in a persistent treatment plan.

Controlling these small areasneeds to be a priority since this willprobably be the best opportunity toeradicate the weed in an area.Persistence is the key. Follow-up

treatments will be needed for sev-eral years to control missed stemsand seedlings. Many leafy spurgecontrol efforts have failed becausefollow-up treatments were notapplied or were skipped for one ormore years. Commitment, vigi-lance, and persistence in control-ling small stands will substantiallyreduce the cost and effort neededto control the weed once largestands have become well estab-lished.

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You will often find stands of leafyspurge along small drainages,streams and riverbanks. Leafyspurge control along open water isneeded to prevent further spread ofseed by water or animals. Sincemost herbicides cannot be used

near water and it takes large num-bers of biological control agentsmoving into the area from dryeruplands, a multi-tool approach maybe the most effective. Herbivoreslike sheep and goats will utilizeleafy spurge in these areas, andspecific herbicides (i.e. Krenite Sand glyphosate - Rodeo or similarformulations only) can be usedsafely near water. However, leafyspurge control around open wateris difficult. Which combination oftools will be acceptable and mosteffective depends upon the circum-stances. Managers should workwith area experts to effectively andaffordably deal with leafy spurgenear water.

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Krenite S (fosamine) can beused safely near water. Kreniteshould be applied at 1.5 to 2 gal-lons per acre during the true flowergrowth stage. Control with Krenitehas been inconsistent and shouldbe applied when soil moisture isabundant and the relative humidityis high for best results. A follow-uptreatment will be needed the nextyear to control seedlings wheneither Krenite or glyphosate isused. A 2,4-D formulation labeledfor use near water at 1 to 2 pints(4 pound-per-gallon concentrate)applied from June to mid-July willkill emerged seedlings. A 2,4-D for-mulation labeled for use nearwater can be applied as an annual

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Commitment and persistence incontrolling small stands of leafyspurge will save substantial dollarsand labor down the road.

treatment to prevent seed-set andreduce expansion of a leafy spurgeinfestation.

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• Krenite can be applied to flood-plains where surface water is

not present, terrestrial areas ofdeltas, and low lying areaswhere water is drained but maybe isolated in pockets due touneven or unlevel conditions. Donot apply Krenite through irrig-tion systems or use on food orfeed crops.

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Some herbicides, suchas Rodeo, are labeledfor use in or nearwater. However, mostare not. Read the labelcarefully before usingany herbicide nearstreams and river-banks.

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Common Leafy Spurge HerbicidesProduct Application Rates Time of Application Potential Level of Control Precautions More Info. Comments

Tordon 4 to 8 pt (1 to 2 lb/A) Leafy spurge: True flower growth 85 to 95% control after 1 Restricted use, long soil See pages Commercial mixture with 2,4-D available, Grazon P+D.(Picloram) stage or fall regrowth. year. residual. 10-12

Banvel 4 to 16 pt (2 to 8 lb/A) Leafy spurge: True flower growth 95% control after 3 annual No grazing for 7 to 90 days. See pages Consult label for grazing restrictions. Surfactant improves consistency of control.(Dicamba) stage or fall regrowth. treatments. 12-13 Re-treatment necessary.

Plateau 8 to 12 fl oz/A Early to mid-September. 90% control 1 year after Can injure or kill lilacs. See pages May be used on CRP, pasture, rangeland, industrial sites, roadside right-of-way or(Imazapic) (2 to 3 oz/A) treatment. Do not exceed 12 oz/A 13-14 non-cropland. Apply with methylated seed oil (MSO) type adjuvant plus 28% urea

in 1 year. ammonium nitrate (UAN) each at 1 qt/A. Rates above 8 fl oz. can reduce grass production, especially cool season species. Safe undermost tree species but willcause temporary yellowing of spruce candles. See label for additional information.

Paramount 0.5 lb DF Fall: Prior to frost 90% control after 2 annual The current maximum labeled See pages Do NOT use on pasture and rangeland areas to be grazed or cut for hay. Use an MSO(Quinclorac) (0.375 lb/A) Leafy spurge: true flower or growth applications. rate is 0.5 lbs/A. 14-15 type adjuvant at 2 pt/A. Provides only suppression of leafy spurge at the current labeled

stage actively growing. rate.

