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- Name: Canada Thistle (Cirsium arvense)
- Introduction: Native to southeastern Eurasia, contaminated crop seed
- Habitat: Rich, heavy loam, clay loam, and sandy loam, with an optimum soil depth of 20 inches
- Infestation: Crops, pasture, rangeland, roadsides, stream banks and landscaping. It can crowd out forage
- grasses by up to 60 percent. It can also invade native plant communities.
- Available Control: Mechanical, chemical, biological
- Priority of Control: Deplete its root reserves before rosette has a chance to over-winter.
- Biological controls: For more information about the biological control of Canada Thistle, please visit WSU Extension Integrated Weed Control Project.
- For More Detail: Visit the Washington Noxious Weed Control Board listing for Canada Thistle.
