Written evidence submitted by Advanced Invasives Limited (JKW0011)

 

Advanced Invasives

 

Advanced Invasives is an invasive plant species consultancy. We solve invasive plant species problems, with a specialist focus on Japanese knotweed and the complex technical, legal and public relations challenges faced by large landowners, private companies and herbicide manufacturers.

 

Based in South Wales, Advanced Invasives was founded in 2016 by Dr Daniel Jones (PhD, GCIEEM) and Dr Gareth Bruce (PhD) from Swansea University’s Department of Biosciences out of a desire to set a new standard of evidence-led invasive species management.

 

Projects and Clients

 

Our work bridges the gap between scientific enquiry, commercial application and public understanding of invasive species problems across six main areas: in-field research and product testing, invasives strategy, complex site survey, risk mapping, information design, and expert witness.

 

Our clients include: Network Rail Cymru Wales; Monsanto UK; Monsanto Europe; Israel Chemicals Limited (ICL) and Hardwicke Law.

 

Research

 

In 2018 in partnership with Swansea University, Dr Dan Jones published the results of his PhD research in the open-access, peer-reviewed journal Biological Invasions. The paper; ‘Optimising Physiochemical Control of Invasive Japanese Knotweed’ (Jones et al. 2018), provides the most comprehensive scientific evaluation of knotweed management practices in the world to date, benchmarking nineteen of the key chemical and integrated knotweed treatment methods. The underlying field-trial work completed from 2011 onwards is valued conservatively at approximately £1.2 million.

 

The Jones et al. (2018) paper presents a new model linking choices in herbicide selection and application with the seasonal changes in the surface-to-rhizome energy flows of the knotweed plant. Because the model is informed by knotweed physiology, it serves as a more objective framework for better decision-making on herbicide selection, timing and dose. It effectively provides a standalone evidence base from which to assess the relative merits of the different approaches to knotweed control, particularly those involving the use of herbicides.

 


Executive summary

 

●        Japanese knotweed is a fast-growing invasive non-native plant species that spreads very easily and can be destructive to property. The plant has underground, laterally growing root-like structures, rhizomes, that form an extensive network and make knotweed difficult to control or remove entirely.

 

●        Japanese knotweed is now subject to an array of legislative restrictions about handling, treatment and waste disposal, and has recently been the focus of a high-profile common law case between Network Rail Infrastructure Ltd and a homeowner whose property value was reduced due to knotweed growing on railway land near his property.

 

●        Japanese knotweed creates a range of quite complex, interlinked effects on mortgage lending and property valuation decisions. These have arisen in response to concern about the actual damage caused from the plant, uncertainty about its possible impacts and the best course of treatment and legal liability. The wider context is a trend towards the more defensive practise of surveying, the withdrawal of government guidance on the ‘best practice’ management of Japanese knotweed, and also somewhat irresponsible media coverage.

 

●        The set of issues caused by Japanese knotweed is one of actual damage and costs, but also more intangible issues including loss of amenity, stigma, uncertainty, the perception of possible future impacts and the unwanted burden of having to resolve the issue.
 

●        Lender positions vary with respect to the presence of Japanese knotweed; the more risk-averse lenders may still refuse a mortgage application outright, even where a treatment plan can be arranged. Many lenders will only agree to lend after a full cycle of knotweed treatment is completed, creating the issue of a multi-year delay on buyers and sellers being able to raise mortgages and transact freely, even where treatment is planned. Others will lend on a case-by-case basis and only where a course of professionally applied herbicide treatment, which takes a minimum of three years, is supported with evidence of that treatment in a management plan, and the now standard provision of the insurance-backed-guarantee (IBG) on the agreed work.

 

●        Lender requirements for evidence of knotweed treatment create a particular problem where homeowners are affected by knotweed on neighbouring land - knotweed may fall within the 7 metre proximity, yet homeowners will lack the access rights needed to arrange for treatment. On railway land in the UK, which is almost all managed by Network Rail, this is especially problematic; nationwide there is a large habitat often abutting private homes and this space is prone knotweed invasion. The highly publicised Williams & Waistell v Network Rail Infrastructure case, and subsequent appeal (which Network Rail lost), highlights how in extreme cases knotweed results in a major loss of property amenity value, and substantial reduction in the attainable market value of a property. The Williams case set a new precedent in common law for knotweed related nuisance due the diminution in value and is widely understood as the test case for knotweed liability more generally.

