Common names: tocalote; Malta starthistle
Centaurea melitensis (Malta starthistle, tocalote) is a bushy annual (family Asteraceae) found throughout most of California and in many other western states. Malta starthistle prefers disturbed and open areas, including grasslands, open woodlands, agricultural fields and roadsides. It is most invasive in California’s central western and southwestern regions. While Malta starthistle is less invasive than yellow starthistle (Centaurea solstitialis), it still spreads quickly by producing great quantities of seed if given the proper conditions. Insects such as the false peacock fly (Chaetorellia succinea) and hairy weevil (Eustenopus villosus) have been used as biological controls with some success.Cal-IPC Rating: Moderate?
CDFA Rating: -*?
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
- Tackling invasive plants on California Sept. of Fish & Game lands. O'Rourke, Brianne; Horenstein, Julie. Vol 17, Issue 1
- Results of the CalEPPC questionnaire at Symposium ’98 in Ontario. DiTomaso, Joe. Vol 06, 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.
- Aridity constrains the adaptive potential of plant invaders under nitrogen deposition. Valliere, Justin (2023)
- Mapping weeds and rare plants to inform management and conservation in the Zaca and Jesusita fires. Calloway, Stephanie; Schneider, Heather; Knapp, Denise (2018)
Other Centaurea melitensis Information
- CalPhotos - Images of plants taken mostly in California.
- Calflora - Distribution map and records of this species in California.
- CalWeedMapper - Distribution map of this species in California with ability to determine regional priorities.
- EDDMapS - Distribution of this species in North America.
- Jepson Interchange - Information on this plant's taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
- USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.