Japanese Knotweed News | Green Leaf Remediation

Japanese Knotweed News discussed by South Wales Knotweed Services

Japanese knotweed, also known as Bamboo due to its bamboo-like appearance and Peashooters is thought to be one of the most invasive plants in the UK. Japanese Knotweed will spread extremely quickly from one tiny crown or rhizome and is a perennial weed that grows and spreads rapidly if not controlled. Knotweed will suppress plants growing around it and will quickly take over. Knotweeds looks like it has died off above the ground in winter and will then re-emerge above ground at the end of spring, early summer. Established shoots can grow more than 9ft high and will colonise the soil within a few years if not controlled. Read our Japanese Knotweed News and find out everything you need to know.

Some Japanese Knotweed News articles will say you can kill the roots of Japanese Knotweed with chemicals, however, you do need an NPTC qualified person to work with the required chemicals and knows the best process to follow as a result of new legislation which covers the management and removal of Japanese Knotweed. It is extremely difficult to control and remove knotweed without expert knowledge and most often successful unless you use a Knotweed specialist who has the knowledge and expertise. During the height of its growing season, 60% of its roots are underground meaning it’s is extremely difficult to remove as well as risky. Only one tiny fragment of crown or rhizome (root) is needed to make it spread quickly underground which is why it is such an invasive plant. Understanding if you have Knotweed is difficult due to its ever-changing appearance during the different seasons and trying to remove it yourself will likely result in it spreading to other areas of soil which were previously unaffected so always use an NPCT qualified person or business to identify it and remove it.

(Japanese Knotweed News Article sourced from www.telegraph.co.uk/  – Henry Bodkin, science correspondent 16 MAY 2019, 6:01 AM)

Japanese knotweed wrongly wiping value off homes because mortgage lenders rely on ‘flawed science’

Japanese knotweed is wrongly destroying the value of thousands of homes because mortgage lenders are relying on discredited scientific evidence, an investigation by MPs has found.

A report by the House of Commons Science and Technology Committee said banks are adopting an “overly cautious” approach to the issue, leaving homeowners unable to sell, even in cases where the invasive plant poses no practical threat.

The committee contrasts the stance of UK lenders with that of European counterparts, finding that mortgage companies on the continent are far less risk-averse.

The report focuses particular criticism on the continued use of the “seven-metre” proximity rule, which was proposed in 2012 by the Royal Institution of Chartered Surveyors (RICS) but has since been ditched because it lacks a solid evidence base.

Formally known as Fallopia japonica, Japanese knotweed is a fast-growing invasive plant with bamboo-like stems.

It was first introduced to the UK in the mid-nineteenth century as an ornamental plant in parks and gardens but has since become a nuisance.

The species can grow through tarmac, disrupt paving and exploit cracks in buildings.

It is particularly hard to eradicate, requiring excavation or treatment with herbicide over several years, a process which can cost £5,000.

While acknowledging that Japanese knotweed can cause damage, the report noted recent evidence suggesting the effects on buildings “might not be as significant as previously believed.”

The committee pointed to other invasive plants which do not have the same “chilling effect” on property prices.

A 2017 survey by the Crop Protection Association suggests that among individuals affected by knotweed, 15 per cent had a property deal fall through, 20 per cent saw a drop in the value of their house, while 10 per cent had to compensate someone because of the plant.

Norman Lamb MP, Chair of the Science and Technology Committee, said: It is clear that the UK’s current approach to Japanese knotweed is more cautious than it needs to be, especially when comparing it to that of other countries.

“We need an evidence-based and nuanced approach to the issue, one that reassures owners and buyers that they will not be subject to disproportionate caution when trying to sell or buy a property.”

It is estimated that more than two per cent of development sites and 1.25 per cent of residential properties in Britain are affected by the plant, amounting to tens of thousands of sites in total.

The report recommends that the Department for Environment, Food and Rural Affairs, commission a study of international approaches to Japanese knotweed in the context of property sales.

It also found that owners houses neighbouring land owned by Network Rail where there is a knotweed issue find it particularly challenging to secure insurance-backed guarantees for mortgage lenders.

Last year a study by the University of Leeds with engineering firm Aecom argued that Japanese knotweed does not cause significant damage to buildings, even when growing in close proximity.

The research examined 68 homes where knotweed was found, as well as 81 additional sites.

