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WSU/Pend Oreille Extension introduced the Sense of Place series in 1999, with a focus on local landscape and natural history of Pend Oreille County, Washington. A partnership with the Kalispel Tribe of Indians Natural Resources Department has allowed us to expand this program through EPA funding to include more classes, a newsletter and this website.

Pend Oreille Weeds

...and Change


What do we mean by alien, exotic, invasive…or even the term “weed”? The US Department of Agriculture - Agricultural Plant Health Inspection Service (APHIS) defines a weed as any plant that poses a major threat to agriculture and, or natural ecosystems within the United States. This definition is more specific than a typical dictionary offers: “a plant growing in an undesired location”—and so more accurately portrays the economic and ecological impact specific weeds can cause.

Under the Revised Code of Washington (RCW) Chapter 17.10, Section .010 (1) we define a noxious weed as “…a plant that when established is highly destructive, competitive, or difficult to control by cultural or chemical practices.” State and local noxious weed boards refine the working definition by creating a list of noxious weeds revised each year to reflect new introductions. The 2003 Pend Oreille County Noxious Weed List has 42 species found in the county plus 58 species not known to occur here, but mandatory to control if found growing within the county.

By Presidential Order (no less) invasive weeds are defined as “alien” or “not native” (synonyms: exotic, introduced, non-indigenous). Although in Washington and Idaho our definitions do not explicitly state that noxious weeds must be of a non-native origin, it has been the policy of both states to only include alien species on official weed lists. Alien species have the added advantage on their side of being relatively free from predators (herbivores, parasites, and disease).

Do all non-native plants introduced into our area cause a problem? No, only 10% of those introduced will establish here, and of those, only 10% will go on to cause a problem – becoming weedy. What gives the plants in this group the upper hand? Invasive plants can better harness the local resources of the area they are introduced into than the native plants of that community. They may be prolific seed producers and have high seed germination rates. Many are easily propagated by root or stem fragments or mature more rapidly than surrounding natives. Some have roots that extend farther down. Newer research is revealing that many of our problem plants exude chemicals that inhibit herbivore damage. Interestingly, they may stop producing these chemicals after a number of generations here and divert that energy to increased reproductive potential.

Usually we think of weeds as garden pests or a problem for agriculture. Weeds can cause problems in the wild too, even jeopardizing rare and endangered plant species. In Glacier National Park, a spotted knapweed invasion has caused six native plants to be classified as rare and has extirpated seven species previously designated as rare.

More than any other means, people are the primary spreaders of weeds. Our vehicles often pick up seeds at an infested site and deposit them in another. This is why infested roadsides are such a common sight. Clothes and camping gear can also collect seeds, depositing them at the site of our next outing. Off-road vehicles, even snowmobiles, transport weeds deeply into the woods where we recreate. Feed for stock animals may be contaminated with weed fragments, endangering back-country areas with infestation.

Our sorriest means of spread comes from picking the “pretty wildflowers” from one area, then as they wilt, tossing them off in another area that may not have been infested. Often avid gardeners dig up these plants and transport them to their home gardens where they infest the urban habitats, becoming readily available for transport back into the forest.

Of course, wind, water and wildlife also transport weeds, however, the distances are not as great. In our forests, these vectors pose a threat to invasion behind locked gates.

The Pend Oreille County Noxious Weed Control Board

Established in 1986, the Pend Oreille County noxious weed program is governed by a volunteer board of landowners representing five districts.

Our Mission

Our mission is to act as responsible stewards of the land and natural resources in the county of Pend Oreille by protecting and preserving the productivity and diversity of our agricultural lands and natural resources in the most cost-efficient manner from the deleterious impact of noxious weeds; while at the same time, protecting human health and the environment by promoting the implementation of integrated and responsible management measures.

From the policy statement…

“First control priority goes to weeds that are uncommon or do not occur in the county but nonetheless pose a threat. Measures are required to prevent them from becoming established in the county.…

Second control priority goes to weeds that are more common but not particularly widespread. The main objective in developing control strategies is to contain infestations within their current boundaries and prevent invasion into uninfested areas.

The last control priority goes to weeds that are widespread throughout the county. The objective for controlling these weeds is to minimize their further spread into areas that are being actively farmed and the landowner/manager is implementing a weed control program…”

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