Weed Department

Since the Weed Superintendent may be out doing field work, he may not be available to answer your call. Please leave a message and he will return your call as soon as possible.

Noxious Weeds

Idaho has about 800 of the nation's 2,000 weed species, most of which are alien to the state. Idaho's noxious weeds have been introduced from other regions. We do not have the natural systems to keep them in check. Importing natural controls is not possible for all weeds and it takes decades to and vast resources to introduce naturals controls. As a result, noxious weeds overwhelm native plant communities and disturbed areas, spreading steadily year by year. Several species that were previously unreported have been found each year over the last 10 years. Recognition of invaders is the first step in dealing with them.


Noxious weeds spread rapidly as if a cancer in the natural system. They reproduce, multiply, and spread as an explosion of environmental pollution, in slow motion. While many pollutants tend to decay and become dilutes, weeds become concentrated and spread to new locations. Once the habitat becomes infested it may never recover to a native community even with intensive management.


Prevention and inspection are the most economical management system for reducing the rate of noxious weed spread. Once noxious weeds have become established expect to spend $30 to $70 per acre for management on your land or in higher taxes for their management on public land.

Designation of Noxious Weeds

Noxious weeds are plant species that have been designated "noxious" by law. The word "noxious" simply means deleterious, and all listed weeds are deleterious by definition.  There are hundreds of weeds species in Idaho; however, only 35 are designated noxious by Idaho Law as of 1997. Currently, the Idaho Department of Agriculture uses the following criteria for designation of a noxious weed:
  • It must be present in but not native to Idaho.
  • It must be potentially more harmful than beneficial to Idaho.
  • Eradication must be economically physically feasible.
  • The potential adverse impact of the weed must exceed the cost of control

Idaho Noxious Weed Law

The purpose of the Idaho Noxious Weed Law is to protect lands within the state from invasion by noxious weeds. The Idaho Noxious Weed Law requires landowners to eradicate noxious weeds on their land, except in special management zones.