King County Yard and Garden Resources - http://dnr.metrokc.gov/topics/yard-and-garden/index.htm
Provides information and programs related to environmentally friendly gardening and yard care. Find information on safer gardening and pest control, how to identify noxious weeks as well as a Northwest Native Plant Guide.
Noxious Weed Control Board - http://www.nwcb.wa.gov/index.htm
Noxious Weeds are non-native plants introduced into Washington State. They spread quickly and may be difficult to control. They invade our croplands, rangeland, forests, prairies, rivers, lakes, wetlands, and estuaries, causing both ecological and economical damage.
Noxious Weeds slide show: Identification and Control - http://dnr.metrokc.gov/wlr/lands/weeds/pdf/Seattle-Invasive-Weed-Slideshow.ppt
This slideshow is a good introduction to noxious weeds. Titled “Backyard Invasions: Noxious Weeds in Seattle’s Greenspaces,” it is a resource from the King County Noxious Weed Program.
Washington State Department of Agriculture - http://agr.wa.gov/default.htm
The Washington State Department of Agriculture helps protect the state's resources by preventing the establishment of high-risk insects, plant diseases and weeds. Staff conducts surveys and inspections, enforces agricultural quarantines and ensures that consumers and the nursery industry are provided healthy, pest-free and disease-free plant materials.