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  • Noxious Weed Identification List

    Plumeless Thistle


    (Carduus acanthoides)

    Info Sheet Adobe PDF Icon

    Colorado List B - Eradication required in Jefferson County

    General

    • Family: Sunflower (Asteraceae)
    • Herbaceous
    • Biennial (short-lived perennial)
    • Rosettes formed the first year and bolt early in May to June of the next year.

     

    Habitat

    • Found in disturbed areas, such as overgrazed pastures, rangelands, roadsides and right-of-ways

     

    PLANT

    Vegetation

    • Dark green with lighter, mid-rib
    • Spines along edges of stems and leaves
    • Hair on underside of leaves
    • Stems are winged
    • Mature plants are 3 to 8 feet tall with flower heads at the tips of shoots

     

    Roots

    • Tap root

     

    Flower

    • Color: reddish-purple
    • Second season: June to September
    • 1/2 to 1 inch wide
    • Bracts are narrow and tipped with a spine

     

    Seed

    • Lacks Pappus

     

    Seedling

    • Seedlings spend their first growing season as rosettes

     

    Reproduction

    • Seed

     

    CONTROL

    Biological

    • Not allowed

     

    Chemical

    • Apply one of the following during rosette through early bolt stage (spring or fall):
      • 2,4-D plus Dicamba; or
      • Escort; or
      • Milestone; or
      • Overdrive; or
      • Tordon (restricted-use pesticide)

     

    Cultural

    • Prevention – maintain health of site
    • Removal; hand pulling works when populations are small and isolated; taproot must be severed at least 2 to 3 inches below ground
    • Revegetation of highly disturbed sites
    • Grass competition; promote grass growth with fertilization, irrigation and reseeding.

     

    Mechanical

    • Burning - N/A 
    • Grazing - N/A 
    • Mowing - Not effective alone 

     

    Use all chemicals according to the manufacturer's label. Listing the above methods or products does not imply a specific recommendation or endorsement.



    Alicia Doran
    Weed & Pest Management Specialist
    303-271-5989
    adoran@jeffco.us

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    weed-pest-b-plumeless-thistle-habit

    weed-pest-b-plumeless-thistle-rosette


    Last Updated: 7-31-2013