Knotweed and the case of the disappearing weed killer?


Japanese Knotweed is a blight on many areas of the country. It is highly invasive and spreads via a complex root system which travels long distances underground.

Recent research by Swansea University has shown that even after three years of optimal treatment it is never completely killed, but the above ground growth can be curtailed. Despite this, the root system remains viable.

The research demonstrated that the most effective method to control (but not kill) Japanese Knotweed was the appropriately timed use of weed killer containing glyphosate. This weed killer, however, recently featured in a legal case brought in California. Dewayne Johnson, a former school groundsman who is terminally ill sued Monsanto, the chemical company which makes glyphosate, claiming that it was this chemical in weed killers which gave him cancer. Mr Johnson won his case (although Monsanto are likely to appeal) leading to the prospect that if glyphosate is a cancer risk, where does that leave its use in the treatment of Japanese Knotweed?

In December 2017 the licence for use of glyphosate in weed killers in the European Union was renewed for five years. In the vote, 18 countries supported its use, nine objected and there was one an abstention. While the UK supported the renewal various governments have, including France, suggested that it should be phased out.

There is, therefore, some ongoing doubt as to what the future holds in respect of the treatment of Japanese Knotweed.

We will try to bring you more as the story unfolds. In the meantime, if you have any issues with Japanese knot weed please do not hesitate to contact us.

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