Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Andrea Watts; Tim Harrington; Dave Peter
    Date: 2015
    Source: Science Findings 176. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 6 p.
    Publication Series: Science Findings
    Station: Pacific Northwest Research Station
    PDF: Download Publication  (4.22 MB)


    Herbicides are primarily used for protecting agricultural crops from weeds and controlling vegetation competition in newly planted forest stands. Yet for over 40 years, they have also proven useful in controlling invasive plant species in natural areas. Nonnative invasive plant species, if not controlled, can displace native species and disrupt an ecosystem by changing soil chemical and biological properties. However, before an herbicide may be applied in a U.S. national forest, toxicological and ecological assessments and field testing are required to ensure it won’t negatively affect the landscape or people.

    In the Gifford Pinchot National Forest, scientists with the U.S. Forest Service Pacific Northwest Research Station established experimental plots to test effects of aminopyralid (a plant growth-regulating herbicide) on both the nonnative and native meadow plant species. When applying less than the manufacturer’s maximum labeled rate, researchers found the herbicide reduced the cover of Canada thistle and other nonnatives without strongly affecting native species.

    Aminopyralid, along with aminocyclopyrachlor and clopyralid (also plant growth-regulating herbicides), were also tested in a growth chamber trial for their effectiveness in controlling the germination of Scotch broom, a large invasive shrub that often reduces survival of young Douglas-fir. Spraying the soil with each type of herbicide controlled up to 90 percent of the germinating Scotch broom seedlings.

    Publication Notes

    • Visit PNW's Publication Request Page to request a hard copy of this publication.
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Watts, Andrea; Harrington, Tim; Peter, Dave. 2015. Herbicides: an unexpected ally for native plants in the war against invasive species. Science Findings 176. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 6 p.


    herbicide, invasive plant, native plant, Canada thistle, Scotch broom, Tim Harrington, David Peter

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page