It gets everywhere, and this is partly down to the plant’s ability to regenerate from small fragments of rhizome, the plant’s root system. A piece of rhizome the size of a fingernail can give rise to a new plant, and this ability, combined with human interference, has allowed for its dramatic spread.
Its appearance can be attractive. Young shoots quickly develop within weeks to bamboo-like stems with purple specks and obvious nodes, growing up to 3m in height. The lush green heart-shaped leaves, which grow to around 14cm long, are alternate, forming a ‘zig-zag’ pattern along the stem. In late summer, the plant produces clusters of small creamy-white flowers, which stand out from the dark green leaves. After flowering, in late autumn, the plant naturally dies back and remains dormant over winter, losing its leaves to reveal the dead, dark brown canes which remain standing through winter.
Chemical control of this plant takes dedication and patience, with repeat applications of herbicide over a number of years to ensure that the plant is properly eradicated. This approach may not always be suitable, for example, within development areas.
An alternative to chemical treatment is mechanical excavation of the plant and rhizome system, which can extend up to 7m laterally from surface growth and to depths of 2 to 3m. Excavated material can be dealt with in a number of ways, including: disposal to licensed landfill, burial on site in sealed geotextile cells, transfer on site waste management areas for further chemical control, or screening of excavated material to remove the rhizome.
Japanese knotweed is a Schedule 9 species under the Wildlife and Countryside Act 1981, making it illegal to plant or allow it to spread into the wild. If removed from site, waste containing knotweed is classified as ‘controlled waste’ under the Environmental Protection Act 1990 and will require to be disposed of appropriately at a licensed facility.
Find the right arborist for you
Here, the Arboricultural Association offers its advice on hiring a tree surgeon for your self-build site.
Stage 1: ask for a quote
A reputable arborist will always give a positive response.
1. Are you insured?
If the answer is yes, please show evidence of insurance – Employers’ Liability & Public Liability (recommended minimum of £5m).
2. Do you work to a British Standard?
If yes, which one?
Should be BS3998: 2010 ‘Tree Work – Recommendations’.
3. What qualifications do you and your staff hold? (ask to see copies)
Compulsory: they must have NPTC/Lantra Awards** certificates for chainsaw use.
Recommended: certificates for other skills and machines. Arboricultural knowledge, e.g. national certificates and diplomas in arboriculture.
4. Will you provide a written quotation?
If no, reject the contractor.
5. Are you a member of a professional organisation?
Membership does not guarantee work standards but does show a degree of commitment.
6. Can you provide me with the phone number of a referee who can show me some of your work?
If yes, follow up the reference.
Stage 2: choosing the quote that suits you
When you receive your quotations, check they include the following before deciding which one to accept:
•Reference to BS3998: 2010 ‘Tree Work – Recommendations’.
•Clear and full details of the work to be undertaken (the specification).
•What will happen to the timber and brushwood?
•What will happen with the tree stumps?
•Whether VAT is included.
•Who will be responsible for obtaining permission if the trees are protected?
•What steps will be taken to protect you and your property
(the risk assessment)?
•Be aware that there may be a limited quote validity period.
Stage 3: consumer protection
If problems arise you can get help and advice from industry bodies such as the AA, ISA or TrustMark.
* Obtain more than one quote, ideally three.
** NPTC and Lantra Awards are national organisations that assess competence of people using chainsaws and other arboricultural equipment. Competent arborists will be able to show you an A4-sized certificate or plastic ID card if requested.