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What is Japanese Knotweed?
Japanese knotweed (Fallopia japonica) is a large perennial plant that grows throughout much of the UK. It was imported to Britain from Japan during the mid 19th century as a popular ornamental feature to many gardens. Today, Japanese knotweed is recognised as one of the most invasive species present in the UK and is known for rapidly spreading and causing substantial damage to areas where it is present.
What does Japanese knotweed look like?
Japanese knotweed emerges as small asparagus-like shoots green/purple in colour. As the plant develops it produces small red/green shield-shaped leaves growing from the stem’s many distinct raised nodes or ‘knots’. Once mature, the leaves become a vibrant green colour reaching lengths of up to 120mm. The red/green stems of adult Japanese knotweed have a hardy bamboo- like appearance which grows in thick clumps or ‘stands’. During the months of September and October, creamy white flowers are produced, growing in clusters at the end of the stems. As the plant sheds its leaves and dies off, the stems become hollow brown skeletal remains that are easily broken. The dead stems often remain upright amongst new growth during the following season. Scroll down to see the Japanese knotweed ID pics 👇👇👇
WHat damage can japanese knotweed cause?
Japanese knotweed is able to colonise a variety of urban and rural environments. Due to its ability to exploit weaknesses in construction material, such as concrete and tarmac, new knotweed growth can cause damage to structures and roads thus affecting the value of property as it rapidly develops. As Japanese knotweed grows along riverbanks it is able to colonise large areas as stems and rhizomes are carried downstream to ultimately spread the infestation causing severe damage to flood defence structures. Ecosystems can be disrupted by the presence of Japanese knotweed which can starve the surrounding native plants of resources, seriously impacting on the delicate balance of local food chains.
How can you kill japanese knotweed?
Japanese knotweed infestations can be controlled and eliminated through a variety of methods. Depending on factors such as timescale, location of infestation and its surrounding environment the method can vary but through correct application and management Japanese knotweed growth can be stopped and prevented from returning. The main methods of control are Herbicide Treatment, Dig & Dump, On Site Burial, Bund Creation, Cutting, Burning, and Biological Control
Japanese knotweed Treatment Methods
Heribicide Treatment – Qualified and competent personnel are permitted to use herbicides to control and eliminate Japanese knotweed. The application method and specific chemical used will depend on factors such as the infestations proximity to watercourses and local wildlife.
Burial – If time is a factor and it is unfeasible to wait for the numerous growing seasons that herbicide treatment may take to eradicate an infestation Japanese knotweed can be excavated and buried on site. All material contaminated with Japanese knotweed is encased in a root barrier membrane that prevents further growth and buried at a depth greater than 5m below the surface to prevent the material being disturbed and re-infesting the area.
Bund – If burial on site is not an option a bund can be created by designating an area of the site to place all material and soil contaminated with Japanese knotweed. The bund is then treated with herbicide allowing the original area of infestation to be developed or managed without the presence of Japanese knotweed being an issue. This method can be applied if there is sufficient time and space to relocate contaminated material and treat it on site, preventing the high costs of disposing Japanese knotweed at a licensed waste management facility off site.
Cutting – Japanese knotweed stems can be cut and dried out however this will only address the growth above ground and will take many years to effectively control the infestation without the use of chemicals or digging out the Japanese knotweed rhizome.
Burning – As with cutting this method can be ineffective without excavating Japanese knotweed rhizome from the soil and burning it with all plant material.
Biological Control – After careful research and development, tiny plant-eating insects called psyllids have been identified as a possible means to control Japanese knotweed, with tests being done to establish whether to release them nationwide. The ‘knotweed bugs’ have been released in some parts of England as part of a trial. Although they may control the Japanese knotweed they will not eradicate it fully otherwise the bugs would have nothing left to eat and they would die.
Burial – If time is a factor and it is unfeasible to wait for the numerous growing seasons that herbicide treatment may take to eradicate an infestation Japanese knotweed can be excavated and buried on site. All material contaminated with Japanese knotweed is encased in a root barrier membrane that prevents further growth and buried at a depth greater than 5m below the surface to prevent the material being disturbed and re-infesting the area.
Bund – If burial on site is not an option a bund can be created by designating an area of the site to place all material and soil contaminated with Japanese knotweed. The bund is then treated with herbicide allowing the original area of infestation to be developed or managed without the presence of Japanese knotweed being an issue. This method can be applied if there is sufficient time and space to relocate contaminated material and treat it on site, preventing the high costs of disposing Japanese knotweed at a licensed waste management facility off site.
