Meadow Knapweed

Meadow Knapweed (Centaurea debeauxii)

Report

Photo credit: Jennifer Andreas, Washington State University, Bugwood.org

Management Category

ID Characteristics

General: Meadow Knapweed is a perennial flowering plant from the Asteraceae (Daisy) family.

Flowers: Meadow Knapweed flowers grow individually at the end of stems. They range from light pink to purple and are up to 2 cm in diameter.

Stems: Are upright, and 0.5 – 1 m tall. They are reddish with vertical ridges.

Leaves: Are pointy (lance-shaped) with fuzzy hairs. The leaves get smaller up the stem. Lower leaves are toothed or lobed, while upper leaves are rarely toothed or lobed.

Seeds: Meadow Knapweed are white to light brown, sometimes hairy on the end.

Roots: Seedlings have a taproot, while mature plants form clustered roots below a woody crown.

Similar Species

Invasive:

WBP4-VillageNorth-03-Centaurea-biebersteinii-C.-maculata-Fitz-Creek-bioswale-2007-08-14-9318-for-SSISC-e1725484058275

Photo credit: B. Brett

Spotted Knapweed (Centaurea stoebe) is an invasive plant in the Sea to Sky region that is often mistaken for Meadow Knapweed. However, you can tell them apart by their leaves: Spotted Knapweed has grey-green, deeply lobed leaves, while Meadow Knapweed features pointy, lance-shaped leaves.

Habitat & Origin

Meadow Knapweed is native to Europe, and likely developed as a hybrid between black (C. nigra L.) and brown (C. jacea L.) knapweeds. It’s possible it was brought to North America for foraging.

It thrives in sunny but also wet conditions, such as roadsides, riparian areas, pastures, vacant lands, and wet meadows.

How it Spreads

Meadow Knapweed spreads predominantly through seeds, though root crown segments can also spread the plant. Seed dispersal can occur through wind, water, vehicles, and hay.

Impacts

Ecological:

Outcompetes native plants, reducing biodiversity and threatening native habitats.
Can hybridize with other Knapweeds, allowing for aggressive dispersal.

Economic:

Not palatable to livestock.
Reduces forage for grazers up to 63%.
Interrupts Christmas tree production.

Stop the Spread

Meadow Knapweed is not yet found in the Sea to Sky region, but is found in neighbouring areas and may arrive here soon. The goal is to prevent Meadow Knapweed’s introduction by focusing on education and awareness. If prevention fails, the goal will become immediate eradication following the proposed SSISC EDRR protocol.

What you can do:

Regularly monitor properties for weed infestations.
Remove plant material from equipment, vehicles or clothing used in infested areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
Ensure soil and gravel are uncontaminated before transport.
Minimize soil disturbances (e.g., use grazing plants that prevent soil exposure from overgrazing), and use seed mixes with dense, early colonization (e.g., alfalfa or barley) to re-vegetate exposed soil and resist invasion.
Ensure invasive plant (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g., landfill). Do NOT compost.

Control

Mechanical Control:

Combined hand-pulling and digging of small infestations and saplings is effective.
Mature plants have root clusters which prevent effective mechanical removal.

Chemical Control:

Spot spraying with glyphosate while the plant is actively growing is effective, especially before the plant blooms and goes to seed. Aminopyralid is effective while the plant is growing, or in the fall before frost.

We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.