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Noxious Weeds

The term weed means different things to different people. In the broadest sense, it's any plant growing where it's not wanted. Weeds can be native or non-native, invasive or non invasive, and noxious or not noxious.

Legally, a noxious weed is any plant designated by a Federal, State or county government as injurious to public health, agriculture, recreation, wildlife or property.

A noxious weed is also commonly defined as a plant that grows out of place (i.e. a rose can be a weed in a wheat field) and is "competitive, persistent, and pernicious."

Are invasive plants the same as noxious weeds?

No. Invasive plants include not only noxious weeds, but other plants that are not native to this country. Plants are invasive if they have been introduced into an environment where they did not evolve.

As a result, they usually have no natural enemies to limit their reproduction and spread. Some invasive plants can produce significant changes to vegetation, composition, structure, or ecosystem function.

Reducing noxious weed spread

Here are a few guidelines to help lessen the spread of noxious weeds:

  • Avoid driving in noxious weed infested areas. Seeds can become stuck in tire treads or mud on the vehicle and be carried to unaffected areas.

  • Don't transport flowering plants you can't properly identify.

  • If you find a small number of isolated noxious weeds that have no flowers or seeds, pull the weeds and leave them where you found them to dry out.

  • If you find noxious weeds and they have flowers or seeds, pull them, place them in a plastic bag or container to avoid spreading seeds, and either burn them or dispose of them in a sanitary landfill.

Some common weeds listed by the federal government as being noxious:

  • Common Crupina

  • Diffuse Knapweed

  • Russian Knapweed

  • Spotted Knapweed

  • Purple Loosestrife

  • Perennial Pepperweed

  • Punturevine

  • Tansy Ragwort

  • Medusahead Rye

  • Rush Skeletonweed

  • Yellow Starthistle

  • Canada Thistle

  • Musk Thistle

  • Scotch Thistle

  • Dalmatian Toadflax

  • Mediterranean Sage

  • St. Johnswort

  • Leafy Spurge

  • Whitetop

  • Dyers Woad