Controlling Noxious Weeds


Controlling Noxious Weeds

If you've discovered noxious weeds on your property, your next steps are:

  • to figure out what species you have.
  • whether their control is required (we recommend controlling them all regardless to be a good neighbor and a good land steward). 
  • to decide what best management practices will work best for you. 

You may want to contact your local County Noxious Weed Control Board. Your local conservation district or WSU Extension office are also excellent resources.

Staff at your County Noxious Weed Control Board are available to provide educational and technical assistance in developing a plan to control noxious weeds and foster healthy plant communities. 

Some also offer: 

  • free site consultations to help you determine what noxious weeds you have and the best strategies to control them. 
  • voucher or grant programs to help landowners to control their noxious weeds and/or purchase non-invasive replacements. 

You can also use our search tool to assist in identifying and learning how to control your noxious weeds. We offer a variety of free publications that provide more information about identification, control, and preventing future infestations.

Integrated Pest Management: A Primer on Effective, Long-Term Weed Control Methods

Read our brochure on controlling noxious weeds and creating healthy plant communities. 

Curious about integrated pest management?

Have you ever wondered about how IPM (integrated pest management) principles are used? 

WSDA and the Washington State Noxious Weed Control Board recommend this comprehensive approach to managing noxious weeds using thoughtful, coordinated methods to develop healthy plant communities and mitigate economic and ecological impacts from noxious weeds.

New! Learn more about the Clallam County Integrated Vegetation Weed Management Plan, a new initiative to create valuable ecological resources for pollinators and tax payers in Clallam County. Check out their plan and watch the presentation on youtube.

The goal of integrated weed management is to choose the best control tools  - often a combination of tools - and the best time of year for the weed or weeds you are targeting for control on a particular site. 

Some of these tools include:

Mechanical Control Methods 

  • Hand-pulling 
  • Digging 
  • Mowing
  • Tarping and mulching
  • Tilling

For small infestations, hand-pulling can minimize soil disturbance while  leaving desirable species intact.

Cultural Control Methods

  • Heavily seeding and planting desirable species 
  • Improving soil conditions 
  • Managing water and light availability

These management practices make site conditions less favorable for noxious weeds and better for desired plants.

Biological Control Methods 

  • Biocontrol agents, such as approved, host-specific insects, can effectively target a specific noxious weed and will not feed on native species or commercial crops.  
  • Grazing animals, such as goats, sheep, or other livestock, control some noxious weeds but may also eat desirable vegetation, so plan to replant afterward if necessary. 

Chemical Control Methods

Chemical control includes treating noxious weeds with carefully chosen herbicides. Your county noxious weed control board can help you to determine which herbicide is appropriate for your situation. Some herbicides can only be applied by a licensed pesticide applicator- for more information about licensing, visit the Washington State Department of Agriculture's Pesticide Licensing Program.

Herbicides can open up sites for other plants to take root; make sure that revegetation is part of your follow-up plan. Be sure to follow the label instructions (the label is the law) and ask for help in choosing the best product for your site and weeds. The Washington State Department of Agriculture provides these tips for applying home and garden (H &G) herbicides.

Herbicide recommendations for many noxious weeds can be found in the Pacific Northwest Weed Management Handbook. The National Pesticide Information Center also provides helpful, science-based information about pesticides, which includes herbicides, and related topics.

Use an integrated weed management approach to reach your land-use goals. 

  1. First, determine your land-use goals. Is the land to be used for wildlife habitat, feeding pollinators, forage production, recreational land maintenance, or for attractive home landscaping?
  2. Decide how much of each weed is acceptable on your site, but be sure to control those noxious weeds as necessary by law. 
  3. Design your management plan to create sites for the species you want and to help prevent weeds from invading.  
  4. Set yourself up to succeed by dividing large noxious weed infestations into sections. Limit the size of the area you work on to something that is manageable and then target a new area. 
  5. Monitor your progress periodically to see if noxious weeds are decreasing, new weeds are appearing, and desired plants are establishing. Taking pictures can help gauge progress, and comparing before-and-after pictures is rewarding! 
  6. Adjust your control methods as needed, or get more help  from your county weed board, conservation district, or WSU Extension office if you don’t think you are making enough progress.
  7. Remember, it’s critical to revegetate bare ground with desired plant species before weeds get a chance to grow back. Have a plan in place before you begin your noxious weed control.

Timing is important.

  • Fall and spring are the best times to control noxious weeds and establish native plants. 
  • Hand-pull weeds in the spring and fall when the soil is moist and roots - especially taproots - are more easily removed. This is also a great time to reseed with annual grasses, since disturbing the soil can cause buried weed seeds to germinate.   
  • Control weeds when they are young.  Seedlings and rosettes take less effort and resources to treat, whether you are tilling, hand-pulling, digging, tarping, or applying herbicide. Controlling before flowering means you don’t have to worry about them setting seed that year. 
  • If you are unable to treat noxious weeds before they bloom, try to time control efforts after pollinators have visited and remove and discard flowerheads before they set seed if possible. 
  • Well-established infestations take longer to convert to desirable vegetation. It may be best to reseed with grass as a placeholder for the first few years. That way you can hand-pull or use a selective herbicide to treat any emerging weeds and then plant native, broadleaf species when the seed bank has been depleted.