Extension Special Series 34 Revised 2010 Noxious Weedsoglalalakota.sdcounties.org/files/...Weeds-of-South... · • The weed is not native to South Dakota. Local noxious weeds Weeds

Extension Special Series 34Revised 2010

South Dakota State UniversityCollege of Agriculture & Biological Sciences

Cooperative Extension ServiceU.S. Department of Agriculture

NoxiousWeeds

of South Dakota

Noxious weeds are a big problemOver 4 million acres infested in South Dakota. Statewide losses from noxious weeds exceed $140 million annually. The acreage and cost will continue to increase unless those responsible take action to control and eradicate noxious weeds on the land.

Noxious weed characteristics A weed must possess the following characteristics to be declared noxious statewide: • Theweedisperennial. • Theweedhasuniquecapabilitytospreadrapidly. • Theweedisnotcontrollablewithoutspecialpreven-

tion or management. • Theweediscapableofdecreasingthevalueofland. • Theweediscapableofmateriallyreducingthepro-

duction of crops or livestock. • TheweedisnotnativetoSouthDakota.

Local noxious weeds Weeds may be designated locally noxious upon requestfromcountiesandapprovalfromtheSouth Dakota Weed and Pest Control Commission. Local nox-ious weeds have the following characteristics: • Theweedisbiennial,perennial,ora

pernicious annual. • Theweediscapableofspreadingrapidly. • Theweedisnotcontrollablewithoutspecialpreven-

tative or management practices. • Theweediscapableofmateriallyreducingproduc-

tion of crops and livestock. • Theweediscapableofdecreasingthevalueofthe

land.

Cover photo: Common tansy



Cooperative Extension ServiceU.S. Department of Agriculture

NoxiousWeeds

of South Dakota

Canada thistle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Leafy spurge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Perennial sowthistle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Hoary cress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Purple loosestrife. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Saltcedar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Russian knapweed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Spotted knapweed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Diffused knapweed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Musk thistle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Plumeless thistle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Bull thistle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Scotch thistle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Sulfurcinquefoil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Field bindweed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Absinth wormwood. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Dalmatian toadflax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Yellow toadflax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Houndstongue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Common tansy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

St. Johnswort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Puncturevine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Common mullein. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Common burdock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Giant knotweed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Chicory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Poison hemlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

European common reed (Phragmites) . . . . . . . . . . . . . . . 32

Black henbane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Table of Contents

5

Weed: Noxious statewide. Creeping perennial.

Leaves: Smooth,mediumgreen,spine-tipped,crinkled margin. Smaller than biennial thistle.

Stems: 2-to5-feettall,grooved,branchingattop.

Flowers: Numerous flowers on branched heads. About .75-inch.Usuallylavender,maybepinkorwhite.Separate male and female flowers.

Roots: 10- to 15-feet deep.

Sites: Grows statewide. Common in pasture and range; also grows in trees and cultivated fields.

Notes: Difficult to control.

Canada thistleCirsium arvense

6


Leaves: Alternate,long,narrow,drooping,darkgreen.

Stems: 2- to 3-feet tall. Plant contains milky sap.

Flowers: Small green flowers surrounded by yellow-green bracts. Seed explodes from a 3-celled capsule.

Roots: Dark brown with pink buds. May reach 20-feet deep.

Sites: Growsinallcultivatedcrops,pastures,range,trees,and wetlands.

Notes: Capable of rapid spread. Seed matures 7 to 10 days after first flower color.

Leafy spurgeEuphorbia esula

7


Leaves: Alternate.Dandelion-shaped,4-to8-inches.Irregu-larlylobed,spine-tippededges.

Stems: Smooth,3-to7-feettall.Entireplantcontainsmilkyjuice.

Flowers: Branchedclusters,yellow-orange,about1.5-incheslong.

Roots: Deep,spreading.

Sites: Cultivatedfields,pastures,roadsides,especiallyinwet,moistsites.

Notes: Capable of rapid spread. Most persistent in wet areas.

Perennial sowthistleSonchus arvensis

8


Leaves: Lowerleavesspatulate,tapered,slenderbase. Upperleavesclasparoundstem.Wavy,indented leaf margins.

Stems: 1-to2-feettall,branchedtowardtop.Finewhitishhairs.

Flowers: Small,white,4-petalled,borneinflat-toppedclusters.

