Devon Invasive Species Initiative – Japanese Knotweed

Japanese knotweed by watercourse

Japanese Knotweed is Britain’s most invasive non-native plant. It was originally brought from the Far East as an ornamental plant by the Victorians but it has now widely naturalized and occurs across the UK as well as Europe, USA, Canada and New Zealand. This website is designed to help you find the information you need to help you recognize and deal with Japanese Knotweed, and its relatives, and to help the Forum achieve its aim of controlling Japanese Knotweed in Devon.

  • What is Japanese Knotweed?

    Japanese Knotweed (Fallopia japonica) was first introduced to Britain by the Victorians as an ornamental plant – and was actually awarded a gold medal at a prestigious flower show. It is referred to under its previous name of Polygonum cuspidatum in The English Flower Garden by John Murray. In the 1907 edition it is cited as “easier to plant than to get rid of in the garden”.

    In its native countries of Japan, North China, Korea and Taiwan, the weed presents nowhere near the problem it now poses across Europe, America and New Zealand. With its natural habitat being on the slopes of volcanoes, it is no surprise that the less harsh and more fertile environment of Britain has allowed this plant to flourish to extreme proportions. Furthermore, outside of Asia, the plant has no natural biological enemies to check its spread. In Japan, for example, at least 30 species of insect and 6 species of fungi live on the plant.

    This plant is perennial and extremely invasive. It thrives on disturbance. The tiniest piece can re-grow, and has been spread by both natural means and by human activity. It soon overruns riverbanks, railway embankments, road verges, gardens and hedgerows, threatening the survival of other native plant species and in turn insects and other animal species.

    In riparian areas, high water flows disperse fragments of the plant downstream where new colonies form. In the past, fly-tipping and transportation of soil containing rhizome fragments have been a major cause of spread, particularly in the urban environment. Green waste recycling schemes are also sites of potential contamination which is a cause for concern. Local Authorities, including those in Devon, are desperate to find ways of eradicating this serious pest.

    Huge sums are being spent in the UK controlling the weed. In 2004, a DEFRA review of non-native species policy stated that a conservative estimate for the costs involved in eradication would be £1.56bn. The aggressive spread of the plant following its first escapes into the wild in the 19th Century resulted in it occurring in most parts of the UK (except Orkney) and eventually being listed in the Wildlife and Countryside Act 1981 as a pest species. All parts of the plant are considered as controlled waste under the Waste Regulations.

  • How to Identify Japanese Knotweed

    Japanese knotweed shoots in early spring
    Japanese Knotweed shoots in early spring

    In the early spring red/purple shoots appear from the ground and grow rapidly forming canes. As the canes grow the leaves gradually unfurl and turn green.

    The plants are fully grown by early summer and mature canes are hollow with a distinctive purple speckle and form dense stands up to 3 metres high. The plant flowers in late summer and these consist of clusters of spiky stems covered in tiny creamy-white flowers. These provide a good source of nectar for insects. The seeds are rarely fertile and in Britain the plant spreads mainly by vegetative means.

    The canes can arise from the rhizome which grows underground, from an existing crown, where previous growth has taken place, or from a cut stem. During the late autumn/winter the leaves fall and

    Purple Speckled stems of Japanese Knotweed
    Purple Speckled stems

    the canes die and turn brown. The canes remain standing throughout the winter and can often still be seen in new stands in the following spring and summer.

    The rhizome is the underground part of the plant. It is knotty with a leathery dark brown bark and when fresh snaps like a carrot. Under the bark it is orange or yellow. Inside the rhizome is a dark orange/brown central core or sometimes it is hollow with an orange, yellow or creamy outer ring, although this is variable. Young rhizome is very soft and white. The ‘knots’ are nodes, spaced at 1-2cm intervals where there are often small white fibrous roots or buds emerging. Each of these ‘knots’ can potentially become a new plant if the rhizome is cut up (e.g. through digging).

    White flowers of Japanese Knotweed
    White flowers of Japanese Knotweed

    zig zag stems with alternating leaves
    zig zag stems with alternating leaves

     

     

     

     

     

     

     

     

  • Knotweed in Devon

    Originally native to the countries of Japan, North China, Korea and Taiwan, Japanese Knotweed is now widespread across Europe from southern France and Northern Italy to Norway, in many states in the USA from California to Washington, throughout Canada and now New Zealand where it is spreading rapidly and causing enormous problems. In its non-native situation it has no natural diseases or grazers and it flourishes.

    In Britain it has now been recorded in over 50% of the 10 km squares used to map plant distribution. The only place it is not found is the Orkney Islands.

    Devon is experiencing its own problems with the plant and it now occurs in most parts of the county. It is mainly found in gardens, on road verges, river banks, railway embankments and waste ground.

    Distribution Map of Japanese Knotweed.

    This first map shows the known distribution of Japanese Knotweed in Devon in 2011. It occurs in gardens, on road verges, railway embankments, riverbanks and waste ground.

    This second map shows the currently known distribution of other invasive knotweeds in Devon. However, this is likely to significantly under-estimate the extent of some of these lesser known knotweeds, so this map will change as our knowledge improves.

    Recording

    Without surveying and recording the distribution of Japanese Knotweed there is no way of knowing where it occurs, whether it is increasing and the typical habitats it colonises. Knowing the full extent of the problem of Japanese Knotweed colonisation in the county will help the Devon Knotweed Forum identify priorities for control and management. It is therefore important to report any sightings of the plant in the county to the Devon Biodiversity Records Centre. Please note the Devon Biodiversity Records Centre are not responsible for controlling Japanese Knotweed and do not provide general advice on Japanese Knotweed.

  • What’s the problem?

    So why are people so concerned about Japanese Knotweed?

    There are four main reasons why Japanese Knotweed is a problem in Devon and elsewhere:

    • It spreads easily via rhizomes and cut stems or crowns
    • It out-competes native flora
    • It is difficult and expensive to control or eradicate.
    • It can cause structural damage to buildings.
    • Because of its regenerative properties and invasive habit Japanese Knotweed is listed under the Wildlife and Countryside Act 1981 as a plant that is not to be planted or otherwise introduced into the wild. The
    • Environmental Protection Act 1990 also lists it as ‘controlled waste’ to be disposed of properly. You have a legal obligation not to cause it to spread if it occurs on your land.

    Specific problems caused by Japanese knotweed are:

    • Damage to paving and tarmac areas.
    • Damage to flood defence structures.
    • Damage to archaeological sites.
    • Reduction of biodiversity through out-shading native vegetation.
    • Restriction of access to riverbanks for anglers, bank inspection and amenity use.
    • Increases erosion when the bare ground is exposed in the winter.
    • Obstructs visibility and access on roads and paths.
    • Reduction in land values.
    • Increased risk of flooding through dead stems washed into river and stream channels.
    • Increased risk of soil erosion and bank instability following removal of established stands in riparian areas.
    • Accumulation of litter in well established stands
    • Aesthetically unsightly.
    • Expensive to treat (£1/sq.m for a spraying regime over 3 years not including re-landscaping)

    A 2004 British Government Review of Non-Native Species Policy gives an estimate of the costs to control knotweed countrywide of £1.56 billion which, although unfeasible, gives an indication of the extent of the problem and the high costs associated with control were it to be attempted. Swansea is one of the worst affected areas in the country and as such has the most experience with the costs associated with managing knotweed. These are some of their cost estimates:

    £140,000 for planning department treatment of established populations over the last 6 years.

