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July Weed of the Month: Canada Thistle

Heath Keirstead | July 10, 2024
A square graphic for Canada thistle with four images and this information: Flowers are clusters of small, purple heads ½ to ¾ inch in diameter. Leaves have wavy margins with prickles along edges; not as hairy as bull thistle. Stems can be slightly hairy or without hairs. Can spread by rhizomatous roots, making it very difficult to eradicate. May form dense stands in overgrazed pastures. Not palatable to livestock and reduces forage potential. Can reduce the growth of tree seedlings. Repeated, frequent pulling or hand-cutting of individual plants typically promotes growth and is not advised for larger infestations. Mow repeatedly throughout the season to prevent seed production prior to flowering. Avoid mowing in full flower, as cut flowers may still form viable seeds. Replace with Douglas aster. For more info visit www.marionswcd.net/plants/canada-thistle/ brought to you by Mid Willamette CWMA
An 8.5 x 11 flyer for Canada thistle. For a pdf version, click here.
A square graphic for Canada thistle with four images and this information: Flowers are clusters of small, purple heads ½ to ¾ inch in diameter. Leaves have wavy margins with prickles along edges; not as hairy as bull thistle. Stems can be slightly hairy or without hairs. Can spread by rhizomatous roots, making it very difficult to eradicate. May form dense stands in overgrazed pastures. Not palatable to livestock and reduces forage potential. Can reduce the growth of tree seedlings. Repeated, frequent pulling or hand-cutting of individual plants typically promotes growth and is not advised for larger infestations. Mow repeatedly throughout the season to prevent seed production prior to flowering. Avoid mowing in full flower, as cut flowers may still form viable seeds. Replace with Douglas aster. For more info visit www.marionswcd.net/plants/canada-thistle/ brought to you by Mid Willamette CWMA
A square graphic for Canada thistle. For a pdf version, click here.

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Native and Invasive Plant Specialist
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