USDA 

-=--~-= 

D 

United States Department ofAgriculture 

Field Guide for Managing

Russian Knapweed

in the Southwest 

Forest Southwestern 

Service Region TP-R3-16-13 Revised June 2017 
 

 

 

 

Cover Photos 

Upper left: Steve Dewey, Utah State University, Bugwood.org 

Upper right: Steve Dewey, Utah State University, Bugwood.org 

Bottom center: Steve Dewey, Utah State University,Bugwood.org 

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Russian knapweed (Rhaponticum repens L., formerly Acroptilon repens L. 

Sunflower family (Asteraceae) 

Russian knapweed is an invasive plant that has been listed 

as a noxious weed in both Arizona and New Mexico. This 

field guide serves as the U.S. Forest Service’s 

recommendations for management of Russian knapweed 

in forests, woodlands, and rangelands associated with its 

Southwestern Region. The Southwestern Region covers 

Arizonaand New Mexico, which together have 11 national 

forests. The Region also administers 4 national grasslands 

located in northeastern New Mexico, western Oklahoma, 

and the Texas panhandle. 

Description 

Russian knapweed (synonyms: hardheads, Turestan thistle, 

creeping knapweed, mountain bluet, Russian cornflower) 

is an introduced, long-lived, creeping perennial. It can be 

distinguished from other knapweeds by its scaly, brown to 

black, spreading rhizomes and by its unique flowering 

bract features. 

Growth Characteristics 

• Long-lived, creeping perennial; relatively shade 

intolerant; slow to establish but can spread rapidly 

once present; difficult to eradicate. 

• Grayish-green rosette base; dense hairs; emerges in 

early spring. 

• Erect branching stem, 18 to 36 inches tall, covered 

with cobwebby hairs. 

• Brown to black, scaly rhizomes; long lived, deep 

vertical root system (grows to 20 feet deep or more). 

• Flowers from June to September; pink tolavender, 

thistle-like, terminal flowers; urn-shaped flower 

heads, 0.25 to 0.5 inch in diameter; rounded bracts 

with papery tips. 

• Reproduces mainly vegetatively via root buds near 

each scale on the rhizome; forms dense patches of 

cloned plants. Also produces seed (50 to 500 seeds 

per plant; viable for 2 to 3 years). 

• Releases allelopathic chemicals that can inhibit 

growth of other plants; has sesquiterpene lactones 

that are toxic to horses. 

Ecology 

Impacts/Threats 

In dense stands, Russian knapweed develops into a near 

monoculture due to its ability to out-compete resident 

vegetation. Such monocultures can contribute to reduced 

wildlife presence and a decline in species diversity.This 

knapweed is toxic to livestock (especially horses), and its 

presence reduces forage availability. 

Site/Distribution 

Russian knapweed adapts to a variety of soil types, 

including poorly drained and alkaline/saline soils. It 

prefers areas with moist but not excessively wet soils. It 

readily invades pastures, degraded croplands, alfalfa fields, 

rangeland, roadsides, riparian and runoff areas, river 

bottoms, drainages, and irrigated fields. 

This invasive weed is the most widely distributed of the 

various knapweed species. It is widespread in northern 

states including Colorado, Montana, and Wyoming and is 

currently becoming more common in New Mexico and 

Arizona. Large populations are distributed extensively 

throughout northern New Mexico, and smaller populations 

are present in most central and southern counties of the 

State. In Arizona, Russian knapweed is a concern in 

northeastern and southeastern counties. 

Spread 

Although Russian knapweed produces seed, it spreads 

mainly through vegetative propagation that arises from 

adventitious buds along a creeping, perennial root system. 

Root fragments of 1 inch or more in length can produce 

new plants if the fragments are buried in soil to a depth no 

greater than 6 inches. Seed or root fragments may be 

introduced into new areas via waterways such as irrigation 

ditches, streams, or rivers. Russian knapweed may also 

spread through transported hay that is not certified to be 

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weed free or by attachment of propagules that adhere to 

undercarriages of off-road vehicles and road maintenance 

equipment. 

