What are the best Japanese knotweed removal methods?

There are a variety of methods that can be used to remove Japanese knotweed; the best method will depend on the site specific conditions.

Dig & Dump, which involves the excavation and removal of all knotweed infested soil to a registered landfill, is now described by the Environment Agency as the method of last resort.

An excellent eco-alternative is Environet’s Xtract™ method, which removes the rhizome from the soil at a fraction of the cost of alternative removal methods, avoiding the need to dispose of vast quantities of otherwise good soil. Xtract™ can be completed in a matter of days and is normally 50% of the cost of alternatives such as Dig & Dump.

Insurance Backed Guarantees

When instructing a company to remove Japanese knotweed, you should insist that any works are supported with an insurance backed guarantee for a minimum period of 5 years.

Environet offer insurance backed guarantees underwritten at A-rated Lloyd’s, for up to 10 years on all our removal projects.

Be sure to check the fine print on all guarantees, to ensure they are underwritten by a reputable insurer.

Read more about insurance backed guarantees.

Issues with knotweed on commercial development sites

There are legal, technical and financial issues associated with developing a site infested with Japanese knotweed.

Legally, under the provisions of the Wildlife and Countryside Act 1981, it is an offence to allow knotweed to grow in the wild. Knotweed is also classified as controlled waste, and must be taken to a registered, licensed landfill site.

The technical issues will vary depending upon the chosen method. This, as well as the financial implications of each method, will be discussed with you.

Our handy knotweed guide for Landowners and Developers contains all the information you need to know about knotweed.

Beware of Japanese knotweed dormancy

Where knotweed has been previously herbicide treated it is possible that the rhizome is put into dormancy, making it look like the knotweed is dead, but leaving the underground rhizome system alive.

This can have dire consequences if the ground is then disturbed causing the knotweed to be spread around the site. The Environment Agency Code of Practice makes reference to a 20 year dormancy period, and we have seen a site with a 10 year dormancy period.

We offer Site Supervision for clients who have access to plant and labour. Our experts will supervise the development works to ensure that if dormant knotweed is discovered, it is dealt with in the appropriate manner.