    Using quoted figures of £1 per square metre for spraying and £8 for landscaping estimates for completely treating the current infestation in Swansea would cost around £9.5 million.

    At the current rate of treatment (2ha/yr) the current infestation will take 50 years to treat without accounting for its rapid spread (more than 2ha/yr)

    The costs of removal from development sites are very large – One 30m x 30m site cost developers an extra £52,785 to deal with the Knotweed on the site.

    I’ve got Japanese Knotweed, what do I do?

    Don’t panic! But do start to plan how you are going to control, contain or eradicate it. Here is a checklist of actions:

    • Find out more – is the plant really Japanese Knotweed? What can I do to control it? Look at the other links on this website.
    • Seek advice from the Devon Knotweed Forum members if appropriate.
    • Seek advice from the Environment Agency if treating Japanese Knotweed near a watercourse.
    • Find out the best options for your kind of site.
    • Make a plan of action to control it and expect an expensive, long-term undertaking.
    • Implement treatment, suitable for your site, to control it – early treatment is best.
    • Notify the Devon Biodiversity Records Centre of the location and size of the colony if you live in Devon.
    • Remember you have a legal obligation not to allow it to spread.
    • Remember: Early treatment of a new colony is vital as it can soon invade large areas and this will make it more expensive and difficult to control later.

  • Japanese Knotweed and the Law

    In the UK, there are three main pieces of legislation that cover Japanese Knotweed. These are:

    Wildlife and Countryside Act 1981

    Listed under Schedule 9, Section 14 of the Act, it is an offence to plant or otherwise cause the species to grow in the wild. It is the responsibility of the landowner to control these plants, but they don’t have to remove them as the natural growth of these plants and spread of the plants is not illegal. However, allowing the plants to spread onto land outside of the ownership or control of the landowner can be seen as an offence.
    Causing the plants to spread by removing or disposing of them incorrectly would be illegal.
    The police are responsible for investigating any offences and each police force has a wildlife liaison officer who can be contacted.
    An offence under the Wildlife and Countryside Act can result in a criminal prosecution.
    If the police cant take action, a civil action may have to be taken against a person to ensure that the invasive plants on their land are controlled.

    Environmental Protection Act 1990

    Japanese Knotweed is classed as ‘controlled waste’ and as such must be disposed of safely at a licensed landfill site according to the Environmental Protection Act (Duty of Care) Regulations 1991. Soil containing rhizome material can be regarded as contaminated and, if taken off a site, must be disposed of at a suitably licensed landfill site and buried to a depth of at least five metres.
    An infringement under the Environmental Protection Act can result in enforcement action being taken by the Environment Agency which can result in an unlimited fine. You can also be held liable for costs incurred from the spread of Knotweed into adjacent properties and for the disposal of infested soil off site during development which later leads to the spread of Knotweed onto another site.

    Anti-social Behaviour, Crime and Policing Act 2014: anti-social behaviour

    Local councils and the police (in most cases it will be the local council) have the power to issue notices for invasive non-native species like Japanese Knotweed. Note that in Devon this refers to the District Councils or Unitary Councils, such as Torbay and Plymouth, but not Devon County Council. The notice can place restrictions on a person’s behaviour and, if necessary, force them to take steps to rectify the behaviour that is having a detrimental effect on the community.
    This means if an individual, or organisation, is not controlling Japanese Knotweed or other invasive plant and could reasonably be expected to do so, the notice could be used to get them to stop the anti-social behaviour.
    The notice could include a requirement to stop a specified action or behaviour, or a requirement to take reasonable steps to prevent future occurrence of the problem. Breach of any requirement of a community protection notice would be a criminal offence, subject to a fixed penalty notice or prosecution. For more information go to the Home Office’s webpages on Anti-social Behaviour, Crime and Policing Act: anti-social behaviour.

  • Knotweed Do’s and Don’ts

    Japanese knotweed growing up a fence in PlymouthTo help prevent the spread of this highly invasive plant look at the do’s and don’ts in this section. Causing Japanese Knotweed to spread is illegal so it is important to avoid activities which risk this happening.

    Do’s

    • Do make a plan to eradicate Japanese Knotweed from your site.
    • Do contact the Environment Agency National Customer Contact Centre for further information on preventing the spread and control of Japanese Knotweed on 0370 850 6506 or their website.
    • Do use herbicides safely and effectively.
    • Do obtain the approval of the Environment Agency prior to treatment if you intend to use a herbicide in or near water on 0370 850 6506.
    • Do follow the manufacturer’s instructions regarding protective clothing and the safe and effective use of herbicides.
    • Do take care to avoid drift, and any damage to non-target plants when applying herbicides. Spraying should be performed during still dry conditions, without rain for 6 hours.
    • Do check qualifications – spraying on land which is not your own should be carried out by an approved contractor with a National Proficiency Tests Council Certificate of Competence.

    Don’ts

    • Don’t flail Japanese Knotweed as this could cause it to spread. Cutting with sharp hooks, slashers etc or hand pulling is recommended to avoid any dispersal of cut fragments.
    • Don’t cause the spread of Japanese Knotweed stem and crowns. If you cut down Japanese Knotweed, it is best to dispose of it on site. Material taken off site must be safely contained and disposed of at a licensed disposal site.
    • Don’t try to dig up Japanese Knotweed as this will lead to a significant increase in stem density. Even a tiny fragment of the cut rhizome is capable of regeneration.
    • Don’t spread soil contaminated with Japanese Knotweed rhizome. Any soil that is obtained from ground within 7 m of a Japanese Knotweed plant could contain rhizome. The rhizome is highly regenerative and will readily grow into new plants.
    • Don’t chip Japanese Knotweed material. Mechanical chippers don’t kill Japanese Knotweed. If you spread the chipped material on soil, Japanese Knotweed could regrow.
    • Don’t add Japanese Knotweed to compost. Compost it separately (preferably on plastic sheeting to prevent rooting) so that you can be sure it is dead before you apply it to land.
    • Don’t take Japanese Knotweed to recycling centres that receive garden waste as it will contaminate the compost.
    • Don’t dump garden waste contaminated with Japanese Knotweed in the countryside.
    • Don’t waste time. If Japanese Knotweed appears on your site, treat it immediately. Don’t allow it to become established.
    • Don’t break the law. Remember, if you cause Japanese Knotweed to spread you are guilty of an offence under the Wildlife and Countryside Act, 1981.

  • Control of Knotweed

    Control of Japanese Knotweed relies on the death of the extensive rhizome system, which usually takes a number of years. So far in Devon there are no records that the plant has produced seed so treatment of the existing plants is the key to the problem in the county.

    Japanese knotweed stems     Japanese knotweed growing around a building

    Methods of spread

    In the UK Japanese Knotweed has not yet been recorded as producing viable seeds, however, hybrid crosses can produce viable seed. So far all Japanese Knotweed plants recorded in the UK are female and all male plants have been shown to be hybrids. Fertile hybrids will add a whole new dimension to the control of the spread of Japanese Knotweed which currently only reproduces vegetatively.

