Chinese knotweed

General description

Perennial, scrambling, mat-forming, herbaceous vine < 1 m tall or climbing to < 10 m. Rhizomes are stout. Leaves are ovate, lanceolate or elliptic, < 16 x 8 cm and smooth or covered in stiff hairs. Flowers are small, white/pink and borne in inflorescences in autumn.

What you need to know

To help protect our environment:

• You must not breed, distribute, release or sell Chinese knotweed. As Chinese knotweed is an Unwanted Organism, these restrictions apply within the Auckland region and across the whole of New Zealand.

Habitats

Forests, riparian margins, grasslands, disturbed sites, crops, roadsides, urban areas.

Dispersal

Seeds dispersed by birds. Vegetative spread from stem and root fragments. Human-mediated dispersal through dumping of garden waste and deliberate plantings.

Impact on environment

Forms dense mats, smothering native vegetation and suppressing seedling recruitment.

Control

Recommended approaches

If found in the environments listed below, please report to Auckland Council.
- Rural areas
- Mapped wetlands
- Properties bordering wetlands.
- within a flood zone of wetlands

For all environments, the recommended approaches are listed below.

Physical control

Manual removal: This is not recommended, as manual removal and disposal may spread the weed further as it regrows from small plant fragments. Auckland Council are carrying out trials on manual removal.

Biocontrol

Biocontrol is currently not available for this species.

Community agrichemical control recommendations

No qualifications: Seek advice from herbicide stockists.

Basic Growsafe certified Foliar spray 200ml Glyphosate 360 + 10ml organosilicon/10L (backpack.

Certified Handler/Experienced agrichemical user: Foliar spray 10g metsulfuron-methyl 600 + 200 Glyphosate +10ml organosilicon/10L (backpack) Or Foliar spray 200ml Glyphosate 360 + 10ml organosilicon/10L (backpack)

* Apply chemicals as per instructions on the herbicide container.
* PPE gear should always be worn when mixing and applying chemicals.