Roundup or 2 pt of a 3 lb ae/gal conc. Leafy spurge: After July 1 to 80 to 90% control. Non-selective. See pages Other vegetation will also be killed. Avoid spraying tree foliage. Non-selective, non-residualsimilar or 1.6 pt of a 3.7 lb ae/gal actively growing plants. 16-17 herbicide. Retreat the following spring with 2,4-D at 1 to 2 qt/A to control seedlings andformulations conc. or 1.5 pt of a 4 lb escapes. Refer to label for adjuvant use. Add ammonium sulfate (AMS) fertilizer.(Glyphosate) ae/gal conc. or 18.5 oz of

a 65% SG (0.75 lb/A)

Campaign or 54 fl oz or 3.38 pt. Leafy spurge: Seed set stage 95% control if applied in late Severe grass injury if applied See page Some grass injury and stunting may occur. Injury is greater with fall than spring treatments.Landmaster BW (0.38 + 0.63 lb/A) or actively growing in fall. June and followed by in the fall and if applied for 2 13 Not to be used in consecutive years.(Glyphosate Tordon + 2,4-D the next year. consecutive years.+ 2,4-D)

Tordon + 2,4-D 1 to 2 pt + 2 pt of a 4 lb/gal Leafy spurge: True flower 85 to 95% control after 4 See pages Retreatment at the same rate will be necessary for several years regardless of herbicide(Picloram conc. (0.25 to 0.5 + 1 lb/A) growth stage or fall regrowth. annual treatments. 10-12 or rate. Annual control was greater and years of retreatment needed were less with the+ 2,4-D) 2 pt/A Tordon rate. Use 2 pt/A rate for fall application.

2,4-D 2 to 4 pt of a 4 lb/gal conc. Leafy spurge: actively growing. <40% control. Ester formulation is volatile. See pages A 2,4-D formulation labeled for use in or near water, such as PBI Gordon Amine 400 is(1 to 2 lb/A) 15-16 available for use near streams or ditches.

Rodeo or similar 2 pt of a 4 lb/gal conc. Mid-July to mid-September. 80 to 90% control. Consult with dealer for See page Apply with a non-ionic surfactant (NIS) approved for use near water. Control seedlingsformulations (0.75 lb/A) surfacants that are safe 18 with a 2,4-D formulation near water in subsequent years.(Glyphosate) to use near water.

Norosac 10G 60 to 80 lb 10G Leafy spurge: Late November 80% control. Do not plant sensitive See page Season long suppression only. Must be applied before leafy spurge emerges. No POSTor Casoron 4G 150 to 200 4G to early March - before plants the following spring 17 control.(Dichlobenil) (6 to 8 lb/A) emergence. if applied at 8 lbs/A.

Krenite S 12 to 16 pt True flower growth stage or 80 to 90% for 1 season. Do not apply through irrigation See pages Inconsistent control. Best control with high humidity and good soil moisture at application.(Fosamine) (6 to 8 lb/A) early fall for leafy spurge along systems or use on food or 18-19 Do not contaminate water during application.

streams or ditches. feed crops.

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Often treatments fail because of improper calibration and plugged nozzles.

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Proper sprayer calibration iscritical to accurate herbicideapplication. Sprayers that are notcalibrated result in poor weedcontrol from under-application, ornon-target plant damage fromover-application. To properly cali-brate your sprayer you need toknow spray tank capacity, nozzletype, pressure setting, pumpingarrangement and operatingspeed.

Prior to calibrating yoursprayer, service the sprayer byfixing leaks, cleaning lines, strain-ers, and nozzles, and replace any

worn spray tips. Nozzles shouldonly be cleaned with a soft-bris-tled brush such as a toothbrush,never with a metal object. Spraytanks should be rinsed carefullyand filled with clean water prior tocalibration.

There are several methods forcalibrating a sprayer. Includedhere are simple calibration tech-niques for boomless spray equip-ment such as backpack sprayers,high-pressure hand guns, andboom-buster or boom-i-nator noz-zles mounted on off-road equip-ment. Consult the manufacturerfor calibration of large multi-noz-zle spray equipment.

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Backpack or hand gun sprayequipment with one nozzle areused for spot treating small infesta-tions or in rugged terrain whereother application methods are notpossible. Over-application with thisequipment is a common occurrenceso calibration is critical. When cali-brating your sprayer, select anapplication style that gives the bestcoverage. This is normally a gentle,side-to-side, sweeping motion thatcovers the ground as you walkbackward away from the spraysolution. You may want to practiceon a hard, clean surface that willshow your application patternbefore actually calibrating thesprayer. Remember to keep pres-sure constant during calibration andfield application. Note: You mustuse the same application tech-nique during calibration as youuse during a field application. Ifyou vary speed or pressure, it

will affect your sprayer outputand thus the herbicide applica-tion rate.

This method of calibrating back-pack or hand gun equipmentinvolves very little math or formu-las. It is based on the followingprincipal: one gallon = 128 ouncesand the test area to be sprayed is1/128 of an acre, thus ounces col-lected = gallons per acre.

