Japanese Knotweed Claims

In this article I consider the problems caused by Japanese Knotweed and some of the types of legal claims that can be made, in the light of some recent court decisions.


Fallopia Japonica is a large herbaceous perennial of the knotweed and buckwheat family Polygonaceae. It has a number of common names, often related to animals - elephant ears, donkey rhubarb, monkeyweed, but perhaps the most appropriate is the Chinese: tiger sticks.

European adventurer Philipp Franz von Siebold first transported the plant from a Japanese volcano to Holland. By 1850 a specimen from this plant was added to Kew Royal Botanic Gardens. It proved popular with gardeners because it looked like bamboo and grew in all conditions. It spread is thought to have been aided by rail and water networks.

Japanese Knotweed is not difficult to find. If you are a rail commuter like me, you can usually look out of the window and see it along the sides of the track.

It has hollow wooded stems with raised nodes that look a bit like bamboo, thick and straight at the base, but curving over elegantly at the top; the broad oval leaves are red initially, turning to dark green; in late summer and autumn it has small white flowers in spikes which stand upright from the crown of the plant.

It is quite common to see patches where it has been partially treated, but with smaller new plants emerging from amongst the scattered dried stems.

What will not be visible is the large underground network of rhizomes (roots) which can grow 10 feet down: it is these that make the plant so difficult to eradicate once established.


To eradicate the plant the roots need to be killed. All above-ground portions of the plant need to be controlled repeatedly for several years in order to weaken and kill the entire patch. The right herbicide is essential, to travel through the plant and into the root system below.

The growth of the plant can be significantly reduced by applying herbicides, but these have not been proven to provide complete long term elimination.

Digging up the roots is a common, potentially quicker, solution for developers, but the risk is that if even a few centimeters of root are left in the soil, the plant will quickly reappear.

More recent experiments have involved the use of biological pest control agents from Japan: the Mycosphaerella leafspot fungus and the aphid Aphalara Itadori.

Criminal Offences and Planning Provisions

Sub-section 14(2) of the Wildlife and Countryside Act 1981 states that "if any person plants or otherwise causes to grow in the wild any plant which is included in Part II of Schedule 9, he shall be guilty of an offence." Japanese, Giant and Hybrid Knotweed all appear in that Schedule.

Private gardens are generally thought not to come within the definition of "the wild" and for what it may be worth, the Environment Agency Knotweed Code of Practice (published on 12 August 2013 but withdrawn on 11 July 2016) had stated that "It is not an offence to have Knotweed on your land and it is not a notifiable weed".

Sections 33 and 34 of the Environmental Protection Act 1990 contain prohibitions and duties relating to the deposit, treatment, keeping or disposal of controlled waste, which under the wide definitions in schedule 2B would include Knotweed material or soil containing it.

Section 43 of the Anti-Social Behaviour, Crime and Policing Act 2014, empowers authorised persons to issue community protection notices where

(a) the conduct of the individual or body is having a detrimental effect, of a persistent or continuing nature, on the quality of life of those in the locality, and

(b) the conduct is unreasonable.

The Act does not explicitly refer to Japanese Knotweed (or any other species of invasive plant) but written guidance published by the Home Office indicates that a community protection notice could be used to require a landowner to address such a problem.

Planning authorities do have some relevant powers. Under section 215 of the Town and Country Act 1990

"If it appears to the local planning authority that the amenity of a part of their area, or of an adjoining area, is adversely affected by the condition of land in their area...

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