EC03-177 Noxious Weeds of Nebraska: Purple Loosestrife · Title: EC03-177 Noxious Weeds of Nebraska: Purple Loosestrife Author: Stevan Z. Knezevic Keywords: EC03-177, noxious weeds,

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnHistorical Materials from University of Nebraska-Lincoln Extension Extension

1-1-2003

EC03-177 Noxious Weeds of Nebraska: PurpleLoosestrifeStevan Z. KnezevicUniversity of Nebraska at Lincoln, [email protected]

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University of Nebraska Cooperative Extension EC03-177-S

Noxious Weeds of Nebraska

PurpleLoosestrifeStevan Z. Knezevic, Integrated Weed Management Specialist

Biology

Identification

Distribution

Control

Figure 1. Thick stand of purple loosestrife.

1

Purple loosestrife (Lythrum salicaria) isan introduced invasive weed that is

overrunning thousands of acres of wet-lands and waterways in the Midwest.Once purple loosestrife (Figure 1) invadesa wetland, natural habitat is lost and theproductivity of native plant and animalcommunities is severely reduced. Theselosses in turn interfere with various levelsof the ecosystem and area recreationalactivities such as fishing, boating andhunting, diminishing revenue from tour-ism and impairing the social and eco-nomic well being of local communities.A single control measure cannot providelong-term, sustainable control of thisweed. An integrated approach, using avariety of mechanical, cultural, biologicaland chemical control methods, is neces-sary for long-term management.

History

Purple loosestrife is an invasive plant species believed to have been introduced to thenortheastern United States by European settlers in the early 1800s. Within several

decades it spread and major infestations developed throughout several states (Figure 2).Since then, it has slowly invaded wetlands and waterways, primarily around the GreatLakes and northeast United States (Figure 3). The fastest expansion occurred in the last50 years, aided by human activities such as recreational boating among water bodies.From 1950 to 2000 about 16 million acres became infested with loosestrife (Figure 4).Purple loosestrife infestations are documented in 40 states north of the 35th parallel,with the most severeinfestations around theGreat Lakes and in thenortheastern UnitedStates.

PurpleLoosestrife

Figure 2. Distribution of purple loosestrife in the first part of the 1800s.

Figure 4. Current distribution of purple loosestrife.Figure 3. Distribution of purple loosestrife in the mid 1900s.

Acres infested

Moderate to HeavyLight to ModerateUnknown

2

Impacts of Purple LoosestrifePurple loosestrife can have a major

negative impact on native wetlandhabitats, resulting in reduced productiv-ity of native plants and loss ofbiodiversity. Loss of native habitat andwildlife interferes with various levels ofthe ecosystem and influences manyrecreational activities, creating a negativeeffect on the social and economic wellbeing of local communities. With theloss of recreational land for fishing,boating and hunting, the local commu-nities also lose revenue from tourism.

Just a few years ago several loosestrifespecies — purple loosestrife, wand loose–strife (L. virgatum) and hybrid crosses —were sold across Nebraska as homelandscape species. While sellers said theywere “male sterile,” meaning they couldnot produce pollen, they could be cross-pollinated by other purple loosestrifeplants and produce viable seeds. In 2001the Nebraska Legislature officiallydeclared purple loosestrife a noxiousweed and made it illegal to grow or sellany loosestrife species.

Once loosestrife invades wetlands(Figures 5 and 6), the natural habitat isout of balance and the productivity ofnative plant and animal communities isseverely reduced. Song birds don’t feedon loosestrife seeds, muskrats can’t useroots for food or shelter, and waterfowllose nesting sites from dense stands ofloosestrife. Local wildlife populationstend to move to other habitats.

Loosestrife growing vigorously inirrigation canals, ditches, stream banksand reservoirs will clog the waterways,making less water available for cropproduction. Recreational lands also willbe affected, directly limiting recreationalactivities and tourism revenue. Fundsspent on weed control might be betterspent on improving wildlife habitats,boat ramps, and camping grounds.

Figure 6. When purple loosestrife invades wetlands, it can choke out native plants.

Figure 5. Infestation of a typical wetland habitat with purple loosestrife.