Roots: 10-to15-feetdeep.Fine,branching,penetrating.

Sites: Small,scatteredinfestationsstatewide.Commoninroadsides,pastures,andrange.

Notes: Requirestreatmentinearlyspring(May). Metsulfuron is more effective than growth regulators (2,4-D,dicamba,picloram,oraminopyralid).

Hoary cressCardaria draba

9


Leaves: Opposite,linear,smoothmargins,nopetiole.

Stems: 4-to8-feettall.Stiff,woodywith4or6sides.Olderplants are heavily branched.

Flowers: Purple-magenta,5-to6-petalled.Arrangedinlongspikes.

Roots: Veryheavyroot,newbranchesfrombase.

Sites: Seriousinvaderinmarshes,alongstreamsandinwetlands. Limited to “wild” infestations.

Notes: Seed develops in floating capsules.

Purple loosestrifeLythrum salicaria

10

Weed: Noxious statewide. Perennial shrub or tree.

Leaves: Alternate,cedar-likeonslender,branchedgreenstems.

Stems: Smooth,woody,darkbrowntoreddish-brown.

Flowers: White to deep pink. 5-petaled. Formed in finger-like clusters in mid to late summer.

Roots: Deep,extensivetaproot.

Sites: Floodplainsalongrivers,lakes,andornamentalplantings.

Notes: Excessive water consumer; depletes surface water. Very invasive. Spreads from seed or stem fragments.

SaltcedarTamarix spp.

11


Leaves: Grayish,knaplikehairs,lowerleavesdeeply indented,upperleavesshort.

Stems: 2-to3-feettall.Veryhairy,tough,branched.

Flowers: White to light rose. Small clusters on branched tips.

Roots: Deep,darkbrown-black,scaly.

Sites: Wasteareas,grassland,andoccasionallyin cultivated fields.

Notes: Scattered,smallinfestations.Persistent.

Russian knapweedAcroptilon repens

12

Weed: Local noxious. Biennial or short-lived perennial.

Leaves: Alternate,deeplydividedintonarrowsegments.Much smaller near top.

Stems: 1-to3-feettall,hairybranched.

Flowers: About.75-inchacross,pinktopurple,darkspotsonflower bracts.

Roots: Biennial taproot. Forms rosette first season.

Sites: Pastures,range,androadsides.

Notes: Diffuseknapweedsimilar,butlacksdarkspotsonflower bracts.

Spotted knapweedCentaurea biebersteinii

13

Weed: Local noxious. Biennial or short-lived perennial.

Leaves: Alternate,hairy,narrow,divided.Grayish-green.Basalleaves whorled.

Stems: 1-to2-feet,rough,erect.

Flowers: White to rose or purplish. Bract tips under the flower have yellow spine with comb-like teeth.

Roots: Long taproot. Rosette first season.

Sites: Pasture,range,androadsides.

Notes: Very competitive plant.

Diffuse knapweedCentaurea diffusa

14

Weed: Local noxious. Biennial.

Leaves: Coarselytoothed,darkgreenwithwhitemidrib.Spine-tipped lobes.

Stems: 4-to6-feettall.Stout,wing-likegrowth.

Flowers: Large,2-inch,powder-puffshape.Deeproseto lavender,bornesingularly,noddingoncurvedstem.

Roots: Heavy,branchingtaproot.Formsrosette1stseason.

Sites: Pastures,range,trees,alongcreeksanddugouts.

Notes: Prolific seed producer. Aggressive. Control before bloom at rosette stage in fall or spring.

Musk thistleCarduus nutans

15


Leaves: Deeplydivided,crinkly,hairy.Lobestippedwithlong,yellowish spines. White midrib.

Stems: 3-to5-feet,branched.Spiny,wing-likegrowth.

Flowers: .5-to.75-inch,reddish-purple.Producedinclusters.

Roots: Heavy,branchedtaproot.Formsrosette1stseason.

Sites: Pastures,range,trees,alongcreeksanddugouts.

Notes: Aggressive weed. Control before bloom. Treat at rosette stage in fall or spring.

Plumeless thistleCarduus acanthoides

16


Leaves: Large,deeplylobed,thick,darkgreen,spine-tipped,covered with hair.

Stems: 3- to 6-feet tall. Branched.

