Noxious Weed Control

Investigation Requests

If you would have a question about possible noxious weeds on your own property, or have a complaint about a neighboring property, please fill out the Investigation Request Form (PDF). The Asotin County Noxious Weed Control Board (ACNWCB) will do their best to address Investigation Requests in a timely manner.

Mission Statement

The mission of the Asotin County Noxious Weed Control Board is to carry out the State Noxious Weed Law (RCW 17.10) in a manner which assists the land managers and land users of Asotin County in becoming ever better stewards of the land and resources by protecting and conserving our agricultural lands, recreational areas and natural resources from the degrading impact of invasive noxious weeds.


The goal of the Asotin County Noxious Weed Control Board is to eradicate, contain and/or control noxious weed populations in Asotin County. Noxious weeds, according to RCW 17.10, are defined as, any plant which, when established, is highly destructive, competitive, or difficult to control by cultural or chemical practices.

The board promotes a system of practices using integrated vegetation management. Integrated vegetation management means using all practical methods of weed control at the most effective time. Management recommendations may include mechanical, cultural, chemical or biological control efforts. The Board is committed to educational projects that enhance the public’s awareness of invasive species.

Biological Invasions

Noxious weeds are biological invasions. They invade ecosystems where they have never been before, and cause dramatic changes in these ecosystems. They contribute to the loss of habitats and biodiversity by affecting the processes of succession.

Grasslands Under Duress

Grasslands face the greatest threat from invasive weeds. Land dominated by invasive weeds has accelerated soil erosion and surface runoff. Silt accumulation in the Snake River tributaries is a major negative factor in native salmon recovery programs. Soil disturbance by grazing, rainfall, fire, flood and erosion make the southeast corner of Washington susceptible to weedy invaders.

The presence of invasive weeds can change an ecosystem dramatically. Successful invasions of weeds form monocultures that become climax communities. Predation by alien species has been ranked as the second largest threat to biodiversity by the Nature Conservancy.

Early Detection Priority

Early detection of new invasive species and a subsequent aggressive control/eradication program may help contain or eliminate some weedy invaders before they can cause harm to our agricultural and natural areas. Monitoring of these sites is essential to long term control. A prime example of new weeds in Asotin County are the scattered infestations of:

  • Common Bugloss
  • Dalmatian Toadflax
  • Hawkweeds
  • Japanese Knotweed
  • Leafy Spurge
  • Mediterranean Sage
  • Musk Thistle Hybrid
  • Rush Skeletonweed
  • Spotted Knapweed
  • Whitetop
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These weeds should be aggressively treated where ever they are found.

Landscape Problems

Weeds that are “landscape” problems need a different outlook. Yellow starthistle dominates tens of thousands of acres northeast of a line drawn from the northwest corner to the southeast corner of the County. Sulfur cinquefoil has a strong grip on the southwest corner of Asotin County. A line needs to be drawn between areas that are infested and areas that are not. Yellow starthistle and sulfur cinquefoil should be chemically treated in “new” areas or in areas that can be carefully monitored (someone’s horse pasture, for example).

Other areas with a “landscape” problem need biological controls (yellow starthistle) or a program that includes wide spread use of herbicides (sulfur cinquefoil). These areas need to be carefully monitored.