Spotted Knapweed
Management Prioritization
Identification
Common Name: Spotted Knapweed
Scientific Name: Centaurea stoebe L. ssp. micranthos (Gugler) Hayek or Centaurea maculosa
Legal Status: Prohibited - Control
Efforts must be made to prevent seed maturation and dispersal of plants into new areas. Additionally, no transportation, propagation, or sale of these plants is allowed. Failure to comply may result in enforcement action by the county or local municipality. Minnesota Noxious Weed Law .
Background
Spotted knapweed is a native of Europe and Asia. It was introduced to North America in the 1890s as a contaminant in agricultural seed and through soil discarded from ship ballast. It has become a serious problem of pastures and rangeland in the western United States.
Spotted knapweed grows 2- 4 feet tall and has a long tap root.
Leaves
In the first year, the plant is a low-lying rosette with deeply lobed leaves and a thick taproot.
In the second year, the plant bolts, producing stout, branching stems with alternate leaves having few to no lobes, and becoming progressively smaller up the stem.
Foliage is gray-green.
Flower
Flowers are small, oval, pink to purple, produced at the end of branched stems. Blooming occurs from June through August.
Bracts
Flowers are covered with stiff bracts marked with dark, upside-down “V” markings, giving them a spotted appearance.
Spotted knapweed bracts
Root
Spotted knapweed has a large taproot.
Spotted knapweed taproot
Rosette
In the first year, the plant is a low-lying rosette with deeply lobed leaves
Distribution
Current Distribution Model
- Point data collected from EDDMapS; not all locations in the state have been recorded, but points on distribution map have been reported and verified.
- Distribution model takes location data and environmental factors into account to create a prediction of current distribution
Management Prioritization
Influenced by:
- distribution models
- actual reports
- economic benefits
- land cover
- conservation features
- trails
High priority areas surround areas of high density to prevent further large infestations and loss of biodiversity.
Infestation Examples
01 / 03
1
General Infested Area
population in the midst of other populations
Management here is involved.
2
Leading Edge
Sparse populations in the transition from infested areas to un-infested areas.
Management is involved but can prevent further spread or large establishment of stands.
3
Isolated Population
Location far from other known populations.
Management here is efficient and cost effective.
Lifecycle: Treatment Timing
Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR). The Trust Fund is a permanent fund constitutionally established by the citizens of Minnesota to assist in the protection, conservation, preservation, and enhancement of the state’s air, water, land, fish, wildlife, and other natural resources. Currently 40% of net Minnesota State Lottery proceeds are dedicated to growing the Trust Fund and ensuring future benefits for Minnesota’s environment and natural resources.
