Cirsium arvense
Quick ID:
- Perennial with purplish pink flowers less that 2.5cm across.
- Prickly stems and leaves.
- Extensive creeping rhizome.
Habitat:
- Deep creeping rhizome that allows it to survive below the cultivation zone.
- A single plant is capable of producing over 6m of rhizome per year.
- Stems up to 120cm tall, are leafy and hollow, becoming hairy with age.
- An individual plant may produce over 40,000 seeds.
- Seeds are viable in soil for up to 21 years.
How It Got Here:
- Introduced from France in the late 1700’s.
- Now found throughout Canada and the northern half of the United States.
How to kill it with Stem Injection: Cut tops to have 2-4 inches above ground or just inject stem of thistle plant 2-4 inches above ground using Cavity, Hardened, or Shortened Needle and deliver 2mls herbicide in concentrated form.
Reasons for Concern:
- Canada thistle is an aggresive weed and has the potential to reduce crop yeilds by 100%.
- The rhizomes are unaffected by cultivation as they grow below normal tillage depths.