Back to Target Weeds for Control
Why should we care?
How to Identify
- Like the Plumeless Thistle and Bull Thistle, this plant colonizes primarily in disturbed areas such as pastures, roadsides, ditch banks, hayfields and disturbed prairies. It generally does not pose a threat to high quality areas. Because it is distasteful to most grazing animals, the bull musk affects available forage.
About the Plant and Where it came from
- Biennial herbaceous plant, between 1.5–6 feet tall, multi-branched stem. Plants overwinter in the rosette stage. The leaves are alternate, coarsely lobed, dark green with light green midrib, smooth and hairless. Large first year rosette leaves. The flowers are disk-shaped flowerheads that contain hundreds of tiny individual purple flowers which bloom from June through July. Flowerheads droop to a 90 degree angle from the stem when mature. The roots consist of a fibrous taproot.
How to Control
- Carduus nutans
- This native of western Europe was introduced to the US in the Early 1800s, and is declared an agricultural pest.
- Cultural control: Hand-pulling or mowing in early bud or bloom stage, then dispose offsite.
- Chemical control: Spot-spraying with lyphosate, triclopyr or metsulfuron when plants are in rosette stage (first year) in the fall when non-target plants are less susceptible.
- Biological control: Thistlehead-feeding weevil and rosette-feeding weevil. Caution: Observations of weevils feeding on native thistles.