Japanese Knotweed Management Plan by Andrew McGuinness

Japanese Knotweed Management Plan Talbotâ&#x20AC;&#x2122;s Tower, Kilkenny [Dec, 2017]

Prepared by Envirico on behalf of Kilkenny County Council

www.envirico.com

Report Prepared by: Dr. Amanda Greer

Table of Contents 1. INTRODUCTION ................................................................................................... 2 1.1 Site Owner/Manager ..................................................................................... 2 1.2 Site Address: .................................................................................................. 2 1.3 Site GPS Co-Ordinates: .................................................................................. 2 1.4 Request to Prepare a Japanese Knotweed Management Plan (JKMP): ........ 2 1.5 Scope of Survey ............................................................................................. 2 1.6 Survey Limitations ......................................................................................... 2 2. ABOUT JAPANESE KNOTWEED ............................................................................ 3 3. LEGISLATION........................................................................................................ 4 3.1 Invasive Alien Species .................................................................................... 4 3.2 Japanese Knotweed Disposal ........................................................................ 5 3.3 Use of Herbicides (Chemical Treatment) ...................................................... 5 4. SURVEY FINDINGS ............................................................................................... 6 4.1 Site Description: ............................................................................................ 6 4.2 On-Site Presence of Japanese Knotweed ...................................................... 6 4.3 Off-Site Presence of Japanese Knotweed...................................................... 6 4.4 Site Access ..................................................................................................... 6 4.5 Previous Site Management ........................................................................... 7 4.6 Possible Source of Infestation ....................................................................... 7 4.7 Likely Sources of Reintroduction ................................................................... 7 4.8 Future Site Development .............................................................................. 7 5. JAPANESE KNOTWEED MANAGEMENT PLAN ..................................................... 8 5.1 Summary........................................................................................................ 8 5.2 Preparatory Works ........................................................................................ 8 5.3 Landscaping/Resurfacing Works ................................................................... 9 5.4 Herbicide Treatment ..................................................................................... 9 6. CODES OF PRACTICE/SOURCES OF INFORMATION FOR INVASIVE KNOTWEED SPECIES .................................................................................................................. 12 7. ABOUT ENVIRICO .............................................................................................. 13 8. TERMS AND CONDITIONS ................................................................................. 14 APPENDIX I – Site Map .......................................................................................... 15 APPENDIX II – Photographic Record ..................................................................... 15

1 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

1. INTRODUCTION

1.1 Site Owner/Manager:

Kilkenny County Council

1.2 Site Address:

Talbot’s Tower Lower New Street Kilkenny

1.3 Site GPS Co-Ordinates:

52.647963, -7.252607

1.4 Request to Prepare a Japanese Knotweed Management Plan (JKMP): We have been engaged by Kilkenny County Council to undertake a survey of the Talbot’s Tower historical monument in order to determine the presence/absence of invasive alien plant species Japanese knotweed on the site. Additionally, if Japanese knotweed is present, we undertake to map and describe the extent and location(s) of the infestation and to devise a management plan for the eradication of the knotweed. The survey was undertaken by Envirico Ltd. on the 4th Dec, 2017. This document represent Revision 2 of the JKMP, following completion of the supervision of the excavation of topsoil at the Talbot’s Tower site on 11th Jan, 2018. 1.5 Scope of Survey: Our survey will cover the following items: • • • • • •

Botanical identification of Japanese knotweed Map and describe the extent of the infestation Previous site management Current risk of structural damage to property Considerations before commencing a treatment programme Treatment options and recommendations

1.6 Survey Limitations: While every effort is taken to identify the presence or absence of Japanese knotweed on the site, this survey consists of a visual inspection only and cannot be taken as a guarantee that there is no Japanese knotweed present. Japanese knotweed can be temporarily concealed if the canes are cut back and covered over with gravel, mulch, turf, hard standing etc. As this survey was conducted during the winter season when the plant has died back, signs of new shoots may no longer have been visible. 2 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

