Knowledgebase

Canada thistle management #930475

Asked May 03, 2026, 8:43 PM EDT

What foliar herbicides are effective to spot treat Canada thistle plants, or are only broadly spread herbicides effective? Are any pet safe, and safe for grass and desirable plants such as hostas?

Hennepin County Minnesota

Expert Response

Spot treating Canada thistle in spring and fall using systemic herbicides  which kill the roots while remaining safe for grass is more effective than using broadly spread herbicides.  Herbicides that can be effective include 2,4-D, dicamba, clopyralid, aminopyralid, picloram, glyphosate, and sometimes triclopyr. Spot treating can harm desirable broadleaf plants like hostas, so you must  use a shield to prevent drift or carefully wipe the leaves. Most options are pet safe once the spray has completely dried.
For more information, see 

https://extension.umn.edu/identify-invasive-species/canada-thistle
https://www.mda.state.mn.us/plants/pestmanagement/weedcontrol/noxiouslist/canadathistle
Diane M Replied May 04, 2026, 1:37 PM EDT

Loading ...