Widely distributed but controllable. High priority for control or eradication where possible.
Quick Facts
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Report on EDDMapSYellow Starthistle
Centaurea solstitialis
Overview
Yellow starthistle is an annual plant from the Mediterranean that is one of the most problematic invasive plants in the western United States. It is toxic to horses, causing a fatal neurological condition called "chewing disease." Dense infestations can cover millions of acres.
How to Identify
Annual 1-4 feet tall. Yellow flower heads surrounded by long, sharp yellow spines (1-2 inches). Deeply lobed basal leaves. Upper leaves are narrow and clasping with winged margins.
Control Methods
Mowing before flowering can reduce seed production. Herbicide treatment in early spring on rosettes. Biological control agents are available. Competitive seeding is essential.
Herbicide Recommendations
Clopyralid, picloram, or aminopyralid. Apply in early spring on rosettes for best results.
⚠️ Always read and follow pesticide label directions. Contact your county weed superintendent for site-specific recommendations. Permits may be required near water.
Need help managing this weed?
Skyline CWMA can connect you with technical assistance, cost-share programs, and licensed contractors for treatment on your property.