    The plant does have an extraordinary ability to spread vegetatively from crown, stem and rhizome (underground root). Even tiny amounts of cut stem, crown or rhizome are capable of producing a new plant. Controlling spread is therefore dependent on preventing the spread of stem, crown or rhizome.

    Rhizomes grow rapidly underground and are responsible for the spread of the plant on site. They produce long white shoots at the apices of the rhizome which send up shoots to the surface.

    If the rhizome is cut it will produce a shoot. Digging or other disturbance is known to increase stem density. If soil contaminated with rhizome is moved to another part of the site or to another site it will regrow and cause spread. Rhizome is particularly resistant to dehydration and freezing. As little as 10 mm or 0.7 gm of rhizome can regenerate into a new plant.

    Crown and stems are also capable of regenerating and even small fragments of cut crown or stem are capable of regenerating and becoming a new plant. If the plants are cut back it is important to dispose of the crown and stems properly. Once stems are thoroughly dried they are unable to regenerate.

    Preventing spread

    It is important that an effective Japanese Knotweed management programme is established including, where possible, herbicide treatment otherwise the plant will inevitably spread. All cut or pulled stems of Japanese Knotweed should be treated with extreme care as they can potentially re-sprout and cause spread. They should be kept on site, or disposed of in a licensed landfill site that can carry out deep burial (by prior arrangement) to prevent spread onto other sites. Treatment of colonies on riverbanks should be treated as soon as possible because bank erosion can lead to plant material breaking off and dispersing downstream,

    As stems, crowns and rhizomes readily regenerate, they must be allowed to dry out thoroughly after they have been pulled or cut, this can be helped by putting the material onto a plastic sheet, or raised wooden platform, rather than on the ground. Regular checks should be made to ensure that this material is not contaminating watercourses or other sites, or developing roots. Thoroughly burning plant material on site after cutting and drying, where current by-laws allow, can be an effective means of disposal provided that the waste is burnt on site and not removed to other land.

    Ensure that machinery, tools and work clothes are free of fragments of Knotweed before leaving the site. Tracked vehicles, off-road tyres, tools and even work boots can harbour fragments of Knotweed and could potentially cause spread to another site. These items should be thoroughly cleaned before leaving a Knotweed contaminated site.

    Japanese Knotweed material is regarded as ‘controlled waste’ and not disposing of it properly would be an offence under the Environmental Protection Act, 1990. Allowing the spread of Japanese Knotweed into the wild is also an offence under the Wildlife and Countryside Act 1981.

    Code of Practice

    Environment Agency – Prevent Japanese Knotweed from spreading
    Environment Agency – Prevent harmful weeds and non-native plants from spreading

    Methods of Control

    Chemical Treatment

    NB This information is not designed to be specific but to raise awareness of what you need to consider and be aware of before using herbicides. The Devon Knotweed Forum provides this information in good faith and cannot be held responsible for any problems arising from the interpretation and use of this advice.

    The use of herbicides is often the most effective option for the control of Japanese Knotweed but there are issues that need to be considered first.

    The main issue is whether the stand is near water or not. Consent is required from the Environment Agency if herbicides are to be sprayed near water and only two products are approved (see below). It is advisable to contact 08708 506 506 if you are considering using herbicides near a watercourse and they will be able to advise you on your options.

    There are health and safety issues and those administering herbicide need to be properly trained and hold a Certificate of Competence. Herbicides should only be used in accordance with the advice on the label otherwise it is considered an offence. It is also an offence to use products that are not approved. Check that the herbicide formulation is approved for the intended use. Furthermore there is an obligation to avoid the spread of herbicide to non-target areas so spraying needs to be carried out in dry weather (no rain for 6 hours, preferably 24), spraying should also not be carried out in wind speeds above Force 2 on the Beaufort Scale to avoid spray drift.

    Japanese Knotweed can become very tall which makes it difficult to apply herbicides. The plants should ideally be sprayed in the spring when they are about 1m tall or after cutting when they have re-grown to this height. There are various methods of application including tractor-mounted spraying for large areas; knapsack spraying for small areas; lance sprayer for tall stands or for stands in inaccessible places (such as steep slopes and river banks); controlled droplet application; injection method for small stands and weed wiper or herbicide gloves for direct application onto leaves of specific plants.

    Dense stands of Japanese Knotweed can be treated with a glyphosate-based herbicide, such as ‘Roundup Pro Biactive’. Glyphosate is a systemic herbicide which acts by blocking a plant’s enzyme system. The herbicide is absorbed through growing leaves and stems where it is translocated throughout the plant and root network. It kills virtually all annual and perennial weeds including grasses. Glyphosate is quickly broken down in soil or sediment and is harmless to animal life. Not all formulations containing Glyphosate are approved for use in or near watercourses under the Control of Pesticides Regulations 1986.

    If the Japanese Knotweed is sparsely distributed, use a 2,4-D amine preparation such as Dormone, which is specific to broadleaved plants and will not harm the grasses. It may take two or three years to completely kill the entire plant. More effective control can be achieved if Japanese Knotweed is cut or sprayed in early summer, then sprayed again in late summer, just before the winter dieback.

    More targeted methods of applying herbicides are being developed for sites where it is important to protect the native flora. This includes using a weed wiper to apply the herbicide directly to the leaves of the plant rather than spraying or injecting herbicide directly into the plant. This ensures that only target plants are treated.

    The plants should be treated between March and October when they are in the growing phase. Plants can take up to 6 weeks to show signs of die-back. There are two main groups of herbicides and the one you choose will depend on the site. The main recommended herbicides are:

    For environmentally sensitive habitats and those near water
    Glyphosate*
    2,4-D Amine*

    For habitats not near water
    Picloram
    Triclopyr
    Imazapyr

    * Not all herbicides containing these active ingredients are suitable for use in or near water. Use of herbicides in or near water requires consultation with the Environment Agency.

    There are detailed fact files on these products in The Japanese Knotweed Manual by Lois Child and Max Wade. You can also telephone Environment Agency’s Ecological Appraisal Team for Devon on 08708 506 506 for further information and advice on aquatic situations. Specialist contractors can also advise.

    Non-Chemical Treatment

    Cutting, Mowing or Pulling

    Regular pulling will, after a number of years, eventually exhaust the rhizome and kill the plant. This is only an effective method of control if it is carried out continually over a number of years and is only effective on small or newly established stands. Cutting and mowing can be used to prevent spread, to reduce vigour and to reduce underground biomass and are useful to use before applying herbicide but not as the sole control method. With all these methods the main problem is the safe disposal of the cut or pulled stems to prevent spread.

    It is important that all cut or pulled stems of Japanese Knotweed are kept on site, or disposed of in a licensed landfill site that can carry out deep burial (by prior arrangement). Burning of fresh growing material has little effect on the plant.

    Cutting – can be carried out with loppers, cutters, hooks, scythes, bladed cutters such as those with a metal circular blade or strimmers with a metal blade. Do not use bladed cutting equipment such as brush cutters or strimmers near a watercourse (even ditches) as fragments of Knotweed could enter the water and spread downstream. Cut material should be collected up, then dried out and burnt on site or removed and taken to a licensed landfill site. Ensure workers use protective clothing and face visor and they clean equipment before leaving the site and to avoid leaving fragments of Knotweed spread around the site.