Invasive Features 

Russian knapweed’s competitiveness is believed to be 

related to its ability to release harmful allelopathic 

chemicals that can inhibit growth of other plants. As a 

possible result of allelopathic effects, revegetation efforts 

following Russian knapweed control are often hampered 

unless measures are taken to mitigate soil condition. The 

weed can also cause as much as an eight-fold increase in 

zinc concentration in nearby soil surface layers as 

compared to upper layers of soils without knapweed. 

Management 

Russian knapweed is quite difficult to control once 

established. Prevention, early detection, and eradication are 

the best management tools for controlling this noxious 

weed. The following action measures should be considered 

when planning an overall management approach: 

• Maintain healthy plant communities and the presence 

of ground litter to prevent or limit knapweed 

infestations. This may involve using improved 

grazing management to prevent excessive grazing, 

and reseeding areas with desirable grasses and forbs 

after disturbance. 

• Use certified weed-free seed, mulch, hay, and fill 

materials; use pellets to feed horses in backcountry 

areas. 

• Eradicate new populations of Russian knapweed as 

early as possible. 

• Detect, report, and map large infestations. Keep 

annual records of reported infestations. 

• Combine mechanical, cultural, biological, and 

chemical methods for most effective control. 

• Implement a monitoring and follow-up treatment 

plan for missed plants and seedlings. 

Table 1 summarizes some management options for 

controlling Russian knapweed under various situations. 

Further details on these management options are explained 

below. Choice of individual control method(s) for Russian 

knapweed depends on the extent and density of infestation, 

current land use, and site conditions (accessibility, terrain, 

microclimate, other flora and fauna present, etc.). Other 

important considerations include treatment effectiveness, 

overall cost, and the number of years needed to achieve 

control. More than one control method may be needed for 

a particular site. 

Physical Control 

A number of mechanical control methods for Russian 

knapweed have been examined, but most have limited 

effectiveness. In general, mechanical control methods need 

to be combined with chemical spraying for long-term 

management of Russian knapweed (see the “Integrated 

Control Methods” section below for further information). 

Manual Methods 

Hand pulling or digging – Hand pulling or hoeing can be 

effective for small, less established infestations of Russian 

knapweed if repeated annually over multiple years. 

Removal is generally easier and more effective in late 

spring when soil is moist and plants are beginning to bolt 

(but before seed set). It is very important to pull up all 

parts of the plant, especially the roots. Wear gloves and 

properly dispose of debris by burning or by bagging and 

burying in a landfill to prevent spread. 

Mechanical Methods 

If using machinery to manage Russian knapweed, the 

equipment should be cleaned after use to prevent 

movement of root fragments and seed into un-infested 

areas. 

Tillage – Shallow cultivation or tillage without herbicide 

spraying as a follow-up treatment should be avoided since 

this practice often leads to an increase in knapweed 

dominance. Disking or plowing cuts roots into fragments 

that can survive desiccation and promote further spread. If 

feasible, tillage may be used before reseeding to alleviate 

residual allelopathic effects in soil from the knapweed. 

Mowing – If repeated continually throughout the growing 

season, mowing will suppress shoots and flowers. 

However, mowing by itself will not reduce Russian 

knapweed populations. 

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Table 1. Management options* 

Site Physical Control Cultural Control Biological Control Chemical Control 

Roadsides, Mow at 2 to 3 week Use seed, mulch, and fill material A gall-forming wasp and a Use truck or tractorfence lines, intervals during growing certified to be weed-free. gall midge are recommend as mounted spraying 

or non-crop 

areas 

season but before seed set. 

Follow up with an 

herbicide application in the 

fall. 

Avoid driving vehicles and 

equipment through infested 

areas; wash if travel through 

these areas is unavoidable. 

