Pests Addressed

Canada Thitsle

A perennial with extensive underground creeping roots – which makes this weed a challenge to control. Canada thistle is a native of Eurasia but was introduced to North America in the late 18th century.


1. Biological control - Canada thistle gall-fly or stem-mining weevil feed on foliage

2. Mechanical control – mowing just prior to flowering inhibits spread and seed production. Chemical control is effective for herbicides registered for Canada thistle. Always read and follow label directions.


Deep horizontal and vertical creeping roots which are the primary method of spread.
Rosette leaves are smooth, irregularly lobed, and the leaf margins have spiny teeth.
Grows erect, hairless, and hollow in cross-section. Plants can grow up to 1.2 m in height.
Pink, purple, or white flowers arranged in clusters and smaller than others in the thistle family. Plants are either male or female, but only female flowers can produce seed.
Single tan-colored seeds with a slight curve; each seed has a feathery pappus to disperse via wind.

Want to learn more?

Check out our Weed Management: The Herbicides ProTraining course:

Weed Management: The Herbicides

Understanding the weeds - how they grow and reproduce - is important step in successful weed management. This course will provide an in depth lesson on weed biology and how it relates to controlling various weed species.

Take This Course Today

Sign in to your PestWeb Canada account now, or become a PestWeb Canada member to start learning online.

Join PestWeb Canada Log In

Back to top