Page 16 - ALG Issue 3 2018

General
Japanese knotweed (Fallopia japonica)
Originally hailing from Japan, Taiwan
and northern China, Japanese knotweed (Fallopia japonica) was first introduced
to the United Kingdom during the early 1800s. It was brought back by the
Plant Hunters as an ornamental plant, considered worthy of growing on the large country estates of the landed gentry. The leaves contributed to the autumn colour, turning a beautiful butter yellow in the autumn. Also, rather conveniently, the plants grew in great thickets that provided cover for game birds come the Glorious 12th of August (the start of the game
bird shooting season)! Thriving in moist conditions, Japanese knotweed escaped along riverbanks and began to spread, colonising other areas, becoming the invasive nightmare that we have today. Japanese knotweed is now listed as
an invasive non-native plant species in Schedule 9 of the Wildlife and Countryside Act 1981.
In recent years there have been articles appearing in the garden media suggesting that the early young red shoots have a superior taste to rhubarb. Having sampled
it as a young boy – and lived to tell the tale
– with or without custard, I fear the taste would leave a lot to be desired! We used the hollow stems as pea shooters.
It is suggested that there is no harm
in cutting and cooking the tender shoots
as long as the plants themselves aren’t disturbed. However, removing knotweed from its place of origin without taking it to a registered landfill is an offence under Section 34 of the Environmental Protection Act 1990. The cutting and removal of sections of the plant, followed by their removal to
the kitchen, preparation for cooking and subsequent disposal of shoots/plant waste could fall foul of this legislation.
It isn’t an offence to allow Japanese knotweed to grow on your land but you are responsible for the control and prevention of it spreading into the wild or onto neighbouring areas. It is a public offence (covered by the Anti-social Behaviour, Crime and Policing Act 2014) to let it be a source of nuisance. ‘These notices can be issued to individuals
or organisations
to compel them
to control invasive
species where
they are having a
detrimental effect on
the quality of life of
others’.
Cutting down and Digging out
Cutting and digging out are considered not to be effective methods of control either, as they can take many years to have any effect. The plants have an extensive underground rhizomatic root system that can grow many metres deep. It is almost impossible to remove every last piece of root. Any that remain regenerate, developing into new plants. There is also the problem of safely disposing of the excavated material because it is considered to be controlled waste and has to be contained and disposed at a suitably licensed or permitted waste site. It must be transported by a registered waste carrier.
Do not be tempted to compost any part of Japanese knotweed. This precaution is to prevent spreading it around the area.
Chemical control of Japanese knotweed
A Glyphosate based herbicide is the best way to treat Japanese knotweed. A professional strength of glyphosate must be applied to the plants. The herbicides available to amateur gardeners aren’t
Always seek advice and permission from the appropriate agencies when using chemicals near water.
There are specialist companies that can organise the eradication and disposal of waste materials.
The Environmental Agency does not endorse specialist offering Japanese knotweed treatment. You must make sure that the specialist you use:
• Operates within the conditions in ‘treatment and disposal of invasive non-native plants: RPS 178’
• Has the relative environmental permit
You do not need to hire a specialist contractor to treat Japanese knotweed,
but there are a number of companies that specialise in Japanese knotweed treatment. Many of these companies belong to one of these trade bodies:
• Invasive Non-native Specialists Association
• Property Care Association
Use a waste carrier to take Japanese knotweed offsite. You must use a registered waste carrier to an authorised landfill site or suitable disposal site.
You must dispose of Japanese knotweed offsite by transferring it to a disposal facility that’s permitted, such as a landfill site that has the right environmental permit.
You must not:
Dispose of Japanese knotweed with other surplus soil.
You can only re-use knotweed- contaminated soils after treatment, on the site where they were produced.
For further government information on the control and eradication of Japanese knotweed and other invasive non-native plants, see below:
https://www.gov.uk/guidance/prevent- japanese-knotweed-from-spreading
The responsibility
for controlling Japanese knotweed lies with the owner of the land, unless the tenant has agreed to the contrary in the lease. Allotment Associations must always inform the Local Authority or landlord of the presence of Japanese knotweed on allotment land.
Treatment and Control of
Japanese knotweed
Do not strim, flail or mow Japanese knotweed. This could significantly increase the risk of spreading the plant.
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The herbicides available to amateur gardeners aren’t effective enough to completely kill Japanese knotweed
effective enough
to completely kill Japanese knotweed.
Always make sure that the person carrying out the spraying holds
a Certificate of Competence for Herbicides, or is
working under the control and direction of someone who holds a Certificate.
The optimum time to use the herbicide is late-summer / autumn. It must be applied after the plants have flowered. This is when they are at their most vulnerable. If the chemical is used early in the year the plants may be ‘knocked back’ but are vigorous enough to regrow. It may take two to three years to kill larger, established stands of Japanese knotweed. Always treat once a year in the late summer / early autumn after flowering.
By Anneli Salo [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons