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Japanese Knotweed

Common Name Japanese Knotweed
Other Names

Asian Knotweed, Himalayan Fleece Vine, Monkeyweed, 

Japanese Bamboo, Elephant Ears

Scientific Name

Fallopia japonica 

(syn. Polygonum cuspidatum)

Weed Type Herbaceous Perennial Plant, Invasive Species
Affected Areas

Waysides, Beds, Borders & Paving, Wasteland

Main Causes

Creeping Roots

Timings Seen in Late Spring to Autumn, Treat in Summer

What is Japanese Knotweed?

Japanese Knotweed is a fast-growing, tall and strong perennial weed. Its stem growth is renewed each year from the stout, deeply penetrating rhizomes.Introduced into Europe in the 19th century as an ornamental plant, as well to provide ground cover and fodder, it’s brought untold worry and turmoil to grounds everywhere ever since. 

Identification & Appearance

In the spring red/purple fleshy shoots rapidly appear from crimson pink buds at ground level. By summer they have formed dense stands of tall bamboo like canes which can grow to 7ft tall. These canes have purple flecks and produce branches from the nodes the entire way along the branch. The leaves are shovel or heart shaped and are situated in a zig zag like pattern along the stems. The creamy-white flower tassels which are produced in late summer can reach up to 15cm.

The stems will die back to ground level in the winter months however the dry canes will remain for several months or longer. It is important to positively identify Japanese knotweed as it can be easily confused with other plants including Russian vine and Himalayan honeysuckle.

The Problem

Japanese Knotweed is a highly invasive species which can sprout from small sections of rhizomes. It forms a wide-ranging root system which can go as deep as 3m and upto 7m in all directions and once established it can become highly invasive by supressing all over plant growth. It can cause devasting destruction to concrete foundations, buildings, flood defences, roads, paving, retaining walls and architectural sites with it's invasive root system and strong growth. 

It is also an offence to instigate the growth of Japanese knotweed in the wild under the Wildlife & Country Act. You can also be issued with an ASBO if you are found to be failing to stop the spread of the weed from your property. There are legal regulations to buying and selling property which may have Japanese knotweed present on the premises.

How to Prevent & Control?

Eradication requires a lot of persistence and determination as it can be extremely difficult to remove once it is established. The transportation and disposal of Japanese Knotweed stems, roots and contaminated soil is now strictly controlled. 

Non Crop Situations (motorway & railway embankments, roadsides & industrial areas (excluding airfields):

I-Cade: Tough Invasive Herbicide Which Will Not Harm Grass

Spot Spraying:

Roundup Pro Vantage 480 5L: The Strongest Amenity Glyphosate On The Market

Stem Injection: Round up Pro Vantage 480 5L The Strongest Amenity Glyphosate On The Market

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