 

Responses to the terms of reference

 

Question 1

What scientific evidence exists on the effects of Japanese Knotweed on the built environment?

 

  1. To date, almost all peer-reviewed studies of Japanese knotweed have focused principally on plant biology, rather than the direct impact on buildings (see: Callaghan et al. 1991; Adler 1993; Brock 1995; Strašil and Kára 2010).

 

  1. Fennell et al. (2018) is the first peer-reviewed journal article to directly examine the impacts of knotweed on the built environment. While this study is an excellent first step in quantifying the impact of knotweed growth on built structures, there are three main limitations with respect to this study.

 

Firstly, the case study investigating property damage caused by knotweed is restricted to three streets of derelict housing stock (built prior to 1900) located in northern England. Consequently, it is difficult to generalise from this case study to new build housing developments and older housing stock that is well maintained, or to other regions of the UK, where underlying environmental conditions and the history of knotweed infestation differ significantly.

 

  1. Secondly, the sample size used in the contractor surveys is statistically small. It does not in our view adequately capture the damaging impacts by knotweed upon buildings as reported by surveyors more generally, or damage to out-buildings and paving for example.

 

  1. Thirdly, though rhizome extension is reported as rarely extending more than four metres from aboveground plant growth, this relies upon a small sample size of the contractor questionnaire and only considers relatively smaller knotweed stands of limited area.

 

  1. Broadly however, we agree with Fennell et al. (2018) that the typical effects of Japanese knotweed in terms of damage to building has been overstated, particularly in press coverage on the issue.


Question 2

How the presence of Japanese Knotweed in the UK affects mortgage lending decisions and property valuations.

 

  1. As far back as the 1930s knotweed began to affect the value of property prices. Japanese knotweed became a much more serious issue in recent years, when a number of lenders began to decline loans on properties affected by Japanese knotweed. This has been, and continues to be, the subject of prominent newspaper coverage, which tends to highlight only the most extreme cases of Japanese knotweed infestation, in turn fuelling public concern about the effects of knotweed on property.

 

  1. Lender restrictions, and the worsening public perception of these, took the knotweed issue from 'a complication that was simply 'difficult to solve’ to one that could result in property sales failing.' As a result, some lenders became very risk averse on the knotweed issue (RICS, 2012). Today, Japanese knotweed is widely known to be a major cause of property blight. Homeowners must disclose the presence of knotweed, or any history of the plant, using the Law Society Property Information Form (TA6) - a mandatory form completed by the seller to supply information used in the property conveyancing process. Through the TA6 disclosure, any history of knotweed infestation is therefore likely to reduce the future marketability and resale value of a property.

 

  1. Japanese knotweed has direct effects on property via the physical encroachment of rhizomes and vigorous growth of aboveground shoots. Rhizome and shoot growth may be destructive to masonry, growing through existing weaknesses, such as cracks in walls, gaps between materials and poorly sealed structures. Knotweed may also grow through newly laid aggregate materials such as tarmac.

 

  1. Japanese knotweed also has indirect effects on property amenity and the perception of value. Even where it has been successfully treated with herbicides (the most widely used method of treatment for residential infestations of knotweed), the continued presence of rhizome material in the soil prevents the affected area from being used as normal, and in turn creates a stigma affecting property marketability.

 

  1. A further complexity is that Japanese knotweed affects property even where it has not physically encroached, but is simply within close proximity, due to the potential for significant lateral growth of the rhizome network. The industry has settled on a somewhat arbitrary threshold distance of 7 metres lateral rhizome network growth, following the risk assessment framework set out in the RICS 2012 information paper; Japanese Knotweed and residential property, in turn informed by the Environment Agency 2006 discussion of rhizome system growth (see next question for more detail).

