Japanese Knotweed
What is it?
Japanese Knotweed (scientific name Fallopia japonica) is a fast-growing, non-native plant which is causing problems in the UK.
Where does it come from?
As the name suggests, Japanese Knotweed is native to Japan but also Taiwan and China. It was originally grown as an ornamental plant in the early 19th century but has now spread over large areas in the UK.
What does it look like?
JKW is a member of the dock family (scientific name Polygonaceae); it has broad, rounded leaves with hollow, bamboo-like stems covered in purple speckles, often reaching 2-3m in height. Between August and October the plant has small creamy-white flowers.
Why is it a problem?
JKW tends to flourish wherever it grows and out-competes many of our native plants. It can grow up to 40mm per day. It is a rhizomatous plant (meaning that it produces underground stems) and its stems may extend beyond 7m from and 2m beneath the parent plant. Because of this, the plant can spread fast.
Both urban and rural areas are affected by the colonisation of JKW. Problems include disrupting sight lines on railways and flood defences in the riverside environment. It pushes through tarmac and paving and can cause severe damage to the areas of concrete and the foundations of buildings. It out-competes other species in planting programmes; litter and vermin are also attracted to its dense thickets.
Because of its high regeneration rates, JKW can spread widely through natural and human means. Fragments of rhizomes or cut stems that are washed into water courses under high water flows can form new plants downstream. Many unsuspecting gardeners may spread or introduce JKW through contaminated top soil. Fly-tipping garden waste or transporting soil from infested sites during construction works are the main ways that people spread the plant.
What should I do if I see it?
In most cases, you need not do anything, as long as the plant can be contained on your land.
It is not an offence to simply have JKW growing in your garden or on your land and there is no legal requirement (unless stated in a particular contract or arrangement) to control it. JKWs not listed in the Weeds Act and is therefore not 'notifiable', meaning there is no need to report its presence on your land.
But, under the Environmental Protection Act 1990 any soil that is contaminated with JKW is likely to be classified as 'controlled waste' and therefore its disposal must be regulated. It would therefore be an offence to dispose of cut stems or soil containing rhizomes in the usual way, for instance by taking it to the tip or by putting stems or rhizomes in your green waste bin. JKW must be disposed of by an authorised person who is registered. It is the responsibility of the authorised person to obtain a waste transfer note which gives the receiver sufficient information to enable the receiver of the waste to handle it in accordance with their own duty of care.
You may also wish to prevent the spread of JKW in order to protect your property or to prevent its spread to your neighbours or to public land. Under section 14(2) of the Wildlife and Countryside Act 1981 it is an offence to "plant or otherwise cause to grow in the wild" any plant listed in Schedule 9, Part II to the Act (which includes JKW).
Other legislation
The Control of Pesticides Regulations (COPR) 1986:
Any person using a pesticide/herbicide is required to take all reasonable precautions to protect the health of human beings, creatures and plants, safeguard the environment and avoid the pollution of water.
The Hazardous Waste Regulations 2005 (HWR 2005):
Any JKW that has been treated with certain herbicides may then be classified as hazardous waste. Details about the hazardous properties of waste, along with any special handling requirements, should be specified on a Consignment Note, issued under the above regulations.
The Waste Management Licensing Regulations 1994:
'Waste relevant objectives' in Paragraph 4 of Schedule 4 require that waste is recovered or disposed of "without endangering human health and without using processes or methods which could harm the environment..."
How can I get rid of JKW?
Herbicide treatment is the most effective way to treat and eradiate JKW although this will still usually take up to 3 years.
JKW is susceptible to a range of herbicides which include the active ingredient glyphosate, for example 'roundup'. Glyphosate is a translocated herbicide which means that the plant carries the herbicide down to its rhizome. Unless the rhizome receives a lethal dose of herbicide, the plant will regrow.
Burning can also be used to dispose of the stems responsibly, but it will be harder to get rid of rhizomes in the soil unless herbicide is applied via the stems.
Note : Use of glyphosate near water requires permission from the Environment Agency.
Who is responsible for the control of JKW?
The landowner or the tenant of the land is responsible. The Environment Agency or local government are not obliged to control JKW on behalf of landowners.
What if I have JKW growing from an adjoining property?
It is best to try and co-operate with neighbouring landowners to share costs and labour of eradication. A community approach is the best way to tackle this nationwide problem.
What is the council doing?
In the same way that a landowner has a duty to control the spread of JKW on their land, the council has a programme of control for its own land.
The council can be contracted to deal with small areas of growth, but they will bring in specialist outside contractors to address larger areas of growth of the weed.
Where can I find out more?
How to dispose of JKW
We do not offer a service for the disposal of Japanese Knotweed. It is an invasive and distructive weed which can dominate and drive out other flora. Ensure you comply with the law regarding its disposal. Do not take it off-site. It is illegal to spread it and to do so renders you liable for prosecution. For advice on disposal, see this article, courtesy of Cornwall County Council. See Wikipedia for more information about Japanese Knotweed. There are specialist commercial services who can help you with eradication and disposal.
If you require more information or want to make a report of someone illegally moving or disposing of JKW, please contact us