Table of Contents
Introduction
Japanese knotweed damage can often occur when the invasive plant attempts to grow through the weakest points of a property’s foundation & out-structures.
Knotweed Services (UK) Ltd stands at the forefront in the identification, inspection, and eradication of this invasive species.
The Biology of Japanese Knotweed
Japanese Knotweed, or Fallopia japonica, is an aggressive pesky plant often characterised by its striking features and formidable growth habits, including the ability of Japanese knotweed to grow through concrete, tarmac, poorly built brickwork, paving, and disrupt independent structures such as garden sheds, greenhouses, and fences.
Understanding its biology is crucial to recognising the challenges in controlling this invasive species. The impact of Japanese knotweed growing on properties includes its invasive nature, the responsibility to control its spread, its potential to cause structural damage to buildings, and disrupt independent structures such as garden sheds, greenhouses, and fences.
Additionally, the way Japanese knotweed grows and the specific ways its growth can cause damage to property walls, fences, and other structures highlight the resilient and invasive nature of Japanese Knotweed. Japanese Knotweed rhizomes lurk underground and can create new plant growth to re-emerge for up to 20 years, especially if the ground is disturbed, exerting pressure and causing damage to buildings, hard surfaces, and underground infrastructure.
Japanese Knotweed Plant Characteristics
Description of its Appearance
Japanese Knotweed emerges with reddish-purple shoots that swiftly develop into bamboo-like stems, reaching heights of up to 2-3 metres. During spring and early summer, its leaves unfurl in a distinctive heart or shovel shape. By late summer, the plant is adorned with clusters of small, creamy-white flowers, adding a deceptive allure to its otherwise threatening presence.
Growth Patterns
It can sprout as much as 10 cm per day in peak growing seasons, displaying a stark resilience that often overwhelms native vegetation. This rapid growth is supported by an extensive root system, or Japanese Knotweed rhizomes, that can burrow deep into the ground exploiting minute cracks and weaknesses in both natural and man-made structures.
Reproductive Strategies
How it Spreads So Effectively
Japanese Knotweed reproduces both vegetatively through its rhizomes and via its seeds. A small fragment of this root can sprout into a new plant, making disposal – tricky. Its pieces can be transported by water or inadvertently moved with soil during construction activities, leading to new infestations.
How deep are Japanese knotweed roots?
The Environment Agency revealed that Japanese knotweed rhizomes can extend 7 meters horizontally and 3 metres vertically from the visible ‘above-ground’ growth. This is why Japanese Knotweed damage can be so harmful.
Read this article: Can You Build On Land With Japanese Knotweed? for further information about land owners’ responsibilities.
Japanese knotweed has the potential to grow as much as 10 centimetres per day in the summer, giving it the ability to spread quickly.
Survival Techniques
Its Resilience Against Conventional Removal Methods
One of the most daunting aspects of Japanese Knotweed is its capability to resist common eradication methods. Cutting back the stems provides only a temporary fix, as the rhizomes remain alive and vigorous beneath the earth. Herbicides can sometimes be an effective control measure. Still, they must be applied consistently over several years.
The plant’s ability to regenerate from root segments that remain in the soil post-eradication attempt means it can resurrect itself after dormant periods, complicating long-term removal efforts and management strategies. Japanese Knotweed Damage is always lurking just beneath the surface and soil!
Understanding the complex biology of Japanese Knotweed is the first step in battling this invasive menace and indeed Japanese Knotweed Damage. It’s not merely about removing what’s visible; it’s a deep-rooted issue that requires comprehensive strategies and persistent efforts.
What Structural Damage Can Japanese Knotweed Cause?
Its extensive rhizome system is capable of destabilizing and damaging property foundations, disrupting piping and water supplies, and compromising fences, boundaries, outbuildings, and even flood defences.