Step 1. Measure an area 18.5by 18.5 feet which is equal to1/128th of an acre. This should bedone in the field on weed-infestedterrain similar to where you plan tomake the herbicide application.

Step 2. Spray the measuredarea uniformly with water,recording the number of sec-onds required to spray the area.During application be sure to main-tain a constant sprayer pressure. Ametronome is very helpful in main-taining a constant walking speedand the use of a marker dye helpsthe applicator apply a uniform spraypattern. Repeat several times and

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A variety of spray equipment is available for use indifferent topographies.

use the average time.

Step 3. Spray into a containerfor the same amount of time ittook to spray the measured area.Be sure to maintain constantsprayer pressure.

Step 4. Measure the number ofounces of water in the bucket.

Step 5. The number of ouncescollected from the bucket isequal to the number of gallonsper acre the sprayer is deliver-ing.

Volume Sprayed _____ ounces =Gallons Per Acre (GPA)

Step 6. Add the proper amountof herbicide to the tank. For back-pack sprayers, use the table onpage 25 to determine how muchliquid herbicide to add to each gal-lon of water. Find your spray vol-ume in gallons per acre and readacross the chart to determine theamount of herbicide to add to eachgallon of water. Example: You cali-brate your sprayer and the output is30 GPA, and your sprayer holds 3gallons. The label requires an her-bicide application rate of 1 pint/acrefor the target weed. Go to the chartand read across from 30 gal/A. Theamount of herbicide to add to eachgallon of water is 3 teaspoons (15ml). Since your sprayer holds 3 gal-lons of total solution you would adda total of 9 teaspoons (45 ml) ofherbicide to 3 gallons of water ineach backpack tank.

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The refill method of calibration issimple and easy to understand.This should always be done in thefield on terrain similar to where youplan to make the herbicide applica-tion. Field surface conditions cangreatly affect sprayer speed, whichin turn affects application rate.Basic steps for the refill method areas follows.

Step 1. Park the sprayer on levelground, then fill the spray tankwith water to an easily deter-mined point (mark this on thetank).

Step 2. Adjust the pressure torecommended level. Most nozzleswork best between 30 and 35 psi(pounds per square inch).

Step 3. Select a speed that canbe easily maintained for fieldconditions. Field conditions will

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Precise measuring of chemicalsand water is critical in anyherbicide application.

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Spray Amount of Herbicide to Add to Each GallonVolume Recommended Herbicide Rate/AcreGal/A 1 pint 1 quart 2 quarts 3 quarts 4 quarts

15 6 tsp 2 fl oz 4 fl oz 6 1/4 fl oz 8 1/2 fl oz20 5 tsp 10 tsp 3 1/4 fl oz 4 3/4 fl oz 6 1/3 fl oz30 3 tsp 6 tsp 2 fl oz 3 1/4 fl oz 4 1/4 fl oz40 2 1/3 tsp 4 3/4 tsp 1 2/3 fl oz 2 1/3 fl oz 3 1/4 fl oz50 2 tsp 3 3/4 tsp 1 1/4 fl oz 2 fl oz 2 1/2 fl oz60 1 2/3 tsp 3 1/4 tsp 6 1/3 tsp 1 2/3 fl oz 2 fl oz70 1 1/3 tsp 2 3/4 tsp 5 1/2 tsp 1 1/3 fl oz 1 3/4 fl oz80 1 1/4 tsp 2 1/3 tsp 4 3/4 tsp 7 1/4 tsp 9 1/2 tsp90 1 tsp 2 tsp 4 1/4 tsp 6 1/3 tsp 8 1/2 tsp

100 1 tsp 2 tsp 3 3/4 tsp 5 3/4 tsp 7 2/3 tsp120 3/4 tsp 1 1/2 tsp 3 tsp 4 3/4 tsp 6 tsp

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have a large effect on speed, whichaffects application rate. For exam-ple a sprayer calibrated at 4 mphbut driven at 3 mph will over-applyby 33%, potentially damaging non-target vegetation!

Step 4. Spray a measured area(spray swath width and length).Measure a length to spray, such as200 feet, and drive that length at aspeed that negotiates terrain andminimizes drift. Measure the sprayswath width during this step.

Step 5. Return to the fillingpoint. Be sure to park equipment inthe same location to refill the tank.

Step 6. Measure the amountof water required to refill thetank. Use a calibrated pail so youcan accurately measure waterrequired to fill the sprayer to theoriginal mark.

Step 7. Calculate the sprayrate. The final step is to determinethe spray rate; in this case it will bein gallons per acre (gpa).

