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Image by Jasmin Schreiber

Presenter -  Lauren Vorona, Integrated Pest Management &

                                                Noxious Weed Control - March 11th, 2024

What are noxious weeds?

Noxious weeds are non-native plants that are highly destructive, competitive and difficult to control or eliminate. They have been introduced accidentally or as ornamentals in peoples' gardens. Some are poisonous to humans and livestock and most grow rapidly and overwhelm desirable vegetation. They can reduce crop yields, destroy beneficial native habitat, damage recreational opportunities, clog waterways, and diminish land values.

Noxious weeds are found everywhere in King County—in urban, suburban and rural areas; on developed and undeveloped land, farmland, forests and other natural open spaces as well as in lakes, rivers, streams and Puget Sound.  Some of the noxious weeds found in King County include:

  • Giant hogweed - predominantly an urban weed and an escaped garden ornamental, its sap can cause skin blistering and scarring.

  • Garlic mustard - one of the worst forest understory weeds in the Great Lakes and Northeastern United States, it is now spreading from urban to rural areas in the Pacific Northwest, threatening woodlands and sensitive habitats.

  • Tansy ragwort - likely to infest pastures and roadsides, it has toxins that can be fatal to cows and horses and it reduces pasture quality.

  • Spotted knapweed - threatens wildlife habitat, pastures, and grasslands by displacing beneficial species.

  • Purple loosestrife - grows in wetlands and along lakes, rivers and streams; it chokes out wildlife habitat and clogs drainage ditches and irrigation canals. Purple loosestrife invades wetlands in 48 states, crowding out native plants and endangering the wildlife that depend on the native plants.

  • Parrotfeather - chokes out prime salmon habitat and reduces availability of refuge, exposing salmon to predators.

  • Invasive knotweeds - aggressive, hard to control perennials that are destroying riparian habitat in the Pacific Northwest.


Lauren Vorona

is an Education Specialist with King County’s Noxious Weed Control Program. Prior to working for King County, she has worked in ecological restoration in the Puget Sound region. Lauren graduated from Whitman College with a BA in Chemistry and has a Masters in Land and Water Systems from the University of British Columbia.

Presentation topic: Integrated Pest Management and Noxious Weed Control


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