The authors acknowledged knotweed can worsen existing cracks in structures, but in general, prefers to grow around obstacles rather than burrow through them.

“The current framework lacks a clear and comprehensive evidence base and yet is causing significant problems to some house vendors and purchasers,” said Mr Lamb.

(Japanese Knotweed News Article sourced from www.cornwalllive.com/ – Gayle McDonald 11:40, 1 AUG 2019)

Warning over Japanese knotweed hybrid that’s taking over gardens

A warning has been issued about a Japanese knotweed hybrid species – that could be even more destructive than its parent plant.

The national trade body the Property Care Association (PCA) says reports of a Japanese knotweed hybrid, ‘Bohemian knotweed,’ are on the increase.

Also known as Hybrid knotweed, the invasive non-native plant is produced by cross-fertilisation between Japanese knotweed and Giant knotweed.

According to Dr Peter Fitzsimons, group technical manager of the PCA’s Invasive Weed Control Group, it could be a real concern if it gains a foothold nationally.

Dr Fitzsimons said: “Bohemian knotweed, although less common, has been around for almost as long as the better-known Japanese knotweed, but is not always recognised.

“As a result, it has remained largely below the radar, but the reason for concern is that these hybrid plants can be even more vigorous than the parent plants.

“We also need to be alert as, in other parts of the world where Hybrid knotweed is more common, they are seeing signs of fertile seed production, known as backcrossing.

“If so, this could be a major concern for the future as the existence of seed-producing hybrid knotweeds may enable these plants to spread even more rapidly.”

Japanese, Giant and Hybrid knotweed are all listed under Schedule 9 of the Wildlife and Countryside Act.

Dr Fitzsimons added: “Japanese, and other closely related knotweeds are nuisance plants because they spread easily via their rhizome network, grow rapidly and are capable of causing disruption around buildings.

“Since the PCA formed the Invasive Weed Control Group in 2012, we’ve always maintained the position that whilst this plant is disruptive around buildings it can be brought under control using established techniques and processes.

“However, its presence can impact on the ability to gain a mortgage and on the development cost of land.

“More research is needed to see what the impact is of Bohemian knotweed, but for now we should be aware of the issue.

“If anyone has concerns about this or any type of invasive, non-native weed, PCA’s Invasive Weed Control members can advise on the identification and the necessary treatment.”

(Japanese Knotweed News Article sourced from www.weather.com/ -Jan Wesner ChildsMay 09 2019 ,04:12 PM) 

Aggressive Japanese Knotweed is Making Its Way Across U.S., Pushing Out Native Species in its Path

A killer is stalking the U.S., terrorizing victims as it makes its way from big cities to the suburbs, from populated areas to isolated forests.

Its name is Japanese knotweed.

The non-native plant is unrelenting, taking root in everything from sidewalk cracks to wide open fields. It can grow as much as eight inches a day in the summer, according to to the University of New Hampshire Extension, and can reach heights up to 15 feet. What’s more, its root system can spread more than 70 feet.

Like other invasive species, knotweed crowds out native plants and creates a hostile environment for competitors. In turn, that also affects the food supply, shelter and other vital factors for wildlife. The International Union of Conservation ranks knotweed among the world’s top 100 most invasive species, plant or animal.

So far, its infestation has been limited mostly to the northeast. But knotweed is found in every U.S. state except North Dakota, Nevada, Arizona, New Mexico, Texas, Florida and Hawaii, according to the University of New Hampshire Extension.

(MORE: Britain Goes One Week Without Coal Power, Breaks Record That Dates Back to the Industrial Revolution)

Most Americans, especially southerners, are probably more familiar with kudzu, the prolific vine that blankets trees and fields, robbing them of natural light and killing anything it covers.

Knotweed’s potential is worse, in part because it is still spreading into new territory. Besides infesting fields and forests, it can grow through cracks in cement, between floorboards, and even through asphalt.

“Frankly, kudzu pales by comparison in its effects to Japanese knotweed,” Robert Naczi, a curator of North American Botany at the New York Botanical Garden, told Slate magazine. “There are plenty of invasives [where] yes, they spread, but they’ve occupied most of the habitat that they will occupy. Japanese knotweed still has a ways to go and it appears it will … Japanese knotweed is a very serious invasive. A very, very problematic species. One of the worst invasive species in Northeastern North America.”