Educate road crews and others 

to identify and report 

infestations. 

classical biocontrol agents if 

available. 

equipment to broadcast 

treat. Wash underneath 

vehicle after application 

to prevent spread. 

Rangeland, Deep cultivation (12 Use seed and forage hay Manage grazing to prevent In areas difficult to 

pasture, or inches) repeated over 3 certified to be weed-free. Use overuse. Consider grazing access, an ATV-mounted 

riparian years can be effective. pellets for horses in heavily infested sites in late sprayer or backpack unit 

corridors Shallow cultivation/tillage 

is not recommended as 

severed root fragments 

may regrow. 

Burning is ineffective and 

may contribute to further 

knapweed dominance. 

backcountry areas. 

Check animals, clothing, and 

vehicles for seeds. 

Always evaluate the need to 

reseed with native perennial 

grass when considering 

knapweed control. 

summer or early fall rather 

than spring. Maintain litter 

cover to reduce knapweed 

germination. 

A gall-forming wasp and a 

gall midge are recommend as 

classical biocontrol agents if 

available. 

may be the most 

practical application 

methods. Wash 

underneath vehicle after 

application to prevent 

spread. 

Wilderness, Hand pulling, hoeing, or Use seed and forage hay Same as above. Use backpack or handother natural digging must remove all certified to be weed-free. Use held sprayers. Broadcast 

areas, and/or root stock to be effective; pellets for feeding horses in spraying with ground 

small wear gloves for pulling; backcountry areas. methods may be used on 

infestations pull when soil is moist; 

most effective on newly 

established plants. 

Check animals and clothing for 

seeds. 

Post signs warning visitors to 

remove seeds after passing 

thicker stands if allowed. 

Remove seed from 

clothing to prevent 

spread. 

through infested areas. 

Always evaluate the need to 

reseed with native perennial 

grass when considering 

knapweed control. 

* Choice of a particular management option must be in compliance with existing regulations for the land resource. 

Prescribed Fire 

Burning as a single control method is not recommended. 

New plants from roots are quickly produced after fire, 

which often leads to increased dominance by Russian 

knapweed. However, fire may be used as a secondary 

treatment in combination with other control methods such 

as disposal of debris. 

Cultural Control 

Prevention, early detection, and plant removal are critical 

for preventing Russian knapweed establishment. Land 

managers, road crews, and the local public should be 

educated on identification of knapweed species so that they 

can help report all suspected infestations. Seed and 

materials used for mulch, forage, or fill should be certified 

to be weed-free; pellets may be used to feed horses in 

backcountry areas. 

Vehicles, humans, and livestock should be discouraged from 

traveling through infested areas. A program to check and 

remove seedfrom vehicles and livestock after travel 

through infested areas should be implemented to help stop 

dispersal. To prevent seed from being transported by 

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irrigation systems, use weed screens on water intakes within 

infested areas if possible. Reseeding with native perennial 

grasses after disturbance should always be considered in 

controlling knapweed. 

Biological Control 

Grazing 

Livestock (including cattle, sheep, and goats) normally 

will not graze Russian knapweed due to its bitter flavor; 

however, animals may graze the weed lightly during early 

growth. The weed is especially toxic to horses and should 

not be grazed by them. The time of grazing preferred for 

pastures infested with Russian knapweed should occur 

during late summer, early fall, or winter. Use grazing to 

encourage perennial grass growth and competition against 

Russian knapweed. Reduce grazing pressure in early 

spring when grasses are first starting to grow and allow 

grasses to tiller and produce seed. Utilization of knapweed 

by livestock should be carefully monitored, and heavy 

grazing should be avoided. 

