Noxious Weeds Profile - Canada Thistle


  • English - Canada thistle
  • French - chardon des champs, chardon du Canada
  • Latin - Cirsium arvense (L.) Scop.


Canada thistle

Current Status

  • Ontario Weeds Act - noxious
  • Other provinces - noxious in AB, BC, SK, MB, and QC
  • Canadian Federal Seeds Act - Class 3
  • U.S. Federal Noxious Weed - no
  • U.S. Noxious State Reg - 42 states (incl. Illinois, Indiana, Mich, Ohio, Penn, New York, Minn, Wisc,)


  • Pub 505 - no
  • NE Weeds - no
  • Canadian Poison Plant - not listed
  • Cornell Poison Plant - not listed


  • Common in pastures, roadsides and waste areas.

Growth Habit

  • Perennial

Method of Propagation

  • Seeds, Wind blown, Roots/rhizome


  • Can be controlled by dicamba and glyphosate products. Spray at early bud stage or in early fall. Repeated applications are needed to kill all root buds. 2,4-D gives top growth control only. Light to medium infestations can be controlled with repeated mowing at 21 day intervals.

Other Comments

  • Similar to Japanese barberry which does not normally host the rust fungus. Hybids of these two species may host the fungus. Populations are relatively stable and much lower than for European buckthorn. Rust does not occur every year but can cause significant impact in some years.


Related Links

For more information:
Toll Free: 1-877-424-1300
Author: Mike Cowbrough - Chief Weed Inspector Ontario Weeds Act/OMAFRA
Creation Date: March 2003
Last Reviewed: 07 February 2006