Japanese Knotweed; an Invasive Species in the UK

There are many invasive species in the world, which have the unfortunate ability of spreading and surviving at the cost of the local fauna and flora. There are multiple reasons why this happens, such as environmental resistance, fast growth, rapid reproduction or high dispersal ability.



One plant that has a number of these qualities is Japanese knotweed (otherwise known as Fallopia Japonica). It is a highly invasive species and currently listed on Schedule 9 of the Wildlife and Countryside Act 1981. This makes it an offense to either plant or cause (or encourage) the plant to grow in the wild. However, there is no obligation to report or remove it if it is growing on your land, but doing so is in your best interests. Unfortunately, when it comes to removing knotweed, it isn’t just a case of cutting it back.



Japanese knotweed is known for its ability to regenerate from very small pieces of plant and its roots can reach 7 metres horizontally and 3 metres deep making it difficult to remove by excavation. Attempts at excavation are in fact a way in which knotweed is able to spread, since any contaminated soil disposed of incorrectly (via fly tipping for example), will then go on to regrow. The strong underground system also gives the plant protection against cutting, from which it simply resprouts. For these reasons it is also classed as "controlled waste" requiring disposal at licensed landfill sites.



One of the most effective methods of eliminating Japanese knotweed is with the use of herbicides. For the best results this should be applied just before the knotweed’s flowering, which generally occurs in late summer or early autumn. The correct application of herbicides (such as Glyphosate), which penetrate the whole plant, including the root network, can eradicate Japanese Knotweed in as little as a year. This can and should be performed by many companies who specialise in knotweed removal.



Some other research has also been conducted into possible control methods. Sea water has proven effective where herbicide use is questionable and separate research into leaf spot fungus, which has been known to inhibit knotweed in Japan, has shown positive results. The UK has also made the decision to release the insect "Aphalara itadori" into the UK since they feed on Knotweed.



Some more creative methods of control have included eating Knotweed to help stem its growth. Since it is quite a sweet plant with a similar taste to rhubarb, there are a multitude of recipes available, including cakes, soup, crumbles, curries, pies and more. So keep on the look out for it! It might not to get rid of it, but you can at least slow it down by having it for dinner!





The author specialises in Japanese Knotweed Removal and Japanese Knotweed Eradication in the UK. A great way for Japanese Knotweed Control.