Classical Biological Control 

There are three approved classical biocontrol agents for 

Russian knapweed (table 2). A gall nematode (Subanguina 

picridis) has been released in northwestern New Mexico 

to help control Russian knapweed. It forms galls on stems, 

leaves, and root crowns; however, this biocontrol agent 

does not spread unaided and significant Russian knapweed 

reductions have not been observed in areas where it has 

been established. Two newer biocontrol agents, a gallforming wasp (Aulacida acroptilonica) and a gall midge 

(Jaapiella ivannikovi) are now becoming more readily 

available. Impacts on Russian knapweed populations have 

been demonstrated by the gall midge. 

Organisms (insects, pathogens, etc.) used as biocontrol 

agents in southwestern States should be adaptable to arid 

environments and local conditions. Public, tribal, and 

private land managers may obtain biocontrol agents for 

release directly from local offices of the USDA Animal 

and Plant Health Inspection Service (APHIS) when these 

agents are available. Other sources for biocontrol agents 

include locally developed insectaries or private 

companies. 

A permit must be obtained from APHIS before biocontrol 

agents can be transported across State lines. Regulations 

and permit applications (PPQ 526 permit forms) 

pertaining to interstate shipment of biocontrol agents can 

be found at https://www.aphis.usda.gov/aphis/ourfocus/ 

planthealth/import-information/permits/regulatedorganism-and-soil-permits/sa_apply/ct_plantpest 

_howtoapply. Although biocontrol agents may be 

collected and released internally in a given State without 

an APHIS permit, the State’s department of agriculture or 

agricultural extension service should be consulted for any 

regulations relating to movement of these agents within 

the State. 

Table 2. Classical biocontrol agents approved for Russian knapweed 

Species Type of 

Agent Site of Attack/Impact Use/Considerations for Release Remarks 

Subanguina 

picridis 

gallforming 

nematode 

Galls reduce biomass and 

seed production stems, 

leaves, and root crown. 

Impacts limited to plants on moist sites. 

Low impact and inability to spread unaided 

prevent this biocontrol agent from being 

cost-effective. 

Not recommended for new 

releases 

Aulacida 

acroptilonica 

gallforming 

wasp 

Galls stunt plants, reduce 

seed production. 

Populations still limited in US with minor 

impacts Parasitism of gall wasps has been 

observed. Releases best done by rearing out 

adults so parasites are excluded. 

Recommended for new 

releases or redistribution. 

Jaapiella 

ivannikovi 

gall midge Larval galls stunt plants, 

reduce seed production 

significantly 

Populations are still limited. Recommended for new 

releases with lab colonies or 

field redistributions by moving 

infested plants or rearing 

adults. 

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Chemical Control 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Russian knapweed is best controlled with a selective, postemergent herbicide. Typically, the main herbicide entry 

into the plant is through the leaves and stems; but certain 

herbicides can enter through the roots. Control results can 

vary due to weather and plant growth stage. Herbicides 

generally provide significant reduction of a knapweed 

population with a single application; however, follow-up 

treatment should always be anticipated. 

All herbicides recommended in table 3 will effectively 

control Russian knapweed when properly applied. 

Selective herbicides used for effective control of Russian 

knapweed include picloram, aminocyclopyrachlor, 

aminopyralid, and clopyralid. Picloram is a restricted-use 

pesticide and should not be used near waterways or 

whenever the water table is near the surface. Glyphosate or 

imazapyr can be used for follow-up spot treatment, but 

these treatments may create a bare ground situation. 

Table 3. Herbicide recommendations 

Each herbicide product will have different requirements 

and restrictions according to the label. Read and 

understand the label prior to any application. Aquatically 

approved herbicide formulations and surfactants must be 

used in or near water. To prevent development of 

resistance in Russian knapweed for repeated treatments, 

the label should be consulted for guidelines on rotating 

herbicide active ingredients. Consult the registrant if you 

have questions or need further detail. 

