More than 100 non-native plants have been designated as noxious weeds by the Washington State Noxious Weed Control Board. Another 23 are being monitored.
"The list is the basis for regulation around the state," said Steve McGonigal, executive director of the board.
Locally, county noxious weed control boards and weed districts carry out the state's noxious weed laws. The laws assign primary responsibility for noxious weed control to landowners, either private or public.
The Noxious Weed Control Board updates its noxious weeds list annually and helps coordinate and assist the work of county weed control boards and weed districts. County weed boards and districts can make their lists stricter than the state list but not less strict.
The noxious weeds list designates which plants will be considered noxious weeds and where in the state control will be required.
The list is divided into three classes. Class A weeds have not yet become established in the state. Eradication is required statewide. Examples include johnson grass, wild four-o'clock and giant hogweed.
Class B weeds may be established in parts of the state. Depending on location, they may or may not be designated for control.
"Scotch broom is pretty much considered to be out of control in parts of western Washington," said McGonigal. "Scotch broom is on the B list and is not designated for control in western Washington. However, to keep it from generally infesting eastern Washington, it is designated for control there."
Class C weeds are well established. Control is not mandated. "However, each county can designate them for control at the wishes of the county weed board," McGonigal said. Examples include field bindweed, jointed goatgrass and Canada thistle.