Canada Thistle in Grape Plantings
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Canada thistle (Cirsium arvense) is a difficultto-manage perennial that spreads by seeds and rhizomes. Leaves have spines and are deeply lobed; leaf margins wrap around bases of stems, causing stems to look spiny. Flower heads are purple to pink. Root systems may extend more than 10 feet deep.
Canada thistle seedling.
(Photo: LL Berry, Bugwood.org)
Canada thistle foliage.
(Photo: Mary Ellen (Mel) Hart, Bugwood.org)
Canada thistle in bloom.
(Photo: Leslie Dietz, Bugwood.org)
Management:
- Avoid cultivation.
- Cut or mow plants to help reduce root reserves and to starve plants.
- Apply spot applications of herbicides when shoots are at least 10 inches tall and before flowers open (when plants are most susceptible to herbicides).
