top of page
Irrigation System

Invasive Plant Species Identification & Control Guide
Selected Weeds of Scott Valley, California

Invasive plant species pose risks to our local biodiversity by reducing or out-competing native plant populations, changing the intensity and spread of wildfires, altering aquatic ecosystems, and reducing forage for livestock and cropland for ranchers and farmers. Once noxious or invasive weeds become established it is extremely difficult to eradicate them and bring back the native plant communities that have been displaced. The intended purpose of this guide of some of the most invasive weeds in Scott Valley, California is to promote awareness of invasive species, as well as assist land users in identifying, reporting and controlling invasive plants. 

"Noxious (or invasive) weed"  means any species of plant that is, or liable to be, troublesome, aggressive, intrusive, detrimental, or destructive to agriculture, silviculture, or important native species, and difficult to control or eradicate, which the Secretary of the California Department of Food and Agriculture, by regulation, designates to be a noxious weed. (Definition from the California Food and Agriculture Code.)

Dyer's Woad
Perennial pepperweed (tall whitetop)
Scotch Broom
Canada Thistle
Spotted Knapweed
Diffuse Knapweed


  • Selected Noxious Weeds of Northeastern California

  • Weed Control in Natural Areas in the Western United States (Weed Research & Information Center, University of California). 2013.

bottom of page