Medway Council. Greenspace Services. Control of Invasive Plant Policy. Japanese Knotweed

Transcription

1 Medway Council Greenspace Services Control of Invasive Plant Policy Japanese Knotweed Prepared by Reviewed by Next Revision Alan Darlington, Simon Catchpole (External) Alan Darlington Rob Lucas, Colinda LeGall April 2011 October 2012 April 2014 October 2015

2 Table of Contents 1 Introduction 1.1 Map and Description 1.2 Medway Council Management Objectives 1.3 Limitations and Threats to Management Objectives 2 Introduction to Japanese Knotweed 2.1 The History 2.2 The Plant 2.3 The Identification 2.4 The Problem 2.5 The Method of Spread 2.6 The Prevention of Spread 3 Management Plan 3.1 Description of Management Plan 3.2 Setting Priorities 3.3 Preventing Further Spread 4 Specific Control for Japanese Knotweed 4.1 Control Plan 4.2 Control Options 4.3 Action Plans 4.4 Evaluation of Plans 4.5 Results of Evaluation 4.6 Resources 5 Summary Information Table 1: Example of Priority Table 2: Example of Control Methods Table 3: Example of Implementation Schedule Table 4: Example of Projected Resources and Costs 6 Legislation, Codes of Practices and Other Required Reference

3 1 Introduction 1.1 Map and Description Medway is a unitary authority in South East England. The Unitary Authority was formed in 1998 when the City of Rochester-upon-Medway amalgamated with Gillingham Borough Council and part of Kent County Council to form Medway Council, a unitary authority independent of Kent County Council, though still within the County of Kent. It is colloquially known as The Medway Towns (Strood, Rochester, Chatham, Gillingham, and Rainham). Over half of the unitary authority area is rural in nature and includes parts of the North Kent Marshes, an environmentally significant wetlands region, with several Sites of Special Scientific Interest (SSSI's). Other similar areas of conservation include Ranscombe Farm, on chalk grassland and woodland between Strood and Cuxton, with rare woodland flowers and orchids present. 1.2 Medway Council Management Objectives The responsibility for the control of Japanese Knotweed sits with the landowner where the plant is situated. Medway Council is responsible for controlling Japanese Knotweed on areas of land within its ownership. Ownership of property within the Medway Council estate is controlled by several internal departments, Greenspace Services provide an advisory service to all departments on the management of Japanese Knotweed and if requested will engage and supervise a duly appointed specialist Contractor.

4 The aim of this policy is to create a framework through which any areas reported within Medway Council ownership as being contaminated with Japanese Knotweed can be investigated and dealt with, following an agreed format and procedure. The purpose of the investigation will be: To determine whether the plant reported is Japanese Knotweed and whether it is situated on either Medway Council land or land it does not own. On Land Not Within Medway Council Ownership If the reported Japanese Knotweed is identified and situated on land not owned by Medway Council it will, as far as is reasonable practical, inform the landowner and advise on the most appropriate action. On Medway Council Land Determine the exact location of reported Japanese Knotweed identified and provide a detailed map for the distribution to the appointed Contractor. Determine the extent of the contamination, and prioritise its treatment. Where required contain the area of contamination to minimise risk of spread. To prevent aerial growth from which new rhizome systems may develop by the timely application of herbicide. Determine regular monitoring periods. Engage appointed Contractor. 1.3 Limitations and Threats to Management Objectives The presence of Japanese Knotweed on sites within Medway will increase the financial burden on the Council in terms of the cost of treating the problem. If left untreated the problem will not go away and, should the Council not be able to provide the necessary finance to treat the sites of contamination, the future costs will be exponentially higher than if a treatment problem be adopted in the short term. The presence of Japanese Knotweed on any sites of public access will eventually make the area unusable without significant risks of spreading the contamination. 2 Introduction to Japanese Knotweed 2.1 The History Japanese Knotweed is an invasive non-native species having been brought to Britain during the Victorian era as an ornamental garden plant. This original plant was first at Kew Gardens from there it was distributed into the gardens of large properties. This original plant was female and all of the Japanese Knotweed in this country is a direct descendant of this original plant. As a result all Japanese Knotweed plants in this country are female, as such it cannot reproduce from the seeds that are produced in late summer/early autumn, as they usually remain sterile.