 

  1. In response to lender precaution, insurers and contractors have created two relatively new instruments; an express IBG and also the knotweed treatment compliant mortgage. An express IBG can be issued at the outset of treatment to reassure lenders more expediently. A knotweed treatment compliant mortgage allows for pre-funding of a treatment plan (and any future re-treatment) to be held in escrow, ring-fenced from the contractor undertaking the treatment.

 

  1. Following the Williams case, joint experts instructed in the Smith v Line (2018) case (a dispute between two neighbouring homeowners) suggested that: ‘Continued presence of JK, untreated, on Ms Line's land close to the boundary with the claimants' land had the effect of reducing the current value of the claimants' land by 10%, from £800,000 to £720,000. Legal cases therefore help to quantify measurable impacts of Japanese knotweed on property, yet by definition will be only a very small subset of the total number of instances where knotweed affects a property - many buyers will simply reject those properties where knotweed is present. Anecdotally, this is likely to be more of an issue in areas where many alternative properties unaffected by knotweed are readily available, or where the costs of knotweed treatment are relatively higher as proportion of the purchase price.

 

  1. In the example of leasehold properties, the presence of knotweed may be raised on the LPE1 form - a voluntary form held by landlords, management companies and managing agents to capture information about a property. The presence of knotweed anywhere on the estate, or within 7 metres of the entire estate boundary affects all of the respective leaseholds, regardless of the actual effect of knotweed on their building.  The Guardian (Anna Tims article, 06/04/2017) provide an example of a leaseholder, adjacent to railway land, who cannot resell their property because of the inability of prospective buyers to obtain a mortgage, due to a lack of sufficient evidence of knotweed treatment issued by Network Rail.

 


Question 3

Whether mortgage lending decisions relating to the presence of Japanese Knotweed are currently based on sound scientific evidence of its effects on the built environment?

 

  1. There is a very limited evidence-base with respect to the effects of Japanese knotweed on the built environment. Most decisions by lenders appear to be informed by the guidance set out in the 2012 RICS information paper, originally written for the benefit of RICS members to: ‘help residential practitioners [surveyors] consider the implications of a Japanese Knotweed infestation on or near a dwelling, when undertaking valuations and surveys of residential property in the UK.’ (RICS 2012).

 

  1. Th RICS 2012 paper introduces a risk assessment framework for Japanese knotweed, using a threshold of knotweed within 7 metres proximity to habitable structures (the so called ‘7 metre rule’), combined with a judgment on actual damage to built structures, to define four categories of knotweed risk to habitable property.

 

  1. The 7 metre rule is itself based on the suggestion in the Environment Agency Knotweed Code of Practice (2006) that ‘the rhizome system may extend to, and beyond, a depth of at least 2m and extend 7m laterally from a parent plant.’

 

  1. The RICS risk assessment framework was released to help surveyors undertake knotweed surveys and quantify the case-by-case real impacts of the plant on residential property and in turn and assimilate knotweed issues into the valuation process like any other issue of property blight. In practice however, the risk framework has been applied by surveyors practising more and more defensively (in part due to the increasingly risk of knotweed related liability following the Williams case), to the extent that the presence of knotweed within 7 metres of a habitable property boundary, often irrespective of any actual damage, is effectively stigmatising to a property. Unfortunately, what was clearly intended as a descriptive framework to better reassure lenders has become a prescriptive label, whereby many mortgage companies may automatically refuse to lend on properties within 7 metres of a Japanese knotweed infestation.

 

  1. While the wording of the RICs paper is slightly ambiguous; using ‘and/or’ in the ‘Category 4’ description of risk (the most severe category of knotweed risk), the spirit of the risk assessment framework is one of pragmatism and encouraging further investigations by qualified surveyors - presumably to see whether or not knotweed is actually causing damage to a property.

 

  1. That mortgage lenders should automatically reject mortgages applications because knotweed is within 7 metres of a habitable space, irrespective of the context, seems to be an over response to the actual issue of damage - in many instances of typical knotweed infestations the 7 metre threshold will overstate the direct impacts of knotweed. At the same time, the reliance on the 7 metre threshold is unsatisfactory as it will underestimate the likely impacts of very large knotweed stands that happen to be only slightly further than 7 metres away from a habitable space - a dense, well established area of knotweed ‘forest’ say 20 metres wide but 8 metres away from a property, poses more of a practical risk than a small newly established sprig, only 6 metres away. There are also a small number of extreme examples where knotweed lateral rhizome growth exceeds 7 metres.

