Noxious Weeds


A noxious weed is a plant defined as a pest by law or regulation. All of the designated noxious weeds are invasive and need to be eradicated or controlled. The State of California has compiled the Noxious Weed list and assigned a rating to each reflecting California Department of Food and Agriculture's view of the statewide importance of the pest, likelihood of successful eradication, and present distribution. The revised language of the rating policy assigns a rating of  A, B, C, Q, D, and W.

How Does Contra Costa County Control Noxious Weeds?

Contra Costa County Department of Agriculture is committed to eradicate all weeds within its borders with an "A" or "Q" rating. We also place special emphasis on weeds with a "B" rating. Although we devote little effort to "C" rated weeds, we strongly encourage landowners to control any noxious weeds existing on their property.

Some of the Noxious Weeds Contra Costa County Department of Agriculture focuses on are:

  • Artichoke Thistle - Spiny plant found throughout Contra Costa County.
  • Purple Star Thistle - Invasive plant with minimal distribution in Contra Costa County.
  • Japanese Dodder - Parasitic plant that can attach itself to most any plant and eventually kill its host. It had been found mostly in the Richmond and San Pablo areas, and a couple places in Antioch.
  • Purple Loosestrife - An introduced species found along the banks of rivers and streams. Fast spreading and it will crowd out native plants.
  • Red Sesbania - Found in riparian areas, along streams and in marshes. Fast to spread and it will crowd out natives, parts of this plant are poisonous.