Cutting – Japanese knotweed stems can be cut and dried out however this will only address the growth above ground and will take many years to effectively control the infestation without the use of chemicals or digging out the Japanese knotweed rhizome.
Burning – As with cutting this method can be ineffective without excavating Japanese knotweed rhizome from the soil and burning it with all plant material.
Biological Control – After careful research and development, tiny plant-eating insects called psyllids have been identified as a possible means to control Japanese knotweed, with tests being done to establish whether to release them nationwide. The ‘knotweed bugs’ have been released in some parts of England as part of a trial. Although they may control the Japanese knotweed they will not eradicate it fully otherwise the bugs would have nothing left to eat and they would die.
Himalayan Balsam Pics
Himalayan Balsam Treatment Methods
The most suitable treatment method for eradicating Japanese Knotweed will depend on a number of factors such as the infestation's proximity to buildings, watercourses and local wildlife. The timescale for completion of the project will also influence the choice of Japanese Knotweed treatment. The treatment options are below:
Herbicide Spraying
Qualified and competent personnel are permitted to use herbicide spray to control and eliminate Japanese knotweed. The application method and specific chemical used will depend on factors such as the infestations proximity to watercourses and local wildlife.
Stem injection
Using a specialist stem injector tool, herbicide is applied directly into the Japanese Knotweed stem. This allows for targeted treatment of the Japanese Knotweed with minimal risk to surrounding plants and the environment.
weed wiping
Herbicide is applied directly to the leaves and stems of the Japanese Knotweed plants by using a weed-wiper. This eliminates the possibly of herbicide drifting on to nearby plants, as can happen with spraying.
dig & dump (offsite disposal)
Relocation & Herbicide treatment
Japanese Knotweed can be excavated and relocated on site, then treated with herbicide until eradication is complete. This allows the original location of the infestation to be developed or managed without the presence of Japanese knotweed being an issue. This method can be applied if there is sufficient time and space to relocate contaminated material and treat it on site, preventing the high costs of disposing Japanese knotweed at a licensed waste management facility off site.
on-site burial
If time is a factor and it is unfeasible to wait for the numerous growing seasons that herbicide treatment may take to eradicate an infestation Japanese knotweed can be excavated and buried on site. All material contaminated with Japanese knotweed is encased in a root barrier membrane that prevents further growth and buried at a depth greater than 5m below the surface to prevent the material being disturbed and re-infesting the area. Burial at a shallower depth may be possible, depending on a variety of factors such as the intended future use of the site.
root barrier
A root barrier membrane can be fitted in the soil to prevent Japanese knotweed from spreading from one area to another. This may be useful along site boundaries to prevent a neighbouring infestation of Japanese knotweed encroaching into your site.
Screening / Sifting
The Japanese knotweed is mechanically excavated and put through a specially designed machine that will separate the weed from the soil. The Japanese knotweed is removed and disposed of at a licensed landfill site. This method is best suited to dry, sandy soil. There are limitations to this method. Please contact us for more info.
Other Japanese Knotweed Services
ON Site supervision / watching brief
Our team will be on site to supervise development works to ensure compliance with environmental legislation and to prevent the spread of Japanese knotweed. Accurate records of the site works will be produced and submitted to the client.
decontamination
Our team will establish a decontamination area to allow for cleaning of machinery, footwear, tools etc. to be decontaminated prior to leaving the Japanese Knotweed area.
soil analysis & reporting
Soil samples will be collected and taken to a lab for analysis. A full report on the soil will be produced. This service may be required if off-site disposal or on-site burial of Japanese Knotweed are being considered to achieve eradication.
digging trial holes / pits
Trial pits or trial holes may provide the opportunity to determine how deep a stand of Japanese knotweed is growing and how far it extends laterally. The results of the trial pits should permit more accurate calculations of the volume of Japanese Knotweed affected soil. This is particularly useful when trying to work out the cost of Japanese Knotweed disposal or the volume of soil to be buried or relocated.
Japanese Knotweed Eradication Process
1. survey
A professional Japanese Knotweed site survey is an integral part of the treatment programme for controlling this invasive non-native weed.
Our team provide comprehensive site surveys which identify the extent of the Japanese Knotweed infestation, the potential impact on the environment and the intended use of the site.
