Wash. Admin. Code § 16-302-100
The following are considered prohibited noxious weeds for the purpose of seed certification.
| english orcommon name | botanical orscientific name |
| Austrian fieldcress | Rorippa austriaca |
| Field bindweed | Convolvulus arvensis |
| Hedge bindweed | Calystegia spp. |
| Camelthorn | Alhagi maurorum |
| Canada thistle | Cirsium arvense |
| Dodder | Cuscuta spp. |
| Hairy whitetop | Lepidium appelianum |
| Hoary cress | Lepidium draba |
| Jointed goatgrass and jointed goatgrass hybrids | Aegilops cylindrica |
| Leafy spurge | Euphorbia esula |
| Palmer amaranth | Amaranthus palmeri |
| Perennial pepperweed | Lepidium latifolium |
| Perennial sowthistle | Sonchus arvensis |
| Quackgrass | Elymus repens |
| Knapweed complex: | |
| Bighead | Centaurea macrocephala |
| Vochin | Centaurea nigrescens |
| Black | Centaurea nigra |
| Brown | Centaurea jacea |
| Diffuse | Centaurea diffusa |
| Meadow | Centaurea x moncktonii |
| Russian | Rhaponticum repens |
| Spotted | Centaurea stoebesubsp. australis |
| Purple starthistle | Centaurea calcitrapa |
| Yellow starthistle | Centaurea solstitialis |
| Serrated tussock | Nassella trichotoma |
| Silverleaf nightshade | Solanum elaeagnifolium Cav. |
| Sorghum perennial such as, but not limited to, johnsongrass, columbus grass, and perennial sweet sudangrass | Sorghum spp.Sorghum halepenseSorghum almumSorghum bicolor (L.) Moench ssp. drummondii |
| Tansy ragwort | Jacobaea vulgaris |
| Yellow-flowering skeleton weed | Chondrilla juncea |
| White cockle | Silene latifolia (only in timothy) |
| Bladder campion | Silene vulgaris (only in timothy) |
| Lepyrodiclis | Lepyrodicilis holosteoides |
| Velvetleaf, Butterprint | Abutilon theophrasti |
[Statutory Authority: RCW 15.49.005, [15.49].021, [15.49].310, [15.49].370, 15.140.030, and chapter 15.49 RCW. WSR 25-09-035, s 16-302-100, filed 4/9/25, effective 5/10/25. Statutory Authority: RCW 15.49.005, [15.49].021, [15.49].310, [15.49].370, and chapter 34.05 RCW. WSR 18-19-017, § 16-302-100, filed 9/10/18, effective 10/11/18. Statutory Authority: RCW 15.49.005, 15.49.081, 15.49.310, 15.49.370(3), and chapter 34.05 RCW. WSR 14-20-050, § 16-302-100, filed 9/25/14, effective 10/26/14. Statutory Authority: Chapter 15.49 RCW. WSR 09-16-006, § 16-302-100, filed 7/22/09, effective 8/22/09. Statutory Authority: RCW 15.49.005, 15.49.081, 15.49.310, 15.49.370(3) and chapter 17.24 RCW. WSR 00-24-077, § 16-302-100, filed 12/4/00, effective 1/4/01.]