Japanese Knotweed: The Plant That’s Invading Britain Japanese knotweed has received widespread media coverage over the last 5 years as more and more residential and commercial properties are being affected by this invasive plant. Whilst many homeowners and landlords have opted for DIY treatment methods, Japanese knotweed often recurs causing widespread damage to buildings. Failure to take action to permanently remove the knotweed from your premises, could result in an Antisocial Behaviour Order. To unravel the complexities surrounding Japanese knotweed, we’ve called in the experts to give us the low down on how to successfully remove and eradicate the plant that’s invading Britain. Nic Seal, is the Managing Director of Environet UK, specialists in Japanese knotweed removal. Environet was established in 1996 and is a recognised leading UK firm in the fight against Japanese knotweed. We asked Nic to bring us up to date on the latest: What is Japanese knotweed?
Japanese knotweed is a plant imported by the Victorians, with a large heart shaped leaf canopy. The canes are hollow self-supporting stems, which grow to 3m in height. This is all supported by a large underground rhizome root system, which can extend 2m deep and spread laterally 2-7m. It originates from Asia, on the side of volcanos. Often described as an early coloniser, which means it’s not fussy as to the environment it lives in. It favours harsh environments where predators are less abundant. In Asia, Japanese knotweed spreads via its seed and it’s kept in check by its native predators. Here in the UK, the plant doesn’t spread by seed, but by fragments of the root. There are no natural predators here to control it, except of course, companies like mine, hence its invasive nature.
Why is Japanese knotweed considered so negatively, when in the summer it has lovely flowers?
It’s true that the plant does have pretty flowers, in fact some people might even call the plant beautiful, but beauty is, as always, in the eye of the beholder. It has been known that some people plant knotweed in their garden because of this. Unfortunately a mortgage lender will not see Japanese knotweed in the same way. Nature can’t control this weed, so we have to. It has no respect, causing significant damage to property, earning the title from the Environment Agency as being “indisputably the UK’s most aggressive, destructive and invasive plant”.
Can Japanese knotweed cause damage to properties?
Yes it can, although I there is some overhyped scaremongering in the press. Typically Japanese knotweed will grow up through hard surfaces such as asphalt drives, brick paviours, and through the cracks in concrete. A misperception often printed in the press is that knotweed can grow through concrete. This is where the scaremongering comes in, as people start to believe knotweed will take over their homes. It’s actually the expansion joints and cracks that the knotweed takes advantage of, in its quest for light. It’s also known to cause damage to drains, as the knotweed grows into them and blocks them. I’ve seen lots of examples of knotweed pushing over boundary walls, showing no respect to neighbouring properties.
How can Japanese knotweed removal be achieved?
Japanese knotweed eradication can be achieved in 2 ways, either through successful herbicide treatment, or through complete removal of the knotweed and its associated rhizome system. There is a distinction between “eradication” and “control”, eradication meaning the intent is to completely remove or destroy the plant, whereas control refers to preventing it from further spread and damage.
How long will it take to achieve eradication of Japanese Knotweed?
Using the herbicide method, where conditions are right, eradication can be achieved in one growing season, which is typically between April and October. However there are a number of variables that can affect the effectiveness of treatment, which may well mean that the treatment program may take further growing seasons. With a removal method, it takes just a matter of days, obviously depending on the volume of soil that needs to be excavated and removed. It’s not uncommon after a removal process to find some small new shoots of knotweed appearing, which typically emanate from a small fragment of rhizome that has been left. On the internet you will read that 0.7g of rhizome can regenerate into a plant. These pieces of regrowth are not difficult for a specialist to deal with, so it is nothing to worry about. Insurance backed guarantees are available to ensure that any regrowth will be dealt with by the company that completed the treatment.
What’s the difference between Japanese knotweed treatment and removal?
The simple answer to this question is that treatment refers to methods using herbicides, whereas Japanese knotweed removal relates to the physical removal of the whole plant, including the underground rhizome root system. Each infestation needs to be assessed in order to understand what the best method is. Japanese knotweed treatment is a much less disruptive process and generally speaking, is cheaper. Time constraints often mean removal is the best option, but herbicides are effective when this is not the case. Removal of Japanese knotweed needs to be completed by specialist Japanese knotweed removal companies. Contact Environet UK today for expert advice in the removal and eradication of Japanese knotweed.
Find out more at www.environetuk.com