Guest Article – Japanese Knotweed

Following my recent call for guest articles, on LinkedIn, I am happy to share with you my first guest article which has been written by Stuart Reynolds Cert CII from Pi Property Insurance.  Here Stuart covers the topic of Japanese Knotweed and the key facts you need to know.  I am hoping, over the next few weeks, to have a few more guest articles covering different (but closely linked) professions to give you all a little variety!  Stuart’s contact details can be found at the end of the article for those who may wish to discuss this and/or who may have further queries!

What is Japanese Knotweed?

Japanese Knotweed, also known as Fallopia Japonica, was originally introduced to the UK in the 1800s as an ornamental plant from native Japan. It has characteristics that mean it will grow rapidly almost anywhere, killing the habitat which it grows in. This invasive plant can be a significant problem for property owners and property managers causing serious damage to asphalt, lamp posts and buildings as well as blocking drains, cracking tarmac and undermining foundations.

The plant has zig-zag stems with green shield shaped leaves which are speckled purple and produce creamy-white flower tassels from August-October. Should you become aware of the plant immediate action should be taken.

Total annual costs of Japanese knotweed to the British economy are estimated at £166 million.

Can I get insurance cover for damage caused by Japanese Knotweed?

Property owners policies do not include cover for damage as a result of Japanese Knotweed for some of the reasons as listed below:-
• It is considered to be gradually operating and hence excluded.
• Damage to Land is often excluded under a property owner’s policy or very limited and only covers the first metre. Japanese Knotweed can grow up to 3 metres in depth and 7 metres in length in just one season.
• Limited cover as part of a property owner’s policy for the removal of the plant is available, provided it has started growing on the policy period and not prior to the cover being in place.

Cover for third party damage is covered both in the way of legal defence costs and compensation, however this is dependent on the policyholder taking reasonable steps and precaution to manage their property against the risks arising from Japanese Knotweed.

There are specialist insurance policies available that can provide indemnity for a number of aspects of the process of managing and eradicating Japanese Knotweed these include;
• The survey of the land to identify the Japanese Knotweed;
• Treatment costs of maintaining and removing including prevention of any reoccurrence of the Japanese knotweed;
• Legal defence expenses;
• Residual reduction in market value;
• And any other costs with written confirmation from the insurer.

How do I remove Japanese Knotweed?

Whilst it is not illegal to have Japanese Knotweed growing on your premises, it is considered to be controlled waste under the Environmental Protection Act 1990, which means it is illegal to cause it to grow in the wild and there are strict regulations about who can dispose of it and how. It can lead to a fine of up to £2,500 (£20,000 as a business) and even an anti-social behaviour order (ASBO) or a prison sentence in the worst instance.

Attempting to destroy Japanese Knotweed by yourself can be incredibly difficult and takes a long time so you need to carefully plan if you intend to manage it yourself. There are three ways to get rid of the plant, as follows:

– Digging it up: this can be very time-consuming given the spread of the roots can be 3m deep and 7m wide but this is the fastest way remove the plant. However, digging it out of the ground can also cause the plant to spread further as it can regenerate from small segments.
– Chemical Solutions: this can take longer as you may need several seasons to completely eradicate the weed. Specialist contractors are available who can complete the chemical removal process for you.
– Biological Treatment: this is how it is controlled in native Japan by local insects called pysllids. Some have been released in the UK but the insects are not currently widespread or available to gardeners.

What next?

If you have any further questions about Japanese Knotweed or would like to speak to us regarding a specialist insurance policy that provides indemnity for the process of managing and eradicating Japanese Knotweed then please call me Stuart Reynolds on 01789 761 664 or 07973 790218 or Email me on  For regular updates follows us on Twitter (@PiPropertyIns) or LinkedIn.

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