Synonyms: Acosta diffusa (Lam.) Sojak
Common names: diffuse knapweed
Centaurea diffusa (diffuse knapweed) is usually a biennial plant (family Asteraceae) that forms dense infestations. Seeds disperse when stems break off and tumble in the wind. Diffuse knapweed is not very common in California, but is one of the most invasive species in many other western states.Cal-IPC Rating: Moderate
CDFA Rating: A*
Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.
Species ID Card
Invasive Species ID Card - To support field identification of early detection species, Cal-IPC has designed a set of Species ID cards that can be downloaded, printed double-sided, and trimmed to size.
Weed Management Notes
- Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.
Cal-IPC Newsletter Articles
- Celebrating park stewards. Cal-IPC. Vol 24, Issue 2
- Weeds and climate resilience in Sierra meadows. Brusati, Elizabeth; Johnson, Doug. Vol 24, Issue 1
- Eradication in the central Sierra. Cal-IPC. Vol 24, Issue 1
- Progress in the Sierra and beyond. Cal-IPC. Vol 22, Issue 1
- Weed biological control agents approved for California. Pitcairn, Michael J.; Smith, Lincoln; Moran, Patrick. Vol 22, Issue 1
- “Dip-and clip”: A new treatment for herbaceous weeds. Erskine Ogden, Jennifer A.; Renz, Mark; Donaldson, Sue. Vol 14, Issue 4
- Fighting weeds in the Tahoe basin. Donaldson, Sue. Vol 11, Issue 2
Cal-IPC Symposium Presentations
Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.
There are no Symposium presentations associated with this species yet.
Other Centaurea diffusa Information
- CalPhotos - Images of plants taken mostly in California.
- Calflora - See the distribution of this species on Calflora's map of California.
- CalWeedMapper - Distribution information with ability to determine regional priorities.
- Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
- CDFA - California official noxious weeds.
- USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.
- Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.
- EDD MapS - North American distribution based on Early Detection and Distribution Mapping System.