3

Purple loosestrife is a prolific seed pro-ducer and has a perennial root system

(rhizome). In one season each plant canproduce up to two million seeds, each ofwhich can remain viable for many years.Seeds are spread by water, wind, birdsand people. The rhizome grows well inmarshy soils and, if washed away bywater or other means, will further spreadthe plant population. Purple loosestrife isa highly competitive plant, growing fastand quickly trapping nutrients andsunlight. The soft muddy floor ofwetlands becomes a woven mat of tough

Biology

roots with no significant food value formany wildlife species. Few birds, fish, oranimals feed on purple loosestrife. Mostfeed, however, on other plant species thatgrow around purple loosestrife. By doing

Purple Loosestrife and Its Imitators

Figure 7. Purple loosestrife leaf (above) and flowering spike infull bloom. Figure 8a. American germander leaf (above) and flowering

plant.Figure 8b. Vervain leaf (above) and flowering plant.

Several plants native to Nebraska have purple flowers which may looksimilar to those of purple loosestrife. These plants, which include

American germander and various vervain species, are also commonlyfound near rivers, creeks and other bodies of water. To differentiate

between these species and purple loosestrife, carefully examine theplant’s leaves. The purple loosestrife leaf has a broad, rounded base andnarrows to a pointed tip. Leaves of both the American germander andvervain are more ovate in shape with serrated leaf edges.

With purple loosestrife no longer available for Nebraska landscapes, home gardeners mightuse spiked speedwell, lilies, Siberian iris, spiked gayfeather and garden sage, which offer

much of the beauty without posing a threat to the environment. Check with a local CooperativeExtension office for recommendations on alternative landscape species. Several NU CooperativeExtension publications also include information on selecting alternative species:

• “Growing Perennials“ (G-828),• “Perennials” (G-1015) and• “Perennial Flowers for Water-Wise Gardeners“ (G-1214).

this they indirectly eat themselves out ofhouse and home. As native vegetation isconsumed, more space is created forpurple loosestrife to spread and producenew plants.

4

Purple loosestrife (Figure 7) is relativelyeasy to identify; however, several na-

tive species produce purple flowers andmay be mistakenly identified as purpleloosestrife. Examples are American ger-mander (Teucrium canadense) (Figure 8a)and various vervain species (Verbena sp)(Figure 8b). They are commonly foundalong rivers, creeks and ditches in Ne-braska. Their purple flowers develop atthe same time as loosestrife; however,their leaf shape can be used as a distin-guishing feature. Purple loosestrife has arounded or heart-shaped leaf base and asharply pointed tip (Figure 7). Leaves ofAmerican germander and most vervainsare ovate in shape and have serrated leafmargins (Figures 8a and 8b).

In general, young purple loosestrifeshoots (Figure 9) start growing frommarshy river floors when the soil-watertemperature reaches about 60oF. Eachplant can produce several 3- to 9-foot tall

Figure 11. Portion of a dry spike with seed capsulesat the season end.

Figure 12. Individual seed capsules containingnumerous seeds.

Figure 9. Purple loosestrife seedling (3 inches tall). Figure 10. Square stem with opposite leaf arrangements.

stems. These stems are tough and oftenwoody at the base (Figure 10). Leaves arealternate, thin and sharply pointed. Eachstem can have up to five 1- to 3-foot longspikes on which the flowers are arranged.In Nebraska, loosestrife can flower fromJune to September. Flowers range fromred to rose-purple in color (Figure 7).

The fruit is a small oblong capsulewith two valves containing many smallseeds. There are many capsules within aspike (Figure 11). Purple loosestrifecollected in Nebraska has 50 to 150capsules per spike, depending on thespike length. Each of these capsules maycontain 40-100 seeds (Figure 12), so thateach plant may produce several hundredthousand seeds. The tiny brownish seedsare readily moved by wind, water, andanimals. Seeds will germinate whenexposed on bare soil with germinationrates as high as 95 percent. The rootsystem is very strong and when plantsmature, the root branches become thickand woody.

Identification

5

Purple loosestrife has no native natural enemies and outcompetesother plants, making it difficult to stop itfrom spreading. The biggest challenge isstopping the spread of the weed in cur–rently infested wetlands across Nebraska.Control should be based on an inte-grated management approach whichincludes a variety of mechanical, cultural,biological and chemical methods.

Prevention and EducationPublic education is a major element

in preventing the spread of purpleloosestrife. The private sector and variousstate and federal agencies should join tomake the public aware of the detrimentaleffects of this species. Without knowingthe potential ramifications, the publicmay inadvertently aid in its spread. Forexample, duck hunters may use purpleloosestrife stems to build duck blinds andcamouflage their boats, spreadingloosestrife seeds as they travel up anddown a river. Developing and dissemi-nating educational materials is a highpriority in the fight against this weed.

