Inquiry into the impact of Japanese Knotweed on the built environment

The Science and Technology Committee are holding an oral evidence session in early 2019, specifically to explore the science behind the effects of Japanese Knotweed on the built environment.

To inform that session, written submissions were invited and the Amenity Forum has made a response.

The Amenity Forum welcomed the inquiry. Whilst there has been research and studies on the topic, it is felt more is needed if we are to fully understand the impact and implications. There has been a number of studies observing specific sites where structural damage has been caused but it is felt that more scientific studies are very much required.

The Forum also feels that more economic analysis is needed and indeed is vital to establish the financial implications now and in the future. This would assist Government greatly in establishing both its strategy and future plans to combat the issue. It is undoubtedly the case that the presence of Japanese knotweed rhizome within a construction, if left unchecked, can produce significant damage especially within masonry and hard surfaces.

The Forum also states that what has already emerged, in looking at the range of controls, is the importance of chemical products including those with the active ingredient, glyphosate. Whatever approach has been trialled, chemical treatment remains extremely important and provides the most effective approach in any integrated plan for knotweed management. They go on to say knotweed management is a long term plan and cannot be seen as a quick fix.

Clearly it can be controlled by treatments but the point at which such a treatment plan is complete remains uncertain. There would appear to be a need for more research and examination of the rhizome that remains following professional treatment. Establishing the facts relating to the viability of that material when disturbed is key to establishing protocols for sites that have been subjected to a treatment programme.

Professor John Moverley, Chairman of the Amenity Forum, very much welcomed the focus on this topic and emphasised the need to use professionally trained operatives in managing the problem. He said: ‘’What is vital is that knotweed control needs to be undertaken properly and by professionally qualified operators and organisations who fully subscribe to the standards and best practice laid down.

"The Amenity Forum is currently developing an overarching assurance standard for the sector and we would urge all employing any operators to ensure that they candeliver to such a standard and, in so doing, fully support the work and objectives of the Amenity Forum. Bad practice and unqualified operators can make the situation far worse and sadly there is evidence of such practices existing. The need for assured practice and the need for users such as local authorities to adopt these is vital."

The Amenity Forum is holding a series of half day Updating Events across the UK over the coming months. These are free to attend and will update those attending on current issues and concerns. There will be time for questions and essential networking.

For more information on the location and timings of these events, please contact Whilst free to attend, it is important that you register in advance.

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