Environmental Impact of Invasive Species
The relentless spread of Japanese Knotweed wreaks havoc on the environment. From choking local ecosystems to destabilising riverbanks, its impacts are both diverse and destructive.
Ecosystem Disruption
Displacement of Native Plants
By forming dense thickets, Japanese Knotweed overshadows native flora, hoarding sunlight and nutrients. It’s an unfair competition where the native greens stand little chance.
As Knotweed asserts dominance, the indigenous plants, which insects and animals have co-evolved with and depend on, dwindle and disappear. This reduction in plant diversity not only degrades habitat quality but also threatens the survival of local species.
However, it’s important to note that woody species, in general, can also lead to the displacement of native plants, albeit through different mechanisms such as deeper root systems that compete for water and nutrients.
Effects on Local Wildlife
Animals and insects, left without their usual food and shelter, are forced to move or face potential decline. Bird species that rely on native plants for nesting materials and cover find their routines disrupted. Japanese Knotweed offers poor sustenance to native insects, leading to a ripple effect where birds and other insectivores struggle to find food.
Soil Quality and Erosion
Impact on Soil Composition
Dominance by a single species like Japanese Knotweed can alter the very makeup of the soil. It can disrupt the delicate balance of microorganisms and affect soil pH and nutrient levels, leading to a less hospitable environment for other plants.
Contribution to Erosion Due to Root Systems’ Effect on Soil Cohesion
Beyond its visible growth, Japanese Knotweed’s roots can contribute significantly to soil erosion. While its rhizomes are tough and extensive, they don’t bind the soil in the same way as native plants. When Knotweed displaces long-established flora, the soil loses its natural cohesion and stability, making it more susceptible to being washed away, particularly during heavy rainfall.
Waterways
Risk to Riverbanks and Floodplains
Japanese Knotweed loves waterway margins, but its affection is far from beneficial. On riverbanks and floodplains, its root systems can cause the banks to weaken and collapse, altering the natural flow of rivers and increasing the risk of flooding. When floodplains are unable to absorb excess water efficiently due to the dense mats of Knotweed, surrounding land and properties are at greater risk.
Blockage of Natural Watercourses and Risk to Aquatic Life
The tenacity of this plant means that it can grow through and around man-made structures, causing blockages in drains and ditches. Its presence along watercourses can lead to decreased water quality and altered habitats that affect fish and other aquatic life.
Japanese Knotweed’s environmental impact is profound. It’s not just a gardener’s nemesis—this is a plant actively redrawing the ecological map, with dire consequences for the habitats it invades.
Furthermore, this invasive plant is notorious for causing the sudden collapse and ruin of older buildings and structures, making it clear that its days as a harmless ornamental plant are long gone.
Typical damage from Knotweed includes:
Tarmac, Paving & Patios – Japanese knotweed can grow between hard surfaces, like paving slabs, bricks, block paving’s, and even force its way through tarmac.
Water Supply & Drainage Pipes – Japanese knotweed roots can find their way into underground pipes in search of water, which can further damage and clog your drainage system. Large, densely packed knotweed roots and rhizomes can cause disruption in drain runs & water pipes alike. In the worst cases, these pipes have to be replaced completely.
Building Foundations – Japanese knotweed can penetrate, or at the very least, weaken significantly, just about any hard surface you place it up against. Including your properties foundations.
Retaining Wall Structures – Japanese knotweed can undermine garden walls by attacking their shallow foundations and old or poorly constructed fences. Its dense masses can cause retaining walls & fence supports to ‘push over’ with sudden collapse.
The Financial and Legal Implications
Japanese knotweed unfurls beneath the surface of our green and pleasant lands. It intertwines a web of financial and legal complexities for property owners across the UK. Mortgage lenders often have reservations about properties affected by Japanese knotweed, as its presence can significantly hinder the ability to secure a mortgage, complicating the buying or selling process for such homes.
