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® herbicide effectively controls 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), or in fall ( A seeding mix, that includes wildflower options tolerant to Milestone, and also includes structural diversity (height) and flowering times for pollinators, was 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”

Published May 2013; Reviewed and updated June 2019.

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Milestone herbicide 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. When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. State restrictions on the sale and use of Milestone apply. Consult the label before purchase or use 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. ©2019 Corteva

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