2. ABOUT JAPANESE KNOTWEED Japanese knotweed (Fallopia japonica) was introduced to Europe by the horticultural activities of Philippe von Siebold, who plucked the plant from the side of a Japanese volcano in the 1840s. It is a fast growing, perennial, herbaceous plant, native to East Asia (Japan, northern China, Taiwan and Korea). In its home range, the plant is not a threat because a host of native predators, fungi and herbivorous insects keep it in check. However, outside Japan it is classified as one of the Worldâ&#x20AC;&#x2122;s Worst Invasive Species (World Conservation Union). The date of its first introduction to Ireland is not known, but is believed to be in the mid to late 19th century. Japanese knotweed can grow >3m high, with young shoots in spring growing up to 10 - 30cm per day, quickly resulting in dense stands that shade out other species. The leaves are a distinctive shape with a tapered tip and a flat base (up to 18cm long) and the mature hollow stems have nodes and look somewhat like bamboo canes. The underground rhizome system can be vast, extending up to 3m deep and 7m horizontally from the nearest visible growth. Japanese knotweed produces small cream or white flowers in late summer or early autumn. There are only female plants in the UK and Ireland so sexual reproduction is negligible; however, hybrids with related plants can be produced (e.g. Giant knotweed; Russian Vine) and are found occasionally. Even without sexual reproduction, the plant spreads at a rapid rate by rhizome extension. New plants can also grow from tiny fragments of rhizome (as little as 0.7 grams) or stems, which means that traditional control methods such as cutting or strimming will actually further spread a knotweed infestation. Some of the most likely routes for knotweed spread are via our roads, rivers and railway lines as tiny fragments are dragged along these routes enabling them to quickly colonise new areas. Knotweed is also often spread by the movement of contaminated soils offsite and the improper disposal of the weed in garden clearings. It can grow on a wide range of soil types, pH and salinity; has the ability to withstand droughts, heat, cold, sulphurous soil; and is tolerant towards heavy metals. This hardiness ensures a wide distribution across habitat types. Japanese knotweedâ&#x20AC;&#x2122;s massive rhizome system and vigorous growth can seriously damage walls, foundations, roads and buildings, including historic sites. The plant can also disrupt the integrity of man-made flood defense structures, increasing costs in repair and maintenance. Railway tracks, roads, pavements, and other constructions are also frequently affected. Other highly invasive knotweeds that occur in Ireland are Giant knotweed, Fallopia sachalinensis, Himalayan knotweed Persicaria wallichii and Bohemian knotweed Fallopia x bohemica, which is a hybrid between Japanese and Giant Knotweed. These other knotweeds are increasingly found in Ireland, though still to a much lesser extent than the Japanese knotweed.

3 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

3. LEGISLATION The Invasive Species Ireland project identified Japanese knotweed as one of the highest risk (most un-wanted) non-native invasive species in Ireland. There is strict legislation surrounding Japanese knotweed in Ireland. Ireland has also ratified a number of international conventions that oblige the Government to address the issue of non-native invasive species, including the Convention on Biological Diversity, the Bern Convention and the International Plant Protection Convention 3.1 Invasive Alien Species Irish Statutory Instrument 477/2011 The EC Birds and Natural Habitats Regulations introduced important legislation concerning invasive species in the Republic of Ireland. Japanese, giant, Himalayan and bohemian (hybrid) knotweeds are listed in Part 1 of the Third Schedule, and soil contaminated with Japanese knotweed, giant knotweed or their hybrid is classified as a vector material. Article 49 prohibits the introduction, breeding, release or dispersal of certain species; and Article 50 prohibits dealing in and keeping certain species. Article 49 (2) “Save in accordance with a licence granted under paragraph (7), any person who plants, disperses, allows or causes to disperse, spreads or otherwise causes to grow in any place specified in relation to such plant in the third column of Part 1 of the Third Schedule, any plant which is included in Part 1 of the Third Schedule, shall be guilty of an offence.” Article 49 (3) states that you can defend against allegations that you committed an offence under Article 49 (1) or (2) by proving that you took all reasonable steps and exercised all due diligence to avoid committing the offence: Article 49 (3) “Subject to paragraph (4), it shall be a defence to a charge of committing an offence under paragraph (1) or (2) to prove that the accused took all reasonable steps and exercised all due diligence to avoid committing the offence. Article 50 (2) “Save in accordance with a licence granted under paragraph (7), a person shall be guilty of an offence if he or she imports or transports – (a) an animal or plant listed in Part 1 or Part 2 of the Third Schedule (b) anything from which an animal or plant referred to in Part 2 of the Third Schedule can be reproduced or propagated, or (c) a vector material listed in Part 3 of the Third Schedule,

