The knotweed problem – is your stadium prepared?

The UK’s Japanese knotweed crisis has hit papers again following the EU failure to

reach a decision on the renewal of herbicide Glyphosate. David Layland, Joint Managing Director of Japanese Knotweed Control and co-author of the new Code of Practice for the Management of Japanese Knotweed, explains how pitches and stadiums can be kept clear of infestations.

Japanese knotweed, the invasive plant brought into the UK as a decorative flower in the nineteenth century, is currently thriving due to the mild winters and wet summers of recent years. The spread of infestations is aided by the abundance of false information and poor advice in circulation, which can lead to costly mistakes for managers of land and buildings. Sports venues across the UK are at risk

– there is a known case of knotweed infestation within at least every 10km square of the British Isles. Some stadiums may be especially vulnerable if they are located near busy transport links such as railways, tramlines or canals, which create ‘vectors’ for the weed to spread along. Stadiums could risk excessive recurring

costs, damage to man-made structures, and even legal action if an infestation takes place. The plant can spread from a fragment smaller than a fingernail, and grow through cracks in concrete and tarmac to undermine the structural integrity of buildings. Yet it is possible to control, as long as stadium managers familiarise themselves with the most up-to-date advice, to ensure they are prepared if they encounter or need to manage land susceptible to, or infested, with the invasive plant. The first step for any stadium manager is

to learn to recognise the plant, and ensure staff are trained to identify and report any sighting of Japanese knotweed. It is most easily distinguishable in summer, where it develops an abundance of green leaves, distinctive white flowers, and a bamboo-like stem with purple speckles. The leaves wilt

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and brown in autumn, and during winter it draws back into its rhizome (roots) whilst the canes lose colour and turn into woody stalks. It is always best to identify the plant as early as possible. Despite the claims of some companies

and websites, knotweed cannot be removed without professional help – the products required to successfully destroy the roots are not available to the public. Stem injection is widely regarded as the most cost effective, timely and environmentally friendly method of removal, but to be successful it must be undertaken by a trained professional with the specialist equipment. Damaging, uprooting, composting

or otherwise disturbing the plant will exacerbate matters by encouraging further growth. Stadium managers must ensure that the affected area is fenced off to prevent further contamination in the short term. A common myth about Japanese

knotweed is that once it has been treated, the problem has disappeared. In reality, without warranties, insurance and long-term remediation strategy, knotweed treatment can leave stadiums just as much at risk as when the first distinctive leaves are identified. When a herbicide is applied to the plant,

it translocates through the root system to stop plant cells from growing. Over time it rots into the soil, but until it has completely decomposed, small nodules of viable material may still be present, making it imperative that the plant is left in situ and undisturbed. If the plant is left alone, herbicide is by

far the least expensive and a highly effective treatment method. However, the plant stores

nutrients in a maze of roots underground, enabling it to hibernate during the winter months. The plant appears to be dead, but is in fact alive and will spread and cross contaminate if disturbed. This is not cause for panic provided that

stadiums implement a long-term remediation strategy, and ensure that the correct warranties and insurance are in place. Any reputable invasive plant professional will be able to provide these, giving stadium managers peace of mind that the knotweed is under control in the form of a legal guarantee. Familiarisation with the laws on knotweed

is useful in navigating the complex legislation surrounding waste and biodiversity. It is an offence to plant or cause Japanese knotweed to spread in the wild under the Wildlife and Countryside Act 1981, and all waste contain- ing Japanese knotweed is subject to Part II of the Environmental Protection Act 1990. If infested soil needs to be removed

from site, stadium managers should keep the amount of infested soil excavated to a minimum, and remember that infested soil should not be taken off site, unless it is by a licensed haulier and to a landfill site that is licensed to handle Japanese knotweed. If a pitch or grounds require external

topsoil to be bought in, it is imperative that it has first been inspected for Japanese knotweed, to avoid starting a new infestation. Japanese knotweed may seem like a

huge threat, but the most important point to remember is that it can be controlled, providing stadium managers arm themselves with the most up-to-date facts and advice.

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