Identifying and disposing of Japanese knotweed

It is the landowner’s responsibility to prevent the spread of this invasive plant off-Site, and fines of up to £5,000 or even a custodial sentence for up to two years can be incurred if found guilty of allowing contaminated soil or plant material to spread into the wild.

The recent update states that any business wanting to burn Japanese knotweed waste must register for a waste exemption (if they can meet the conditions) and notify their local Environmental Permitting Regulations waste team at least a week before they intend to carry out the burning.  This applies to all businesses, including farmers.

Japanese knotweed is a real problem in the UK, having been introduced from Japan in the 19th century as an ornamental plant.  Its growth and relentless spread is rapid, and it aggressively over-runs native plants and can have a devastating effect on buildings and development sites.

Prevent the spread of Japanese knotweed

The plant cannot be simply dug out of the ground as its difficult to eliminate the rhizomes, meaning rapid re-growth, in some cases up to a metre per week.

• Chemical spray: spraying with herbicides can work, however, this must be managed for around three years until the underground rhizomes become dormant.
• Burial: this will require a permit.  Burial of the waste needs to be at a depth of at least five metres, with a “root barrier membrane layer” covering it to prevent regrowth.
• Burning: Always notify the Environmental Agency (as mentioned above).  Knotweed crown and rhizome may survive burning so disposal of remaining material must follow burial or off-site disposal guidance.

See our Japanese knotweed services.

For more information, visit Environmental Agency: Prevent Japanese Knotweed from spreading

Related article: Warm weather causes outbreak of Japanese knotweed