• facebook
  • twitter
  • YouTube
  • RSS feed
  • 651-201-6000
  • 800-967-2474
  • 711 TTY

NodeFire Save Document
Home > Plants, Pests & Pest Control > Pest Management > Noxious & Invasive Weed Program > NWAC > Risk Assessments > Canada Thistle

Canada Thistle Risk Assessment

Canada Thistle Plant, photo by MDA
Canada Thistle, photo by Minnesota Department of Agriculture

Common Name: Canada Thistle
Latin Name: Cirsium arvense (L.) Scop.

Reviewer: Roger Becker
Affiliation/Organization: University of Minnesota

Date: 08/16/2013
FILE #: MDARA00034CANT_2_24_2014

Final Results of Risk Assessment

Review Entity | Outcome

  • NWAC Listing Subcommittee: Restricted Noxious Weed
    Comments: First review – 06/20/2013, Final Review 08/12/2013
    The general consensus of the subcommittee based on the risk assessment data and the widespread nature of Canada thistle, was to reclassify this species as a Restricted Noxious Weed.
  • NWAC Full-group: Voted 8 – 4  to recommend reclassifying Canada thistle as a Restricted Noxious Weed.
    Comments: Review 12/18/2014 – Members agree unanimously that Canada thistle is widespread and has been a large focus of weed management for over a century in MN. However, a difference in opinion arises when the discussion centers on whether or not current efforts have any impact on controlling or eradicating populations. Some members expressed concerns that the risk assessment is ignoring the fact that without the century-long battle against this plant by counties and townships, this species would be worse today.
  • MDA Commissioner: The commissioner rejected NWAC’s recommendation and has directed that  Canada thistle remain as a Prohibited-Control species to support the counties' and townships' opinions, in addition to comments from the Farmer’s Union and MN Crop Improvement Association, that any changes would be detrimental to grazing agriculture and potentially cause confusion within the seed industry.
    Comments: Reviewed 02/24/2014 - Petition letters received by the commissioner’s office from four member organizations overwhelmingly disagreed with NWAC’s final recommendations for Canada thistle. Counties and townships also reflected the displeasure their constituents had with the notion of reclassifying this species from an enforcement perspective. They also indicated that their constituents and citizens consider this to be one of the most important weed species statewide. The MDA also received other comments regarding the recommendations to reclassify Canada thistle that basically reflected that farmers and private landowners alike would be upset if the recommendation was approved.


Box Question Answer Outcome
1 Is the plant species or genotype non-native? Yes (Slotta et al., 2010). Go to Box 3.
3 Is the plant species, or a related species, documented as being a problem elsewhere? Yes, in the northern hemisphere world-wide (Donald, W. 1994). It is a US Federal Noxious Weed, and is declared a noxious weed in 33 states (PLANTS database, Accessed 8/16/13). Go to Box 6.
6 Does the plant species have the capacity to establish and survive in Minnesota?    
6A Is the plant, or a close relative, currently established in Minnesota? Yes. U of M Herbarium records show the first specimen from Minneapolis in 1878. Maps show distribution throughout the US in 43 states and all but 2 Canadian Provinces (USDA Plants) and in every county in Minnesota (EDDMapS). Go to Box 7.
7 Does the plant species have the potential to reproduce and spread in Minnesota?    
7A Does the plant reproduce by asexual/vegetative means? Yes (Moore 1975). Go to Box 7B.
7B Are the asexual propagules effectively dispersed to new areas? Yes. Go to Box 7F.
7C Does the plant produce large amounts of viable, cold-hardy seeds? Yes (Becker et al., 2008). Bold/italic text is provided as additional information not directed through the decision tree process for this particular risk assessment.
7F Are sexual propagules – viable seeds – effectively dispersed to new areas? Yes, by various vectors such as on equipment, in mulch and hay, in feed and seed, etc. However, wind dispersal attached to pappi is minimal.(Becker et al., 2008). Go to Box 7I.
7G Can the species hybridize with native species (or other introduced species) and produce viable seed and fertile offspring in the absence of human intervention? No. Bold/italic text is provided as additional information not directed through the decision tree process for this particular risk assessment.
 7I Do natural controls exist, species native to Minnesota, that are documented to effectively prevent the spread of the plant in question? Not presently. There is a long history of biological control efforts on Canada thistle (McClay 2002), which have resulted in some elements of control with insects and pathogens but currently none effectively prevent spread on a broad geographical basis. Ceutorhynchus litura (F.) (synonym Hadroplontus litura) may provide significant reductions of Canada thistle in Minnesota with augmented release, but has yet to be widely accepted as host specific (personal observations) nor have wide-spread efforts been made to implement C. litura in Minnesota. (personal communication, Monika Chandler MDA). Go to Box 8.
8 Does the plant species pose significant human or livestock concerns or have the potential to significantly harm agricultural production, native ecosystems, or managed landscapes?    
 8A Does the plant have toxic qualities, or other detrimental qualities, that pose a significant risk to livestock, wildlife, or people? No known plant toxins. Physical deterrent; spines on leaves of some biotypes are fairly rigid and pose a risk to foraging animals when mature and in wide-spread, vigorous populations. Go to Box 9.
 8B Does, or could, the plant cause significant financial losses associated with decreased yields, reduced crop quality, or increased production costs? Yes (Ziska, L. 2010; Bork, et al., 2007; Grekul, C.W. and E.W. Bork. 2004; Donald and Khan, 1996). Bold/italic text is provided as additional information not directed through the decision tree process for this particular risk assessment.
 8C Can the plant aggressively displace native species through competition (including allelopathic effects)? Debatable. Bold/italic text is provided as additional information not directed through the decision tree process for this particular risk assessment.
 8D Can the plant hybridize with native species resulting in a modified gene pool and potentially negative impacts on native populations? No. Bold/italic text is provided as additional information not directed through the decision tree process for this particular risk assessment.
 8F Does the plant have the potential to introduce or harbor another pest or serve as an alternate host? No. Bold/italic text is provided as additional information not directed through the decision tree process for this particular risk assessment.
9 Does the plant species have clearly defined benefits that outweigh associated negative impacts?    
 9A Is the plant currently being used or produced and/or sold in Minnesota or native to Minnesota? No. Go to Box 10.
10 Should the plant species be enforced as a noxious weed to prevent introduction &/or dispersal; designate as prohibited or restricted?    
 10A Is the plant currently established in Minnesota? Yes (see Box 6A). Go to Box 10B.
 10B Does the plant pose a serious human health threat? No (though can be a physical deterrent, see Box 8A). Go to Box 10C.
 10C Can the plant be reliably eradicated (entire plant) or controlled (top growth only to prevent pollen dispersal and seed production as appropriate) on a statewide basis using existing practices and available resources? No, not on a statewide basis (self-evident in distribution maps and history in the state). Yes, at the local, field-specific level (Bork et al., 2007; De Bruijn, S.L. and Bork, E.W. 2006; numerous others). List as Restricted Noxious Weed. If effective biological control programs could be developed in Minnesota, then list as a Prohibited/ Control Noxious Weed