GPA = gallons sprayed[from Step 6]

x 43,560 sq/ft/acreswath width (ft)x swath length (ft)

[as measured in Step 4]

Step 8. Add the proper amountof herbicide to the tank.Example: Your spray tank holds 30gallons total. If you want to applyone pint of herbicide per acre, andyour spray rate is 15 gallons peracre (as calculated in Step 7), thenyou would add two pints of herbi-cide to the tank and fill with waterto the 30-gallon mark.

Liquid conversions: tsp = teaspoons; TBS = tablespoons; fl oz = fluid ounces; 1 fl oz. = 29.57 ml.1 teaspoon = 5 ml 3 teaspoons = 1 tablespoon 8 fluid ounces = 1 cup1 tablespoon = 15 ml 2 tablespoon = 1 fluid ounce 1 cup = 16 tablespoons

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Traditionally, an economicallyfeasible weed control practice isdeemed one in which the benefitsof treatment exceed the costs.

While this view is certainly true,quantifying treatment benefitsresulting from improved grasslandhealth and alternative land uses isdifficult, making economic thresh-olds difficult to determine. Conse-quently, the following discussionassumes that leafy spurge must becontrolled regardless of the size orlocation of the infestation (i.e. thereis no economic threshold belowwhich weed control should not beattempted). Based on this assump-tion, economically feasible weed

control depends on minimizingcosts. To the rancher it is one ofthree things:

(1) saving on treatment costsand obtaining the same or a betterdegree of weed control;

(2) improving the quality and/orquantity of a marketable commodi-ty; and

(3) improving land quality andsustainability (economic value andecological health).

Economic control at the federal,state or local level includesincreased revenue from salesand/or taxes, reduced expendituresfor weed control and increasedconsumer satisfaction and utiliza-tion of the land for non-agriculturalactivities.

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Early detection of leafy spurge infestations and implementation of a well-planned control program are your best weapons in battling leafy spurge.The longer you wait, the bigger your problem will become.

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In general, we can say that eco-nomically feasible control practicesare those that expend less cash forthe same or better weed controland/or an increase in the amount ofcash returned for every dollar spenton weed control at the local, state,and federal levels.

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Perhaps the single most impor-tant factor to consider when deter-mining if herbicide treatments areeconomically feasible is the size ofthe infestation. Large, well-estab-lished stands of leafy spurge willrequire a significant economic com-mitment. Treatments on infestationsgreater than 2 acres in size onrangeland with carrying capacitiesless than 0.5 Animal Unit Months(AUMs) per acre are almost nevereconomically sustainable. In thisinstance, it may be better to sprayonly the leading edge or perimeterof the infestation (ring) to containits spread, while also employingother pest management tools likeleafy spurge flea beetles or sheep.Another approach is to, again, ringthe infestation with herbicide appli-cations and, as it is controlled inthe treated area, progressivelyspray more of the untreated stand.This approach will take longer, butleafy spurge will be contained andyou should eventually control largerinfestations. The approach reduces

annual expenditures on herbicides,but the cost of application will haveto be sustained over many years.Failure to follow through with thetreatment for one or two years willallow leafy spurge to repopulate thearea and many benefits of thespray program will be lost.Therefore, you must be committedto follow through with the programor the approach will fail.

The most economical use of her-bicides is in controlling small patch-es. If single plants or small standscan be identified and treated early,larger infestations can be PRE-VENTED and the need for long-term applications will be reduceddramatically. In this instance, theintensity of the spray program isgreatest during the first few years.It is more economical in the longterm to expend more dollars forfewer years during the beginning ofa weed invasion than to try to con-tain and control large, well-estab-lished infestations. Again, it isimperative that managers are vigi-lant and the annual spray programis carried through without fail.Failure to spray or missing a previ-ously treated stand for even oneyear can result in the loss of muchof your economic investment. Oneimportant consideration to remem-ber when treating small stands isthat eradication of the weed maybe possible. The possibility of erad-ication is an added incentive tocommit more resources and take amore aggressive approach since it

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can potentially eliminate the needfor future herbicide expenditures.

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Integrating herbicide control withother tools can often reduce thecost of control. However, herbicidesare still an essential part of a com-prehensive control program. Othercontrol tools that should be consid-ered include biological control(using insects) and sheep grazing.Each of these tools are often onlyeffective when dealing with largeleafy spurge infestations.

Biological control has proven tobe very effective in reducing leafyspurge populations, however, ittakes several years for the popula-tion to produce sufficient numbers

of insects to achieve sustainablelevels of control. Therefore, biologi-cal control should initially be usedwith other tools capable of rapidlyimpacting the magnitude of theinfestation and preventing furtherspread. The advantage of combin-ing herbicides with biological con-trol is that the insects will eventual-ly be able to maintain infestationsat an acceptable level with little orno use of herbicides. The cost oflong-term maintenance is dramati-cally reduced, which is a huge,long-term economic advantage.

