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National Invasive Species Information Center
U.S. Department of Agriculture
  1. Home
  2. Terrestrial Invasives
  3. Terrestrial Plants
  4. Russian Knapweed

Russian Knapweed

Scientific Name

Rhaponticum repens (L.) Hidalgo (ITIS)

Common Name

Russian knapweed, Turkestan thistle, creeping knapweed, mountain bluet, Russian cornflower, hardheads

Synonym

Centaurea repens (L.), Acroptilon repens (L.) DC. (ITIS)

Native To

Eurasia (Zouhar 2001)

Date of U.S. Introduction

Early 1900s (Zouhar 2001)

Means of Introduction

Accidentally as a seed contaminant (Zouhar 2001)

Impact

Crowds out native species and desirable forage; toxic to horses (Zouhar 2001)

Russian knapweed

Russian knapweed, plants

Credit

Photo by Norman E. Rees; USDA, Agricultural Research Service

Source
Invasive.org.

Find more images

Spotlights

  • Russian Knapweed Biological Control Success with Host Specific Wasps and Midges

    • Dec 16, 2022

    • CAB International. Invasives Blog.

    • Russian knapweed (Rhaponticum repens) is a nonnative weed in the western United States. It was introduced in the late 1800’s and is now invading and degrading cropland, rangeland, riparian areas, and roadsides. This deep-rooted perennial is persistent and difficult and expensive to control by conventional means, is toxic to horses and outcompetes native vegetation by producing chemicals that inhibit plant growth. Russian knapweed is listed by the State of Colorado as a noxious weed, to be suppressed, contained, or locally extirpated.

      The Colorado Department of Agriculture (CDA) offers biocontrol agents to help suppress weeds and insect pests. When two gall-forming agents were developed and tested by CABI, and became available for use against Russian knapweed, the CDA was prepared to use them against the more than 50,000 hectares of the weed that currently infests Colorado.

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