Latin Name: Fallopia x bohemica

Origin:  Asia

Physical Description:  It is a tall herbaceous, rhizomatous perennial. Roots can extend up to 3 meters deep and 20 meters wide in the soil.   Stems are stout, cane-like or bamboo-like, hollow between nodes, somewhat reddish-brown, typically branched and extend up to 3.5 m tall. Leaves are green with smooth edges, alternate and up to 25cm long and 17cm wide. Leaf shape varies from a heart‐shaped base to a flat base and leaf tip is gradually to sharply tapered. The flowers are small, creamy white or greenish white to pink and grow in branched clusters near the ends of the stems.

This species is the hybrid offspring of Japanese and Giant Knotweed.  Key identifying feature from its parent plants include the hairs on the leaf undersides, along the mid-vein are short and broad-based (triangular-shaped), compared with long and wavy in giant knotweed and reduced to barely noticeable bumps in Japanese knotweed.

Habitat: It can grow under partial shade or full sun conditions and tolerates both moist and dry soils. It is often found along road side ditches, in the flood zone along rivers and creeks, railroad rights‐of‐way, unmanaged lands, wetlands, neglected gardens, and other moist areas.

Impacts:  It can displace native vegetation, create bank erosion, decrease riparian habitat, limits sight visibility along road ways and roots can growth through dense material, such as asphalt and cement, impacting housing foundations and infrastructure. Seeds can be viable for as long as 15 years depending on how deep they are in the soil.

Reproduction: Re produces by seed and vegetatively from rhizomes and roots. Root fragments, as small as 1 cm can form new plant colonies and can also be spread in contaminated fill material. Cut or broken stems will sprout if left on moist soil or put directly into water, or if moved by beavers or earth‐moving equipment.  Each node on the plant stock is able to produce roots and new plants.

Mechanical: Manual/mechanical control methods (mowing, pulling, digging) is not recommended.  These methods may impact the above ground vegetation but do not target the extensive underground rhizome structure, which is essential for successful management. In addition, these actions may result in increase root fragments in the soil, leading to re-growth and spread.  Mechanical removal can be considered in areas where herbicide treatment is not an option, however the entire root system must be removed or the plant will continue to grow. This means digging wide and deep.

 Chemical: Due to the extensive rhizome system, chemical control with a systemic herbicide is the most effective treatment method. Several herbicides with the following active ingredients can control Bohemian knotweed: glyphosate, imazapyr, aminopyralid + metsulfuron methyl, aminopyralid and triclopyr. For available products, contact your local agri-supply store. Prior to any herbicide application, read and follow the label instructions

 Biological: Not available.

Additional Resources:

Best Management Practices for Knotweed Species in the Metro Vancouver Region