California Invasive Plant Council

Fallopia ×bohemica

Common names: Bohemian knotweed

Fallopia ×bohemica (Bohemian knotweed (Japanese x Giant knotweed) is a perennial (family Polygonaceae) with white flowers and broad leaves found in northwestern California. It is native to Japan. It favors grasslands and riparian and bottomland habitat. It spreads via rhizomes and seeds and is dispersed along watercourses and in garden waste.

Cal-IPC Rating: Watch

CDFA Rating: A*?

Explanation of CDFA ratings

• A – A pest of known economic or environmental detriment and is either not known to be established in California or it is present in a limited distribution that allows for the possibility of eradication or successful containment.
• B – A pest of known economic or environmental detriment and, if present in California, it is of limited distribution.
• C – A pest of known economic or environmental detriment and, if present in California, it is usually widespread.
• D – An organism known to be of little or no economic or environmental detriment, to have an extremely low likelihood of weediness, or is known to be a parasite or predator.
• * – An asterisk next to the rating indicates that a plant is included in the CCR Section 4500 list of California State Noxious Weeds.

More details

Assessment(s)

Plant Risk Assessment - An evaluation of the potential for a plant to be invasive in California.

Weed Management Notes

• Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.

Cal-IPC Newsletter Articles

• CDFA expands noxious weed list and revises process. Kelch, Dean. Vol 23, Issue 2

Cal-IPC Symposium Presentations

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

• 2019 Weed Alerts. Burger, Jutta; Price, Bob (2019)

Other Fallopia ×bohemica Information

• Calflora - Distribution map and records of this species in California.
• EDDMapS - Distribution of this species in North America.
• USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.