Widely spread across Utah. Control efforts focus on reducing or eliminating new or expanding populations.
Quick Facts
Report your sighting through EDDMapS to help us track and respond to new infestations.
Report on EDDMapSCanada Thistle
Cirsium arvense
Overview
Canada thistle is one of the most widespread and economically damaging invasive plants in North America. Its extensive creeping root system makes it nearly impossible to eradicate. It invades agricultural fields, rangelands, and disturbed areas, reducing crop yields and forage production.
How to Identify
Perennial 2-5 feet tall. Small pink to purple flower heads (no spines on flower heads). Deeply lobed, spiny leaves. Spreads aggressively by creeping roots. Separate male and female plants.
Control Methods
Long-term integrated management is required. Combination of herbicide, biological control, and competitive seeding. Mowing before flowering reduces seed production but does not kill the plant.
Herbicide Recommendations
Clopyralid, picloram, or aminopyralid. Apply in spring or fall. Multiple treatments over several years are required.
⚠️ 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.
