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Diffuse Knapweed

Centaurea diffusa

What is it?

Knapweeds, such as bighead, black, brown, diffuse, meadow, and spotted, knapweeds, are perennials, native to Europe. They grow very aggressively and quickly can infest an area if left unchecked.

 

Why is it a problem?

Knapweeds can impair wildlife habitat, decrease plant diversity, and increase soil erosion. They also can cause crop losses and reduce forage, decrease the appeal of recreational lands, and pose wildlife hazards. Diffuse knapweed has spines that can damage the mouths and digestive tracts of livestock, significantly reducing forage opportunities. Knapweed can also cause skin irritation in some people. As a precaution, anyone working with spotted knapweed should wear gloves and avoid getting sap into open cuts or abrasions.

 

Management Techniques:

Knapweed can spread quickly by stems that are carried on vehicles or that are in infested hay or seed. Early detection and prompt control of knapweed infestations are by far the most economical ways to manage this weed.

They are readily controlled with herbicides but will re-invade unless cultural techniques are reinforced.

 

What can we do? 

Preventing knapweed from spreading is extremely important:

  • Mowing during or after flowering can cause the seeds to spread. The plant can also spread in hay and under vehicles. People need to be careful of using hay from road ditches of main roadways, or hay purchased from known infested areas.

  • If a small population of this plant is found, you can easily pull it by hand when the ground is damp. Be sure to pull the entire root.

  • Flowering plants can be bagged and removed from the site.

  • Individual plants or small populations of knapweed should be controlled before they become large populations.

 

Entities working on this invasive in the Gunnison Basin:

  • National Park Service

    • PDF, that looks at invasive and exotic plant monitoring in Black Canyon of the Gunnison N.P. nad Curecanti N.R.A..

       

General Information On Diffuse Knapweed:

 

 

 

 

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