    Studies have shown that with four cuts a year the plant loses vigour and underground biomass. The first cut should be carried out when the first shoots appear and the last cut should be done when the plant is at its most luxuriant in late summer but before it dies back in the autumn (September/October). Annual cutting will be required.

    Cutting can also be used to reduce plant height before chemical treatment. Allow a re-growth of 2-3 ft before spraying to be most effective.

    You should monitor the extent of the Knotweed stand to make sure it is not spreading sideways as there is evidence that cutting can cause the rhizome to spread laterally.

    Regular (fortnightly) mowing in parks, gardens and on road verges is a good way of controlling the growth of Japanese Knotweed, however, if mowing is stopped then the plant can take over the site again. It is not known how long the rhizomes persist in the soil. Avoid using a flail mower as this may result in small, viable fragments of stem regenerating in neighbouring, non-infested areas. It is preferable to use a mower with a collecting box for Knotweed areas. Mowings should be collected up and left on site. Compost should be checked for re-growth.

    Pulling as a method of eradication is only really useful when treating small or new infestations where only a few stems have established. It is an excellent method to use on sites with native or sensitive species growing and where the use of herbicides is undesirable (e.g. on wildlife sites or riverbanks) as it specifically targets Knotweed plants. Care should, however, be taken to avoid trampling valuable flora in the vicinity.

    Stems should be pulled regularly when they reach full height. They should be pulled near the base to include some rhizome. Control of a small infestation could be achieved in 3 years but this method requires regular, sustained treatment to work.

    You must ensure that pulled stems are disposed of correctly to avoid spread.

    Grazing

    Japanese Knotweed is used as animal fodder in the Far East and here in Britain it is known that cattle, sheep, horses, donkeys and goats graze the plant. Animals prefer the young shoots as they emerge in the spring and after about June the stems become rather woody. Grazing may reduce shoot densities and height but will not eradicate it. Although grazing can help reduce the spread into uninfested areas it is not a method of control. Dead stems should be cut back in winter as these can deter grazing in the spring. Continued grazing will ensure the supply of new shoots throughout the growing season.

    Grazing is therefore not an eradication tool but is helpful in suppressing the plant and reducing spread.

    Biological Control

    There is scope for the introduction of insects or fungi from the original native areas of Japanese Knotweed that could help manage the plant but this control method would have to undergo extensive trials and will not be available for some years.

    Summary of non-chemical control methods:

    1. Removal of dead stems Cutting with loppers, cutter, hook or scythe Winter Annually
    2. Preparation of site prior to chemical treatment Cutting with loppers, cutter, hook or scythe. Allow 2-3 ft of re-growth before spraying March – October Annually
    3. Preventing invasion of an adjacent stand of Japanese Knotweed into amenity grassland Mowing or grazing Throughout the growing season (March – October) Mow every 2 weeks. Allow livestock to graze throughout the growing season
    4. Reducing the vigour of the plant Cutting or mowing March – October Four times a year
    5. Removing individual stems of Japanese Knotweed in mixed vegetation Pulling All year As new shoots appear
    6. Reducing plant height prior to chemical treatment Cutting March – August
    7. Allow regrowth to attain a height of 0.5 – 1.0 m (2-3 ft) before application of herbicide As required

    (from The Japanese Knotweed Manual)
    Note: Digging of established Japanese Knotweed stands will lead to a significant increase in stem density. The cut rhizome is capable of regenerating, even small fragments are capable of producing a new plant.

    Methods of Knotweed control case studies

    Below is a list of case studies underlining some of the different approaches to Japanese knotweed control. These programmes have been undertaken in Devon by members of the Devon Knotweed Forum.

    Knotweed control in gardens – Bicton College Gardens:

    Japanese knotweed original stand at Bicton gardens

    Bicton College has extensive grounds and gardens which are open to the public. Within the grounds there are three stands of Japanese knotweed which are probably the remains of deliberate planting in the past when it was regarded as an attractive exotic species.

    Control of the Japanese knotweed has been focused on one particular stand which was threatening to move across a ha-ha wall into adjacent farmland. If this had been allowed to progress it may have also damaged the historic wall itself. Because the knotweed was located away from other desirable plants the stand was sprayed with Glyphosate. The plant was first sprayed when it had grown to between 1.2 and 1.5 metres tall, then the treatment was repeated ten days later. The stand was then left for the rest of the growing season until the leaves were about to turn brown. The Japanese Knotweed original stand Bicton Gardens this stage the plant was then sprayed again, with a repeat spraying ten days later.

    The stand has now been reduced to a few individual stems which will continue to be treated in subsequent years. As the stand has been sufficiently reduced, stem injection becomes a more attractive action.

    Community involvement in knotweed control – Lee, North Devon:

    Original knotweed stand at Lee, Devon Japanese knotweed removal can benefit from a concerted effort from local landowners meaning community projects can be very successful. The project in Lee has treated 23 sites in the area involving 18 different landowners and demonstrates the community principal.

    The project for Lee and Lincombe originated with a public meeting identifying the spread of knotweed as a significant problem. A steering committee was established and the Environment Agency was consulted. As knotweed treatment by professional contractors can be very costly the committee decided that they would organise a treatment programme themselves. A training programme was established to promote skills within the local community which resulted in six people gaining the necessary qualifications to undertake chemical treatment work. Gaining the trust of local landowners was also vital as it allowed for widespread take-up of the programme. Free knotweed treatment was offered but many made a donation to augment funding from North Devon District Council and North Devon AONB. These sources paid for training, equipment and the chemical needed to undertake the work.

    Knotweed growing along a river Depending on the nature of the Japanese knotweed stand, a variety of control methods have been implemented including cutting and burning, spot and knapsack spraying, weed wiping and stem injection. Some key lessons have been learnt:

    • Engage with the whole community to develop trust.
    • Involve and communicate with the community throughout the programme.
    • Persuade landowners to sign agreements committing them to the knotweed initiative as this provides certainty when planning how to progress the programme.
    • Engage with the Environment Agency

    Multi-agency knotweed control – The Exmoor Knotweed Control Project

    The Exmoor Knotweed Control Project is a collaboration between the Environment Agency, English Nature, The National Trust and Exmoor National Park Authority, supported by both Devon and Somerset Highways Authorities. The overall aim of the project which began in 2000 is to control and eventually eradicate knotweed (Japanese, Himalayan, giant, and associated hybrid species) from within the National Park and its associated river catchments. There are currently over 680 known knotweed sites on Exmoor, covering a total area of over 8000m². The plant is found in a range of locations and habitats, including riverbanks, hedges, roadside verges, and gardens.

    The details of known knotweed sites are reported, recorded and mapped. The landowner is then contacted to determine if they would like the site to be treated as part of the Project. The site is surveyed and where the knotweed is growing on or near a watercourse, the Environment Agency is contacted on behalf of the landowner to obtain consent to carry out treatment with herbicides. Summer survey work initially concentrated on the Lyn and Heddon river catchments, but over the last few years it has been extended to cover the whole of the National Park.

    Currently the most effective method of control is repeated spraying with herbicides over a number of years, which gradually reduces the vigour of the plant. With funding from the project partners, a qualified contractor is employed to carry out a programme of herbicide spraying. Many sites have now greatly reduced in size and vigour but are still treated every year to prevent re-growth or spread

    If you have Japanese Knotweed don’t forget to send records to Devon Biodiversity Records Centre using the on-line recording form. Please note the Devon Biodiversity Records Centre is not responsible for controlling Japanese Knotweed.