Herbicide Application 

The most effective period to spray Russian knapweed 

generally is in the fall (preferably after a frost) when 

rosettes begin to emerge or mature plants appear dormant 

(grey stems, no leaves). Spraying earlier may provide only 

short-term control. Precautionary measures should be 

taken if nontarget plants (including woody species) need to 

be protected. This includes situations where spray drift, 

soil erosion, or water movement potentially could occur. 

Common 

Chemical Name 

(active 

ingredient) 

Product 

Example1 

Broadcast 

Treatment 

(rate per 

acre) 

Spot Treatment 

(spray 

solution)2 

Time of 

Application Remarks 

Picloram3 Tordon 22K 1–2 quarts 1–3% Most effective in 

late fall after 

frost. Apply 1 

pt/acre if used in 

combination with 

cultivation and 

reseeding. 

Wait 2 months to reseed perennial grasses. 

May be used in combination with 2,4-D.4 

Restricted use herbicide that is selective 

although persistent. Picloram may pose a risk 

to groundwater in permeable soils or in areas 

where the water table is near the surface. 

Aminocyclo- Perspective 4.75–8 ounces Add 5–9 grams of Most effective in A selective blend of active ingredients labeled 

pyrachlor + dry flowable late fall after for non-crop use (includes natural areas such 

chlorsulfuron powder to each 1 

gallon water. 

frost. as wildlife management areas, wildlife 

habitats, recreation areas, campgrounds, 

trailheads, and trails). Persistent; selective for 

broad-leaved plants; may cause temporary 

injury to some grass species. 

May also be used on public, private, and tribal 

lands as part of an early detection and rapid 

response (EDRR) in treating infestations of 

invasive weed species. 

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Table 3. Herbicide recommendations (cont.) 

Common 

Chemical Name 

(active 

ingredient) 

Product 

Example1 

Broadcast 

Treatment 

(rate per 

acre) 

Spot 

Treatment 

(spray 

solution)2 

Time of Application Remarks 

Aminocyclopyrachlor + 

metsulfuron 

methyl 

Streamline 4.75–9.5 

ounces 

Add 5–9 grams 

of dry flowable 

powder to each 

1 gallon water. 

Most effective in late 

fall after frost. 

A selective blend of active ingredients labeled 

for non-crop use (includes natural areas such 

as wildlife management areas, wildlife 

habitats, recreation areas, campgrounds, 

trailheads, and trails). Persistent; selective for 

broad-leaved plants and certain brush species; 

may cause temporary injury to some grass 

species. 

Can be used in riparian areas. May also be 

used on public, private, and tribal lands as 

part of an early detection and rapid response 

(EDRR) in treating infestations of invasive 

weed species. 

Aminopyralid Milestone 4–6 fluid 

ounces 

5–10% Spring and summer at 

bud to flowering 

growth; or in late fall 

on dormant plants. 

May be used in combination with 2, 4-D.4 

Use higher rate on older stands; late fall 

treatment of dormant plants can be very 

effective. Add 0.25–0.5 percent nonionic 

surfactant for mature plants or for adverse 

conditions. 

Labeled for use up to water’s edge. No 

grazing restrictions. 

Clopyralid Curtail 1–2 quarts 1–3% Bud to full bloom or 

in late fall after frost. May be used in combination with 2,4-D.4 

Can be used on rangeland, irrigated pasture, or 

meadows but not directly to water. Wait 30 

days to reseed perennial grasses. 

Reclaim, 

Transline 

1–1-1/3 pints 1–3% 

Glyphosate Roundup, 

many 

products 

4–4.8 quarts 2% Late bud to early 

flower; late summer or 

fall. 

Use primarily as follow-up spot 

treatment. Direct spray or use a wipe 

method when desirable plants are present. 

Imazapyr Arsenal 2 pints 1% Anytime plants are 

growing or in the fall 

after frost. 

Use primarily as follow-up spot 

treatment. Direct spray or use a wipe 

method when desirable plants are present. 

This herbicide is a non-selective amino acid 

inhibitor. In addition to spray drift, nontarget 

plants may also be killed or injured by 

imazapyr through runoff, residue movement 

in soil, or root exudates from treated plants. 