MechanicalManual. Pulling and digging plants

can be effective for small areas. Pulling ismost effective on plants that are one totwo years old. Loosestrife spreadsvegetatively from stems and can regener-ate from discarded plants. Pulled plantsshould be dried and burned. If pullingplants is not feasible, remove flower headsin July and August before seeds set.Cutting actually can spread loosestrife ifthe cuts are not removed because the cutroot and stalk can sprout. Remove andburn all cuts and make sure that all plantparts are in a carton or protected site sothat they can dry completely withoutdanger of being spread by wind, water orhuman or animal activity.

Mowing and disking. The basicassumption with repeated mowing(Figure 13) and disking is that repeatedremoval of new loosestrife regrowth willeventually deplete the rootstock ofnutrients and energy to regrow.Mechanical control measures make

loosestrife less competitive againstsurrounding native plants. Since loose-strife is commonly found in “semi-dry”areas, mowing or disking during dryperiods can be helpful and repeatedoperations will reduce the density ofloosestrife. Of the two methods, repeateddisking is more effective. Disking ormowing should begin in late May and berepeated three to four times per season. A

Figure 14. Controlled burns help control purple loosestrife by reducing seed on the soil surface and removing dead biomass, whichwill improve the efficiency of any herbicide application.

Figure 13. Repeated mowing operations, especially during dry periods, can help reduce the density of purple loosestrife infestations.

single disking or mowing operationpromotes loosestrife growth by creatingmany cuts that have a tendency to sprout,creating a thick mat of weed cover. Asingle disking or mowing operationshould be coupled with other controlmethods. The effectiveness of disking ormowing depends on the age of theloosestrife stand. Younger stands (less thanthree years old) can be suppressed by

Control Methods

6

Figure 15. Galerucella beetles are one of several biologicalcontrol methods available for purple loosestrife. Top tobottom left: Galerucella egg mass, larvae, adult beetle.Above: Resulting damage to purple loosestrife.(Insect photos courtesy of Don Hamilton, University of Guelph.)

safety and minimize risk. Adequate fuel,usually last year’s dead grass, is necessaryfor satisfactory results. Burning does notcontrol the root system and must becoupled with other control methods suchas disking or herbicides.

Flooding or drainage. Water levelmanipulation will not control thisspecies. Flooding suffocates young plantsthat grow from seeds, but will increasestands of taller and older plants. Incontrast, site drainage creates open baregrounds and increases seed germinationand expansion of loosestrife whenhigher water levels return. Permanentdrainage, however, can be an effectivecontrol method if the ground water tableis at least 10 feet below the soil surfaceand away from loosestrife’s root system.

Figure 16. Rearing pit for biological control agents, such as the Galerucella beetle, is approximately10x10 feet with at least 3 inches of water in the base, which is approximately 1 foot deep.

Figure 17. Pots with purple loosestrife plants covered by mesh sleeves provide a containedenvironment for rearing a starter population of biological control agents.

Flooding or drainage is not recom-mended unless it is carefully planned aspart of an integrated control project.

Intensive grazing. Loosestrife doesnot provide much food value to anyanimal species; however, deer or cattlewill graze small sprouts (less than 6inches tall). In certain pasture settings,intensive cattle grazing of a confinedarea beginning in early May can be partof an integrated approach.

Biological ControlBiological weed control or

biocontrol is the use of natural enemiesto reduce weed populations to economi-cally acceptable levels. Biocontrol agentsare an important component of anintegrated approach to stop the expan-sion of purple loosestrife in Nebraska.Several insect species have been intro-duced from Europe, including the rootweevil (Hylobius sp.), two beetles(Galerucella pusilla and G. calmariensis),and flower-feeding weevils (Nanophyessp.). Both adults and larvae are defoliatorsand feed only on purple loosestrife.These insects, in combination with othernaturally competing plant species, helpcontrol loosestrife in Europe.

Biocontrol agents are especiallyvaluable for sites that are not easilyaccessible for other control methods.For example, an aerial herbicideapplication can’t be used for purpleloosestrife growing under a large tree.Local insectariums could be establishedat such sites to rear and releasebiocontrol insects (Figure 15). Local,

repeated disking or mowing for three tofour years, but older stands require moretime.

Burning. Burning helps reduce seedat the soil surface and removes thickstands of dry biomass, making it easier touse other control methods such asherbicides. A controlled burn (Figure 14)should be timed for early spring (March-April) and approved and supervised bythe appropriate local authorities to ensure

7

Based on a survey conducted in 2001, it is estimated that about 12,000 acres of Nebraska’swetlands are infested with purple loosestrife, mostly along the main rivers and waterways

(Figure 19). The perfect loosestrife habitat is shallow, still, or slow moving water; however, thisweed will grow wherever there is standing water or a high ground water table.

Figure 19. Purple loosestrife distribution in Nebraska.

Distribution

Acres infested

Moderate to HeavyLight to ModerateNone

Table I.Herbicides, recommended rates and percent purple loosestrife control at 70 days after herbicide treatment (DAT) and a year later (365 DAT).*

Herbicide Active Ingredient Rate/acre Percent control at70 DAT 365 DAT

1. Rodeo Glyphosate 4.0 pts 85 802. Rodeo Glyphosate 6.0 pts 95 853. 2,4-D 2,4-D 2.5 pts 75 404. 2,4-D 2,4-D 5.0 pts 90 605. Garlon 3A Triclopyr 3.0 pts 78 456. Garlon 3A Triclopyr 5.0 pts 90 607. Arsenal Imazapyr 4.0 pts 85 998. Arsenal Imazapyr 6.0 pts 90 1009. Escort Metsulfuron 2.0 oz 75 9010. Escort Metsulfuron 4.0 oz 85 9511. Krenite Fosamine 3.0 gals 50 6512. Krenite Fosamine 5.0 gals 65 7013. Garlon + 2,4-D 3.0 pts + 2.5 pts 95 5014. Escort + 2,4-D 1.0 oz + 2.5 pts 90 75

*These recommendations were current as of Jan. 1, 2003. See “Guide for Weed Management in Nebraska” EC-130 for yearly updates.

state and federal agencies have collabo-rated to develop a biocontrol programin Nebraska. The program includesrearing and releasing the black-margined loosestrife beetle (Galerucellacalmariensis) and the golden loosestrifebeetle (Galerucella pusilla) (Figures 16 and17). For more information see NUCooperative Extension NebGuide,“Rearing and Releasing GalerucellaBeetles to Control Purple Loosestrife”(G01-1436).

Rearing and releasing insects is justone step in the biocontrol process.Monitoring insect establishment, spread,and impact is crucial to its success.Monitoring programs will determine theeffectiveness of Galerucella beetles. Formore information see the NUNebGuide, “Biological Control of PurpleLoosestrife: Monitoring GalerucellaEstablishment and Impact” (EC02-175).Finally, some experts believe that insectsalone can not provide adequate control

of purple loosestrife in North Americabecause such control is slow, taking 10-15 years before negative effects of insectfeeding can be observed. Thus, it is notvery useful as a short-term strategy andmuch research is needed before deter-mining its long-term usefulness.

ChemicalWhile herbicides are available for

controlling purple loosestrife, their usemay be limited because of wetlandhabitats. Herbicide selection and applica-tion rate are critical in providing selectivecontrol of purple loosestrife and notdamaging desirable wetland plants such ascattail (Typha sp) and bulrush (Scirpus sp.).Aquatic formulations of glyphosate canbe used to control purple loosestrife andnot permanently injure desirable speciessuch as: American germander (Teucriumcanadense L.), Partridge pea (Cassia sp.),sweet clovers (Melilotus spp), and nutsedges(Cyperus spp). When carefully used,herbicides can be effective tools instopping the expansion of purpleloosestrife, especially considering thatbiocontrol agents are slow in achievingthe desired level of control. Herbicidescan be used along roadsides and ditches,common corridors for the spread ofpurple loosestrife. Furthermore, the use ofherbicides once in a three- to five-yearperiod integrated with other controlmethods may prove to be a soundmanagement strategy.

Recommended herbicides include:Rodeo, Garlon 3A, Arsenal, Escort,Krenite, and 2, 4-D (Table I). Before usinga herbicide, check the label carefully forrecommended rates, appropriate additivesand plant species sensitivity. The best timeto apply herbicide is at the beginning ofthe flowering stage, usually in late Juneand July. This timing is preferred becauseplants can be easily identified (purpleflowers), and flowering is one of the mostvulnerable stages for chemical control ofperennial species. Herbicide solutions canbe applied using a backpack sprayer,tractor-mounted or pulled sprayer, or boator aerial application in solutions rangingfrom 10 to 20 gallons per acre.

Each of the recommended herbicides(Table I) has benefits and risks associatedwith its use. Garlon, 2,4-D, or a mixture

8

of the two will provide short-termsuppression. Yearly applications will beneeded for several years, but annualexpenses will be low. Following herbi-cide application, purple loosestrifedensity should decline, allowing nativegrassy and cattail populations to increase.