Becker, R.L., M.J. Haar, B.D. Kinkaid, L.D., Klossner, and F. Forcella. Production and Wind Dispersal of Canada Thistle (Cirsium arvense L.) Achenes. 2008. MN DOT Report #: 2008-39.

Bork, E.W., C.W. Grekul, and S.L. DeBruijn. 2007. Extended pasture forage sward responses to Canada thistle (Cirsium arvense) control using herbicides and fertilization. Crop Protection 26(10): 1546-1555.

De Bruijn, S.L. and E.W. Bork. 2006. Biological control of Canada thistle in temperate pastures using high density rotational cattle grazing. Biological Control: Theory and Application in Pest Management. 36(3): 305-315.

Donald, W.W. (1994). The biology of Canada thistle (Cirsium arvense). Reviews of Weed Sci. 6:77-101.

EDDMapS. 2013. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Accessed August 16, 2013.

McClay, A. 2002. Canada thistle. pgs. 217- 228. In Van Driesche, R., B. Blossey, M. Hoddle, S. Lyon, and R. Reardon. 2002. Biological Control of Invasive Plants in the Eastern United States, USDA Forest Service Publication FHTET-2002-04, 413 p.

Moore, R.J. 1975. The biology of Canadian weeds. 13. Cirsium arvense (L.) Scop. Canadian J. Plant Sci. 55:1033-1048.

Slotta, T.A.B., M.E. Foley, S. Chao, R.A. Hufbauer, and D.P. Horvath. 2010. Assessing genetic diversity of Canada thistle (Cirsium arvense) in North America with microsatellites.  Weed Sci. 58(4): 387-394.

University of Minnesota Herbarium – Bell Museum. Accessed August 8, 2013.

USDA, NRCS. 2013. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA. Accessed August 8, 2013.


Additional Literature:

Amor, R.L. and R.V. Harris. 1974. Distribution and seed production of Cirsium arvense (L.) Scop. in Victoria, Australia. Weed Research 14: 317-323.

Alexander, J. M., P.J. Edwards, M. Poll, C.G. Parks, and H. Dietz. 2009. Establishment of parallel altitudinal clines in traits of native and introduced forbs. Ecology 90(3): 612-622.

Almquist, T.L. and R.G. Lym. 2010. Effect of aminopyralid on Canada thistle (Cirsium arvense) and the native plant community in a restored tallgrass prairie. Invasive Plant Science and Management 3(2): 155-168.

Anderson, M. 1991. Mechanistic models for the seed shadows of wind-dispersed plants. American Naturalist 137:476-497.

Anderson, M.C. 1992. An analysis of variability in seed settling velocities of several wind-dispersed Asteraceae. American Journal of Botany 79:1087-1091.