Flowers: 1- to 2-inches. Shaving-brush shape. Rose to deep purple,spinybase.

Roots: Heavy,branchedtaproot.Formsrosette1stseason.

Sites: Pastures,range,trees,andfarmsteads.

Notes: Less aggressive than some biennials. Capable of producing dense stands.

Bull thistleCirsium vulgare

17


Leaves: Verylarge,coarse,gray-green,spine-tipped,havedense hair.

Stems: 5- to 6-feet tall. Strongly branched. Heavy winged appendage growth.

Flowers: 1-to2-inches,reddish-purple.Sharpbractsonbase.

Roots: Heavy taproot. Forms rosette 1st year.

Sites: Pasture,range,anddisturbedsitesinsouthwestareaof state.

Notes: Control before bloom.

Scotch thistleOnopordum acanthium

18

Weed: Local noxious. Perennial. Leaves: Alternate on stem. Sparsely hairy. Palmately divided with

5 to 7 leaflets with the longest leaflet in the middle. Leaf margins toothed.

Stems: 1- to 3-feet tall. Hairy. 1 to 3 stems that branch just beneath the flowering inflorescence.

Flowers: Light yellow with yellow center. 5 petals with notches at the tip. Develop in clusters at the ends of the branches.

Roots: Branching taproot. New shoots may emerge from the edgesoftherootmass,causingoldplantstodevelopacircular pattern of shoots.

Sites: Pastures,grasslands,roadsides,wasteplaces. Notes: Most problematic in pastures and grasslands in western

SouthDakota,whereitcanbeverycompetitive.Othersimilarcinquefoilspecies,suchasroughcinquefoil,arecommonbutarenotasinvasive.Roughcinquefoilhas 3leaflets,andtheflowerpetaltipsarenotnotched.

Sulfur cinquefoilPotentilla recta

19

Weed: Local noxious. Creeping perennial.

Leaves: Arrowhead-shaped,usuallyroundedtip.Spreadingbasal lobes.

Stems: Smooth,2-to7-feetlong.Spreadsovertheground.

Flowers: Whiteorpink,funnel-shaped.About1-inch.Twofinger-like bracts below flower.

Roots: 20-to30-feetdeep.Extensive,spreading.

Sites: Cultivatedfields,pastures,range,trees,roadsides,home grounds. Adapted to dry conditions.

Notes: Most widespread noxious weed in South Dakota. Requires2-to4-yearcontrolplan.

Field bindweedConvolvulus arvensis

20

Weed: Local noxious. Perennial.

Leaves: 2-to5-incheslong,alternate.Lowerleavesdeeplydivided. Upper leaves linear and less divided. Gray-green.

Stems: 2-to4-feettall,heavilybranched.Coveredwithgrayhairs,givinggrayish-greencast.Distinctsagefragrance.

Flowers: Small,yellow,compact,short-stalked.

Roots: Extremelyheavy,fibrousroot.Perennialcrownareaswith buds.

Sites: Pastures,trees,androadsides.Primarilyeastof Missouri River.

Notes: Also called “wormwood sage.” Aggressive. Control plants in fall (Sept.–Oct.) or spring (May–June) when less than 12-inches tall.

Absinth wormwoodArtemisia absinthium

21


Leaves: Lightgreen,alternate,dense,broad-based,heart-shaped,individuallyclaspingthestem.Appearwaxyin spring.

Stems: Erect,1-to3-feettall,smooth.

Flowers: Yellow,about.75-to1.5-inches.2-lipped.Bearded,orange throat with straight spur.

Sites: Non-cropland,wasteareas,grassland,andrange.Prefers coarse-textured soils. Black Hills area.

Notes: Mature,establishedplantsextremelycompetitive.Considered toxic to livestock.

Dalmatian toadflaxLinaria dalmatica

22


Leaves: Palegreen,numerous,narrow,pointedatbothends,2.5-inches long.

Stems: Erect,1-to2-feettall,sparsehairsorsmooth.

Flowers: Yellowtopalecream,about1-inchlong.Longbearded throat with straight spur. Often flowers in late summer (August).

Sites: Non-cropland,wasteareas,roadsides,grassland,range,andcultivatedfields.

Notes: Difficulttocontrol,mildlypoisonoustolivestock.

Yellow toadflaxLinaria vulgaris

23


Leaves: Alternate,rough.Basalleavesbroad,12-incheslong.Upperleafnarrow,clasping.

