WEEDAX Industrial & Agricultural Weed Control for Japanese Knotweed and other Injurious & Invasive Weeds

Japanese knotweed (Fallopia japonica, or Polygonum cuspidatum) is regarded by many people as one of the most invasive and undesirable plants in the western hemisphere. Resistant to most weedkillers, devoid of natural enemies and capable of aggressive regrowth from tiny remnants of its root system, it is a gardener's worst nightmare and can cause huge problems to businesses, local councils and the construction industry. Japanese knotweed is common alongside roads and rivers throughout the UK and Ireland, where it forms dense thickets. It has also spread relatively unhindered through many parts of Europe, the USA, Canada, New Zealand and Australia. It is particularly prevalent in parts of London, Wales and southern Ireland.

HISTORY
Its natural habitat is on the volcanic slopes of Japan's mountain ranges, where its spread is well controlled by local pests and parasites. It was introduced to Britain in 1825 as an ornamental plant. Cuttings were distributed and everywhere it was planted it grew vigorously: the land was devoid of any predators, pests or parasites to keep its growth in check. It propagated quickly within gardens, eventually escaping such artificial confines and breaking out into open countryside. Since then, its growth has been alarming. The plant is now found almost everywhere in the UK and Ireland: particularly beside roads and rivers and on waste ground. Its introduction into the wild is forbidden under the 1981 Wildlife and Countryside Act in the UK.

Japanese Knotweed

HOW IT SPREADS
In general, Japanese Knotweed does not spread through seed germination. The secret of its success is in the underground stems, known as rhizomes, which can grow horizontally from a single plant to a distance of up to 20 metres. Each rhizome can form multiple new shoots, each genetically identical to its parent. These rhizomes are almost impossible to eliminate. Less than a centimetre of rhizome can swiftly create a viable plant. As people fought to control the weed, rhizomes were dumped in rivers and along waste ground, spreading the weed to new localities.

IDENTIFICATION

The best time to recognise Japanese knotweed is during mid-summer and early autumn. The plant is characterised by dense clusters of large, heart-shaped leaves, each about the size of the palm of your hand. The plant grows from the ground in multiple woody shoots, which can be green or red in colour. The shoots grow quickly, reaching heights of between one and three metres. Very dense thickets are formed where the weed is long-established. These thickets can spread in size by a few square metres each year, displacing most other plants in the process. The multiple small white flowers, which normally appear in late August and early September, appear together in dense protruding spikes. There is a die-back in winter, but the barren shoots often remain in place throughout the season.

ENVIRONMENTAL DAMAGE

Japanese knotweed is an undesirable plant in a number of different ways. Because of the thickness of its thickets and the density of its leaves, it prevents significant amounts of light from reaching the ground, so no other plants can grow in areas where the weed has become established. It finds most soils to its taste and propagates aggressively, displacing native flora in the process. Rare plants and overall biodiversity are threatened by this plant if it is left unchecked. The shoots can cause damage to buildings and structures, as they are capable of breaking through concrete and tarmac. Cemeteries, roads, residential dwellings and historical sites have all been extensively damaged by the plant. Because even a small quantity of rhizome can cause regrowth, it is extremely difficult to eradicate. In addition, many insects, such as bluebottle flies, are attracted to (and quickly poisoned by) Japanese knotweed. This may have long-term implications for local bird and animal populations

JAPANESE KNOTWEED ERADICATION

Japanese knotweed is not an easy plant to kill. Cutting down the shoots only spurs its growth, and attempts to rid the ground of its dense network of rhizomes are enormous undertakings which are unlikely to succeed. It is resistant to most weed killers but can be killed by the chemical glyphosphate - the active ingredient in a number of well-known commercial products. Even so, repeated application over a period of three years is normally required to completely eradicate the weed.

Because of its high potential for regrowth, the movement of Japanese Knotweed is strictly regulated under various laws and subject to extreme restrictions.

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