Longer term control, which meansspraying once in several years, can beachieved with Rodeo (and other aquaticglyphosates), Escort, Arsenal or a mixtureof Escort and 2,4-D. Arsenal should beused for specifically targeted andcontrolled sites. Due to the nonselectivenature of these herbicides, they should

Figure 18. Perennial life cycle of purple loosestrife in Nebraska.

April May June July August Sept Oct Nov

Spring Summer Fall WinterDevelopment of plants from seed

Established plants

New emergence Stem Multiple shoot Flowering Seed production Root prepares Dormancy& continual crown growth elongation to overwinterdevelopment and branching

April May June July August Sept Oct Nov

Yea

r 1

Yea

r 2*

Spring Summer Fall Winter

Treatment** Treatment***

Emergence Root and crown Stem Flowering Seed production Root prepares Dormancyfrom seed development growth to overwinter

Treatment** Treatment***

*Life cycles in Year 2 and consecutive years are similar.**Spring treatment should be before or at flowering stage.***Fall treatment should be two weeks before killing frost.

be used as part of an integrated and site-specific approach. They also should berotated among different managementunits and different years. Nonselectiveherbicides should not be used continu-ously at the same “management unit” formore than two to three years to allowthe native vegetation to regrow and toavoid the development of herbicideresistant species. Of the recommendedherbicides (Table I), only two products —aquatic glyphosate and aquatic 2,4-D —are currently registered in Nebraska foruse in aquatic sites (sites continuouslyunder water). Information on herbicide

use is updated annually and published inthe NU Cooperative Extension publica-tion, the “Guide for Weed Managementin Nebraska” (EC-130).

Management Tips for Larger Land AreasPurple loosestrife infestations can

initiate from seeds or root segments andcan easily spread over a large area withina few years. Examples of such infesta-tions are evident at many Nebraska sites,ranging in size from several hundred toseveral thousand acres.

Infested areas should be divided intomanagement units (eg. blocks, sections,

9

etc). Each unit should have a controlplan that fits its site-specific characteris-tics. Such an approach is commonlyreferred to as “site specific management.”Common site characteristics include thelayout and configuration of the land aswell as the composition of plant andanimal species. The number of manage-ment units can be adjusted, dependingon the size of the infested area. Largerand more diverse areas can have moremanagement units. The level of purpleloosestrife infestation should be deter-mined for each management unit, usinga simple visual scale ranging from zero to100. The zero indicates no loosestrifeplants while 100 indicates an area totallycovered with loosestrife. The followingexample illustrates a control plan for ahypothetical scenario and integratedcontrol approach.

The hypothetical site was divided intofive management units with infestationlevels ranging from 10 percent to 95percent, including: Unit 1 (less than 10percent); Unit 2 (about 30 percent); Unit3 (about 50 percent); Unit 4 (about 70percent), and Unit 5 (more than 90percent). By using management units,integrated control measures can bematched to the identified need.

In Unit 1 effective loosestrife controlwould be achieved by simply cutting,pulling or digging loosestrife plants andspot spraying with herbicides. Biocontrolagents should not be used alone in thissituation since their population can notgrow as fast as the loosestrife stand.Remember that loosestrife can rapidlyspread through seed production andspreading roots. In Unit 2 control shouldbe based on a combination of repeateddisking and mowing, burning and spot

application of appropriate herbicides.Herbicides should be rotated in alternat-ing years to avoid off-target plantsuppression. Biocontrol agents should notbe used alone for the same reason as inUnit 1.

With Units 3, 4, and 5 control wouldbe more complex and require carefulplanning and timely use of control tools.In these units, control can be based on acombination of repeated mowing anddisking, burning, herbicides andbiocontrol. Remember, however, thatusing any of these methods alone willlikely not provide successful control.Start releasing biocontrol agents to allowbuildup of insect populations. If controlefforts on the first four units are takingmost of the time, control in Unit 5 canbe postponed. In reality, the areas thathave more than 90 percent loosestrifecover are somewhat of a “lost cause” andshould be kept isolated until successfulcontrol is achieved in less infested areas(e.g. Units 1 to 4). Unit 5 should bemonitored as the potential source ofinfestation material for further weedexpansion. If time and expenses allow,the control program in Unit 5 should bebased on the same principle as in otherunits. An aerial application of herbicidesalso should be considered, especially ifthe site is hard to access by land or boat.In general, herbicides should be rotatedbetween units and years to avoid offtarget plant suppression. In this exampleeradication of purple loosestrife is likelypossible in Units 1 and 2, but may notbe possible in Units 3, 4, and 5. Fromboth biological and economic perspec-tives, it’s important to control earlyinfestations of purple loosestrife and notallow them to expand.