Stems: 1- to 4-feet tall.

Flowers: Reddish purple. Fruit divides into 4 nutlets that cling to livestock and clothing.

Roots: Heavy taproot. Forms rosette the 1st year.

Sites: Pasture,range,androadsides.BlackHillsarea.

Notes: Poisonous plant to livestock. Damages liver.

HoundstongueCynoglossum officinale

24


Leaves: Alternate,compoundwithoblongsegmentswithtoothed edges. Bright green.

Stems: 1-to3-feet,stout,erect,usuallysmooth.Unpleasantodor.

Flowers: Numerous,rounded,button-shaped,brightyellow,inflattened clusters.

Roots: Strong,fibrous.Reproducesfromshortrhizomes.

Sites: Roadsides and along streams. Black Hills area.

Notes: Aggressive and difficult to control along streams and under trees.

Common tansyTanacetum vulgare

25


Leaves: Opposite,oblong,blackdotsalongmargin.

Stems: 1-to3-feettall.Smooth,branched,erect,somewhat2-edged.

Flowers: Brightyellow,5-petalled.Blackdotsalongmargin.

Sites: RangelandinBlackHillsarea,roadsides,forests,andnon-crop sites.

Notes: Considered a poisonous plant; acts as a photo sensi-tizertolivestock.

St. JohnswortHypericum perforatum

26

Weed: Local noxious. Pernicious annual.

Leaves: Small,oblong,hairy,dividedintocompoundleaves.

Stems: Hairy,prostrate,formsdensemat.

Flowers: Small,yellow,5-petalled.Producedinleafaxils.

Roots: Simple taproot.

Sites: Roadsides,wasteareas,andalongsidewalksinopen,droughty,traffickedareas.

Notes: Seedsforminsharp,thick-spinedbursthatpuncturetires and shoes. Also called “Texas sandbur” or “goat-head.”

PuncturevineTribulus terrestris

27


Leaves: 6-to18-incheslong,oblong,denselywooly.Paleyellow-green.

Stems: 3-to7-feettall,stout,seldombranched,coveredwithwooly hair.

Flowers: 5-lobed,sulfuryellow.About1-inchacrossindensespikes.

Roots: Branched taproot. Forms rosette 1st season.

Sites: Range,pastures,androadsides.

Notes: Most common in southwestern South Dakota.

Common mulleinVerbascum thapsus

28


Leaves: Large,heart-shaped,darkgreen.

Stems: 3-to5-feettall,branched,hairy,somewhatangular.

Flowers: Numerous red-violet flowers surrounded by hooked bracts that form a .5-inch diameter bur at maturity.

Roots: Large,fleshytaproot.

Sites: Trees,alongcreeksandstreams.Growsstatewide.

Notes: Burs become entangled in hair and wool. Also called “wild rhubarb.”

Common burdockArctium minus

29


Leaves: Cordate (heart-shaped). May be 6- to 12-inches long and 4- to 8-inches wide. Arranged alternately along stem.

Stems: Bamboo-like stems are hollow and swollen at nodes. 5- to 10-feet tall.

Flowers: Numerous racemes containing small greenish-white flowers in late summer.

Roots: Vigorousrhizomes;rootsmayextenddeepinsoil.

Sites: Moistareasalongditches,streambanks.BlackHillsarea.

Notes: Very difficult to control with mechanical or chemical means.

Giant knotweedPolygonum sachalinense

30


Leaves: Alternate.Lowerleavesrosette,toothed.Stemleavesclasp at the base. Narrow. 1- to 3-inches long.

Stems: Erect,branched,haveridges.Containmilkylatex.

Flowers: Blueorpurple.Squaretipwithfine-toothedpoints.

Roots: Taproot,maybebranched.

Sites: Roadsides,wasteareasandpasture.

Notes: Used as a coffee substitute. May cause dermatitis.

ChicoryCichorium intybus

31


Leaves: Fern-like,finelydivided.Leafletstoothed,smooth.Musty odor.

Stems: Erect,3-to10-feettall.Highlybranched,ridged,smooth with purple blotches.

Flowers: White,5petalsformedinanumbel1.5-to3-incheswide.

Roots: Taproot.

Sites: Moistsitesinpasture,range,androadsides.Allpartspoisonous.