Armel, G.R., G.J. Hall, H.P. Wilson, and N. Cullen. 2005. Mesotrione plus atrazine mixtures for control of Canada thistle (Cirsium arvense). Weed Science 53(2): 202-211.

Bakker, D. 1960. A comparative life-history study of Cirsium arvense (L.) Scop. and Tussilago farfara L., the most troublesome weeds in the newly reclaimed polders of the former Zuider Zee. Pages 205-222 in Harper, J. ed. The Biology of Weeds. Blackwell Scientific Publications, Oxford, UK.

Berestetskiy, A., A. Dmitriev, G. Mitina, I. Lisker, A. Andolfi, and A. Evidente. 2008. Nonenolides and cytochalasins with phytotoxic activity against Cirsium arvense and Sonchus arvensis: A structure-activity relationships study. Phytochemistry 69(4): 953-960.

Bicksler, A.J. and J.B. Masiunas. 2009. Canada thistle (Cirsium arvense) suppression with Buckwheat or Sudangrass cover crops and mowing. Weed Technology 23(4): 556-563.

Blumenthal, D., R.A. Chimner, J.M. Welker, and J.A. Morgan. 2008. Increased snow facilitates plant invasion in mixedgrass prairie. New Phytologist 179(2): 440-448.

Boerboom, C.M. and D.L. Wyse. 1988. Influence of glyphosate concentration on glyphosate absorption and translocation in Canada thistle (Cirsium arvense). Weed Science 36(3): 291-295.

Bommarco, R., M. Lonn, U. Danzer, K-J. Palsson, and P. Torstensson. Genetic and phenotypic differences between thistle populations in response to habitat and weed management practices. Biological Journal of the Linnean Society 99(4): 797-807.

Bostock, S.J. and R.A. Benton. 1979. The reproductive strategies of five perennial Compositae. Journal of Ecology 67:91-107.

Bourdot, G.W., D. Baird, G.A. Hurrell, and M.D. de Jong. 2006. Safety zones for a Sclerotinia sclerotiorum-based mycoherbicide: Accounting for regional and yearly variation in climate. Biocontrol Science and Technology 16(4): 345-358.

Bourdot, G.W., G.A. Hurrell, D.J. Saville, and D.M. Leathwick. 2006. Impacts of applied Sclerotinia sclerotiorum on the dynamics of a Cirsium arvense population. Weed Research 46(1): 61-72.

Brandsaeter, L.O., M. Goul Thomsen, K. WcErnhus, and H. Fykse. 2012. Effects of repeated clover undersowing in spring cereals and stubble treatments in autumn on Elymus repens, Sonchus arvensis and Cirsium arvense. Crop Protection 32: 104-110.

Bukun, B., T.A. Gaines, S.J. Nissen, P. Westra, G. Brunk, D.L. Shaner, B.B. Sleugh, and V.F. Peterson. 2009. Aminopyralid and clopyralid absorption and translocation in Canada thistle (Cirsium arvense). Weed Science 57: 10-15.

Bukun, B., R.B. Lindenmayer, S.J. Nissen, P. Westra, D.L. Shaner, and G. Brunk. 2010. Absorption and translocation of aminocyclopyrachlor and aminocyclopyrachlor-methyl ester in Canada thistle (Cirsium arvense). Weed Science 58(2): 96-102.

Burt, G.W. and T.J. Muzik. 1968. The effect of different Canada thistle ecotypes on amitrole activity. Weed Science16:413-414.

Candido, V., T. D’Addabbo, V. Miccolis, and D. Castronuovo. 2011. Weed control and yield response of soil solarization with different plastic films in lettuce. Scientia Horticulturae 130(3): 491-497.

Cimmino, A., A. Andolfi, A. Berestetskiy, and A. Evidente. 2008. Production of phytotoxins by Phoma exigua var. exigua, a potential mycoherbicide against perennial thistles. Journal of Agricultural and Food Chemistry 56(15): 6304-6309.

Clough, Y., A. Kruess, and T. Tscharntke. 2007. Local and landscape factors in differently managed arable fields affect the insect herbivore community of a non-crop plant species. Journal of Applied Ecology 44(1): 22-28.

Collier, T.R., S.F. Enloe, J.K. Sciegienka, and F.D. Menalled. 2007. Combined impacts of Ceutorhynchus litura and herbicide treatments for Canada thistle suppression. Biological Control 43(2): 231-236.

Cripps, M.G., G.W. Bourdot, D.J. Saville, H.L. Hinz, S.V. Fowler, and G.R. Edwards. 2011. Influence of insects and fungal pathogens on individual and population parameters of Cirsium arvense in its native and introduced ranges. Biological Invasions 13(12): 2739-2754.

Cripps, M.G., G.R. Edwards, G.W. Bourdot, D.J. Saville, H.L. Hinz, and S.V. Fowler. 2010. Effects of pasture competition and specialist herbivory on the performance of Cirsium arvense. Biocontrol Science and Technology 20(6): 641-656.

