Common names: Italian thistle
Carduus pycnocephalus (Italian thistle) is a winter annual forb (family Asteraceae) widely distributed in disturbed open sites, roadsides, pastures, annual grasslands, and waste areas in much of California.Cal-IPC Rating: Moderate
CDFA Rating: C*
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.
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
- Weed biological control agents approved for California. Pitcairn, Michael J.; Smith, Lincoln; Moran, Patrick. Vol 22, Issue 1
- Taking to the air to locate, prioritize and treat effectively. Burger, Jutta C.. Vol 21, Issue 2
- Tackling invasive plants on California Sept. of Fish & Game lands. O'Rourke, Brianne; Horenstein, Julie. Vol 17, Issue 1
- Shasta County citizens take on weeds. Dozier, Melissa. Vol 14, Issue 4
- More about Italian thistle. Massera, Jack. Vol 09, Issue 2
- Italian thistles: an ominous threat. Cowan, B.. Vol 08, Issue 1
- Lessons from the front: Taking stock to avoid surprises. Kelly, Mike. Vol 05, Issue 1
- California Exotic Pest Plant Council draft list exotic plants of greatest concern October 1993. CalEPPC. Vol 01, Issue 4
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.
- Two years after the fire: accomplishments in invasive plant control following the 2018 Woolsey Fire. Algiers, Joey (2020)
- Weeds after Woolsey. Algiers, Joseph (2019)
- Mapping weeds and rare plants to inform management and conservation in the Zaca and Jesusita fires. Calloway, Stephanie; Schneider, Heather; Knapp, Denise (2018)
- Fire working group. Clines, Joanna; DiTomaso, Joe; Goode, Suzanne (2004)
- Forbs working group. Pirosko, Carri; Schoenig, Steve (2004)
- Eucalyptus removal on Angel Island. Boyd, David (1997)
Other Carduus pycnocephalus 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.
- EDDMapS - North American distribution based on Early Detection and Distribution Mapping System.