1 Trade names for products are provided for example purposes only, and other products with the same active ingredient(s) may be available. Individual product 

labels should be examined for specific information and appropriate use with Russian knapweed. 

2 Spray solution is the herbicide/water ratio in a spray mix that may be used for spot treatment with backpack or hand-held sprayers. The amount of product 

applied during an annual growing season must not exceed the maximum application rate per acre as specified by the product label – refer to the product 

label for the site type and application. 

3 Restricted use pesticide - A certified applicator’s license is required for purchase and use of these pesticides. 

4 2,4-D is a restricted use pesticide in New Mexico only. 

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Herbicides may be applied by a wiping method, backpack 

or hand-held sprayers, ATV or UTV sprayers, or 

conventional boom sprayers that are pulled or attached to a 

tractor or truck. In situations where Russian knapweed is 

dense and widespread, aerial application by fixed wing or 

helicopter aircraft should be considered. Any equipment 

used to spray herbicide should be calibrated. 

For individual plant treatment (IPT), the foliage should be 

wetted thoroughly in the fall with a backpack sprayer, 

wiper, or sponge applicator (apply until it begins to run 

off). When using picloram or another post-emergent 

herbicide, spray an extra 10 to 15 feet around the infested 

area to ensure control of root, sprouts, and/or seedlings. A 

wiping or direct spray method using a 2 percent solution 

of glyphosate may be used when plants are in bloom but 

before seed matures. This approach is most appropriate 

when other desirable broadleaved plants are present. Areas 

treated with glyphosate can be reseeded after 3 days. 

Integrated Control Methods 

An integrated management strategy that combines control 

methods as necessary should always be implemented when 

possible to reduce or eradicate Russian knapweed. As with 

other creeping perennial weeds, the combination of control 

methods selected to treat knapweed should substantially 

deplete stored nutrients in the root system. As an example, 

a mechanical method-herbicide treatment sequence may 

be used for some sites. Mow or disk at 2 to 3 week 

intervals during growing season, then apply herbicide to 

knapweed regrowth in the fall. Consider reseeding the area 

shortly thereafter with competitive perennial grasses. 

Perform follow-up monitoring and spot treat any new or 

re-growing plants. Grazing should also be managed to 

favor establishment of perennial grasses. 

Management Strategies 

The key to successful Russian knapweed control is longterm planning, integrated management, monitoring treated 

areas on an annual basis, and possibly reseeding in order 

to encourage competition from desirable plants, especially 

perennial native grasses. Planning and treatments to 

control Russian knapweed should be designed to meet 

specific site conditions. 

Initial treatments to control Russian knapweed should 

attempt to remove as much of the knapweed population as 

possible, and secondary treatments will be necessary to 

remove remaining plants. Russian knapweed populations 

growing in small isolated patches on otherwise healthy 

sites should have first priority for treatment, especially 

eradication. Large knapweed infestations should be 

controlled and then eradicated when possible. For heavily 

infested areas, plants at the perimeter should generally be 

treated first to prevent the infestation from spreading. The 

larger, denser cores of the infested area should be 

addressed in the final stage of treatment. 

Before spraying herbicide or using classical biocontrol 

agents for Russian knapweed, evaluate each area closely to 

determine if seeding may be necessary or if the plant 

community will return naturally. Seeding is not typically 

needed when native grasses are still common beneath 

Russian knapweed, as grasses will increase rapidly in the 

following seasons after treatment. The following strategies 

may be considered to restore native plant communities 

infested with Russian knapweed: 

• Strategy for infested sites with an adequate grass 

understory present – Spray a selective herbicide in 

the fall to control Russian knapweed and allow 

native grasses to return naturally in the next growing 

season. Defer grazing on areas sprayed for one or 

more growing seasons to allow grasses to increase 

and gain a competitive advantage. Monitor sprayed 

areas carefully for 2 or 3 years and spot spray 

returning Russian knapweed plants. 