  • Knotweed Forum

    Knotweed logo The Devon Knotweed Forum is an alliance of organizations in Devon with an active interest in the co-ordinated control of Japanese Knotweed, its hybrids and other invasive Knotweeds in Devon.

    Aims and Objectives

    The aim of the Forum is to raise awareness of the problems caused by Japanese Knotweed, share information about control and increase recording.

    The Objectives of the Forum:

    • To assess the true scale of the problem, the costs and implications of Japanese Knotweed infestations in Devon and to disseminate this information widely.
    • To identify centres of best practice for the control of Japanese Knotweed.
    • To develop, evaluate and disseminate information about innovative and successful approaches to the management of Japanese Knotweed.
    • To prevent the further spread of Japanese Knotweed through education, legislation and good practice.
    • To encourage the eradication of Japanese Knotweed and its hybrids through co-ordinated control.
    • To work in partnership with the Cornwall Knotweed Forum and other groups and organizations.

    Organisations involved

    The Knotweed Forum is made up of over 40 organisations including local authorities, countryside and conservation groups, utility and transport operators and developers. The forum is currently chaired by representatives from Devon County Council and the Environment Agency.

    If you want to join the Forum then email nature@devon.gov.uk

    Contacts

    For advice on chemical treatment of knotweed near watercourses, or on the safe disposal of knotweed material, please contact the Environment Agency via their National Customer Contact Centre tel: 08708 506506

  • Advice for Landowners and Gardeners

    As a landowner, gardener, riparian owner or wildlife site manager it is important to be aware of Japanese Knotweed and, if you have it on your site, to control it.

    Japanese knotweed next to a footpath Japanese Knotweed on a river bank Japanese Knotweed on a derelict site

    Advice for Landowners
    Japanese Knotweed is one of Britain’s most invasive plants and the prevention of its spread is a legal obligation for landowners under the Wildlife and Countryside Act 1981. It is difficult and expensive to manage but non-intervention is not really an option. Early treatment of a new colony is quicker, cheaper and preferable to leaving it to become established.

    If you have Japanese Knotweed on your site(s) it important that you devise a strategy to treat and control it. When devising an action plan for Knotweed treatment you should consider the following:

    • Areas of nature conservation value.
    • Areas identified for landscape improvement work.
    • Areas of amenity interest.
    • Areas which are causing rapid spread of Knotweed onto new sites e.g. stream and river banks.
    • Areas where funding opportunities can be used to include Knotweed treatment.
    • Sites where Knotweed is causing a problem for others e.g. damage to property, spreading into private gardens etc.
    • Areas where the presence of Knotweed is a visual eyesore.
    • Sites where resources are available for long-term maintenance.
    • Sites where Knotweed is creating a safety hazard.
    • Sites which are the subject of significant complaints from the public.
    • Seek funding to assist in a programme of Knotweed control Where appropriate, land holding committees should be asked to consider allocating an annual budget for treatment of Knotweed on their land.

    Where appropriate, provision for control of Knotweed should be included in estimates for major landscaping and engineering schemes.

    Explore sources of funding e.g. grant aid, industrial sponsorship.
    Develop a strategy for responsible treatment of knotweed Identify sites with Japanese Knotweed.

    Prepare a control programme for each site.

    Ensure relevant specifications are used in contract documents for building, engineering, landscaping etc. to prevent spread.

    Ensure an appropriate control/eradication method is used for each site.
    Carry out treatment of Knotweed on sites already managed by your organisation Establish whose responsibility it is to supervise and implement treatment of Knotweed.

    Ensure staff/contractors hold a Certificate of Competence to use herbicides.
    Develop the direct provision of manpower for the treatment of Knotweed Establish a good skills base within the staff or establish working relationships with reputable contractors.
    Develop monitoring schemes to record effectiveness of Knotweed control programmes Monitor all sites where Knotweed control is carried out on your site(s)

    Transfer data to Devon Biodiversity Records Centre.

    Share experiences with the Devon Knotweed Forum and other Agencies.
    Develop a strategy for the treatment or disposal of soil contaminated with Knotweed and cut Knotweed stems or crowns. Establish an area for the controlled disposal of Knotweed contaminated soil which could then be treated over a 3 year period.

    Establish an area for the controlled dumping of cut Knotweed stems for composting or drying for burning. This could be an area already contaminated with Knotweed. Regular checks should be made to ensure there is no re-growth and appropriate treatment should be used.
    Ensure all relevant staff are aware of the problems of Japanese Knotweed and what the strategy is for controlling it on site(s). Staff awareness training includes identification, relevant legislation, preventing spread, who to notify if Knotweed is found, Knotweed control, who is responsible for what.
    Advice for Riparian owners
    Japanese Knotweed thrives on riverbanks and can easily spread downstream if the bank erodes and fragments of rhizome, crown or stem break away. Treatment options are more limited because of the need to prevent pollution of watercourses. You will need to consult the Environment Agency before using herbicide. Telephone the Ecological Appraisal Team for Devon on 0370 850 6506, or email enquiries@environment-agency.gov.uk. You can also use the plant tracker website to report all invasive plants to the Environment Agency to help them map and monitor the spread of these species.

    Japanese Knotweed also causes other problems for riparian owners including:

    • Dense stands impede access for anglers and walkers along river banks.
    • Riverbank inspection is made more difficult in summer.
    • River bank maintenance costs are greatly increased.
    • Maintenance can lead to further spread by allowing distribution of plant fragments.
    • Rapidly growing rhizomes and shoots can affect the integrity of flood defence structures.
    • Damage to flood prevention structures is expensive to repair and is ongoing unless the plant is controlled.
    • Bare soil exposed in the winter can cause increased soil erosion, especially on steep river banks.
    • Decaying plant material in the winter can be washed down river and create blockage and risk of flooding.
    • Dense stands on bank sides can impede flow in times of flooding thus exacerbating flooding.
    • As a riparian owner your non-chemical treatment options are cutting, pulling or grazing. Although these are
    • labour intensive, long-term options they are preferable. However, extra care should be taken to prevent
    • Knotweed fragments entering the river and causing spread downstream. Avoid using machinery that cuts up and scatters plant fragments.

    If these mechanical treatments are impracticable due to factors such as terrain then chemical control is your next option.

    For operations involving chemical treatment in or near watercourses you are required to obtain the written approval from the Environment Agency.

    The Environment Agency can assess whether there is any risk to drinking water supplies, water for spray irrigation, or wildlife. The European Commission sets stringent standards for the amount of herbicides and pesticides allowed in drinking water and the Environment Agency is responsible for making sure the risk of contamination is minimized.

    Ensure staff or contractors have a Certificate of Competence to use herbicides in or near water (Environment Agency can advise).

    Remember: any work carried out near water is potentially dangerous.

    If you suspect you have Japanese Knotweed on your property you should take care not to allow it to spread. Even the smallest piece of rhizome, stem or crown can potentially form a new plant. Compost Japanese Knotweed separately, preferably on strong plastic sheeting so it is not in contact with the ground. Check the compost regularly to ensure it is not sprouting. Ensure that it is fully decomposed before spreading it on the garden. Do not shred or strim the plant as this could cause rapid spread. Mowing is only advised if you have a collecting box for mowings which can then be composted. Do not dig Japanese Knotweed as this is known to increase stem density and it encourages sprouting and spread.

