Noxious Weed Control Board

Common Crupina Control

Common crupina (Crupina vulgaris) is a Class A noxious weed in Washington State, requiring eradication. The only population known to occur in the state is in Chelan County on the steep northern slopes of Lake Chelan, about 5 miles south of the community of Stehekin, with an infestation area of approximately 600 acres of both public and private lands. Adapted to a wide range of soil and climate conditions, crupina forms dense stands, displacing native plants and desirable forage for wildlife and livestock.

Crupina does not grow under dense, forest canopy cover, and is typically shaded out above 2,500 feet in elevation. The steep mountain range between Lake Chelan and the Methow Valley to the east serves as an effective natural barrier for crupina. Likewise, Lake Chelan is a barrier along the west side of the infestation. The steep cliffs on the south end of the infestation were not grazed by livestock and are not infested. The south boundary is monitored yearly. At the northern end of the infestation, at the boundary of the National Park Service Land, the aspect changes, and shady forest grows along the lakeshore. Unfortunately, the Flick Creek fire burned this northern end of the infestation in 2006. The burned area is monitored yearly.

Each spring, the Weed Board, in cooperation with the USDA Forest Service, applies for grant funding to continue control work. The management plan is short-term containment and long-term reduction within contained areas. Control methods include hand-pulling and backpack spraying with a reduced-risk, low volume herbicide. Additional activities include survey and monitoring of previously treated areas, currently uninfested areas, and areas recently impacted by wildfires.

Knotweed Control

The Chelan County Knotweed Project began in 2009 as a cooperative effort between the Chelan County Noxious Weed Control Board, the USDA Forest Service and the Washington State Department of Agriculture. The goal of the project was to complete a county-wide survey for invasive knotweed and eradicate patches using both county and state grant funds.

Knotweed is a Class B noxious weed designated for control in Chelan County. East of the Cascades, knotweed can survive on dry, non-irrigated sites, but doesn’t thrive. In riparian areas, knotweed has the potential to seriously impact ecosystems, spreading both vegetatively and by seed. In both the Stehekin River and Mission Creek, knotweed has shown the potential to explode and dominate riparian sites where conditions are favorable.

Although much of the knotweed extant in Chelan County was located in 2009 (244 sites), over 606 additional sites have been found since, with 54 new sites found in 2023. To date, there have been 850 knotweed sites located, and of those, 628 are dead, due to the diligent survey & control efforts of our dedicated knotweed program staff, spanning over 14 years. 

Garden Loosestrife Control

Garden loosestrife is a Class B emergent aquatic noxious weed designated for control in Chelan County. Currently, Fish Lake has the only known infestation of garden loosestrife in Chelan County. It has been documented in Fish Lake by the Washington Department of Ecology (ECY) dating back to 1999. Fish Lake drains into the Wenatchee River, home to several endangered salmonid species. Initial suppression actions were not effective and garden loosestrife has since spread to approximately 75% of the shoreline perimeter.

The Chelan County Noxious Weed Control Board was awarded grant funding from ECY and Washington State Department of Agriculture (WSDA) to control garden loosestrife on Fish Lake in 2020-2023. We have now had 4 years of contracted herbicide treatments and are starting to see significant die back. However, due to the size of the infestation and difficulty in finding all the plants, we expect complete eradication to take at least 6 more years.  

Ravenna Grass Control

Ravenna grass (Tripidium ravennae) is a Class B noxious weed designated for control in Chelan County. It is a large, nonnative, perennial, ornamental grass that can crowd out native and desirable plant species. In Washington, Ravenna grass seeds are spreading from ornamental plantings and have germinated in a wide range of habitats. Prior to the 2012 discovery of escaped plants in Benton County, there were no known sites in Washington.

In early 2015, the first case of Ravenna grass was found by Noxious Weed Board staff in Chelan County. In 2016, the Board was awarded its first grant for Ravenna grass survey and control work. Over the next few years, over 150 cases of Ravenna grass were discovered in the County. Additional grant funding was secured and landowners were notified and given the opportunity to have their Ravenna grass removed on grant funding. In 2021-2022, Chelan County had a 72% reduction in all Ravenna grass cases due to the persistent efforts of Noxious Weed field staff as well as many landowners who decided to do their own control work. Several landowners that were contacted said they had no idea Ravenna grass was a noxious weed and even disclosed that they had purchased their plants at a local nursery just a few years prior.

The Ravenna grass project is ongoing as of early 2024. With continued grant funding, landowner cooperation and community education, we believe we can eradicate Ravenna grass from Chelan County.

Posted: 02/02/2015 09:21 AM
Last Updated: 04/10/2024 05:18 PM