• Strategy for infested sites with little grass 

understory – Consider planting a mixture of native 

grass, shrub, and forb seed. Control Russian 

knapweed first by herbicide spraying in fall and use 

tillage at a later time if feasible to bury allelopathic 

plant residue. Follow up with planting by late fall to 

allow seed to take advantage of any early spring 

moisture that may be available. To use less seed and 

to ensure more successful establishment, consider 

seeding with a grain drill. A no-till rangeland drill 

may be necessary on particularly rocky, steep, or 

hard sites. Select native perennial grass species 

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according to individual site conditions and moisture 

availability. Periodically monitor the next growing 

season for newly emerged Russian knapweed seedlings 

and spot treat them. 

In most cases, at least two or more consecutive years of 

field treatments will be necessary to eliminate or 

substantially reduce Russian knapweed infestations. Since 

it is ordinarily useless to treat an area only one time 

without retreatment, sufficient resources must be allocated 

for the area where control is attempted. After initial 

treatment, it is especially important that resources are also 

available to respray or retreat the treated area as necessary. 

Previously treated areas should be continuously monitored 

to detect recovering Russian knapweed. Failure to perform 

follow-up monitoring and adapt control methods as needed 

could result in recolonization by Russian knapweed and a 

return to pretreatment levels of invasion. 

Adaptive Management 

A persistent, long-term commitment is required for 

successful control of Russian knapweed. Therefore, 

realistic goals and objectives should be established to 

manage Russian knapweed infestations occurring 

extensively throughout a given landscape. To improve 

long-term success, consider using an adaptive management 

approach with the overall goal of restoring desirable plant 

communities. The stepwise process for adaptive 

management involves: 

1. Assessment of the overall weed problem, 

2. Establishing management goals and objectives, 

3. Implementation of control strategies and 

measures, 

4. Monitoring the effectiveness of management 

actions, 

5. Evaluating actual outcomes in relation to 

expected results, and 

6. Adjusting practices as necessary. 

Steps of this process should be repeated in sequence as 

part of a continuous learning cycle that improves 

management planning and strategy by learning from the 

outcomes of previous management actions. In general, an 

adaptive management strategy is considered to be 

successful if: 

1. Stakeholders are actively involved and remain 

committed to the process, 

2. Monitoring and assessment are used to adjust 

and improve management decisions, and 

3. Management goals and/or objectives for the 

resource are being achieved. 

References and 

Further Information 

Beck, K.G. 1998 (rev. 2008). Russian Knapweed. 

Colorado State University Extension Natural 

Resource Series no. 3.111. Available at 

http://www.ext.colostate.edu/ 

pubs/natres/03111.pdf (accessed April2010). 

California Department of Food andAgriculture. 

Encycloweedia Datasheets: Russian Knapweed. 

Available at http://www.cdfa.ca.gov/phpps/ipc/ 

weedinfo/acroptilon.htm (accessed April2010). 

DiTomaso, J.M. and E.A. Healy. 2007. Weeds of 

California and Other Western States. University of 

California Agriculture and Natural Resource 

Publication 3488. Pp. 175–178. Available at 

http://books.google.com/ books (accessed April 

2010). 

Dow AgroSciences. 2004. Milestone Factsheet. Available 

athttp://www.dowagro.com/range/products/ 

milestone.htm (accessed April 2010) 

Duncan, K., K. McDaniel, and M. Renz. 2005. Chemical 

Weed and Brush Control for New Mexico 

Rangelands. Las Cruces: New Mexico State Univ. 

College of Agriculture and Home Economics and 

Cooperative Extension Service. 9 pp. 