4 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

into or in or to any place in the State specified in relation to such an animal or plant or vector material in relation to that animal or plant or vector material in the third column of the Third Schedule.” The Wildlife Amendment Act (2000) of The Wildlife Act (1976) made it an offence to cause an exotic species of flora to grow in the wild anywhere in the state: “Any person who plants or otherwise causes to grow in a wild state in any place in the State any (exotic) species of flora, or the flowers, roots, seeds or spores of flora, otherwise than under and in accordance with a licence granted in that behalf by the Minister shall be guilty of an offence.” 3.2 Japanese Knotweed Disposal In order to transport Japanese knotweed from one location to another, a licence must first be obtained from the National Parks and Wildlife Service. A licence application must include: • As much information as possible on the removal, transportation and treatment of the species in question • A detailed description of the biosecurity measures that will be in place • A copy of the Knotweed Management plan • Details of the timeframe for carrying out the work Under the Waste Management (Facility, Permit and Registration) Regulations 2007, Japanese knotweed waste can only be disposed of at a licenced waste facility. The waste must only be transported offsite by a licenced haulier, and the licenced waste facility must be notified in advance of the nature of the waste and have agreed to accept the waste material. 3.3 Use of Herbicides (Chemical Treatment) The Sustainable Use of Pesticides Regulations 2012 (SI 155/2012) set out who can apply pesticides and the type of training, equipment and maintenance required and where pesticides use is prohibited. The 2012 regulations prohibit the use of pesticides near drinking water abstraction zones within 5m up to 200m distance, depending on the type of abstraction point or borehole (Schedule 2); and the use of pesticides within 15m of a landscape feather that is known to be a ground water vulnerable area including karst areas, sinkholes and collapse features. All Envirico personnel that may apply herbicides are fully trained and certified in the type of application they will undertake and are listed on the Register of Professional Pesticide Users as required by the Sustainable Use of Pesticides Directive, and as maintained by the Department of Agriculture, Food and the Marine. 5 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

4. SURVEY FINDINGS

4.1 Site Description: Talbot’s Tower is an important historical monument in the city of Kilkenny. This tower formed part of the original city wall defences and dates back to 1260. Restoration works began on the tower in 2007 in order to open the site up to public access once again, and these were completed over a five-year period. However, the discovery of Japanese knotweed in western corner of the site has led to the tower remaining closed to the public indefinitely.

4.2 On-Site Presence of Japanese Knotweed There was a small patch of Japanese knotweed visible growing within the Talbot’s Tower site (see Appendix I - Site Map). Table 1 gives the details of the stand. The knotweed is growing directly next to a boundary wall with the neighbouring property to the west. Upon discovery of the Japanese knotweed, Kilkenny County Council took the precaution of boarding off the infestation and keeping this area securely locked to avoid the possibility of further spread due to disturbance. In total, there is an area of approx. 7m2 of Japanese knotweed on the site. The Japanese knotweed had died back for winter at the time of the survey (see Appendix II – Photographic Record). Table 1. Detailed information for each recorded stand of Japanese knotweed ID

Length (m)

Width (m)

Desirable Vegetation

JK01 6.6 Up to 1.6 No Total Coverage of Japanese Knotweed: 7m2

Avg. Stem Height 1 - 2.5m

Max. Stem Diameter 1 - 2.5cm

Close to Close to Water well etc. No No

Individual stands (ID #) are classified as stands separated from other knotweed growth by >1m

4.3 Off-Site Presence of Japanese Knotweed Kilkenny County Council Senior Engineer, Mr. Simon Walton reported that Japanese knotweed is present in the neighbouring garden to the west of the site. However, at the time of the survey Envirico did not have access to the neighbouring property to conduct a survey to determine the extent of the infestation there.

