Japanese Knotweed Control
As you may have heard Japanese Knotweed has rapidly become the most invasive species of plant in Britain today.
Japanese Knotweed was introduced to Britain in the 19th century by the Victorians as an ornamental plant, but over time it has become widespread outcompeting our native plants and animals and damaging our environment.
What does it look like?
• It is lush green in colour
Why is it a problem?
The invasive root system and strong growth can damage foundation, buildings, roads and pavements. Its success is due to its tolerance of temperatures and soil types. It spreads through its crown rhizome (underground stem) rather than its seeds and these rhizomes can extend 7 metres horizontally and 3 metres deep, making excavation very difficult. Studies have shown that a 1cm section of rhizome can produce a new plant in 10 days!
Japanese Knotweed is capable of penetrating hard structures such as concrete, tarmac, brick walls and foundations. All of which are reasons why mortgage lenders are increasingly reluctant to lend on properties with Japanese Knotweed infestations.
South Wales, and in particular the Swansea valley are the worst affected areas in Britain. In Swansea alone the infestation has been estimated to cost 9.5 million in chemical treatment and will take approximately 50 years to eradicate, and that’s not taking into consideration any spread to new areas.
This is rapidly becoming a serious problem for home owners in South Wales.
Japanese Knotweed Legislation
• Wildlife and Countryside Act 1981
Listed under Section 9, Section 14 of the Wildlife and Countryside Act 1981, it is an offence to plant or otherwise cause the species to grow in the wild.
Allowing Japanese Knotweed to spread from your land could make you liable to third party litigation and/or civil prosecution.
• Environmental Protection Act 1990
Japanese Knotweed is classified as “Controlled Waste” and as such must be disposed of safely at a licensed landfill site according to the Environmental Protection Act (Duty of Care) Regulation 1991.
These legislations put a duty of care upon the landowner with Japanese Knotweed infestations to be pro active in the control and eradication of the problem. Significant fines are implemented for those who do not regard the law in relation to the spread of this plant and its increasingly problematic spread in South Wales.
What Can Be Done?
• Chemical Control
All Chemical Control methods must comply strictly to Health and Safety Regulations and must be carried out by technicians holding the NPTC PA1 and PA6 (Safe Use of Pesticides) in accordance with the Control of Pollution of Environment Act 1990 and Control of Pollution of Water Act 1989.
Commonly used translocated herbicides are most effective in late summer during the flowering period. Repeated treatments required over several growing seasons are required for this method to be successful. Continued monitoring of the area must be carried out. This is the most cost effective method of treatment. However, due to time consumption it is not suitable for sites requiring immediate development.
• Excavation on site
Excavating and treating the area with herbicide is the next most cost effective treatment as it eliminates the transport costs. It does however require adequate space to store the Japanese Knotweed to ensure it is thoroughly dry before being burned. Repeated applications may be needed, but studies show that this method if carried out correctly is less time consuming than treating solely with herbicides. Due to the nature of the herbicide used, this is not suitable for riparian sites.
• Excavation and Removal
Excavation and removal of Japanese Knotweed is the quickest and most environmentally friendly method as it eliminates the use of herbicides. However, it is the most labour intensive and costly. Great care is required in this method not to spread any of the plant outside of the site. Japanese Knotweed is classed as Controlled Waste under the Environmental Protection Act 1990 and must be disposed of and transported in compliance with legislation and carried out by a licensed contractor. With increasing costs involved in the removal of Japanese Knotweed this method can be very expensive for large areas and raises sustainability issues.
The Environment Agency’s website also contains a guide for Japanese Knotweed control called:
|All tree work is carried out in accordance with BS 3998 and Public Liability Insurance to £5 Million.
*NPTC qualifications held – PA1 and PA6
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