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Northwest Michigan Invasive Species Network


Invasive Knotweed Treatments


Invasive knotweeds, such as Japanese knotweed, giant knotweed, and Bohemian knotweed, are extremely difficult to control.  Because the plants can reproduce by fragmentation (a piece as small as an inch long or, in extreme cases, a few millimeters can start a new plant!), cutting and digging only make the problem worse.  Because of their volcanic origins, burning these plants is also ineffective.
  • Herbicide:  ISN and our contractors treat with 1.3% aminopyralid (trade name Milestone) OR 5% imazamox (trade name Clearcast) with 1-2% glyphosate (trade name AquaNeat), depending on the best choice for the site.  We work with landowners to help them choose the best herbicide for their site.
    • Milestone treatments usually include 0.2 oz/gal of an aquatic-approved, non-ionic surfactant (such as CygnetPlus).  Clearcast usually uses an aquatic-approved crop oil concentrate (e.g. Agri-dex) at a rate of 4%.
  • Timing:  Treatments can happen twice per year, with the first treatment when the plants are three to four feet high (early June, in our region), and again at least 60 days before the first frost (early August).
  • Methods:  Most often, we use backpack or hand-sprayers to apply the herbicide to the plants’ leaves.  In a few cases, we use an injector to  put herbicide directly into the plant.
  • Other:  Treatments may take as little as one year to be successful, but more often two to four.  In some cases, as many as seven years of active treatment are needed.  In all cases, because of its immense underground root and stem mass, monitoring for new sprouts is needed for at least 5 years past the last treatment.
Note:  It is ILLEGAL to sell, trade, share, or otherwise move invasive knotweeds in Michigan.  This includes fragments of the plant in soil!  Don’t spread this plant!
Picture

Contact US

1450 Cass Road
Traverse City, Michigan 49685
-
(231)941 - 0960
-
​kgrzesiak@gtcd.org
Pleasant Peninsula Design, Habitat Matters 2017 
  • Home
  • About
    • About ISN & FAQs
    • Our Team
    • Our Partners
    • Steering Committee
    • Employment
    • Enewsletter
    • Donate to ISN
  • Events
  • ID & Report
    • Top 12 Species
    • Early Detection Species
    • Awareness Species
    • Other Invasive Species >
      • Hemlock Woolly Adelgid
      • Aquatic Invasive Species
      • Gypsy Moths
    • ID and Reporting Tools
  • Resources
    • Education
    • Tool Library
    • Planting Guide/Ordinance Templates
    • Requests For Bids
    • Treatment Information
    • Other Information
    • Native Plant Seeds
    • Invasive Species in the News >
      • Nature Change
      • ISN in the News
  • Go Beyond Beauty
    • Find Participants >
      • Nurseries >
        • Bioconcentric Farms
        • Birdsfoot Native Nursery
        • Black Cap Farms
        • Cyman Gardens
        • Garden Goods
        • Greystone Gardens
        • Misty Ridge
        • Northwoods Landscaping & Nursery
        • Pine Hill
      • Landscapers >
        • Cre Woodard
        • Cyman Gardens
        • Designs in Bloom
        • Greener Earth Landscaping
        • Dompierre Design
        • Heritage Landscape Design
        • Inhabitect, LLC
        • Lakeview Habitats
        • Laurel Voran, LLC
        • The Mossy Tree, LLC
        • Northwoods Landscaping & Nursery
        • Old Mission Associates
        • Inner-Coastal
        • Perennial Harvest
        • Pine Hill
        • Silverman & Company
        • Sustainable Landscape Design, LLC
        • TruNorth Landscaping
        • Wildlife & Wetland Solutions
      • Community Participants
    • GBB Achievement Program
    • Register >
      • Registration Form (Garden Professional)
      • Registration Form (Individual or other org)
      • Start-up Materials
    • Ornamental Invasive Species
    • Native Plant Species
    • Participant Signs
    • Japanese Barberry Trade-Up Day
    • GBB Resources
  • Contact