Cripps, M.G., G.R. Edwards, N.W. Waipara, G.W. Bourdot, D.J. Saville, and S.V. Fowler. 2009. Does transmission of the rust pathogen, Puccinia punctiformis, require stem mining vectors? Biocontrol Science and Technology 19: 447-454. 

Dandeno, J.B. 1905. The parachute effect of thistle-down. Science 22:568-572.

Derscheid, L.A. and R.E. Shultz. 1960. Seed development of Canada thistle and perennial sowthistle. Weeds 8:55-62.

Davis, J. 2006. Establishing dialogue between alternative agricultural producers and the land-grant university in Colorado. Sustainable Agriculture Research and Education (SARE) research projects--Western Region.

De Bruijn, S.L., E.W. Bork, W. Edward, and C.W. Grekul. 2010. Neighbor defoliation regulates Canada thistle (Cirsium arvense) in pasture by mediating interspecific competition.  Crop Protection 29(12): 1489-1495.

Demers, A.M., D.K. Berner, and P.A. Backman. 2006. Enhancing incidence of Puccinia punctiformis, through mowing, to improve management of Canada thistle (Cirsium arvense).  Biological Control: Theory and Application in Pest Management 39(3): 481-488.

Detmers, F. 1927. Canada thistle (Cirsium arvense Tourn): Field thistle, creeping thistle. Bulletin of The Ohio Agricultural Experiment Station 414:1-45, The University of Ohio, Columbus, OH.

Dixon, F.L., D.V. Clay, and I. Willoughby. 2005. The tolerance of young trees to applications of clopyralid alone and in mixture with foliar-acting herbicides. Forestry 78(4): 353-364.

Donald, W.W. and M. Khan. 1992. Yield loss assessment for spring wheat (Triticum aestivum) infested with Canada thistle (Cirsium arvense). Weed Science 40(4): 590-598.

Dugan, F.M. and D.A. Glawe. 2007. Powdery mildews on weeds in the Pacific Northwest: a miscellany of new records. Pacific Northwest Fungi  2(2): 1-7, n.p.

Durgan, B.R. 1998. Identification of the Primary Noxious Weeds of Minnesota. University of Minnesota Extension Publication, St. Paul, MN. Item no. 05620, Accessed August 2008.

El-Sayed, A.M., J.A. Byers, L.M. Manning, A. Jurgens, V.J. Mitchell, and D.M. Suckling. 2008. Floral scent of Canada thistle and its potential as a generic insect attractant. Journal of Economic Entomology 101(3): 720-727.

Endlweber, K. and S. Scheu. 2006. Effects of collembola on root properties of two competing ruderal plant species. Soil Biology & Biochemistry 38(8): 2025-2031.

Enloe, S.F., R.G. Lym, R. Wilson, P. Westra, S. Nissen, G. Beck, M. Moechnig, V. Peterson, R.A. Masters, and M. Halstvedt. 2007. Canada thistle (Cirsium arvense) control with aminopyralid in range, pasture, and noncrop areas. Weed Technology 21(4): 890-894.

Evidente, A., A. Berestetskiy, A. Andolfi, M.C. Zonno, A. Cimmino, and M. Vurro. 2006. Relation between In Vitro production of ascosonchine and virulence of strains of the potential mycoherbicide Ascochyta sonchi: a method for its quantification in complex samples. Phytochemical Analysis 17(5): 357-364.

Evidente, A., A. Cimmino, A. Andolfi, M. Vurro, M.C. Zonno, C.L. Cantrell, and A. Motta. 2008. Phyllostictines A-D, oxazatricycloalkenones produced by Phyllosticta cirsii, a potential mycoherbicide for Cirsium arvense biocontrol. Tetrahedron 64(8): 1612-1619.

Evidente, A., A. Cimmino, A. Andolfi, M. Vurro, M.C. Zonno, and A. Motta. 2008. Phyllostoxin and phyllostin, bioactive metabolites produced by Phyllosticta cirsii, a potential mycoherbicide for Cirsium arvense biocontrol. Journal of Agricultural and Food Chemistry 56(3): 884-888.

Evidente, A., A. Cimmino, A. Berestetskiy, G. Mitina, A. Andolfi, and A. Motta. 2008. Stagonolides B-F, nonenolides produced by Stagonospora cirsii, a potential mycoherbicide of Cirsium arvense. Journal of Natural Products 71(1): 31-34.

Evidente, A., A. Cimmino, A. Berestetskiy, A. Andolfi, and A. Motta. 2008. Stagonolides G-I and modiolide A, nonenolides produced by Stagonospora cirsii, a potential mycoherbicide for Cirsium arvense. Journal of Natural Products 71(11): 1897-1901.

Ferrero-Serrano, A., T.R. Collier, A.L. Hild, B.A. Mealor, and T. Smith. 2008. Combined impacts of native grass competition and introduced weevil herbivory on Canada Thistle (Cirsium arvense). Rangeland Ecology & Management 61(5): 529-534.