Japanese Knotweed needs to be controlled swiftly and effectively to protect both the environment and the individual’s legal obligation.
By responding quickly to enquiries, we help minimise the spread of Japanese Knotweed and keep the costs associated with treating this weed as low as possible. To book a Japanese Knotweed survey fill in your details below:
Our team provide comprehensive site surveys which identify the extent of the Japanese Knotweed infestation, the potential impact on the environment and the intended use of the site.
Japanese Knotweed needs to be controlled swiftly and effectively to protect both the environment and the individual’s legal obligation.
By responding quickly to enquiries, we help minimise the spread of Japanese Knotweed and keep the costs associated with treating this weed as low as possible. To book a Japanese Knotweed survey fill in your details below:
2. proposal
We issue a proposal document after we have completed a Japanese Knotweed site survey. The proposal details our findings from the survey, quantifies the Japanese Knotweed on site and on adjacent land (as far as possible) and lists the options for controlling the Japanese Knotweed present. Often there are several Japanese Knotweed treatment options available, each with different timescales for completion and prices for each option.
3. MANAGEMENT PLAN
Once a survey has been done, a site specific Japanese Knotweed Management Plan will be written. The management plan includes all relevant site information and identifies a strategy for eradication of the Japanese Knotweed and ensures compliance with relevant environmental legislation such as the Wildlife and Natural Environment (Scotland) Act 2011.
4. TREATMENT
The most appropriate treatment method for eradication of the Japanese Knotweed will have been identified in the Japanese Knotweed Management Plan. Treatment* will take place and the treatment programme will run until eradication has been achieved.
*Treatment is a term used for any of the eradication methods, e.g. herbicide spraying is a treatment. Mechanical removal and disposal of Japanese Knotweed at landfill is also classed a treatment.
*Treatment is a term used for any of the eradication methods, e.g. herbicide spraying is a treatment. Mechanical removal and disposal of Japanese Knotweed at landfill is also classed a treatment.
5. MONITORING
Upon completion of the Japanese Knotweed treatment programme, a monitoring period will run for at least 2 years. Monitoring is done to ensure that any regrowth is controlled before it can become well-established. Monitoring visits take place during the months when active growth would be visible (May-September).
6. GUARANTEE
An insurance back guarantee (IBG) will be issued once the treatment period and 2 years of monitoring have finished. The IBG will run for either 5 or 10 years. Click here for further info on our Japanese Knotweed Guarantee.
Japanese Knotweed Guarantee
Once the Japanese Knotweed treatment programme is complete, we will issue an Insurance Backed Guarantee. We will monitor the site annually to ensure that in the unlikely event of reoccurrence, the Japanese Knotweed will be dealt with swiftly. Our clients have peace of mind knowing that INNSA will still honour our guarantees even if we are unable to do so due to insolvency. If this were to happen, any remedial works would be completed by an alternative INNSA contractor at no additional cost you other than the first £100 for which you would be responsible.
Japanese Knotweed Do's & Don'ts
If you think you have discovered Japanese Knotweed on or near your property
DOKnow what Japanese knotweed looks like! Being able to identify it in all seasons will help you remain vigilant and spot potential infestations on your property quickly.
Restrict access to the affected effected area; even small infestations can spread rapidly if disturbed. Respect the environment! Chemicals used to control Japanese Knotweed can be harmful so unless you are qualified to use herbicides then leave it to the experts! |
DON'TUproot! Disturbing the ground where Japanese Knotweed is growing can expose the plants underground rhizomes. Tiny fragments of material weighing as little as 0.7g can easily be carried on clothing, footwear and tools to later fall and generate more Japanese Knotweed growth.
Add to compost! All cut Japanese Knotweed must be separately stockpiled to ensure material is completely dead before applied to land. Dump! Japanese Knotweed is classed as controlled waste and must be disposed of at authorised facilities. It is illegal to allow Japanese Knotweed to spread in the wild and if disordered incorrectly you may be liable to prosecution under the Wildlife and Countryside Act 1981. Damage! Fragments of Japanese Knotweed stem material can create new shoots and roots, further spreading the infestation. Delay! Everyday that passes without taking action or carrying out effective methods of control, Japanese Knotweed becomes better established and harder to eliminate. Contact IWA and we will be able to give you clear and practical advice to successfully rid your property of Japanese Knotweed! |