4.4 Site Access There is no issue with access at this site. 6 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

4.5 Previous Site Management Unknown if any/what treatment was undertaken at the time of discovery. Kilkenny County Council Senior Engineer, Mr. Simon Walton to revert back with information about previous control attempts.

4.6 Possible Source of Infestation It is likely that the Japanese knotweed on-site results from the larger infestation in the neighbouring garden. Growth on-site may have been stimulated by disturbance of rhizomes during the restoration works.

4.7 Likely Sources of Reintroduction The Japanese knotweed in the neighbouring garden to the west poses a significant threat of reintroduction to the Talbotâ&#x20AC;&#x2122;s Tower site. Therefore, it is critical that the Japanese knotweed on the neighbouring property is surveyed and treated as part of a comprehensive programme, with the consent of the property owner. If an agreement cannot be reached with the neighbouring property owner, the site must be protected from the threat of reintroduction from this source by the installation of a vertical root barrier membrane.

4.8 Future Site Development The closure of the site for a number of years has led to the amenity grass growing into tussocks and being invaded by weeds, and some landscaping works will need to be undertaken before the site can be opened to the public. Kilkenny County Council may decide to resow grass or instead place a hard-standing as the ground surface. A detailed management plan to follow during the landscaping and resurfacing works is outlined in Section 5.

7 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

5. JAPANESE KNOTWEED MANAGEMENT PLAN 5.1 Summary Kilkenny County Council are exploring the possibility of opening the Talbotâ&#x20AC;&#x2122;s Tower attraction to the public by 1st March, 2018. Preparatory works have started in order to prepare the section of the site outside the cordoned off area for landscaping/resurfacing. As part of these works Envirico supervised the stripping of topsoil from a meter-wide trench running directly adjacent to the cordoned off area. No evidence of Japanese knotweed rhizome was found in the topsoil or at the face of the excavation. As no evidence of Japanese knotweed material was found during these works, Envirico have advised Kilkenny County Council that they can now proceed to landscape the designated area. This will involve a combination of bringing in new topsoil for sowing with grass and placing hard standing surfaces. The area currently cordoned off will remain cordoned off and the Japanese knotweed will be treated with herbicides by Envirico until no regrowth has been observed for two years. JK01 will remain boarded off until this time. As part of these works, the Japanese knotweed infestation on the neighbouring property should also be subject to on-going chemical treatment until no regrowth has been observed for 2 years. This will safeguard the Talbotâ&#x20AC;&#x2122;s Tower site from the threat of reinvasion from that source.

5.2 Preparatory Works The Works (11 t h Jan, 2018)

Acting CSJK: Dr. Amanda Greer Envirico marked out a distance of 7m from the nearest visible knotweed using builders lime (see Fig. 3). This area marks the exclusion zone, within which all material is treated as potentially contaminated with Japanese knotweed rhizome. Using a mini-excavator equipped with a ditching bucket, a 1m wide c.6 inch deep trench was dug directly around the cordoned off area. The excavated top soil was placed on top of a layer of Hytex C3 root barrier membrane within the exclusion zone (see Fig. 4). The face of the excavation was monitored and checked thoroughly by a Certified Surveyor of Japanese Knotweed in order to determine if Japanese knotweed rhizome was present or not. There was no evidence of Japanese knotweed rhizome being disturbed or excavated during the preparatory works.

8 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

All of the topsoil that was stripped during the preparatory works can be removed off-site or reused on-site as preferred by Kilkenny County Council. In addition, all of the topsoil outside of the cordoned off area can be stripped and removed off-site or reused on-site.

Biosecurity

Exclusion zones (7m away from visible Japanese knotweed growth) were clearly marked in order to prevent accidental incursion. All PPE, equipment, plant or machinery to enter or work within an exclusion zone were thoroughly clean before entering or commencing work. A designated wash-down area lined with Hytex C3 root barrier membrane was set-up (Fig. 5). At this location all PPE, plant and equipment was thoroughly cleaned and certified as clean by the CSJK. The mini-excavator including tracks and bucket was washed with a power washer. All other equipment and PPE were cleaned with brushes and soapy water. All material that was washed off PPE, plant and equipment was treated as contaminated and added to JK01 for ongoing chemical treatment.