Forcella, F. and D. Archer.  2006. Canada thistle phenology. 2006 North Central Weed Science Society Proceedings 61: 158.

Frank, J.R. and T.J. Tworkoski. 1993. Response of Canada thistle, Cirsium arvense (L.) Scop. and leafy spurge, Euphorbia esula L. genotypes to systemic herbicides. Weed Science Society of America Abstract 33:49.

Gange, A.C., S. Dey, A.F. Currie, and B.C. Sutton. 2007. Site- and species-specific differences in endophyte occurrence in two herbaceous plants. Journal of Ecology 95(4): 614-622.

Ghazoul, J. 2006. Floral diversity and the facilitation of pollination. Journal of Ecology 94(2): 295-304.

Graglia, E., B. Melander, and R.K. Jensen. 2006. Mechanical and cultural strategies to control Cirsium arvense in organic arable cropping systems. Weed Research 46(4): 304-312.

Grekul, C.W and E.W. Bork. 2004. Herbage yield losses in perennial pasture due to Canada thistle (Cirsium arvense). Weed Technology 18(3): 784-794.

Grekul, C.W. and E.W. Bork. 2007. Fertilization augments Canada thistle (Cirsium arvense L. Scop) control in temperate pastures with herbicides. Crop Protection 26(4): 668-676.

Gronwald, J.W., K.L. Plaisance, D.A. Ide, and D.L. Wyse. 2002. Assessment of Pseudomonas syringae pv. tagetis as a biocontrol agent for Canada thistle. Weed Science 50(3): 397-404.

Gruber, S. and W. Claupein. 2009. Effect of tillage intensity on weed infestation in organic farming. Soil & Tillage Research 105(1): 104-111.

Hansen, A.A. 1918. Canada Thistle and Methods of Eradication. USDA Farmers Bulletin 1002, Washington, D.C.

Hansen A.A. 1921. Canada thistle. Penn State Agricultural Experiment Station, Weed Leaflet No. 2, 4 pp., Penn State University, College Station, PA.

Hausman, C.E., J.F. Jaeger, and O.J. Rocha. 2010. Impacts of the emerald ash borer (EAB) eradication and tree mortality: potential for a secondary spread of invasive plant species.  Biological Invasions 12(7): 2013-2023.

Hay, W.D. 1937. Canada thistle seed production and its occurrence in Montana seed. Seed World, March 26. pp. 6-7.

Hayden, A. 1934. Distribution and reproduction of Canada thistle in Iowa. American Journal of Botany 21:355-373.

Heimann, B. and G.W. Cussans. 1996. The importance of seeds and sexual reproduction in the population biology of Cirsium arvense - A literature review. Weed Research 36:493-503.

Hill, R.J. 1983. Canada thistle, Cirsium arvense (L.) Scop. Registration Horticulture Weed Circulation No. 2, (cited dates: April and October 1983), Pennsylvania Department of Agriculture, Bureau of Plant Industry Vol. 9, No. 1-2.

Hodgson, J.M. 1964. Variations in ecotypes of Canada thistle. Weeds 12:167-171.

Hodgson, J.M. and H.D. Moore. 1972. Stomatal variations in Canada thistle and response to herbicides, Cirsium arvense. Weed Science 20:68-70.

Hodgson, J.M. 1968. The Nature, Ecology, and Control of Canada thistle. U.S. Department of Agriculture Technical Bulletin 1386. 32 pp.

Hodgson, J.M. 1970. The response of Canada thistle ecotypes to 2,4-D, amitrole, and intensive cultivation. Weed Science 18:68-70.

Hodgson, J.M. 1971. Canada Thistle and its Control. Leaflet 523. USDA. Washington DC. 8 pp.

Hodgson, J.M. 1973. Lipid deposition on leaves of Canada thistle ecotypes. Weed Science 21:169-172.

Hoebeke, E.R. and A.G. Wheeler Jr. 2003. Sphaeroderma testaceum (F.) (Coleoptera: Chrysomelidae), a Palearctic flea beetle new to North America. Proceedings of the Entomological Society of Washington 105(4): 990-994.

Holmes, R.J. and R.J. Froud-Williams. 2005. Post-dispersal weed seed predation by avian and non-avian predators. Agriculture, Ecosystems & Environment 105(1-2): 23-27.

Holm, L.G., D.L. Plucknett, J.V. Pancho and J.P. Herberger. 1977. pp 217-224 In The World's Worst Weeds. Distribution and Biology. ISBN 0-8248-0295-0. 609 pp. John Wiley & Sons, Inc. New York, N.Y.

Hovick, S.M. and J.A. Reinartz. 2005. Combination of treatments influence survival of woody species planted to suppress Reed canarygrass (Wisconsin). Ecological Restoration 23(2): 126.

Humber, J.M. and L. Hermanutz. 2011. Impacts of non-native plant and animal invaders on gap regeneration in a protected boreal forest. Biological Invasions 13(10): 2361-2377.