Naczi is near the epicentre of the knotweed outbreak in the U.S. The plant first made its way to the U.S. in the late 1860s, according to the Wall Street Journal, as a gift to a Manhattan nursery owner. The weed was eventually planted in several places around New York City, including Central Park. Knotweed has large green leaves and produces multitudes of small white flowers, which at the time made it an attractive addition to landscapes.

Besides its hardiness, several factors are to thank for knotweed’s march into new habitats. The plant has been spread largely by construction when the dirt is disturbed or moved, and flooding. Experts also believe that climate change, which brings heavier rainfall, warmer winters and other conditions that create less favourable conditions for native plants, has contributed to knotweed’s growth.

Knotweed has reached emergency status in Britain, where the plant is blamed for damaging building foundations. Mortgage companies there refuse to issue loans on a property where the plant is present, and the country has embarked on vast, and expensive, attempts to thwart it.

Some herbicides have proven effective against knotweed, but it can take up to five years of repeated application to knock down infestations, the UNH extensions says. Another alternative is to consistently pull up and remove the weeds, especially when they are younger. That method has proved successful in some parts of New York. Still, there is no known way to completely rid an area of knotweed.

“You can see it everywhere, along the roadside, in every city,” Jatinder Aulakh, an assistant weed scientist at the Connecticut Agricultural Experiment Station, told Slate. “There is no insect, pest, or disease in the United States that can keep it in check.”

(Japanese Knotweed News Article sourced from www.cbc.ca/ – Dominika Lirette Aug 08, 2019, 10:16 AM)

‘The monster is underneath’: Interior district steps up fight against Japanese knotweed invasion

Roots of the invasive species can extend 20 metres underground and penetrate home foundations

The green, heart-shaped leaves and bamboo-like stalks of Japanese knotweed may look pretty, but it can badly damage buildings and ecosystems — and now the Thompson-Nicola Regional District is stepping up its fight to root out the plants.

Japanese knotweed is listed by the International Union for Conservation of Nature as one of the 100 worst invasive species, and sightings of it have the district in B.C.’s southern Interior concerned.

“It doesn’t look so scary up top but the monster is underneath, under the ground with its roots,” said Colleen Hougen, invasive plant management coordinator for the district.

The Thompson-Nicola Invasive Plant Management Committee is now asking the public to report sightings of the plant so they can try to develop a strategy to manage Japanese knotweed throughout the region.

The plant can cause serious damage to buildings and infrastructure, Hougen said.

“[Their] roots can extend 20 metres laterally and they’re really, really strong and they can actually penetrate through concrete, asphalt [and] home foundations,” said Hougen.

The weed tends to grow in wet areas and if it grows on a riverbank, it can cause erosion and sedimentation, which can affect aquatic ecosystems, she added.

‘Growing through people’s homes’
Japanese knotweed is not new to the region, but the district is trying to get a handle on the weed “before they get out of control,” Hougen told Daybreak Kamloops’ Jenifer Norwell.

“Out of control could look like root systems growing through people’s homes and showing up on the insides of their homes.”

The plant is much more prevalent in the Lower Mainland and along the coast because of the wet climate, she said.

Pulling out invasive weeds? Don’t put them in the compost bin
However, people in the Interior still plant it and nurseries sell it.

“It’s really unique and people are drawn to that for their gardens,” said Hougen. “What they don’t know is the impacts that the roots can have on the infrastructure surrounding them.”

Call district or specialist for removal
The district does not recommend people remove the plant on their own, because it can easily reproduce through root fragments and shoots.

“Pulling and digging will actually make it worse,” said Hougen.

Instead, the district asks people to contact them or a specialist to try and help remove it. A common treatment option is using herbicides.

Some people are tackling ‘Godzilla’ of weeds with knife and fork
So far, the district has just started outreach with landowners who have Japanese knotweed on their properties, and it has already had one success story with a hotel in Clearwater.

“I feel if we team up with some landowners and land managers and if we work together we can actually make headway, and kind of control these plants before they get out of control.”

Japanese Knotweed NPTC Qualified & Certified Specialist Removal Methods

Japanese Knotweed NewsThere are several methods of getting rid of Japanese Knotweed and if you have read any Japanese Knotweed News Stories then a Knotweed Specialist will be able to quickly identify if you have it and give you advice about the best and most effective way of controlling and removing it.