 

  1. The issue of knotweed stigma and marketability in particular are much harder to neatly define than direct impacts, and in some senses driven by perception. A more nuanced risk assessment tool, and one that is used in the spirit it is designed for, is needed.

 

  1. In the specific context of Japanese knotweed growing on Network Rail (or other railway operator) land and subsequently affecting neighbouring residents’ ability to raise a mortgage, our view is that Network Rail and the affected lenders should work together to agree on an acceptable format and process of issuing evidence of treatment quickly and efficiently.

 

  1. In the LPE1 example we see no reason why knotweed should affect leaseholders simply because it is within 7 metres of the overall estate boundary - a pragmatic judgment needs to be made on whether it can realistically affect the habitable structures.

 

  1. Even with the existing risk assessment framework, the wide variation in lender position with regards to the presence of Japanese knotweed is surprising - across management plans IBGs, express IBGS and ‘knotweed treatment compliant mortgages’ there are a range of intelligent tools already available to help tackle the knotweed issue in the round - lenders should be encouraged to make use of all of these to reduce the burden of knotweed on homeowners.

 

  1. Building on the case studies examined by Fennell et al. (2018), we propose the creation of a more robust and extensive data set evaluating Japanese knotweed impact on the built environment across the UK - this is necessary to alleviate many of the understandable concerns of lenders. Such a dataset should include; UK-wide impact assessment of knotweed growth on built structures (including old and new build housing) and empirical investigation of knotweed growth rate and form under differing environmental conditions such as regional climate and soil types.


Question 4

What guidance for the sector currently exists, the impact of existing legislation, and how else evidence-based responses to the presence of Japanese Knotweed can be encouraged.

 

Guidance for the sector

 

  1. Over the last 30 years or so, Japanese knotweed management guidance has developed in a haphazard and fragmented manner. Guidance is now scattered across a diverse range of government bodies, non-governmental organisations, academics, specialist working groups, and private companies spanning a wide range of sectors. At the national, EU, and international level, there is also extensive documentation on strategic invasive species policy and policy-making procedure.

 

  1. There is no single body of work on Japanese knotweed control that can be regarded as a complete ‘best-practice’ and it is also difficult to separate impartial advice on knotweed control and treatment from commercially driven preferences. Instead, there are a range of resources understood to collectively form the best available guidance in the round. Practical guidance on knotweed control can be divided into two broad types; commercial guidance written for developers and contractors, and homeowner guidance providing information for resolving knotweed issues affecting residential property.

 

  1. Commercial guidance on Japanese knotweed tends to draw on four main documents:

 

●        The Japanese Knotweed Manual (Child and Wade, 2000)

●        The Knotweed Code of Practice: Managing Japanese knotweed on development sites (Environment Agency, 2006, with 2013 addendum, withdrawn in 2016)

●        Code of Practice, Managing Japanese Knotweed (INNSA 2017)

●        Practical Management of Invasive Non-Native Weeds in Britain and Ireland (PCA 2018)

 

  1. The Royal Institution of Chartered Surveyors (RICS UK) and the Property Care Association (PCA) are the two main sources of guidance on the surveying and treatment of knotweed in residential situations. Their key documents are:

 

●        Japanese knotweed and residential property, 1st edition. (RICS UK, 2012, with 2015 addendum)

●        Code of Practice; for the management of Japanese knotweed (PCA, 2014).

●        Japanese knotweed: a guide to the problems caused by Japanese knotweed and how to deal with them (PCA, 2014)

 

  1. Lastly, the gov.uk website and beta.gov.wales websites also provide summary guidance on Japanese knotweed treatment.

 

  1. All of the sources of guidance on knotweed treatment are based on only limited scientific evidence; many rely on outdated information obtained from small scale, short-term experiments and/or contractor case studies, that while useful are mostly anecdotal in nature. Furthermore, many sources contain recommendations for knotweed treatment that are now regarded as incorrect, such as summer cutting of knotweed stems, or even illegal; for example the application of herbicides that have now been withdrawn from use (such as picloram acid). In 2016, the Environment Agency formally withdrew The Knotweed Code of Practice: Managing Japanese knotweed on development sites in recognition of deficiencies in the recommendations for knotweed treatment, particularly those using herbicides.

