Non-native plant species that, because of aggressive growth habits, can threaten native plant communities, wetlands or agricultural lands. The Washington State Noxious Weed Board has the authority to designate certain plants as "noxious" in the state. Eurasian watermilfoil ( Myriophyllum spicatum) is a noxious weed in Washington.
Each state has a list of weeds that are considered noxious in their state. Often very difficult to control, noxious weeds can be particularly troublesome in turf. If a weed is consider noxious by a state and is present is a seed lot, the noxious weed is required to be listed on the seed label..
An unwanted plant specified by Federal or State laws as being especially undesirable, troublesome, and difficult to control. It grows and spreads places where it interferes with the growth and production of the desired crop.
(3) according to the Federal Noxious Weed Act (PL 93-629), a weed that causes disease or has other adverse effects on humans and their environment and is therefore detrimental to public health and the agriculture and commerce of the United States.