State Distribution (20 / 50 states)
Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming
Listings by State
| State |
Classification |
Common Name Listed |
Notes |
| Idaho | Class B | Diffuse knapweed | Restricted |
| Indiana | Terrestrial Invasive | Diffuse knapweed | Herb |
| Iowa | Noxious | Diffuse knapweed | Invasive herb |
| Kansas | Class A | Diffuse knapweed | Prohibited/Eradication |
| Kentucky | Noxious | Diffuse knapweed | Invasive herb |
| Maine | Prohibited | Diffuse knapweed | Do Not Sell List |
| Michigan | Prohibited | Diffuse Knapweed | Biennial forb |
| Montana | Priority 1B | Diffuse Knapweed | Limited presence |
| Nebraska | Class 2 | Diffuse Knapweed | |
| Nevada | Class B | Diffuse Knapweed | Scattered populations |
| New Jersey | Noxious Weed | Diffuse Knapweed | Prohibited seed |
| New Mexico | Class B | Diffuse Knapweed | Biennial/perennial |
| New York | Prohibited | Diffuse Knapweed | Biennial/perennial |
| North Dakota | Prohibited | Diffuse Knapweed | Biennial/perennial |
| Ohio | Prohibited | Diffuse Knapweed | Biennial/perennial |
| Oklahoma | Noxious | Diffuse Knapweed | Biennial/perennial |
| Rhode Island | Invasive | Diffuse Knapweed | Biennial/perennial |
| Utah | Class 2 | Diffuse knapweed | Biennial |
| Washington | Class A | Diffuse knapweed | Biennial |
| Wyoming | Designated | Diffuse knapweed | Biennial |
Data compiled from individual state Department of Agriculture noxious weed lists.
Verify against current official state sources before regulatory use.
| U.S. Noxious Weed Database — generated April 2026.