| Toxicity | Toxic. Horses. |
| Control | Biological, hand pulling/digging, herbicide and mowing. Contact your County Weed District or local Applicator for more information. |
| Habitat | Grassland, rangeland, pastures, cultivated fields, disturbed sites and roadsides. |
| Root | Large taproot that grows to soil depths of 3 to 5 feet. |
| Leaf Shape | Deeply lobed rosette, linear mature leaves. |
| Lifespan | Winter annual; one year life cycle; may germinate in fall or spring. |
| Priority 1A Weed | Not present or limited presence in Montana. If you think you’ve found this plant, please contact your county weed coordinator or Montana Department of Agriculture immediately! |
| Similar Looking Plants | At rosette stage, other knapweeds. |
| Important Information | Yellow starthistle spreads primarily by seed dispersal and seeds remain viable in the soil for up to 10 years. It causes chewing disease in horses and has been known to puncture car tires. |