Sheep grazing of leafy spurgehas also proven to be an effectivemethod of reducing leafy spurgefoliar cover, stressing the weed’sroot system and opening up areaswhere native grasses can grow.However, the practice will not elimi-nate leafy spurge and regrowth will

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Incorporation of herbicides with biologicalcontrol and multi-species grazing providesbetter control than either used alone.

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occur as soon as sheep areremoved as a treatment. The costof sheep grazing can also be high,especially if new fencing and carefacilities are needed, but costs canbe reduced using a number of inno-vative approaches (See TEAMLeafy Spurge’s “Multi-SpeciesGrazing and Leafy Spurge” manu-al). When starting a control pro-gram some herbicides can be usedin combination with sheep grazingto more rapidly achieve acceptableleafy spurge densities. At this pointherbicide use may be discontinuedor substantially reduced as long asthe sheep are maintained in thepasture.

Leafy spurge flea beetles havealso proven to be an effective con-trol method (as described above).Combining herbicides, flea beetlesand sheep can rapidly reclaimheavily invested areas. This prac-tice combines the quick-kill capabil-ities of herbicides (to contain exist-ing infestations and prevent theestablishment of new colonies) withthe selective grazing of new shootsby sheep. Flea beetles, in turn,attack and kill leafy spurge roots.This three-pronged attack is possi-bly the most effective method ofquickly reclaiming large areasheavily infested by leafy spurge (3-5 years depending on your situa-tion); however, there is a substan-tial upfront economic investment inherbicide use and preparing pas-tures for sheep grazing. The silverlining is that once flea beetle popu-

lations are established across thepasture and leafy spurge has beendramatically reduced, the flea bee-tles should be able to maintainleafy spurge at acceptable levels.Again, sustained control isachieved by the no-cost and self-perpetuating biological componentand investments in other treat-ments can be reduced or eliminat-ed altogether.

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An integrated control programcombining two or more methodswill provide a more successful andcost-effective, long-term solution tothe leafy spurge problem than asingle method used alone.Herbicides are most cost-effectiveand the best option to control smallpatches and newly infested areas.Leafy spurge can be eradicatedwith herbicides at this stage.Biological control with insects, orcontrol with grazing animals, ismost cost-effective for large infesta-tions. Both methods have beenimproved when combined with fall-applied herbicides. The key to con-trolling leafy spurge is early detec-tion and treatment of the initialinvading plant. A persistent man-agement program is needed to con-trol top growth and to graduallydeplete the nutrient reserves in theroot systems of well-establishedstands. A successful control pro-gram requires a well-planned strat-egy with consistent and timely fol-low through.

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As mentioned earlier, there areno “silver bullets” or cure-alls formanaging and controlling leafyspurge – simply put, there just isn’tany single tool that will work everytime in every situation.

TEAM Leafy Spurge believesbiologically based Integrated PestManagement (IPM), provides themost effective, affordable and flexi-ble approach for controlling leafyspurge. IPM works because it com-bines the best elements of differenttools, and because it enablesranchers and land managers to tai-lor management programs to fittheir specific needs and goals.

In most IPM scenarios, a tool likeherbicides, grazing, biological con-trol or mowing is used to reduceleafy spurge densities and open upthe canopy, giving more desirableplants a chance to re-establish. Thestress and damage that occurs dur-ing this process weakens leafyspurge, thus making it more sus-ceptible to damage by other tools.

In many cases, herbicides canprovide a solid foundation for othertools to build on.

Herbicides are the most com-

monly used leafy spurge manage-ment tool, and are the preferredtool for containing/preventing thespread of infestations and for eradi-cating new invasive weeds.

Unfortunately, herbicides aregenerally expensive, and use onlarge infestations may not be eco-nomically feasible. In addition, mostherbicides are non-selective andmay adversely impact non-targetspecies. Use in some areas mayalso be restricted by environmentalregulations or inaccessibility toinfestations.

Consequently, the addition ofother IPM tools such as biologicalcontrol and multi-species grazing toa spraying program are becomingmore popular.

The following are brief sum-maries on combining herbicideswith other leafy spurge manage-ment tools.

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In ideal situations, biological con-trol can maintain leafy spurge den-sities below economically signifi-cant levels.

But flea beetles aren’t going towork every time at every site, andintegration with other management

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tools, or simply using other tools,may be required.