Lym, R.G. 2004. Know Your Knapweeds. NDSU 

Extension Service Publication W-1146. Available 

athttp://www.ag.ndsu.edu/pubs/plantsci/weeds/ 

w1146.pdf (accessed April 2010) 

8 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

McReynolds, K.H. and L.D. Howery. 2001. Public 

Education, Mapping and Early Action to Control 

Russian Knapweed in Southeastern Arizona. 

Journal of Extension vol. 39 2. Available at 

http://www.joe. org/joe/2001april/a2.php 

(accessed April 2010). 

Northam, E. and W. Meyer et al. 2009. Non-Native 

Invasive Plants of Arizona. Produced by 

Conservation Districts and RC&D Areas of 

Arizona and the University of Arizona 

Cooperative Extension. Peer reviewed publication 

No. AZ1482. Available athttp://cals.arizona.edu/ 

pubs/natresources/az1482.pdf (accessed April 

2010). 

Renz, M.J. 2005. Russian Knapweed (Acroptilon repens). 

NMSU Extension Weed Factsheet. Las Cruces, 

NM. 

Renz, M and F. Sholedice. 2006. Troublesome Weeds of 

New Mexico. Las Cruces: New Mexico State 

University College of Agriculture and Home 

Economics and Cooperative Extension Service. 

pp. 30-31. Available at http://www.emnrd.state. 

nm.us/fd/Publications/documents/NMTroublesom 

eWeeds.pdf 

USDA Plants Database. 2010. Available at http://plants. 

usda.gov/index.html (accessed April 2010). 

Whitson, T.D. et al. (ed.) Weeds of the West. Western 

Society of Weed Science in cooperation with 

Cooperative Extension Services, Univ. of 

Wyoming. Available at http://plants.usda.gov/java/ 

invasiveOne?pubID=WSWSandhttp://ndweeds.ho 

mestead.com/russianknapweed.html (accessed 

April 2010). 

Williams, B.K., R.C. Szaro, and C.D. Shapiro. 2009. 

Adaptive Management: The U.S. Department ofthe 

Interior Technical Guide. Adaptive Management 

Working Group, U.S. Department of the Interior, 

Washington, DC. Available at http://www.doi.gov/ 

initiatives/AdaptiveManagement (accessed April 

2011) 

Wilson, L.M. and C.B. Randall. 2003. Biology and 

Biological Control of Knapweed (Getting to Know 

Knapweeds). USDA Forest ServiceFHTET-2001-07. 

2nd edition. Available at http://www.invasive.org/ 

weeds/knapweed/chapter1.html (accessed March 

2010). 

Suggested Web Sites 

For information on invasive species: 

National Invasive Species Information Center 

http://www.invasivespeciesinfo.gov/ 

Invasive.org 

http://www.invasive.org/weedus/index.html 

For information about calibrating spray equipment: NMSU 

Cooperative Extension Service Guide A-613, 

Sprayer Calibration. Available at 

http://aces.nmsu.edu/pubs/_a/A-613.pdf 

Herbicide labels online: http://www.cdms.net/ 

9 
 

 

 

For more information or 

other field guides, contact: 

USDA Forest Service 

Southwestern Region 

Forest Health 

333 Broadway Blvd., SE 

Albuquerque, NM 87102 

Or visit the Southwestern Region’s 

website for invasive species: 

http://www.fs.usda.gov/goto/r3/invasivespecies 

line 

The use of trade or firm names in this publication is for reader 

information only and does not imply endorsement of any 

product or service by the U.S. Department of Agriculture. 

Recommendations made here for 

pesticide use are not obligatory, 

nor do they imply that discussed 

uses have been registered. All 

uses of pesticides must be 

registered by appropriate State 

and/or Federal agencies before 

they can be applied. 

CAUTION: Pesticides can be 

injurious to humans, domestic 

animals, desirable plants, and fish or other wildlife—if they are 

not handled or applied properly. Use all pesticides carefully 

and lawfully. Follow recommended practices for the disposal 

of surplus pesticides and pesticide containers.