5.3 Landscaping/Resurfacing Works Landscaping/resurfacing works will be necessary in order to restore the site to a condition suitable for members of the public. During these works the top layer of soil and vegetation will be scraped away and removed off-site, and then new topsoil and seeding will be imported and/or a hard-standing provided to provide for adequate, suitable access arrangements to the site. Because the CSJK has determined that no Japanese knotweed rhizome was disturbed during the preparatory works, further stripping of top soil and landscaping works outside of the cordoned off area can take place without supervision by Envirico. Under no circumstances should works take place within the cordoned off area without prior consultation with the CSJK.

5.4 Herbicide Treatment JK01 will be subjected to on-going treatment with systemic herbicides until there has been no regrowth for two years. Initial treatment will take place around May, with a follow-up around September the same year. JK01 must remain cordoned off for the life of the treatment programme, until Envirico advises that the hoarding can be removed. Once treatment with herbicides has begun, JK01 will no longer be capable of extending its rhizome network, so leaving the plant in-situ (but locked away) does not pose a threat to the rest of the site. 9 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

It is important that the Japanese knotweed present on the neighbouring property (west) is also treated as part of a comprehensive programme. This will prevent the risk of reintroduction from this source.

The Environment Agency (UK, 2013) recommends that wherever possible JK is treated insitu using herbicides. In-situ treatment is the most environmentally-friendly option, and does not pose the same biosecurity risk as mechanical removal. A herbicide treatment programme is also the most cost-effective option; however, it can take 5 or more years to be completely effective. Table 2 details effective herbicide while Table 3 outlines our recommended treatment schedule for in-situ treatment.

Legislative Framework

All professional formulation plant protection products must only be applied by a Professional Pesticide User that is registered with the Department of Agriculture, Food and the Marine (as required by the Sustainable Use of Pesticides Directive, 2012). All herbicides will be applied in accordance with current legislation (Sustainable Use of Pesticides Directive, 2012), in compliance with the label, in appropriate weather conditions and following an environmental risk assessment. Application of pesticides near water must have prior approval from Inland Fisheries Ireland, be applied by appropriately trained personnel (PA6AW) and use only aquatic approved products. Herbicides Effective Against Japanese Knotweed

Currently, the following active ingredients are considered to be the most effective treatment for Japanese knotweed available in the EU. Table 2 outlines some key features of these products. Given the time of year we recommend that the knotweed undergo initial treatment with an aminopyralid triclopyr combination followed by treatment with a glyphosate based herbicide in autumn. In order for a chemical treatment programme to be successful, it is important that the initial leaves and stalks, and any regrowth remain as healthy as possible until the product is applied. A translocated herbicide is drawn into the plant from where it is applied, and moved to other plant organs incl. roots/rhizomes. Because of this mode of action, a translocated herbicide applied via a foliar spray will be most effective if it has a larger leaf area to cover, and the translocation of the product from the leaves down to the rhizomes will be most efficient if the plant is not damaged or water-stressed.

10 Envirico Ltd. trading as Envirico. CRO: 598399 Bonnettstown, Co. Kilkenny, R95 V2T4 www.envirico.com

Table 2. Herbicides currently licenced in Ireland that are effective against Japanese Knotweed. All herbicides are systemic (translocated). Herbicide

*Licensed PCS No. Product

Selectivity Persistence

Timing of Aquatic 1st Approved Application Product

Glyphosate

Roundup Biactive XL

04660

Nonselective

Non-persistent

Aug-Oct

Yes

Aminopyralid + Triclopyr

Icade

04249

Selective

Apr-May

Grazon Pro

05182

Not assessed (not for use on animal feed for 1 year)

2-4D Amine

Depitox

02365

Selective

1 month

May

* Only example licence products are displayed, others may be available.

Table 3. In-Situ Treatment Schedule for JK01 & Japanese knotweed on neighbouring property Site

Action

Time

Year