Research has shown that herbi-cides and biological control can becomplementary if properly used.Timing is the most important factor.Fall herbicide applications (afterAug. 15) are compatible with fleabeetle survival, and can enhancepopulation establishment. Springand summer applications, however,will remove top growth needed byadult flea beetles to complete theirlife cycle, and should be avoided.

It should be stressed that herbi-cide use SHOULD NOT BE ABAN-DONED simply because other toolsare being used. Herbicides shouldALWAYS be considered as the firstline of defense when small, scat-tered patches are found, and whenattempting to contain the spread oflarger infestations.

TEAM Leafy Spurge demonstra-tions and other research haveshown that multi-species grazingand biological control can also bean effective combination. Sheepgrazing reduces leafy spurge densi-ties, giving flea beetles improvedchances of establishing large popu-lations capable of providing signifi-cant control.

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Studies have shown that herbi-cides and grazing can be combinedto provide excellent leafy spurgecontrol. Again, timing is the mostimportant factor. General recom-mendations call for grazing leafy

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Leafy spurge infestations threatenthe western prairie fringed orchid,a perennial herbaceous plant onthe federal endangered specieslist. While it is unlawful to useherbicides within the habitat areasof endangered plant species,demonstration sites in southeast-ern North Dakota are providingevidence that herbicides can beused to control leafy spurgewithout harming the orchid. Othernative plants, endangered by leafyspurge, include the Canadaanemone and the wild prairie rose.

spurge infestations as normal (mid-May through mid-August, for exam-ple), then applying herbicides in thefall after some regrowth of the leafyspurge has occurred.

Grazing may be restricted follow-ing the application of certain herbi-cides; as always, read the herbicidelabel and follow recommendedguidelines.

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Prescribed burns can be used toreduce leafy spurge densities andremove ground litter that can inhibitfoliar cover of herbicides.

If sheep production is a primarygoal, timing of burns needs to beconsidered – burns should general-ly be performed in the fall or earlyspring so that leafy spurge topgrowth is available for sheep or

goats.Similarly, if burning is being used

in combination with biological con-trol, burns should not be conductedfrom mid-May through mid-Augustto avoid interference with the adultphase of the flea beetle life cycle.

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Regardless of the tool or toolsbeing used to reduce leafy spurgeinfestations, reseeding can be usedto speed range recovery. Desirablegrasses can re-establish morequickly after reseeding, thus provid-ing competition for less desirablespecies that may emerge as reduc-tions in leafy spurge infestationsoccur.

Seed mixes for range recoverycan be expensive and will varydepending on geography, climate,long-term management goals andother factors, so careful planningwill pay off in the long run.

Consultation with local experts,such as Cooperative ExtensionService range specialists, USDA-Natural Resource ConservationService personnel and/or otherrange specialists is recommendedto help select seed mixes and planreseeding strategies.

In some cases, financial assis-tance for reseeding and rangerecovery may be available fromvarious state and federal programsand agencies. Check with localsources to see if your weed man-agement/range recovery programqualifies.

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Prescribed burning combined withother tools can help control leafyspurge by reducing ground litter,thereby allowing better coverageof herbicides.

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Topgrowth

Flower

Stem

Roots

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Flea BeetlesPathogensMowingFire

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Gall MidgeLeaf Tier

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Long-hornedBeetle

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%��"��Several methods are currently available for leafy spurge control andshould be used together in an integrated long-term management plan.

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At this point, it should be obviousthat TEAM Leafy Spurge recog-nizes that herbicides are an impor-tant part of an effective, affordableand sustainable leafy spurge man-agement program. Herbicides canbe used as a stand-alone tool, orcombined with other tools such asbiological control or multi-speciesgrazing.

TEAM Leafy Spurge programparticipants have supplementedexisting research with new data,then applied those findings to on-the-ground demonstrations thatpeople can actually see. Thesedemonstration sites clearly showthat herbicides and herbicides +biological control works, and thatboth approaches can be used in aneconomically beneficial manner.

Keep in mind that there are noeasy solutions or “silver bullets” tohelp solve the leafy spurge prob-lem. It will take time, work and along-term commitment.

As always, prevention is the bestsolution for avoiding problems withleafy spurge and other invasiveweeds. Prevention, combined withhard work and persistence, will helpreturn your rangelands to a moreproductive and natural state.

It is also important to recognizethe benefits of WORKINGTOGETHER. The war against leafyspurge and other noxious weedswill not be won individually – it willtake a collaborative, integrated andarea-wide approach to ultimatelysolve a costly problem that isshared by all.

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Field day tours area good source ofinformation on newweed managementtechniques andproducts includingnew herbicidesand IPMmeasures.

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Q. How far into the fall(according to thetemperature) can you sprayleafy spurge and have goodresults?