5 2.2 The Plant Japanese Knotweed has a vigorous growth that can damage buildings, paths, hard surfaces, block waterways, as well as causing problems for native wildlife due to its aggressive growth. Japanese Knotweed has a subterranean rhizome network that extends typically some three metres deep into the soil and can extend laterally for many metres beyond the top growth. Japanese Knotweed starts to grow in early spring with the first shoots developing quickly. It can grow a number of centimetres a day before reaching a typical height of three metres. The leaves are a lush green with a slightly paler underside and the stems are similar to bamboo in appearance. In late summer the plant produces flowers at the top of each stem, which are white in colour and made up of many tiny petals. At the end of the autumn the stems dry out completely giving the appearance that the plant is dead. These stems remain if left undisturbed and disintegrate slowly throughout the following season when the new growth resumes. Japanese Knotweed is not listed in the Weeds Act of 1959 and therefore is not 'notifiable' so there is no need to report its presence on your land. Medway Council has no responsibility for the control of Japanese Knotweed on private property or land that it does not own. 2.3 The Identification Japanese Knotweed typically starts growing in March, emerging as rapidly growing soft red/purple shoots similar to asparagus spears. As the shoots grow into canes the leaves unfurl and the plant turns green. The stems are hollow and bamboo like. Each stem is capable of growing several inches a day. Even tiny amounts of cut or broken stem, crown or rhizome are capable of producing a new plant. Rhizomes are capable of growing in volcanic soil. To be certain that vegetation is non viable it must be fully incinerated or dried such that no moisture exists within the flesh of the plant As little as 0.7g of rhizome can re-generate into a new plant. Activities such as strimming or pulling will cause it to spread. Contaminated material is classed as hazardous waste, and if taken off site can only be moved by qualified hauliers to licensed landfill sites. Comprehensive planning and supervision is required to ensure that containment is absolute for such projects. New shoots can emerge from any part of the rhizome system in the spring. A 1m 2 stand of Japanese Knotweed is capable of producing more than 200 new shoots.

6 The leaves are lush green in colour, with a slightly paler underside. Leaves are alternated in a zigzag pattern. As the stems grow they become hollow and have nodes from where the leaves grow, very much like Bamboo. The stems are speckled with In late summer the plant produces white flowers purple, and can be in excess at the top of each stem. of 2 inches in diameter when fully developed. Each flower is made up of many tiny petals. All plants in the UK are female, being direct descendants and biological copies of the original plant introduced by the Victorians. Many stems can grow from a single crown, and this creates a dark dense canopy preventing the growth of native species. In this country there are no natural predators such as those that regulate its growth in Japan. Recently, scientists have been experimenting with biological control techniques. Beetles, Caterpillars or Rust fungi may help to manage the problem in the future The spread of Japanese Knotweed is a serious threat to our countryside, and the native plants that rely upon it. 2.4 The Problem At the end of autumn the stems dry out completely, giving the appearance that the plant is dead. The stems remain and disintegrate slowly over the following two seasons Seeds are produced in September and October but are not viable. 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 shading of native vegetation Restriction of access to riverbanks for anglers, bank inspection and amenity use Reduction in land values and being an obstacle to mortgage applications

7 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 displeasing Expensive to treat The speed at which Japanese Knotweed has spread throughout Britain has been astonishing. The damage it has already caused to commercial and domestic sites is virtually unquantifiable and it is estimated that it occupies a site in every 10km² of England and Wales. The aggressive growth pattern is capable of exposing weaknesses in structures such as brick walls and foundations, tarmac and concrete. Soil and waste containing Japanese Knotweed is deemed to have the potential to cause ecological harm. Japanese Knotweed material is regarded as controlled waste and not disposing of it properly would be an offence under the Environmental Protection Act, Allowing the spread of Japanese Knotweed into the wild is also an offence under the Wildlife and Countryside Act The Method 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. 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 material. 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. Rhizomes grow rapidly underground and are largely responsible for the spread of the plant. 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 re-grow 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. 2.6 The Prevention of Spread

8 It is important that an effective programme of management of Japanese Knotweed 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 further colonisation. Materials 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. 3 Management Plan 3.1 Description of Management Plan The initial treatment will involve leaving the plant undisturbed for the spring allowing the Japanese Knotweed to draw as much nutrient resource as possible from the rhizome into the above ground parts of the plant. The appointed Contractor will then apply an approved herbicide employing a method of either foliar application or stem injection dependant on the site location and priority. The aim of the application is to maximise the amount of the active ingredients of the herbicide being drawn as deep as possible into the rhizome. In cases where it can be identified that there is a significant benefit to the likely efficacy of herbicide application, then earlier application may be employed. Examples of this could be sites where the plant is unable to mature due to repeated damage from external activity, or where fragments of previously disturbed rhizome, is producing stunted growth. In cases where the initial treatment has been when the vegetation has been allowed to mature, application would then need to be followed up by a programme of regular spray treatments, comprising of 3 treatments per year, for 4 to 5 years, applying an approved herbicide to the area of the established stand. This will provide the benefit of controlling all growth on the area, allowing the appointed Contractor to treat any new Japanese Knotweed growth as it occurs. Very few stems will appear in this period but, if they are not eliminated as they appear, the stand would very quickly regenerate to its original size. The appointed Contractor will inspect adjacent areas and spot treat any Japanese Knotweed that may appear within this period.