 

  1. The lack of an empirical evidence-base to underpin knotweed control practices was the primary driver behind the research by Dr Daniel Jones et al. The multi-year and large-scale methodology underpinning the field-trial is necessary for the proper evaluation of treatment methods directed at a large, long-lived and resilient species such as Japanese knotweed. Furthermore, by testing knotweed treatment response under ‘worst case’, real world conditions, the recommendations of this research can be scaled up, or down, to treat most, if not all knotweed infestations effectively and efficiently, regardless of knotweed stand area and geographic location.

 

Impact of existing legislation

 

  1. There is no single ‘knotweed law’ as such. Instead, a patchwork of different statutory laws in combination with civil cases tackle the different facets of knotweed issues in both criminal and common law. Across the UK there are also slight differences arising from the recently devolved legislatures in Wales, Scotland, and Northern Ireland, and also the influence of binding international EU directives (mostly regarding herbicide use).

 

  1. There are five broad legal perspectives on the issues caused by knotweed that are useful to consider in the round:             

 

●        Japanese knotweed as a threat to native biodiversity and habitats

●        Japanese knotweed waste as a controlled substance and hazardous waste

●        Japanese knotweed control in residential areas

●        The enforcement of Japanese knotweed control

●        Restrictions on the herbicides used in chemical treatment of Japanese knotweed

 

  1. Legal instruments for the treatment, handling and disposal of Japanese knotweed s.l. taxa include, but are not limited to:

 

●        The Wildlife and Countryside Act 1981

●        The Environmental Protection Act 1990

●        Town and Country Planning Act 1990

●        Waste Management Licensing Regulations 1994

●        Hazardous Waste Regulations 2005

●        Anti-social Behaviour, Crime and Policing Act 2014

●        Species Control Orders (Infrastructure Act 2015)             

 

  1. In parallel to statutory legislation on Japanese knotweed control, relevant common law cases are; Williams & Waistell v Network Rail Infrastructure Ltd (Cardiff, 2017), the later appeal of Network Rail Infrastructure Ltd v Williams & Waistell (London, 2018), Line v Smith (Truro, 2018) and, to a lesser extent, Flanagan v Wigan (Leigh, 1995).

 

  1. Taken in the aggregate the range of legal controls on Japanese knotweed in particular, and invasive plant species in general, are confusing and lack harmony, however any person (or organisation) undertaking Japanese knotweed management in the UK must comply with all current legislation.

 

  1. Overall, the effect of legislation, and the recent court cases centred on knotweed liability, is to increase the costs and risks arising from knotweed treatment programmes. For large landowners and public bodies in particular, undertaking effective knotweed treatment at the strategic scale, whilst minimising legal liability, is especially difficult without an authoritative and coherent source of scientifically valid treatment recommendations.

 

  1. Additionally, legislative pressure at the EU level on plant protection products, notably glyphosate - the active ingredient in the most effective herbicide treatments suitable for Japanese knotweed control, combined with environmental concerns has led to a number of local authorities experimenting with alternative weed control methods (see the Cotham trial in Bristol). Our view is that the costs of most of the proposed alternatives are too high to be considered practical, and in any in case the efficacy on Japanese knotweed control has not been proven.

 

Encouraging evidence-based responses

 

  1. Knotweed management is always a trade-off between the cost, time, scale, and ecological constraints of different sites and projects requirements; therefore, it is best viewed as a pragmatic process of considering a menu of suitable methods and treatments, according to the priorities at hand. In the very first instance, preferences for methods and treatment should informed by:

 

●        Scientific research on effectiveness

●        Site specific constraints on herbicide use

●        Legal restrictions on herbicide selection application rates                           

●        Scalability across the habitat being managed                           

●        A common-sense view of practicality and costs                           

●        Avoidance of methods that are ineffective                           

●        Avoidance of methods that spread knotweed inadvertently

 

We suggest:

 

●        A scientific review of all of the academic and grey literature on Japanese knotweed management.