A. The best timing varies byherbicide. Plateau should beapplied in mid-September for bestresults as control may drop 50 per-cent or more if Plateau is applied inAugust or October. Tordon plus

2,4-D has a wider application win-dow and can be applied from late-August to early September.Paramount has provided good leafyspurge control even when appliedin late October following severalhard frosts. Leaf color can varyfrom green to yellow and red. Thekey is to make sure the leafyspurge leaves are still firmlyattached to the stem so the herbi-cide can be translocated to theroots. If leaf drop has begun, it isbest to wait until the following grow-ing season before applying herbi-cides for leafy spurge control.

Q. Can I spray over an areathat has biocontrol agents?

A. Yes, as long as the herbicideis applied in the fall after the adultshave finished egg laying. Avoid her-bicide application in June and Julywhen the adults are feeding onleafy spurge. No herbicide used forleafy spurge control directly affectsAphthona spp. adults or larvae.

Q. How much water do I use?

A. Proper calibration of thesprayer and uniform coverage ismuch more important than spray

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Leafy spurge has a second growthseason in late August andcontinues until the temperaturescool, changing foliage color fromyellowish-green to orangish hues.

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volume. Typically, applicators usingmulti-nozzle spray booms applyherbicides at 10 to 20 gallons peracre. Herbicides applied with a sin-gle-nozzle back-pack sprayer typi-cally use 60 gallons or more peracre.

Q. When is the best time tospray?

A. Proper timing depends on theherbicide you are using. See thetext and flea beetle life cycle charton page 8.

Q. How long before cattle andsheep are allowed to grazeafter a chemical application?

A. Tordon and Banvel can beapplied even if the pasture hasgrazing cattle present. However, donot transfer the livestock from treat-ed areas to pastures or croplandwith sensitive broadleaf plants forat least 12 months without firstallowing seven days of grazing onan untreated grass pasture.Otherwise urine may containenough herbicide to cause injury tosensitive plants. The waiting periodafter treatment with Banvel variesfrom seven to 90 days, so consultthe label before using.

Q. How many applications ofchemical are recommendedif used as an IPM method?

A. The number of applicationswill vary depending on the success

of the other control method used inthe IPM program. When used withAphthona spp. flea beetles, excel-lent control has been achieved withas few as one application, butsometimes two to three annualapplications are needed. If used inconjunction with grazing animals,three annual treatments workedbest.

Q. How close can I spray towater?

A. Long residual herbicidessuch as Tordon and Banvel shouldnot be used within 50 feet or less ofa body of water, depending on theterrain. Other leafy spurge herbi-cides can be used near or in water.See pages 18-19, which describespecific herbicides to control leafyspurge near water.

Q. What size of a leafy spurgepatch generally is too bigfor chemical treatments?

A. This is really dependent onbudget (see pages 26-27).Herbicides should be appliedaround the perimeter of even verylarge infestations to preventspread. It is never too early tobegin a treatment program, but itcan be very costly to start yearsafter the program should havebegun.

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TEAM Leafy Spurge is a USDA-Agricultural Research Serviceresearch and demonstration programfocused on the Little Missouri Riverdrainage in Wyoming, Montanaand the Dakotas, and otherleafy spurge-infesteddrainages in the region.Its goal is to research,develop and demon-strate ecologicallybased Integrated PestManagement strategiesthat can be used toachieve effective, afford-able and sustainable leafyspurge control.

TEAM Leafy Spurge is built onthree important concepts:

• Integrated Pest Management(IPM) – IPM combines managementtools to provide more effective controlthan any single tool could produce.Biological control provides the foun-dation: Biocontrol agents like the fleabeetle are used with other tools –multi-species grazing, herbicides, etc.– for effective, affordable and ecolog-ically sustainable control. IPM offersthe flexibility landowners need todevise different strategies for differentsituations.

• Teamwork – TEAM LeafySpurge has assembled some of the

nation’s most experienced leafyspurge researchers into a focused,goal-oriented team. This collaborationallows participants to share expertise,data and resources to more effective-

ly work toward a common goal.TEAM Leafy Spurge stresses

that EVERYONE, from pri-vate ranchers andlandowners to local,state and federal agen-cies, work together tosolve the problem.

• Regional Approach– TEAM Leafy Spurge is an

area-wide program, and assuch, is evaluating the leafy spurgeproblem on a regional rather than alocal, or place-by-place, basis.

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TEAM Leafy Spurge is funded byUSDA-ARS and managed in conjunc-tion with USDA-APHIS. Other teammembers include the U.S. ForestService, National Park Service,Bureaus of Land Management andReclamation, U.S. GeologicalService, state departments of agricul-ture and other state agencies,Cooperative Extension Services, landgrant universities, county weed man-agers, ranchers and landowners.