Hunter, J.H. and L.W. Smith. 1972. Environment and herbicide effects on Canada thistle ecotypes. Weed Science 20:163-167.

Janz, N. 2005. The relationship between habitat selection and preference for adult and larval food resources in the polyphagous butterfly Vanessa cardui (Lepidoptera: Nymphalidae).  Journal of Insect Behavior 18(6): 767-780.

Jump, A.S., D.A. Dawson, C.M. James, F.I. Woodward, and T. Burke. 2002. Isolation of polymorphic microsatellites in the stemless thistle (Cirsium acaule) and their utility in other Cirsium species.  Molecular Ecology Notes 2(4): 589-592.

Kay, Q.O.N. 1985. Hermaphrodites and subhermaphrodites in a reputedly dioecious plant, Cirsium arvense (L.) Scop. New Phytologist 100 (3):457-472.

Klinkhamer, P.G.L. and T.J. de Jong. 1993. Cirsium vulgare (Savi) Ten. Journal of Ecology 81(1):177-191.

Kluth, S., A. Kruess, and T. Tscharntke. 2005. Effects of two pathogens on the performance of Cirsium arvense in a successional fallow. Weed Research 45(4): 261-269.

Kong, H., C. Blackwood, J.S. Buyer, T.J. Gulya Jr., and J. Lydon. 2005. The genetic characterization of Pseudomonas syringae pv. tagetis based on the 16S-23S rDNA intergenic spacer regions. Biological Control: Theory and Application in Pest Management 32(3): 356-362.

Kong, H., C.D. Patterson, W. Zhang, Y. Takikawa, A. Suzuki, and J. Lydon. 2004. A PCR protocol for the identification of Pseudomonas syringae pv. tagetis based on genes required for tagetitoxin production. Biological Control: Theory and Application in Pest Management 30(1): 83-89.

Lalonde, R.G. and B.D. Roitberg. 1989. Resource limitation and offspring size and number trade-offs in Cirsium arvense (Asteraceae). American Journal of Botany 76(8):1107-1113.

Lalonde, R.G. and B.D. Roitberg. 1994. Mating system, life-history, and reproduction in Canada thistle (Cirsium arvense; Asteraceae). American Journal of Botany 81(1):21-28.

Larson, D.L. 2009. Evaluation of restoration methods to minimize Canada thistle (Cirsium arvense) infestation. USDI, USGS Open-File Report 2009-1130. 56 pp. Accessed May 3, 2013.

Larson, D.L., J.B. Bright, P. Drobney, J.L. Larson, N. Palaia, P.A. Rabie, S. Vacek, and D. Wells. 2011. Effects of planting method and seed mix richness on the early stages of tallgrass prairie restoration. Biological Conservation 144: 3127-3139.

Larson, D.L., J.B. Bright, P. Drobney, J.L. Larson, N. Palaia, P.A. Rabie, S. Vacek, and D. Wells. 2013. Using prairie restoration to curtail invasion of Canada thistle: the importance of limiting similarity and seed mix richness. Biological Invasions DOI 10.1007/s10530-013-0432-0. 15 pp. Accessed May 3, 2013.

Laubhan, M.K. and T.L. Shaffer. 2006. Seed germination of Cirsium arvense and Lepidium latifolium: Implications for management of Montane wetlands. Wetlands 26(1): 69-78.

Leth, V., J. Netland, and C. Andreasen. 2008. Phomopsis cirsii: a potential biocontrol agent of Cirsium arvense. Weed Research 48(6): 533-541.

Link, A.J. and T. Kommedahl. 1958. Canada thistle - spotlight on a troublesome weed. Minnesota Farm and Home Science 15:21-22.

Lloyd, D.G. and A.J. Myall. 1976. Sexual dimorphism in Cirsium arvense (l.) Scop. Annals of Botany 40:115-123.

Lukashyk, P., M. Berg, and U. Kopke. 2008. Strategies to control Canada thistle (Cirsium arvense) under organic farming conditions. Renewable Agriculture and Food Systems 23(1): 13-18.

Lundkvist, A., L. Salomonsson, L. Karlsson, and A-M.D. Gustavsson. 2008. Effects of organic farming on weed flora composition in a long term perspective. European Journal of Agronomy 28(4): 570-578.

Majka, C.G. and L. LeSage. 2006. Introduced leaf beetles of the Maritime Provinces, 1: Sphaeroderma testaceum (F.) (Coleoptera: Chrysomelidae). Proceedings of the Entomological Society of Washington 108(1): 243-247.

McAllister, R.S. and L.C. Haderlie. 1985. Seasonal variations in Canada thistle, Cirsium arvense, root bud growth and root carbohydrate reserves. Weed Science 33:44-49.

McKinney, M. and A. Jerup. 2010. Do you know these infamous weeds? Barnyards & Backyards 6(4): 15.

Mesbah, A.O. and S.D. Miller. 2005. Canada thistle (Cirsium arvense) control in established alfalfa (Medicago sativa) grown for seed production. Weed Technology 19(4): 1025-1029.