The Devaluation Quandary
Properties besieged by the silent encroachment of Japanese Knotweed may witness a perceivable depreciation in their market value. This is not just a matter of aesthetics but also a reflection of the potential costs of remediation and the long-term risks to the property’s structural integrity.
The presence of this invasive plant can make housing markets wary, leading to a decrease in the value of affected properties by as much as 20% in severe cases. This drop in value can make it harder to sell these properties and can also affect insurance and the cost of fixing the problem.
To mitigate this, Knotweed Services (UK) Ltd offers a specialist and tailored approach—accredited by the PCA—ensuring that every client’s situation is addressed with the utmost precision, backed by our commitment to upholding the highest industry standards.
Lenders and Their Reservations
Banks and lenders are cautious when it comes to properties affected by Japanese Knotweed. They often want to see a professional plan for dealing with the weed before they agree to give out mortgages or loans. Without such a plan, some may even reject mortgage applications because they’re worried about the risks and expenses that could come up in the future.
Our experts create detailed Knotweed Management Plans. These plans are key to getting mortgage approvals because they show lenders that we’ve not only identified the threat of knotweed but are also managing it carefully and effectively.
Legislation on Japanese Knotweed
In the UK, the legislative framework surrounding Japanese Knotweed is robust, aimed at preventing its spread and ensuring responsible management. Under the Wildlife and Countryside Act 1981, it’s a criminal offence to plant or otherwise cause Japanese Knotweed to grow in the wild. Moreover, the Environmental Protection Act 1990 classifies the plant as ‘controlled waste’, necessitating specific disposal methods to prevent further contamination.
These laws compel landowners to take action against the spread of Japanese Knotweed, not merely for the sake of biological diversity but also to safeguard the value and integrity of properties.
Responsibilities of Landowners
Landowners harbour the lion’s share of responsibility in preventing the spread of Japanese Knotweed and halting Japanese Knotweed growing. Not only must they ensure that the plant does not encroach on neighbouring properties, but they are also obliged to disclose its presence during property transactions. Failure to manage or disclose Knotweed appropriately can lead to disputes, diminution of property value, and potential legal action.
Penalties for Non-Compliance
The consequences of non-compliance with Knotweed regulations can be severe. Landowners may face legal action from affected neighbours, resulting in financial damages for devaluation of property or costs incurred in removing the Knotweed. Additionally, local councils possess the authority to issue Community Protection Notices, imposing fines on those who neglect their duties in controlling or disposing of the plant properly.
Why Does Japanese Knotweed Cause So Much Damage?
The biggest reason Japanese knotweed causes so much damage is due to ignorance or wilful negligence. All knotweed infestations start small. Whether the infestation begins due to a fragment of rhizome or is the result of a neighbouring patch of land. There is always time to prevent Knotweed from doing any severe damage.
The longer any potential Japanese knotweed infestation is left unchecked, the more opportunity it has to spread, grow stronger and threaten your property with severe damage. Even a small infestation of Japanese knotweed on your property can have a significant impact on the value of your home and your ability to sell it at a later date. Recognizing Japanese knotweed as an invasive weed is crucial, especially since mortgage lenders may be cautious about lending money for properties affected by it, unless the issue is being managed by a professional from the Property Care Association invasive weed group.
How Do I Prevent Damage & Limit Removal Costs?
If you suspect an infestation of Japanese knotweed on your property or that of a neighbour, be sure to contact our Japanese Knotweed Specialists and trained surveyors for further identification and a Japanese Knotweed Survey. Please DO NOT ignore it.
When Japanese knotweed has been identified on your property or a neighbouring property, you should notify your immediate neighbours about it immediately so that they can remain vigilant. Depending on which property the infestation resides on, the homeowner then holds the responsibility of removal of the infestation. Catching it as early as possible in its most diminutive physical form is the most cost-effective method of removal before more severe damage & repair costs follow.
For effective identification, control, and removal of Japanese knotweed, consulting with Japanese knotweed specialists is highly recommended.