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• Gerry Anderson – program director, USDA-ARS Northern Plains AgriculturalResearch Laboratory, 1500 N. Central Ave., Sidney, MT 59270(406/433-9416, [email protected])

• Chad Prosser – program coordinator, Theodore Roosevelt National Park,Medora, ND 58645 (701/623-4730 ext. 3578; [email protected])

• Lloyd Wendel – co-principal investigator, USDA-APHIS PPQ/ Moorefield,Rt. 3 Box 1008, Edenburg, TX 78573 (956/580-7301;[email protected])

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• Rod Lym – North Dakota State University, Dept. of Plant Sciences, LoftsgardHall, Fargo, ND 58105 (701/231-8996, [email protected])

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TEAM Leafy Spurge research anddemonstration projects are designedto build on existing data and explorepromising new areas of leafy spurgeresearch. These projects cover arange of topics, including biologicalcontrol, multi-species grazing, herbi-cides, range management, and theintegration of various control tools.

TEAM Leafy Spurge demonstra-tion sites (Medora, ND; Ekalaka, MT;Buffalo, SD and Devil’s Tower, WY)give ranchers, landowners and landmanagers a first-hand look at theresults produced by various IPM

strategies. Tours of the sites havebeen held periodically to provideupdates about new and improvedmanagement strategies.

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Leafy spurge is a formidable oppo-nent that cannot be controlled oreliminated by any single entity ormanagement practice – a collabora-tive, integrated and area-wideapproach is essential to solving thiscostly program. TEAM Leafy Spurgeexists to promote these concepts,and to serve as a clearing house forproven management strategies.

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• Leon Wrage – South Dakota State University, Extension Service, Ag Hall/Box2207A, Brookings, SD 57007 (605/688-4591; [email protected])

• Tom Whitson – University of Wyoming/Dept. of Plant Science, Ag 1010,Laramie, WY 82071 (307/766-3113; [email protected])

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• Tim Faller – North Dakota State University – Hettinger Research ExtensionCenter, Box 507, Hettinger, ND 58639 (701/567-4323;[email protected])

• Kevin Sedivec – North Dakota State University – Extension RangelandSpecialist, Hultz Hall 100F; Fargo, ND 58105 (701/231-7647;[email protected])

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• Don Kirby – North Dakota Sate University, Dept. of Animal & Range Science,Hultz Hall, Fargo, ND 58105 (701/231-7658; [email protected])

• Jack Butler – USDA Forest Service, Rocky Mountain Research Station, 1730Samco Rd., Rapid City, SD 57702 (605/394-2670; [email protected])

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The following websites provide good information and links to other informationalsites.

• TEAM Leafy Spurge(http://www.team.ars.usda.gov) for information on integrated pestmanagement of leafy spurge, related topics and an extensive listing of otherinformational sources and websites.

• USDA-APHIS Noxious Weeds Home Page(http://www.aphis.usda.gov/ppq/weeds/facts.html) for general informationabout noxious weeds and APHIS management programs.

• NDSU-Department of Agribusiness and Applied Economics(http://agecon.lib.umn.edu/index.html) for information on the economicimpacts of leafy spurge and various management tools.

• Colorado Weed Management Association(http://www.cwma.org) for information on noxious weeds, weed controltechniques and weed management programs.

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“Herbicide Control of LeafySpurge” was published by theUSDA-ARS TEAM Leafy Spurgearea-wide integrated pest manage-ment program. TEAM LeafySpurge is headquartered at theUSDA-Agricultural ResearchService Northern PlainsAgricultural Research Laboratoryin Sidney, Montana(http://www.sidney.ars.usda.gov/)and managed in conjunction withthe USDA-Animal & Plant HealthInspection Service.

“Herbicide Control of LeafySpurge” was written by Rod Lym,North Dakota State University -Fargo, Department of PlantScience; Chad Prosser, TEAMLeafy Spurge coordinator;Celestine Duncan, WeedManagement Services, Helena,MT; Dean Bangsund, NorthDakota State University - Fargo,Department of AgriculturalEconomics, and Gerry Anderson,TEAM Leafy Spurge programdirector.

Funding provided by TEAM Leafy Spurge.September 2002

For information on obtaining additional copies of this manual,call 406/433-2020, e-mail [email protected]

or visit the TEAM Leafy Spurge website athttp://www.team.ars.usda.gov/

This manual can be viewed, printed and downloaded as a PDF(Adobe Acrobat Reader required)

from the TEAM Leafy Spurge website at

http://www.team.ars.usda.gov/herbicidemanual.html

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