Michels, G.J. Jr., V.A. Carney, J. Lydon, R. Ochoa, and R.L. Renn. 2008. New records for Aceria anthocoptes (Acari: Eriophyidae) occurring on Canada thistle in Colorado, Nebraska, and Wyoming, U.S.A. Entomological News 119(5): 483-491.

Miller, A.M., C. McArthur, and J. Smethurst. 2006. Characteristics of tree seedlings and neighbouring vegetation have an additive influence on browsing by generalist herbivores. Forest Ecology and Management 228(1-3): 195-205.

Narumalani, S, D.R. Mishra, R. Wilson, P. Reece, and A. Kohler. 2009. Detecting and mapping four invasive species along the floodplain of North Platte River, Nebraska. Weed Technology 23(1): 99-107.

Navratil, M., P. Valova, R. Fialova, P. Lauterer, D. Safarova, and M. Stary. 2009. The incidence of stolbur disease and associated yield losses in vegetable crops in South Moravia (Czech Republic). Crop Protection 28(10): 898-904.

Newcombe, G. and C. Nischwitz. 2004. First report of powdery mildew caused by Erysiphe cichoracearum on creeping thistle (Cirsium arvense) in North America. Plant Disease 88(3): 312.

Noble, S.D. and T.G. Crowe. 2005. Analysis of crop and weed leaf diffuse reflectance spectra. Transactions of the ASAE 48(6): 2379-2387.

Nordmeyer, H. and A. Hausler. 2004. Impact of soil properties on weed distribution within agricultural fields [in German]. Journal of Plant Nutrition and Soil Science [Zeitschrift fur Pflanzenernahrung und Bodenkunde] 167(3): 328-336.

Norris, R.F. 2007. Weed fecundity: Current status and future needs. Crop Protection 26:182-188.

[ORS] Office of the Reviser of Statutes State of Minnesota. 2007. Chapter 20. Noxious Bushes and Weeds. Accessed August 2008.

Papiernik, S., F. Forcella, R. Gesch, and G. Amundson. 2006. Clopyralid tolerance of cuphea. North Central Weed Science Society Proceedings 61: 25.

Peschken, D.P. 1984. Host range of Lema cyanella (Coleoptera:Chrysomelidae), a candidate for biocontrol of Canada thistle, and of four stenophagous, foreign thistle insects in North America [Orellia ruficauda, Cleonus piger, Cassida rubiginosa, Rhinocyllus conicus].  Canadian Entomologist 116(10): 1377-1384.

Poritz, N. 2003. Biological weed control: education and implementation  Sustainable Agriculture Research and Education (SARE). Project Number FW01-032, West Region.

Prischmann-Voldseth, D.A. 2009. Biological Control of Canada Thistle. Crop and Pest Report.

Pritekel, C., A. Whittemore-Olson, N. Snow, and J.C. Moore. 2006. Impacts from invasive plant species and their control on the plant community and belowground ecosystem at Rocky Mountain National Park, USA. Agriculture, Ecosystems & Environment with Applied Soil Ecology 32(1): 132-141.

Quimby, P.C., S. Gras, T. Widmer, W. Meikle, and D. Sands. 2004. Formulation of Sclerotinia sclerotiorum for use against Cirsium arvense. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz 491-495.

Rancic, D., B. Stevanovic, R. Petanovic, B. Magud, I. Tosevski, and A. Gassmann. 2006. Anatomical injury induced by the Eriophyid mite Aceria anthocoptes on the leaves of Cirsium arvense. Experimental & Applied Acarology 38(4): 243-253.

Rew, L.J., B.D. Maxwell, and R. Aspinall. 2005. Predicting the occurrence of nonindigenous species using environmental and remotely sensed data. Weed Science 53(2): 236-241.

Schreiber, M. 1967. Effect of density and control of Canada thistle on production and utilization of alfalfa pasture. Weeds 15:138-142.

Seefeldt, S.S., J.M.C. Stephens, M.L. Verkaaik, and A. Rahman. 2005. Quantifying the impact of a weed in a perennial ryegrass-white clover pasture. Weed Science 53(1): 113-120.

Sheldon, J.C. and F.M. Burrows. 1973. The dispersal effectiveness of the achene-pappus units of selected compositae in steady winds with convection. New Phytologist 72:665-675.

Shmida, A. 1985. Why do some compositae have an inconsistently deciduous pappus? Annals of the Missouri Botanical Garden 72:184-186.

Shorthouse, J.D. and R.G. Lalonde. 1986. Formation of flowerhead galls by the Canada thistle gall-fly Urophora cardui (Diptera: Tephritidae) under cage conditions. The Canadian Entomologist 118(11): 1199-1203.

Slotta, T.A.B., M.E. Foley, and D. Horvath. 2005. Development of polymorphic markers for Cirsium arvense, Canada thistle, and their amplification in closely related taxa.  Molecular Ecology Notes 5(4): 917-919.

