Japanese knotweed is not a problem.

Recent articles have suggested that after years of research scientists have decided that Japanese knotweed is not a problem.

Funnily the researcher who has suggested that this is the case is the same guy that’s been making a living off Japanese knotweed for about twenty years. He was one of the first people to write a book on the subject and has been lecturing and advising others on the pitfalls of ignoring the issue ever since.

So why would he suddenly decide it’s not a problem?

I think it’s probably because he wanted a bit of press coverage and thought he’d grab a few controversial headlines.

The research suggests that the ‘7 metre rule’ is a ‘less than robust’ system of detecting where the plants roots will extend to.

Well ‘whoop de do’ it’s a fucking plant not a robot.

Of course the seven metre rule is ridiculous – but it’s a starting point. If a client asks me ‘how far has the rhizome extended’ I always want to say …. ‘using my x-Ray vision’ …. I can detect that it is exactly 4.2 metres in diameter.

Nobody can give you an exact location of underground root and rhizome until they have excavated and begun to remove the plant. This is why when quoting for excavation I always suggest to our customers that they go for a ‘re-measure’ so that they only pay for material removed rather than having somebody guess at an amount and give a fixed price.

Other suggestions are that ‘other plants’ can cause more damage than Japanese knotweed – with named reference to buddleja and sycamore. The impacts of these other species are well documented and cannot be ignored but these plants have been around for years and have been causing the likes of Network Rail problems for years as well.

The issues with Japanese knotweed relate to the fact that it is an alien species not from our shores. Since its introduction its particularly aggressive spread and its ability to colonise waste ground very quickly have made it notorious. The spread of viable root fragments by fly tipping has resulted in many green and brown field sites being covered with knotweed with resulting issues in the potential for damage to land values.

It is these areas highlighted for the building of new housing that represent problems for developers and where much of the removal costs associated with the plant come from.

No, it’s not going to batter down your front door.

No, it’s not going to leap up and grab you by the throat.

No, it’s not going to kill you.

No, it shouldn’t stop you getting a mortgage.

If your house was built some time ago and there was no knotweed present it’s highly unlikely that you will have a problem.

If your house has been built recently and your developer had a cavalier attitude to dealing with invasive plants in his site. Then – yes – you could be looking at some major issues. If your house has poorly designed foundations and inadequate structural elements and it’s been built on an actively growing stand of knotweed then you will be looking at a big bill to sort it all out.

However, …. the end of the day it’s a plant.

A particularly aggressive plant and one that shouldn’t be ignored…. but still just a plant.

Perhaps some of the articles that have been written have been a been over the top. This is nothing to do with the Japanese knotweed contractors – it’s down to the British press who just love writing horror stories about destroyed buildings and families in tears because of a plant.

Perhaps a bit of common sense is needed – but please don’t ignore the issues just because some boffin wants to grab a few headlines.

Mike C


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