County's top 10 invasive weeds

June 2, 2011
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Knotweeds: This shrub-like perennial looks like bamboo and can grow up to 10 feet tall. It causes problems to river ecosystems, such as that along the Skykomish, because it affects water temperature, which threatens salmon redds, or nests of eggs. Herbicides only work on this resilient weed in the fall when it tries to produce seeds. The county received a grant to fight it. (Center for Invasive Species and Ecosystem Health)

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