Weed Control
Home ⟩ Noxious Weeds ⟩ Pink and Purple Flower Plants ⟩ Squarrose Knapweed
Squarrose Knapweed
Information | Images
Centaurea virgata
Perennial
Identification and management tips
- Flowers are pink or purple colored. Spiny bracts having a long, recurved (backward pointing) terminal spine.
- Often confused with diffuse knapweed (Centaurea diffusa), but differs principally in the fact that it is a true perennial, and bracts are recurved.
- Unlike diffuse knapweed, seed heads of squarrose knapweed are highly deciduous, falling off the stems soon after seeds mature.
- Squarrose knapweed appears to be more difficult than other knapweeds to control using herbicides.
- Annual treatments for several years will be needed because plants often regrow after chemical application.
Most effective control methods and timing
| March | April | May | June | July | Aug | Sept | Oct |
|---|---|---|---|---|---|---|---|
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Prev Mech Chem Cult |
Prev Mech Chem Cult |
Prev |
Prev Chem Cult |
Prev Chem Cult |
Prevention (Prev) Monitor and destroy new plants before seed production.
Mechanical (Mech) Hand pulling, digging, cutting, mowing and tilling.
Cultural (Cult) Biological control agents, livestock grazing, and revegetation practices.
Chemical (Chem) Selective herbicides based on the plant and the specific location. Check our weed fact sheets for specific control information.