A low impact way of removal where there is little risk of disturbing or killing the plants and flowers growing around and close to it. The stem-injection technique is normally used for smaller areas of Knotweed where it has established itself amongst other plants and vegetation that you want to maintain. Additionally, it is an approach generally applied when Knotweed is near a watercourse. The stem-injection approach can be used in dry or inclement weather conditions and the soil cannot be disturbed following a treatment.

Foliar Spray Application

Is frequently used and among the most favourable control methods as well as stem-injection. The method is used to manage the Knotweed over a number of growing seasons. Dependent on the size of the area of Knotweed is it is normally sprayed 2-3 times in the first year and once in the subsequent years. The chemical used is an Environment Agency approved herbicide and needs dry weather conditions as well as the soil to remain undisturbed in subsequent years in order to work effectively.

Weed Wiping Method

The leaves of the plant are wiped with a sponge that is soaked with the required herbicide. It’s a low impact treatment and does not kill or disturb the foliage adjoining it and its use depends upon the size of the area of knotweed.

Bund/Stockpiling Method

A blended treatment using stem-injection and foliar application, followed by excavation and removal of the underground soil to a different location in which the emergence of ‘new shoots’ can be subjected to additional herbicide application. This process is used on sites where the removal of the knotweed needs to be fast and not done over several seasons so it is particularly beneficial to development sites so that work can proceed without delay.

Cell Burial/Root Barrier Method

A treatment used when there is enough space on-site to create a cell burial area or making use of a root barrier to avoid the high cost and logistics of transporting the soil and waste to landfill. The cell burial method buries the Knotweed waste to a minimum depth, or if encapsulated inside a geomembrane it can be closer to the surface of the ground. Root barriers can be installed both vertically and horizontally when there is a danger of cross-boundary contamination. Again, it is a method most often used on development sites when construction work needs to start quickly.

Excavation & Removal Off-Site

Is a swift control option which has its advantages for development sites if performed correctly, however, a lot of Knotweed Specialists are not advocates of it as it has considerable logistical problems. The challenges faced with this removal method are there is an extremely high risk of the Knotweed spreading as well as the cost to securely transport the material to a designated landfill site. There is also a specific duty of care requirements under the Environmental Protection Act (EPA) 1990 which have to be considered. Excavation & Removal should only be used as an absolute last measure.

There are lots of Japanese Knotweed News Stories relating to the damage it can cause, however, in truth it is one of many plants in the UK that can cause problems to land, buildings and other structures. Other perennial plants can cause similar or worse damage to buildings and underground services and structures.

Using a Knotweed Specialist who has the experience and qualifications to control and remove Japanese Knotweed safely and successfully should be your only consideration and will ensure you are taking responsibility for the Knotweed on your property. Any specialist you use should be NPTC qualified will have extensive Knotweed knowledge and who is trained to use the chemical substances needed under new legislation which covers the management, and removal of Knotweed.

Green Leaf Remediation Services

Green Leaf Remediation Specialists cover the whole of South Wales (including Swansea, Cardiff and Newport), West Wales up to North Ceredigion & Powys and throughout South Glamorgan & Gwent & Tenby. We carry out contracts in the West Country as far North as Shropshire and into the Midlands & Birmingham.

We are a fully qualified Japanese Knotweed Certificated Surveyor (JKCS) and we specialise in controlling Japanese Knotweed, other invasive plants as well as ‘general nuisance weeds’ which are found in the UK for residential and property development sites.

We also provide tree services, such as pollarding, crowning, pruning, felling, through our NPTC chainsaw operators, all of whom possess a vast amount of experience in the forestry industry.

Our Qualifications & Accreditations
  • City & Guilds NPTC Level 2
  • Principles of Safe Handling & Application of Pesticides (PA1/PA6)
  • Principles of Safe Handling & Application of Pesticides near water (PA6AW)
  • Herbicide Stem Injection
  • Property Care Association
  • The Control & Eradication of Japanese Knotweed Surveyor’s Training Course
  • Qualified Technician (PCAQT) in Japanese Knotweed
  • Accredited Surveyor in Japanese Knotweed

If you have read our Japanese Knotweed News and are worried you may have Japanese Knotweed then contact us today on 01269 591651 and one of our Knotweed experts will be able to answer any questions you may have or will arrange a property or land survey for you.