Slotta, T.A.B., J.M. Rothhouse, D.P. Horvath, and M.E. Foley. 2006. Genetic diversity of Canada thistle (Cirsium arvense) in North Dakota. Weed Science 54(6): 1080-1085.

Skinner, K., L. Smith and P. Rice. 2000. Using noxious weed lists to prioritize targets for developing weed management strategies. Weed Science 48:640-644.

Smith, L.M. and L.T. Kok. 1984. Dispersal of musk thistle (Carduus nutans) seeds. Weed Science 32:120-125.

Stringer, L.D., A.M. El-Sayed, L.M. Cole, L-A.M. Manning, and M.D. Suckling. 2008. Floral attractants for the female soybean looper, Thysanoplusia I (Lepidoptera: Noctuidae).  Pest Management Science 64(12): 1218-1221.

Theis, N. and R.A. Raguso. 2005. The effect of pollination on floral fragrance in thistles. Journal of Chemical Ecology 31(11): 2581-2600. 

Theis, N., M. Lerdau, and R.A. Raguso. 2007. The challenge of attracting pollinators while evading floral herbivores: patterns of fragrance emission in Cirsium arvense and Cirsium repandum (Asteraceae). International Journal of Plant Sciences 168(5): 587-601. 

Thines, M., R. Zipper, D. Schauffele, and O. Spring. 2006. Characteristics of Pustula tragopogonis (syn. Albugo tragopogonis) newly occurring on cultivated sunflower in Germany. Journal of Phytopathology 154(2): 88-92. 

Tichich, R.P. and J.D. Doll. 2006. Field-based evaluation of a novel approach for infecting Canada thistle (Cirsium arvense) with Pseudomonas syringae pv. tagetis. Weed Science 54(1): 166-171.

Tichich, R.P., J.D. Doll, and P.S. McManus. 2006. Pseudomonas syringae pv. tagetis (PST) population dynamics both on and in Canada thistle (Cirsium arvense) leaves as affected by rain events. Weed Science 54(5): 934-940.

Toepfer, S., M.M. Ellsbury, R. Eschen, and U. Kuhlmann. 2007. Spatial clustering of Diabrotica virgifera virgifera and Agriotes ustulatus in small-scale maize fields without topographic relief drift. Entomologia Experimentalis et Applicata 124(1): 61-75.

Top 10 invasive plants. 2006. Arbor Age 26:12-14.

Travnicek, A.J., R.G. Lym, and C. Prosser. 2005. Fall-prescribed burn and spring-applied herbicide effects on Canada thistle control and soil seedbank in a northern mixed-grass prairie. Rangeland Ecology & Management 58(4): 413-422.

Turner, S.K., K. Fay, E.L. Sharp and D.C. Sands. 1981. Resistance of Canada thistle, Cirsium arvense, ecotypes to a rust pathogen, Puccinia obtegens. Weed Science 29:623-624.

Tschanz, B., L.F. Bersier, and S. Bacher. 2007. Functional responses: A question of alternative prey and predator density. Ecology 88(5): 1300-1308.

Wandeler, H. and S. Bacher. 2006. Insect-transmitted Urediniospores of the Rust Puccinia punctiformis cause systemic infections in established Cirsium arvense plants.  Phytopathology 96(8): 813-818.

Wandeler, H., W. Nentwig, and S. Bacher. 2008. Establishing systemic rust infections in Cirsium arvense in the field. Biocontrol Science and Technology 18(1-2): 209-214.

Wiese, A.H., D.A. Netzer, D.E. Riemenschneider, and R.S. Jr. Zalesny. 2006. A weed compaction roller system for use with mechanical herbicide application. Northern Journal of Applied Forestry 23(1): 66-69.

Wilson RG, Martin AR, Kachman SD. 2006. Seasonal changes in carbohydrates in the root of Canada thistle (Cirsium arvense) and the disruption of these changes by herbicides. Weed Technology 20: 242-248. DOI: 10.1614/WT-05-052R1.1.

Yuzikhin, O., G. Mitina, and A. Berestetskiy. 2007. Herbicidal potential of Stagonolide, a New Phytotoxic Nonenolide from Stagonospora cirsii. Journal of Agricultural and Food Chemistry 55(19): 7707-7711.

Ziska, L.H., S. Faulkner, and J. Lydon. 2004. Changes in biomass and root:shoot ratio of field-grown Canada thistle (Cirsium arvense), a noxious, invasive weed, with elevated CO2: implications for control with glyphosate. Weed Science 52(4): 584-588. 

Ziska, L.H. 2010. Elevated carbon dioxide alters chemical management of Canada thistle in no-till soybean. Field Crops Research 119(2-3): 299-303. 

Zonno, M.C., M. Vurro, S. Lucretti, A. Andolfi, C. Perrone, and A. Evidente. 2008. Phyllostictine A, a potential natural herbicide produced by Phyllosticta cirsii: In vitro production and toxicity. Plant Science 175(6): 818-825.