    Hand pulling or cutting the plant is a good method of control but will take several years for the rhizome to be exhausted and die. Leave the material on a plastic sheet to dry and then burn it. Do this on site to prevent spread. The cutting and pulling of stems encourages the plant to send up more shoots which can in turn be pulled.

    You can also use chemical herbicides, glyphosate is recommended but treatment will need to be ongoing and may take several years depending on how established the colony is.

    Avoid digging within 7 meters of a colony of Japanese Knotweed, and avoid moving the soil around the garden as the soil could contain rhizome.

    Do not take Japanese Knotweed material to your local recycling centre, Japanese Knotweed has to be treated as ‘controlled waste’. Do not remove Japanese Knotweed material from the site unless you have made a prior arrangement with a licensed landfill site for deep burial. Treatment on site is the preferred option.

    Advice for Wildlife Site Managers

    Japanese Knotweed is a highly invasive alien plant species which, if allowed to establish, will out-compete native flora and reduce the wildlife value of a site. Early treatment of a colony is advisable before it becomes established as large stands are particularly difficult to eradicate. You also have a legal obligation to prevent its spread under the Wildlife and Countryside Act 1981.

    If Japanese Knotweed is found on a wildlife site it is important to plan and commence a control programme as soon as possible. The treatment of this plant can be long-term and expensive but ignoring it is not an option as it is highly invasive. It will continue to spread if left alone. Japanese Knotweed is also capable of sprouting from cut rhizome or stem so the safe disposal of the plant material is vital to prevent spread.

    The choice of treatment is limited on wildlife sites as your objective is to help prevent damage to the site, loss of native flora and loss of wildlife value. The use of herbicides is always an option and there are specific brands of systemic herbicides that can be wiped onto the plant’s leaves to specifically target only the plants you want to eradicate.

    If your site is near a watercourse you will need to consult the Environment Agency before using herbicide. Telephone the Ecological Appraisal Team for Devon on 08708 506 506.

    See Advice for Riparian Owners (above)

    There are two main non-herbicide treatment options to consider:

    Pulling
    As a method of control is only really useful when treating small or new infestations where only a few stems have established. It is an excellent method to use on sites with native or sensitive species growing and where the use of herbicides is undesirable as it specifically targets Knotweed plants. Care should, however, be taken to avoid trampling valuable flora in the vicinity.

    Stems should be pulled regularly when they reach full height. They should be pulled near the base to include some rhizome. Control of a small infestation could be achieved in 3 years but this method requires regular, sustained treatment to work. This is labour-intensive but an ideal activity for volunteer work days.

    You must ensure that pulled stems are disposed of correctly to avoid spread.

    Grazing
    Japanese Knotweed is used as animal fodder in the Far East and here in Britain it is known that cattle, sheep, horses, donkeys and goats graze the plant. Animals prefer the young shoots as they emerge in the spring and after about June the stems become rather woody. Grazing may reduce shoot densities and height but will not eradicate it. Although grazing can help reduce the spread into uninfested areas it is not a method of control. Dead stems should be cut back in winter as these can deter grazing in the spring. Continued grazing will ensure the supply of new shoots throughout the growing season.

    Grazing is therefore not an eradication tool but is helpful in suppressing the plant and reducing spread.

    Herbicide treatment
    For operations involving chemical treatment in or near watercourses you are required to obtain the written approval from the Environment Agency.

    This is not an easy option and the use of herbicides is still a labour-intensive and expensive operation. Dense stands of Japanese Knotweed can be treated with a glyphosate-based herbicide, such as ‘Roundup Pro Biactive’. If the Japanese Knotweed is sparsely distributed, use 2,4-D amine, which is specific to broadleaved plants and will not harm the grasses. It may take two or three years to fully control the plant. More effective control can be achieved if Japanese Knotweed is cut and sprayed in early summer, then sprayed again in late summer, just before the winter dieback.

    More targeted methods of applying herbicides are being developed for sites where it is important to protect the native flora, this includes using a weed wiper or herbicide glove to apply the herbicide directly to the leaves of the plant, or direct injection, rather than spraying.

    The plants should be treated between March and October when they are in the growing phase, the late summer is the best time. Plants can take up to 6 weeks to show signs of die-back.

    For more information on chemical treatment see Control of Knotweed / Chemical Treatment

    Further reading:
    ‘Guidance for the control of invasive plants near watercourses’, available from the Environment Agency

    Child, L.E. and Wade, P.M., The Japanese Knotweed Manual, Packard Publishing Limited, Chichester, 2000, 123 pp, ISBN 1085341-127-2.

    Without surveying and recording the distribution of Japanese Knotweed there is no way of knowing where it occurs, whether it is increasing and the typical habitats it colonises. Knowing the full extent of the problem of Japanese Knotweed colonisation in the county will help the Devon Knotweed Forum identify priorities for control and management. It is therefore important to report any sightings of the plant in the county to the Devon Biodiversity Records Centre. If you have a colony of Japanese knotweed please inform the Devon Biodiversity Records Centre to keep us up to date by filling in their form. Please note the Devon Biodiversity Records Centre is not responsible for controlling Japanese Knotweed

  • Advice for Developers and Hauliers

    This section gives specific advice on what to do if you have Japanese Knotweed on a development site including: formulating a plan of action, reducing the risks of spreading the plant, your legal obligations, treatment options and disposal.

    NB: The Devon Knotweed Forum provides this information in good faith and cannot be held responsible for the efficacy of the treatments described, or any damage to persons, property or the environment that arises from interpretation of the advice given.

    Development Sites

    Japanese Knotweed has the potential to be a serious problem for developers due to its persistent nature and the need to comply with the law. To help prevent the possibility of breaking the law and incurring large fines it is important that you address the problem of Japanese Knotweed if it is present on site. Early identification of contaminated areas is essential. Plans must be prepared to contain, control and remove Japanese Knotweed with clear methods of working to prevent its spread.

    Japanese Knotweed and the Law

    The following advice should be helpful:

    It is important to identify Japanese Knotweed as early as possible. A site survey can be carried out by an Environmental Consultant (look in Yellow Pages). This will help reduce the costs in the long run.
    Discuss and agree treatment proposals with the Environment Agency if the site is near a water course (Ecological Appraisal Team for Devon 0370 850 6506).
    The works and treatment of Knotweed should be supervised and monitored by experts and ongoing survey work should be carried out. Do not break the law by allowing contaminated material to be moved off site which could result in the spread of Japanese Knotweed. Knotweed material is classified as controlled waste and should be disposed of appropriately (for advice call the Environment Agency’s Environment Management Team for Devon on 08708 506 506).
    Don’t allow Japanese Knotweed to spread into neighbouring sites or to spread onto other sites by re-using soil. You will be liable to third party liability claims.
    The following is an extract from the Environment Agency’s Code of Practice:

    What to do when working in an area where Japanese Knotweed is present?

