Forb/Wildflower Seeding Recommendations for Canada Thistle Infested Sites in Prairies

J.B. Bright with the US Fish and Wildlife Service (USFWS) described a successful restoration as “A diverse plant community that will include different levels of canopy cover and structural diversity to serve a wider array of birds, pollinator insects and other wildlife” ( To help land managers meet their restoration goals, cooperative field trials between Dow AgroSciences, USFWS, Dennis Pederson, and University of Minnesota were conducted at multiples sites in the Midwest. Results from these trials show that Milestone® is the most effective herbicide for controlling Canada thistle.  The herbicide should be applied at 5 to 7 fl oz/A in either late spring after all Canada thistle plants have emerged (some may be at the bud stage), and in fall ( A list of wildflower options for a seeding mix that is tolerant to Milestone herbicide, and includes diverse structural diversity (height) and flowering times for pollinators was also developed from these field trials (Table 1). 


For a complete list of forbs tolerant to Milestone herbicide, see section 5 of “Invasive Plant Management with Milestone® and Other Herbicides–A Guide for Natural Area Managers”

 ®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. Milestone is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Label precautions apply to forage treated with Milestone and to manure from animals that have consumed treated forage within the last three days. Consult the label for full details. State restrictions on the sale and use of Transline and apply. Consult the label before purchase or use for full details.
Always read and follow label instructions. 

Active ingredients for herbicide products mentioned in this article: Milestone (aminopyralid), Transline (clopyralid).