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JAPANESE KNOTWEED

Japanese Knotweed is one of Britain’s most invasive plants and the prevention of its spread is a legal obligation for landowners under the Wildlife and Countryside Act 1981.

DO's
Do make a plan to eradicate Japanese Knotweed from your site
Do keep all cuttings onsite
DON'T
Don't waste time - plan and carry through eradication as soon as possible
Don't dig or spread the soil around the plant
Don't transport the cut plant
Don't recycle

What is Japanese Knotweed
Japanese Knotweed is Britain's most invasive non-native plant. It was originally brought from the Far East as an ornamental plant by the Victorians but it has now widely naturalized and occurs across the UK as well as Europe, USA, Canada and New Zealand.
This plant is perennial and extremely invasive. It thrives on disturbance. The tiniest piece can re-grow, and has been spread by both natural means and by human activity. It soon overruns riverbanks, railway embankments, road verges, gardens and hedgerows, threatening the survival of other native plant species and in turn insects and other animal species.
The aggressive spread of the plant following its first escapes into the wild in the 19th Century resulted in it occurring in most parts of the UK (except Orkney) and eventually being listed in the Wildlife and Countryside Act 1981 as a pest species. All parts of the plant are considered as controlled waste under the Waste Regulations.

How to Identify Japanese Knotweed
In the early spring red/purple shoots appear from the ground and grow rapidly forming canes. As the canes grow the leaves gradually unfurl and turn green.
The plants are fully grown by early summer and mature canes are hollow with a distinctive purple speckle and form dense stands up to 3 metres high. The plant flowers in late summer and these consist of clusters of spiky stems covered in tiny creamy-white flowers. These provide a good source of nectar for insects. The seeds are rarely fertile and in Britain the plant spreads mainly by vegetative means.
The canes can arise from the rhizome which grows underground, from an existing crown, where previous growth has taken place, or from a cut stem. During the late autumn/winter the leaves fall and the canes die and turn brown. The canes remain standing throughout the winter and can often still be seen in new stands in the following spring and summer.
The rhizome is the underground part of the plant. It is knotty with a leathery dark brown bark and when fresh snaps like a carrot. Under the bark it is orange or yellow. Inside the rhizome is a dark orange/brown central core or sometimes it is hollow with an orange, yellow or creamy outer ring, although this is variable. Young rhizome is very soft and white. The 'knots' are nodes, spaced at 1-2cm intervals where there are often small white fibrous roots or buds emerging. Each of these 'knots' can potentially become a new plant if the rhizome is cut up (e.g. through digging).

How to eradicate Japanese Knotweed
This is not easy, it is time consuming and lengthy, maybe over 4 years!
Cutting the growing plant with sharp tools near soil level or professional spraying. Pull up stems where possible as this will pull some of the rhizome up and weaken the plant. Do not make any attempt to dig up the plant as this causes it to grow more vigorously.
Covering the soil with plastic or carpet, if possible, after cutting will stop further growth. Make regular checks for any further growth in the area as growth can appear up to 7 metres away.
Cutting and pulling as much as 4 times a year may be necessary.

Disposing of the Japanese Knotweed.
Bag the cut plants in black bin liners. Store the bags on a hard surface or on more plastic to avoid any chance of rooting. Allow to compost naturally. It is an offence to move fresh cut knotweed or the soil off site, DO NOT put in recycling containers or take to local recycling centres.
If you have burning facilities this is easiest and quickest, but seek Park managers advice where applicable.