    Japanese Knotweed contaminated areas should be clearly marked out on site. Areas that do not need to be disturbed during the works should be fenced off, allowing a buffer of at least 7 meters (from the edge of a colony) to allow for the likely extent of the rhizomes.
    Use of tracked machinery should be limited until areas contaminated with Japanese Knotweed have been cleared and/or identified and cordoned off.
    If tracked machinery must be used in areas where Japanese Knotweed is known to be present, then consider using a strong geotextile overlain with hardcore as a base for vehicles to travel on.
    Areas where Japanese Knotweed has been identified should be cleared slowly, one at a time with ongoing assessment of the extent of contaminated ground. Only essential vehicles should be present in areas contaminated with Japanese Knotweed.
    Never stockpile potentially contaminated material within 10 metres of a watercourse.
    On leaving areas of the site known to contain Japanese Knotweed, any tracked machinery that has been used should be thoroughly cleaned within a designated area. This area should be as close as possible to the contaminated area on which the machinery has been working to avoid the spread of Knotweed. This area should be monitored in the spring for Knotweed growth and a spraying programme implemented if necessary. Any machinery used in clearing contaminated areas should be similarly cleaned.
    Care should be taken to ensure that contaminated material is not dropped or transferred to other areas of the site.
    Japanese Knotweed contaminated spoil should only be placed on top of a fabric/membrane in an approved, fenced area. Once the contaminated material is removed from these areas, it should be monitored for regrowth, particularly during the growing season and, if necessary, treated with an appropriate herbicide.
    All site operatives should be made aware of the requirements associated with the removal/disposal of Knotweed in order to help limit accidental spread.
    All haulage lorries or dumpers carrying Japanese Knotweed contaminated material should be covered.
    Never use a strimmer, mower (without collection bucket) or chipper on Japanese Knotweed material.
    If you are working between November and March in an area where Japanese Knotweed is known to be present, then dead shoots from the previous year can be a good indication of its location. In winter no growth is evident above ground but the below-ground parts of the plant will still be alive. Breaking up this root network and transporting either off site or around your site on vehicle tracks will spread the plant. Use the precautions outlined above to reduce the risk of spreading the plant.
    Any Japanese Knotweed contaminated soil or plant material that you discard, intend to discard or are required to discard is classed as ‘controlled waste’ and should be accompanied by appropriate Waste Transfer documentation.

    Japanese Knotweed should be disposed of in a licensed landfill site. Be sure that you notify your waste haulier that the waste to be removed contains Japanese Knotweed. You should also contact the landfill site several days before any material containing Japanese Knotweed is taken there to allow a suitable area to be prepared for its disposal. You have a Duty of Care to make sure that the waste is disposed of properly and there is an ongoing liability until it is.

    Control of Japanese Knotweed

    Although there are a number of options available for the treatment of Japanese Knotweed, the majority of these require a number of years in order to be effective. The two methods outlined below are the most effective in the time scales generally required by the construction industry.

    Spraying with Herbicide
    Spraying the plant with an appropriate herbicide is the most effective option available, however it can take several years and rarely achieves control without mechanical disturbance. Herbicide treatment can give the appearance of control but the rhizome network (roots below ground) may still be viable and disturbing the ground will cause the plant to regrow. Soil movement should not be attempted if any of the rhizome remains in a viable condition. Spraying can only be carried out during the growing season when there is green, leafy material present. Herbicide treatments take effect within a few weeks but control can take a minimum of two sprays in one growing season to achieve. Often, when a contractor takes control of a site, the working programme is tight and does not allow sufficient time for this method of control to be used. Even so, a spraying programme may be an option for weakening the plant before removal or treating regrowth and remaining plants in the spring. If spraying near a watercourse (even a ditch) then you need the consent of the Environment Agency. Anyone planning to spray a herbicide must be “competent in their duties and have received adequate instruction and guidance in the safe, efficient and humane use of pesticides.” This means that the person who will be undertaking the spraying must hold a Certificate of Competence for herbicide use or should work under the direct supervision of a certificate holder. A Certificate of Technical Competence can be obtained by attending a short course at an agricultural college or similar institution. Contact the National Proficiency Tests Council for more details. See Control of Knotweed / Chemical Treatment for general advice. If working near a watercourse see Advice for Riparian Owners.
    Digging and Spraying
    A quicker, but expensive, method of removing Japanese Knotweed involves the clearing of above ground leaf and stem material and the removal of ground material contaminated with rhizomes. The contaminated soil can be landfilled at a licenced landfill site as ‘controlled waste’ (see Advice for Hauliers above) or buried on site (see below). Soil to a depth of at least 3m with 7m around the perimeter of the Knotweed should be excavated for disposal. Care should be taken to ensure that all Japanese Knotweed rhizomes are removed – this is one situation where it pays to remove too much material. Even with great care, a certain amount of regrowth in the spring would be expected and this should be treated with an appropriate herbicide as discussed above. Make sure you prevent the spread of Knotweed fragments around the site during the works. Stems should be cut neatly near the base using cutter, hook or scythe. Cut material can be dried and burnt, however, any stems left for drying should be large enough to not be dispersed by wind or traffic and well away from a water course. Stems should ideally be dried with no contact with the soil (e.g. on plastic sheeting or wooden supporting material) and should be checked regularly for re-growth. Burnt Knotweed material should be disposed of by deep burial or landfilling.
    See Preventing Spread On-site burial is a good option for the material. Ideally at least one herbicide treatment will have been applied to reduce the vigour of the infective material. Digging should be as described above. Burial should be to a depth of at least 5m and the material should be covered with a geotextile layer or a heavy gauge polythene sheet prior to infilling. Ensure that the site is not dug up as Knotweed can lie dormant for many years, the burial site should be marked on a map and future owners should be notified of its presence. If on-site burial is not possible then the material will need to be disposed of at an approved landfill site and the haulier and landfill site operator should be informed that it is Knotweed contaminated material.
    Japanese Knotweed map

    Remember

    You must comply with the law
    Breaking the law will incur extra costs (potentially unlimited fines)
    Planning conditions could be imposed
    Treatment can be expensive
    Failure to treat Japanese Knotweed may result in eventual structural damage, especially to tarmac surfaces.
    Further Reading:

    Child, L.E. and Wade, P.M., The Japanese Knotweed Manual, Packard Publishing Limited, Chichester, 2000, 123 pp, ISBN 1085341-127-2.

    When working with landowners or developers it is important that you check that no Japanese Knotweed is included in any material you are removing. You could potentially be breaking the law and liable for a large fine by aiding the spread of this highly invasive plant. Consider developing a policy on what to do if Japanese Knotweed is found to be present in removed material.

    Japanese Knotweed and the Law
    Any Japanese Knotweed contaminated soil or plant material that you discard, intend to discard or are required to discard is classed as ‘controlled waste’ and should be accompanied by appropriate Waste Transfer documentation. You should not accept contaminated waste unless you can guarantee its appropriate disposal.

    Japanese Knotweed should be disposed of in a licensed landfill site (see below). Your client should inform you that the waste to be removed contains Japanese Knotweed. However, you should always check. You should contact the landfill site several days before any material containing Japanese Knotweed is taken there to allow a suitable area to be prepared for its disposal as it requires deep burial. You have a Duty of Care to make sure that the waste is disposed of properly and there is an ongoing liability until it is.

