Japanese knotweed is no respecter of boundaries. It is a common issue amongst neighbours, when one party refuses or is unwilling to treat their Japanese knotweed, and it starts to invade a new property.
In our experience, once you have mature Japanese knotweed on one side of a boundary the likelihood is that the rhizomes have already spread into the previously untreated garden. The question is what can you do in the event that this is happening?
The Law.
The principle law relating to Japanese knotweed is covered by the Wildlife & Countryside Act (1981). The relevant quotation is:
“if any person plants or otherwise causes to grow in the wild any plant which is included in Part II of Schedule 9, he shall be guilty of an offence.”
(There are other laws relating to the treatment of knotweed and to the movement of Japanese knotweed infested waste from site).
So a few problems can instantly be seen with the Wildlife & Countryside Act. For instance:
1. Define ‘wild’. Are there any true ‘wild’ areas left in Britain? Even the Lake District or the Yorkshire Dales are not truly ‘wild’, as the landscape is the result of many human activities over many centuries. A garden, for instance, cannot by defined as wild.
2. This law is all about moving the plant to new areas, what about existing areas of knotweed?
The short answer is that there is no requirement to treat Japanese knotweed growing on your land. So no-one can force (through legal means) a neighbour to treat their knotweed. Neither the Local Authority nor the Environment Agency has any responsibility for treating Japanese knotweed on any site, unless they own that property.
The best advice that we can give to anyone in a situation like this is to talk to their neighbour. It is always better to persuade someone to take action, in a case like this, rather than resort to legal means. However, if all else fails, than you could consider taking a private action against them as they are causing or have caused a private nuisance to you – by not treating the Japanese knotweed growing on their land and thereby causing it to spread onto your property.
You would need to take appropriate legal advice and write formally to your neighbours placing them on notice about the Japanese knotweed, causing a nuisance, and in my view, you would need evidence that the infestation had originated from your neighbours – this can be the hardest thing to prove of all. Quite often we are called to site to find knotweed on both sides of a boundary, all we can then say is that the knotweed is more established on one side than the other, but this is not proof of the infestation’s origin. The best advice is to get a proper survey carried out (or record it with dated photographs over a period of time), before the knotweed spreads into your property. However the decision of the court (if it gets that far) may not be easy to predict.
Failing all other options, we could (where feasible) insert a deep root barrier (3m deep) to the boundary of your property, this would slow the advance of the Japanese knotweed, but would need an additional herbicide/inspection programme to your property to identify and treat any new knotweed growth. This is not a cheap option!
I hope that this answers the question that Alan asked me, concerning the spread of knotweed from his neighbour. The answer is not clear cut, because the law is not specific in this matter.
Please email me with any specific questions that you want me to address through the blog or otherwise and I’ll try to answer them. Email Brian Taylor here
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