October 24, 2023

The Root of the Problem: Why is Japanese Knotweed a Concern?

Possibly Japan’s most infamous export, the Japanese Knotweed, has become a cause of widespread concern in the UK. This invasive plant species, known scientifically as Fallopia Japonica, presents significant challenges not just to the environment but also to property owners, potentially leading to substantial financial losses.

Decoding the Threat: What is Japanese Knotweed?

A herbaceous perennial plant, Japanese Knotweed, is often mistaken for bamboo due to its bamboo-like stems. It boasts large, green, shovel-shaped leaves and produces creamy-white flower clusters in late summer and early autumn. However, its beauty masks its destructive nature.

This plant is renowned for its rapid growth, ability to thrive in various soil types, and exceptional resilience, making it one of the most invasive plant species in the UK.

An Extensive Roof System

The issue with Japanese Knotweed lies in its extensive root system, known as rhizomes. Rhizomes can spread up to 7 metres horizontally and 3 metres vertically, allowing the plant to colonise vast areas rapidly. Even a small fragment of rhizome left in the soil can sprout a new plant, making it extremely challenging to eradicate.

The destructive power of Japanese Knotweed extends beyond its botanical characteristics. It can cause structural damage to buildings, disrupt gardens and natural habitats, and even lead to financial losses for property owners.

The Infestation and Its Impact on Properties

Japanese Knotweed’s aggressive growth can lead to a wide range of property damages. It seizes on weak points in infrastructure, growing through cracks in masonry, foundations, and even disrupting drain runs.

Property Devaluation

The presence of Japanese Knotweed can knock tens of thousands off a property’s value. Mortgage lenders often refuse mortgages to individuals attempting to buy a property with live Japanese Knotweed on the premises. This not only makes it hard to buy such a property but also complicates the selling process.

Increased Insurance Premiums

Many building insurance policies do not cover damage inflicted by Japanese Knotweed. If property owners disclose the presence of Japanese Knotweed to insurers, they can expect higher premiums.

Structural Damage

Japanese Knotweed can exploit existing weaknesses in building structures, causing significant destruction. It’s capable of growing through concrete and tarmac, infiltrating outbuilding foundations with weak foundations, and disrupting patios, paths, and driveways.

The Legal Implications of Japanese Knotweed

While it’s not illegal to have Japanese Knotweed growing on your property, allowing it to spread from your land onto other people’s property may be seen as a private nuisance, which could lead to legal disputes.

Furthermore, the Environmental Protection Act 1990 classifies soil or plant material contaminated with non-native and invasive plants like Japanese Knotweed as controlled waste. Failure to dispose of it correctly could lead to hefty fines and legal issues.

The Fight Against Japanese Knotweed

Effective control of Japanese Knotweed requires professional treatment. This generally involves the application of approved herbicides over several years. In severe cases, the affected area may need to be dug out and disposed of correctly, which can be a costly process.

Landowners are responsible for stopping the spread of Japanese Knotweed on their land. Failure to do so can result in prosecution, as spreading the plant into the wild is a criminal offence.

The Bottom Line

Japanese Knotweed poses a significant threat to the UK’s ecological balance and property market. Efforts to control and eradicate this invasive plant species are essential to minimise its impact. While the plant can create extensive damage and financial loss, it’s crucial to remember that with proper treatment and management, its threat can be controlled.

As a property owner, it’s your responsibility to prevent the spread of Japanese Knotweed on your land. If you’re unsure about its presence, seek professional advice immediately. Remember, early detection and immediate action can save you from significant damages and financial losses in the future.

Further Resources

For more information on the identification, control and disposal of Japanese Knotweed, visit these pages: