Spotted Knapweed

Centaurea stoebe

Photo Credit: Miesel, Marion SWCD

Short-lived perennial with multiple stems per rosette. Bluish-gray leaves and setms. Flowers are purple; flower head bracts are black-tipped.

Life Forms	Forb
Habitats	Disturbed sites Gravel bars Roadsides
ODA Listing	B
Soil and Moisture Conditions	Dry Rocky or gravelly soil Well drained
Suggested Actions	Report to Oregon Invasives Hotline Use BMPs to control on private property
Shade Preference	Full sun
Mature Height	3'
Distribution	found across Oregon
Control	Repeated mowing can be effective before the plants go to seed; after this point mowing will spread seeds. Small infestations can be pulled while wearing gloves; the area will need to be moitored and repulled for several years.
Disposal Methods	If seed heads are removed, bag and seal and dispose of them in the landfill.
Reproduction and Spread	Spreads by seed with contaminated equipment along disturbed sites - Ditches, field margins, railroad lines, etc.
Introduced	Native to Central, Eastern, and Southeastern Europe. Maybe have entered US as a contaminant in alfalfa seed as early as 1893.
Look Alikes	Other knapweeds
Impact	Infestations can increase runoff and erosion and dominate the landscape.
More Info	https://www.nwcb.wa.gov/images/weeds/Spotted-Knapweed-control_King.pdf https://www.oregon.gov/oda/shared/Documents/Publications/Weeds/SpottedKnapweedProfile.pdf https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1559.pdf https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mtpmspg11294.pdf https://www.invasive.org/browse/subinfo.cfm?sub=3013