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National Invasive Species Information Center
U.S. Department of Agriculture
Home / Terrestrial Invasives / Terrestrial Plants / Diffuse Knapweed

Diffuse Knapweed

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Diffuse knapweed
Diffuse knapweed, flowers - USDA APHIS PPQ, Oxford, North Carolina
Scientific Name: 

Centaurea diffusa Lam. (ITIS)

Synonym: 
Acosta diffusa (Lam.) (ITIS)
Common Name: 
Diffuse knapweed, white knapweed, spreading knapweed, tumble knapweed
Native To: 

Eastern Mediterranean region (Winston et al. 2012)

Date of U.S. Introduction: 

1800s (Wolfson et al. 2005)

Means of Introduction: 

Introduced accidentally through contaminated seed (Zouhar 2001)

Impact: 

Reduces agricultural yields and forage values; crowds out native species (Winston et al. 2012)

Distribution / Maps / Survey Status

Early Detection & Distribution Mapping System (EDDMapS) - Diffuse Knapweed
University of Georgia. Center for Invasive Species and Ecosystem Health.
Provides state, county, point and GIS data. Maps can be downloaded and shared.

Images

Google Images - Diffuse Knapweed
Google.
Invasive.org - Diffuse Knapweed
University of Georgia. Center for Invasive Species and Ecosystem Health.

Videos

YouTube - Diffuse Knapweed

Google. YouTube; Montana Weed Control Association.

Selected Resources

The section below contains highly relevant resources for this species, organized by source. Or, to display all related content view all resources for Diffuse Knapweed.

Council or Task Force
Factsheet - Knapweeds (Mar 2019) (PDF | 1.83 MB)

Invasive Species Council of British Columbia (Canada).

See also: Publications for more resources

Fact Sheet: Diffuse Knapweed (Jan 2014) (PDF | 650 KB)
Alberta Invasive Species Council (Canada).
See also: Fact Sheets for more information about individual invasive species, including those listed as "Prohibited Noxious" and "Noxious" under the Alberta Weed Control Act
Priority Species: Knapweeds

Washington State Recreation and Conservation Office. Washington Invasive Species Council.

Partnership
Global Invasive Species Database - Centaurea diffusa (herb)
IUCN. Species Survival Commission. Invasive Species Specialist Group.
Invasive Plant Atlas of the United States - Diffuse Knapweed
University of Georgia. Center for Invasive Species and Ecosystem Health.
Invasive Species Compendium - Centaurea diffusa
CAB International.
Plantwise Technical Factsheet - Diffuse Knapweed (Centaurea diffusa)
CABI. Plantwise Knowledge Bank.
Federal Government
Biology and Biological Control of Knapweeds, FHTET-2011-05 (2012) (PDF | 45.5 MB)

USDA. FS. Forest Health Technology Enterprise Team.

See also: Invasive Species Publications for more publications
Fire Effects Information System (FEIS) - Centaurea diffusa
USDA. FS. Rocky Mountain Research Station. Fire Sciences Laboratory.
PLANTS Database - Diffuse Knapweed
USDA. NRCS. National Plant Data Center.
U.S. National Plant Germplasm System - Centaurea diffusa

USDA. ARS. National Genetic Resources Program. GRIN-Global.

State and Local Government
Class B Noxious Weed: Diffuse Knapweed
Washington State Noxious Weed Control Board.
Diffuse Knapweed (Centaurea diffusa)

Wisconsin Department of Natural Resources.

Encycloweedia: Data Sheet - Centaurea genus
California Department of Food and Agriculture.
See also: Included on California's noxious weed list; see Encycloweedia: Program Details for additional resources
King County (Washington) Noxious Weed Control Program - Diffuse Knapweed
King County Department of Natural Resources (Washington). Water and Land Resources Division.
Noxious Weed Species - Diffuse Knapweed

Colorado Department of Agriculture. Conservation Services Division. Noxious Weed Program.

Academic
MontGuide - Biology, Ecology and Management of Montana Knapweeds (Aug 2017)

Montana State University Extension.

Weed Control in Natural Areas in the Western United States: Diffuse Knapweed (2013) (PDF | 236 KB)
University of California. Weed Research and Information Center.
See also: Weeds in Natural Areas for more information sheets
Know Your Knapweeds
North Dakota State University. Extension Service.
Natural Resources Series: Range - Diffuse and Spotted Knapweed
Colorado State University Extension.
Noxious Weeds of Nebraska - Spotted and Diffuse Knapweed
University of Nebraska - Lincoln. Cooperative Extension.
Professional
Noxious Weed Information - Diffuse Knapweed
Colorado Weed Management Association.
Weed Identification - Diffuse Knapweed
Montana Weed Control Association.

Citations