    Removal from Site

    Contaminated material should be removed from the site for disposal, unless otherwise agreed with the Environmental Regulator and client. As Japanese Knotweed is considered to be a contaminant, you can apply to Customs and Excise for a ‘Landfill Tax Exemption’ for contaminated soil.
    Any bags/skips containing Japanese Knotweed or contaminated soil leaving the site should be covered to avoid spread along public highways.
    Waste transfer documentation will be required for any contaminated material leaving the site.
    Check with the disposal site in advance that they can receive material containing Japanese Knotweed. Be aware, the disposal site may require notice to allow an area to be prepared for this material away from the landfill liner.

    Landfill sites in Devon that can receive Japanese Knotweed material:
    Heathfield Landfill Site
    John Acres Lane
    Kingsteignton
    Newton Abbot
    TQ12 3GP
    Tel: 01626 853522

    Broadpath Landfill
    Uffculm
    Devon
    EX15 3EP
    Tel: 01884 841288
    Fax: 01884 841548

    Viridor Waste Management run Heathfield and Broadpath Landfill sites.

    Viridor facilities in the South West
    Deep Moor Landfill Site
    High Bullen
    St Giles in the Wood
    Torrington
    North Devon
    EX38 7JA
    Tel: 01805 623496
    Takes small amounts of Knotweed material.

    Devon Waste Management run Deep Moor. Telephone Devon Waste Management on 01392 826444 to discuss your requirements.

    Devon Waste Management
    Contractors for Knotweed Control

  • Advice for Planners

    Advice for planners
    There is a legal obligation on developers not to allow the spread of Japanese Knotweed but planners also have a vital role in helping to prevent the spread of the plant by ensuring that developers are made aware of the invasive nature of the plant and their legal obligations to prevent its spread. Planners can ensure that the law is complied with and this can include requiring developers to implement a control programme if it is present on or near the site.

    Advice for planners

    To allow a co-ordinated approach to the control of Japanese Knotweed in Devon it would be desirable for Local Planning Authorities to have a specific policy within the Local Plan and the emerging Local Development Framework to ensure developers consider Japanese Knotweed and control it on site. Furthermore, planning conditions can be applied to planning permissions where Japanese Knotweed is found on site.

    Development Control Officers should check for the presence of Japanese Knotweed when considering planning applications. If you suspect that Japanese Knotweed is on a development site you should request a survey by an ecological surveyor. If its presence is confirmed then a control programme, suitable for that site, should be drawn up as part of the planning application and this should include the safe disposal of Knotweed material. Planning conditions to ensure that the control programme is carried out should be imposed.

    For more information visit:

    How to Identify Japanese Knotweed
    Japanese Knotweed and the Law
    Control of Knotweed
    Advice for Developers/Hauliers
    Contractors for Knotweed Control
    Planning conditions

    If Japanese Knotweed is known to exist on site or on a neighbouring site it is advisable to impose a planning condition to prevent spread of the plant which is an offence under the Wildlife and Countryside Act 1981. Soil can be contaminated with Knotweed rhizome up to 7m from the edge of a colony.

    Advice to be given to all applicants within known Knotweed zones:

    Japanese Knotweed has been reported on or near this site. It is a highly invasive weed that is capable of structural damage. Disturbance will cause it to spread and its movement is controlled by legislation. Under the Wildlife and Countryside Act 1981 it is illegal to cause it to spread in the wild. You are strongly advised to survey the site for the presence of Japanese Knotweed at an early stage and before any site clearance work and, if found, to formulate plans to control or eradicated it. Please note that Japanese Knotweed can be far more extensive than the visible parts on the surface and that the underground parts of the plants may extend laterally up to 7 meters beyond this. Knotweed in adjoining land may affect the site and should be noted and considered. Detailed advice is given in this Devon Knotweed website

    Here is an example of a planning condition which you could impose if Knotweed is confirmed on or adjoining the site:

    Before any works are undertaken, the site must be surveyed* for the presence of Japanese Knotweed and a copy of this survey sent to the Local Planning Authority. Please note that Japanese Knotweed can be far more extensive than the visible parts on the surface and that the underground parts of the plant may extend laterally up to 7 metres beyond this. Therefore, this survey must also note any knotweed adjoining the site. If Japanese Knotweed is confirmed, full details of a scheme for its eradication and/or control shall be submitted to and approved by the Local Planning Authority prior to the commencement of work on site, and the approved scheme shall be implemented prior to the commencement of the use of the building(s).

    *by an approved environmental consultant

    Further Reading:

    Child, L.E. and Wade, P.M., The Japanese Knotweed Manual, Packard Publishing Limited, Chichester, 2000, 123 pp, ISBN 1085341-127-2.

  • Hybrids and related species

    Giant Knotweed (Fallopia sachalinensis) occurs in Devon. Both the leaves and the stems are much larger than Japanese Knotweed with stands growing to 5 metres (Japanese Knotweed grows to 3 metres). The undersides of the leaves have scattered stiff hairs.

    Himalayan Knotweed (Polygonum polystachum) also occurs in Devon, it has slightly hairy stems, the leaves are narrower and stands are not as tall as Japanese Knotweed, growing to around 1.8 metres.

    There is also a hybrid between Japanese Knotweed and Giant Knotweed called Fallopia x bohemica which occurs in Devon. This hybrid is particularly worrying as it may be capable of producing viable seed. Stands grow to 2.5 – 4 metres. Leaves are intermediate between Japanese and Giant Knotweed and have scattered stiff hairs on the undersides.

    There are other recorded hybrids and the resulting plants have a combination of characteristics making identification ambiguous.

    Stand of Giant knotweed
    Giant knotweed – this man is 6ft 4″!

    Himalayan knotweed stand and close up leaves
    Himalayan knotweed stand

     

     

     

     

     

  • Contractors for Knotweed control

    Listed below are knotweed contractors and consultants operating in Devon. They offer specialist knotweed control services; however, other weed control contractors can be located through trade or business directories

    Reputable contractors should be Amenity Assured, BACCS registered and have a warranty backed insurance. The Amenity Assured scheme involves three totally independent and separate audits being carried out annually on each contractor, including an unannounced on-site assessment, a full audit of a contractor’s premises, records and certification and an end-of-season check with clients to ensure treatments have been successfully completed. Contractors should be contacted before employment to ensure that they meet these criteria.

    a list of knotweed control contractors and consultants

    Disclaimer

    This list has been made available by the Council for information purposes only. The Council makes no representation, endorsement or warranty of any kind as to the standard or competence of any person listed above, or the accuracy of the information provided. Any arrangement for works to be carried out with any person or company listed will be an agreement between you and that person. In no event shall the Council be liable for any loss or damage, including indirect consequential loss or damage, arising out of any use of the list or any goods, works or services provided by any person on this list.

    Contact nature@devon.gov.uk for more information on the list of contractors

  • Recording Knotweed in Devon

    Without surveying and recording the distribution of Japanese Knotweed there is no way of knowing where it occurs, whether it is increasing and the typical habitats it colonises. Knowing the full extent of the problem of Japanese Knotweed colonisation in the county will help the Devon Knotweed Forum identify priorities for control and management. It is therefore important to report any sightings of the plant in the county to the Devon Biodiversity Records Centre. Please note the Devon Biodiversity Records Centre are not responsible for controlling Japanese Knotweed and do not provide general advice on Japanese Knotweed.

Japanese Knotweed Downloadable Information Booklet