 

●        An evaluation of the wide range of methods currently undertaken by knotweed remediation contractors and also a review of the alternative treatments proposed as replacements for glyphosate-based herbicide treatment of Japanese knotweed.

 

●        The creation of a general decision-making framework for large landowners to select knotweed treatment options.

 

●        For herbicide treatment specifically; a scientific evaluation of the current herbicides available for knotweed treatment, and the specific protocols recommended for knotweed control.

 

●        The creation of a guide for large public organisations to release information about Japanese knotweed treatment to the public.

 

●        A review of the terms used in Japanese knotweed remediation, specifically ‘eradication’ and ‘control’ that are currently ill-defined and sometimes used interchangeably.

 

●        Consultation with law firms specialising in knotweed liability to better understand the risks arising from knotweed management at the strategic scale.

 

●        Consultation with reputable contractors undertaking novel methods of knotweed treatment.

 

●        Consultation with mortgage lenders involved in grading knotweed risks to property.

 

 

December 2018

 


References

 

Adler C (1993) Growth and dispersal strategies and associations of the neophyte Polygonum cuspidatum with special regard to mowing. Tuexenia 13:373-97.

 

Brock JH (1995) Technical note: standing crop of Reynoutria japonica in the autumn of 1991 in the United Kingdom. Preslia 66:337-343.

 

Callaghan TV, Scott R & Whittaker HA (1981) The yield, development and chemical composition of some fast-growing indigenous and naturalised British plant species in relation to management as energy crops. Institute of Terrestrial Ecology (Natural Environment Research Council).

 

Child L & Wade M (2000) The Japanese Knotweed Manual: The Management and Control of an Invasive Weed. DPS Partnership Ltd, Burgess Hill.

 

Environment Agency (EA) (2006, with 2013 addendum, withdrawn in 2016) Managing Japanese Knotweed on Development Sites The Knotweed Code of Practice. Environment Agency, Bristol.

 

Fennell M, Wade M & Bacon KL (2018) Japanese knotweed (Fallopia japonica): an analysis of capacity to cause structural damage (compared to other plants) and typical rhizome extension. PeerJ 6:e5246; DOI 10.7717/peerj.5246.

 

Invasive Non-Invasive Non-Native Specialists Association (INNSA) (2017) The INNSA Code of Practice, Managing Japanese Knotweed.

 

Jones D, Bruce G, Fowler MS, Law-Cooper R, Graham I, Street-Perrott FA & Eastwood DC (2018) Optimising physiochemical control of invasive Japanese knotweed. Biol Inv 20(8), 2091-2105 https://doi.org/10.1007/s10530-018-1684-5.

 

PCA (2014) Code of Practice; for the management of Japanese knotweed. https://www.property-care.org/wp-content/uploads/2015/04/Code-of-Practice-for-the-Management-of-Japanese-knotweed_v2.7.pdf.

Accessed 23 March 2015.

 

PCA (2014) Japanese knotweed: a guide to the problems caused by Japanese knotweed and how to deal with them.

https://www.property-care.org/homeowners/invasive-weed-control/japanese-knotweed/. Accessed 23 March 2015.

 

PCA (2018) Practical Management of Invasive Non-Native Weeds in Britain and Ireland. Packard Publishing Limited, Chichester.

 

RICS UK (2012, with 2015 addendum) Japanese knotweed and residential property, 1st edition, information paper.

https://www.rics.org/globalassets/rics-website/media/upholding-professional-standards/sector-standards/real-estate/japanese-knotweed-and-residential-property-1st-edition.pdf.

Accessed 11 November 2015.

 

Strašil Z & Kára J (2010) Study of knotweed (Reynoutria) as possible phytomass resource for energy and industrial utilization. J Res Appl Agric Engng 56:85-91.

 

https://democracy.bristol.gov.uk/documents/s8454/CothamTrialCombinedReport.pdf.

 

https://www.theguardian.com/money/2017/apr/06/network-rail-japanese-knotweed-undermining-house-sale.