🌿 Weed
ANX-WEED-0000262
Canada Thistle
Cirsium arvense
Canada Thistle (Cirsium arvense), a perennial broadleaf weed of the Asteraceae family.
- Family
- Asteraceae
- Growth habit
- Broadleaf
- Life cycle
- Perennial
- Invasive status
- Noxious/regulated weed across most of temperate North America
- Native region
- Europe and Asia, now a major invasive weed of North America.
- Reproduction
- Seed (wind-dispersed by a pappus) and an extensive, deep horizontal root system that regrows aggressively from root fragments.
Environment
Habitat & Growing Conditions
- Habitat
- Cultivated fields, pastures, roadsides, disturbed ground in temperate regions.
- Climate requirements
- Cool to cold temperate; does not tolerate tropical heat well.
- Soil types
- Wide soil tolerance; prefers fertile, moist soils but persists almost anywhere.
Impact
Crops Affected & Economic Impact
- Affected crops
- Cereals, pastures, hayfields, row crops
- Competition impact
- Dense, spiny stands reduce pasture palatability and crop yields, and the deep creeping root system makes eradication extremely difficult once established.
- Economic impact
- Listed as a noxious weed in most of the USA and Canada due to its severe impact on pasture and cropland productivity.
Management
Control Methods
- Control methods
- Repeated mowing/cutting before flowering over several seasons to exhaust root reserves, combined with competitive pasture/crop stands.
- Organic control
- Persistent cutting at the bud stage (before flowering) for multiple consecutive seasons; smother cropping.
- Chemical control
- Systemic broadleaf herbicides (e.g. clopyralid, glyphosate spot-treatment) applied at the bud-to-flower stage for best root translocation.