Canada thistle (
Cirsium arvense) is an aggressive creeping perennial weed that infests crops, pastures, rangeland, roadsides and noncrop areas. Generally, infestations start on disturbed ground, including ditch banks, overgrazed pastures, tilled fields or abandoned sites.
Canada thistle reduces forage consumption in pastures and rangeland because cattle typically will not graze near infestations
Life Cycle
Growth Habit
- Upright, up to 4-feet tall with creeping-root system; reproduces by seed and root
Plant Emergence
- Seedlings emerge in late April to May forming rosettes; flowers late spring to early summer
Characteristics
- Very erect plant with shiny, spined leaves
- Seeds are viable for up to 22 years
- 3/4" purple flower
- Flower matures in late summer into dandelion-like white "puffball" which spreads the seed in the breeze
Control
- Repeated mowing, tilling, cutting or hand removal prior to seed production can provide suppression
- Successful treatment will require several years
- Apply Tordon, Milestone, or Curtail to growing plants through flowering
- Repeated applications of 2,4-D, Banvel, or Roundup to actively growing plants