Notes: Can be lethal. Sometimes confused with non-toxic plants such as wild parsnip.

Poison hemlockConium maculatum

32

Weed: Local noxious. Creeping perennial grass. Leaves: Greenish-gray,maybeslightlydarkerthannative

phragmites. Strap-like and tapper to a point. May be up to 2-inches wide and 24-inches long. Alternate on stem. Leaf sheaths on dormant stems may be more difficult to remove on invasive phragmites than on the native.

Stems: Oftenroughanddullandslightlyribbed,whereasthenative is often smooth and shiny. Often more rigid than native.Usuallydormantstemstan,whereasthenativemaybe reddish. Grows up to 15-feet tall.

Flowers: Fluffyfloweringplumeinmid-tolatesummer.Inflores-cence may be more dense than native phragmites.

Roots: Vigorousrhizomesthatmayformdensemats. Sites: Sunnywetlandhabitatsincludingmarshes,streamsorlake

shores,ponds,wetmeadows,androadditches.Similarhabitat as native phragmites and cattails.

Notes: Appearance similar to the native phragmites (Phragmites australissubsp.americanus),butmoreinvasive.Thenativephragmites is not a restricted local noxious weed.

European common reed (Phragmites)Phragmites australis subsp. australis

33

Weed: Local noxious. Annual/biennial. Leaves: Alternateonstem.Coveredwithfine,slightlystickyhairs.

Large leaves may be up to 8-inches long and 6-inches wide. Coarsely toothed or shallowly lobed margins. Foul odor.

Stems: 1–3fttall.Thick,coarse,andhairy. Flowers: Large,funnel-shapedshowyflowersaregreenish-yellow

with purple veins and a dark purple center. 5 lobes up to 2-inches across. Visible from May to September. Plants producelongspikescoveredwithsmall,pineapple-shapedseed pods on one side of the stem.

Roots: Fleshy taproot. Sites: Pastures,fencerows,roadsides,wasteplaces,disturbed

logging areas. Notes: MostcommonintheBlackHillsarea,butmaybefound

throughout western and central South Dakota. May be toxic tohumansandlivestock,butlivestockusuallyavoidgrazingit. Several broadleaf herbicides may effectively control it.

Black henbaneHyoscyamus niger

The law can be enforcedThe South Dakota Weed and Pest Control Commission is responsible for developing and implementing a state-widecontrolprogram.SouthDakotastatuterequiresevery landowner to control noxious weeds on their land. Voluntary compliance is encouraged.

State law provides enforcement procedures used when landowners fail to comply. The laws and regulations are enforced by the South Dakota County Weed and Pest Boards and the South Dakota Department of Agriculture. Failure to comply initiates a formal process that could resultinfines,taxlevies,andliensagainstthelandsofthe owner.

Uncontrolled noxious weeds that present a nuisance to area lands should be reported to county Weed and Pest officials.


U.S. Department of Agriculture

Program support from South DakotaWeed and Pest Control Commission

South Dakota State University, South Dakota counties, and U.S. Department of Agriculture cooperating. South Dakota State University is an Affirmative Action/Equal Opportunity Employer and offers all benefits, services, education, and employment opportunities without regard for race, color, creed, religion, national origin, ancestry, citizenship, age, gender, sexual orientation, disability, or Vietnam Era veteran status.

This publication can be accessed athttp://pubstorage.sdstate.edu/AgBio_Publications/articles/ESS34.pdf

6M revised copies printed at a cost of ??¢ each. 9-10. AX121.

Noxious Weeds of South Dakota


Leon Wrage, Distinguished professor, emeritus Darrell Deneke, Extension IPM coordinator Mike Moechnig, Extension weed specialist

Thistles

Flowers: A–perennial sow thistle; B–Canada thistle; C–plume-less thistle; D–tall thistle; E–bull thistle; F–Flodman’s thistle; G–musk thistle.

Leaves: A–tall thistle; B–bull thistle; C–musk thistle; D–plume-less thistle; E–Flodman’s thistle; F–Canada thistle; G–perennial sow thistle.

Additional information

County Extension Officeor

County Weed and Pest Supervisor

Extension Special Series 34 Revised 2010 Noxious Weedsoglalalakota.sdcounties.org/files/...Weeds-of-South... · • The weed is not native to South Dakota. Local noxious weeds Weeds

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