9 3.2 Setting Priorities Each site will be assigned a priority as follows: High Priority If the site is in an area of high passing traffic (pedestrian or otherwise), of if a number of broken or damaged canes / branches are observed during the site visit the area will be identified as high priority Medium Priority Should the area not show signs of broken of damaged stems, but some passing traffic is observed then that site will be identified as medium priority Low Priority An area will be identified as low priority if there is minimal passing traffic, thus reducing the potential spread of the contaminated area 3.2 Preventing Further Spread It is critical that the spread of Japanese Knotweed is controlled, as aside, from the legal implications there are significant potential costs in dealing with its distribution. The most likely cause of inadvertent spread is through soil movement, although it is very possible for new stands to propagate from broken stems. Early identification and isolation are the most effective means of limiting the spread of Japanese Knotweed. 4 Specific Control for Japanese Knotweed 4.1 Control Plans The individual requirements for each site will vary, as a result the appointed Contractor will submit a detailed site specific control plan for the treatment of the Japanese Knotweed which will be agreed with the Authorised Officer. 4.2 Control Options Potential control options are: 1 No treatment 2 Herbicide treatment 3 Excavation and removal off site 4 Excavation and burial on site 5 Excavation and stockpiling for future treatment 6 Combined treatment of herbicide application and digging Of the control options available: Option 1 no treatment is not a viable and does not meet Medway Council s objectives and duty of care liability.

10 Option 2 herbicide treatment can provide the required control but will need repeated application and a period of time for eradication. Option 3-6 is a rapid method of removal but is costly and in the long-term, unsustainable, especially where identified cases are sporadic and cover a wide area 4.3 Action Plans The actions planned will vary dependent upon the priority allocated to the sites, as outlined in section 4.2 above. The actions will be as follows: Priority High Priority Medium Low Immediate collection of broken and damaged stems Regular monitoring Application of herbicide Removal / storage of cut stems When the stems that are sufficiently large enough they will be treated by cutting the stem above a node and then injecting concentrated product into the hollow inter-nodal cavity through the cuticle. The remaining smaller shoots will then receive a foliar spray of approved herbicide. This normally reduces Japanese Knotweed by 60-80% on first spray, but requires repeated treatments over a minimum of 2 years for the herbicide to fully penetrate the rhizome in order to achieve an effective kill. Stems that are not of a size for stem injection will be treated by foliar application. All sites will be regularly monitored by the appointed Contractor and receive repeated followup treatments as necessary. 4.4 Evaluation of Plans The appointed Contractor will carry out monitoring with photographic evidence kept as a base line for future monitoring throughout the growing season and subsequent seasons. The appointed Contractor will record all visits and regularly update the Authorised Officer. The records will be retained for either the duration of the contract, or as long as legally required, whichever is the longer. This management plan will be reviewed by both the appointed Contractor and the Authorised Officer on a regular basis. 4.5 Results of Evaluation

11 The results of any individual treatment may not become apparent until the emergence or not of Japanese Knotweed during the following growth season in the year following herbicide application. Individual sites will be regularly monitored by the appointed Contractor with the findings being used to update the control plans and any subsequent priorities. 4.6 Resources All resources required for evaluation and application will be provided by the appointed Contractor. The resource requirement on a site-by-site basis will be evaluated as part of the implementation schedule. 5 Summary Information Table 1: Example of Priority Area Description and justifications of priority Priority Level Maidstone Road Japanese Knotweed overhanging road with high probability of pieces of Japanese Knotweed being damaged and spread further a field. High - 1 Table 2: Example of Control Methods Area Control method Carried out by Maidstone Road Immediate application of approved herbicide by foliar The appointed or stem injection as appropriate Contractor Table 3: Example of Implementation Schedule Schedule the planning, surveying and treatment for JKW for at least the next year. Treatment schedule - Maidstone Road (example) Date Received location from Council. Visit and confirm is JKW 1 May 2011 Application of An approved by stem injection urgently required 15 May 2011 Table 4: Example of Projected Resources and Costs This table to be updated annually after comparing estimated to actual costs. Description (example) Days required Projected Cost Actual Cost Initial visit to confirm JKW Initial application of An approved Follow-up visit # Follow up visit # Legislation, Codes of Practices and Other Required Reference

12 The Control measures outlined within this policy are not exhaustive and will comply with all relevant legislation and codes of practise. These may include: The Wildlife and Countryside Act 1981 The Environmental Protection Act 1990 The Town and Country Planning Act 1990 The Local Government Act 2000 The Environment Agency code of practice 2006 and 2013 for management, removal and disposal of Japanese Knotweed Health and Safety at Work Act 1974 Health and Safety First Aid Regulations 1981 Management of Health and Safety at Work Regulations 1999 Workplace (Health, Safety and Welfare) Regulations 1992 Provision and Use of Work Equipment Regulations 1998 Personal Protective Equipment at Work Regulations 1992 Manual Handling Operations Regulations 1992 Control of Substances Hazardous to Health Regulations 2002 Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013 Code of Practice for Using Plant Protection Products Code of Practice for Suppliers of Pesticides to Agriculture, Horticulture and Forestry Guidelines for the Use of Herbicides on Weeds in or Near Watercourses and Lakes The UK Pesticide Guide The appointed Contractor s Operating Manual Equipment manufacturer s handbook(s) The appointed Contractor s risk assessments for the work being carried out including any site-specific risk assessment