SummaryPurple loosestrife is a serious

perennial weed found in wetlands of theprairie states, including Nebraska. Due tomajor characteristics of the loosestrifehabitat (e.g. marshy land) neitherherbicides nor biocontrol agents usedalone can provide long-term control ofthis weed; however, if they are integratedwith other weed management methods,long-term and cost effective control goalscan be achieved. Developing a site-specificmanagement plan will be most importantin controlling this invasive weed.

AcknowledgmentThe author expresses many thanks to

the following individuals who havecollaborated in research and extensionactivities related to the purple loosestrifeproject: Doug Smith, Dixon Countynoxious weed superintendent; RalphKulm, Holt County extension educator;Don Doty, district conservationist,Papio-Missouri Natural ResourceDistrict, Omaha; Dick Kinkaid, BuffaloCounty noxious weed superintendent;Mick Goodrich, Brown County noxiousweed superintendent; Rod Stolcpart,Rock County noxious weed superinten-dent; Neil Von Eschen, Charles Mix(S.D.) County noxious weed superinten-dent; and Judy Engelhaupt, BoydCounty noxious weed superintendent.

Note: Reference to commercial productsor trade names is made with the under-standing that no discrimination is intendedand no endorsement by CooperativeExtension is implied.

10

The State of Nebraska has had a noxious weed law formany years. Over the years, the Nebraska Legislature hasrevised this law.

The term "noxious" means to be harmful or destructive.In its current usage "noxious" is a legal term used to denote adestructive or harmful pest for purposes of regulation. When aspecific pest (in this case, a weed) is determined to pose aserious threat to the economic, social, or aesthetic well-beingof the residents of the state, it may be declared noxious.

Noxious weeds compete with crops, rangeland, and pas-tures, reducing yields substantially. Some noxious weeds aredirectly poisonous or injurious to man, livestock, and wildlife.The losses from noxious weed infestations can be staggering,costing residents millions of dollars due to lost production. Thisnot only directly affects the landowner, but erodes the tax basefor all residents of the state. The control of noxious weeds iseveryone's concern and their control is to everyone's benefit.The support of all individuals within the state is needed andvital for the control of noxious weeds within Nebraska.

It is the duty of each person who owns or controls landin Nebraska to effectively control noxious weeds on theirland. County boards or control authorities are responsible foradministration of noxious weed control laws at the countylevel. This system provides the citizens of Nebraska with

"local control". Each county is required to implement acoordinated noxious weed program. When landowners fail tocontrol noxious weeds on their property, the county canserve them with a notice to comply. This notice gives specificinstructions and methods on when and how certain noxiousweeds are to be controlled.

The Director of Agriculture determines which plants areto be deemed as "noxious" and the control measures to be usedin preventing their spread. In Nebraska, the following weedshave been designated as noxious:

Canada thistle (Cirsium arvense (L.) Scop.)Leafy spurge (Euphorbia esula L.)Musk thistle (Carduus nutans L.)Plumeless thistle (Carduus acanthoides L.)Purple loosestrife (Lythrum salicaria L. and L. virgatum -

including any cultivars and hybrids)Knapweed (spotted and diffuse) (Centaurea maculosa Lam.

and C. diffusa Lam.)

Whether farmer or rancher, landowner or landscaper, it'severyone's responsibility and everyone's benefit to aid incontrolling these noxious weeds. If you have questions orconcerns regarding noxious weeds in Nebraska, please contactyour local county noxious weed control authority or theNebraska Department of Agriculture.

A Message From the Nebraska Department of Agriculture

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department ofAgriculture. Elbert Dickey, Dean and Director, University of Nebraska, Institute of Agriculture and Natural Resources.

University of Nebraska Cooperative Extension educational programs abide with the non-discrimination policies of the University of Nebraska-Lincolnand the United States Department of Agriculture.

PurpleLoosestrife

Published by University of Nebraska Cooperative Extension in cooperation withand with financial support from the Nebraska Department of Agriculture.

Illustration of the purple loosestrife is by Debra K. Meier; originally publishedin Weeds of Nebraska and the Great Plains and used with permission of thepublisher, the Nebraska Department of Agriculture.