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The Seeds of Doom

The Seeds of Doom

Non-native invasive species have caused significant problems for the countryside – and for property

Kieran Cummins

In the past, many non-native species were sold as ornamental plants or as oxygenator plants for garden ponds.

Around half of Ireland’s flora is non-native, with close to 50% of those considered to be ‘casuals’ in our countryside – that is, that they do not form persistent self-sustaining populations in the wild.

Of those that do establish in the wild, about 60 are problematic in some areas, with around 20 currently considered invasive.

Some estimates have put the cost of invasive plant species to the European economy alone at some €12 billion per annum, with estimates of €1.4 trillion a year to the world economy.

The vast majority of non-native species in Ireland pose no threat to our wildlife or economy, and are not considered invasive species.

The Seeds of Doom

The Seeds of Doom

Swamp thing

The European Communities (Birds and Natural Habitats) Regulations (SI 477/2011) were enacted to combat the growing problem of invasive species. The regulations state that “the Wildlife Act 1976, the Wildlife (Amendment) Act 2000, the Wildlife (Amendment) Act 2010 and these regulations shall be construed together as one”.

Of note are sections 49 and 50. It is fair to say that the latest initiative has largely been as a result of Ireland’s membership of the EU, and the various Habitats and related directives.

Section 49 places a “prohibition on introduction and dispersal of certain species”, while section 50 imposes a “prohibition on dealing in and keeping certain species”.


Some 35 species are then listed in the third schedule to the regulations, while a number of animals are listed separately.

Schedule 3 also specifies a prohibition on the movement of ‘vector material’, with specific reference to “soil or spoil taken from places infested with Japanese knotweed (fallopia japonica), giant knotweed (fallopia sachalinensis) or their hybrid, Bohemian knotweed (fallopia x bohemica)”.

Section 49 provides that (save in accordance with a licence), “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 schedule] shall be guilty of an offence”.

The section also provides for a defence (if it can be proven) that the accused took “all reasonable steps and exercised all due diligence to avoid committing the offence”.


Additionally, section 49 provides that, if the minister considers that a species poses a threat to the objectives of the Birds and Habitats Directives, including the protection of European sites, of habitats, and of species of flora and fauna (including birds), he or she may authorise the destruction by appropriate means.

Section 50 has yet to be enacted (as provided for by section 74). Notwithstanding, section 50 provides that “save in accordance with a licence … a person shall be guilty of an offence if he or she has in his or her possession for sale, or for the purposes of breeding, reproduction or propagation, or offers … for sale, transportation, distribution, introduction or release” certain specified animals, plants and materials.

Moreover, section 50 specifies that “a person shall be guilty of an offence if he or she imports or transports an animal or plant listed [in the third schedule]” – including “a vector material listed in part 3 of the third schedule” – into the State.

Two vectors are referred to. One is blue mussel seed and the second is soil or spoil taken from places with Japanese knotweed, giant knotweed or their hybrid.

Day of the triffids

Persons within the sector should also be aware that section 50 is quite broad in its application, in that it includes an offence for any person who publishes or causes to be published, including on the internet, any advertisement, catalogue, circular or price list likely to be understood as conveying that such person imports into the State, buys, sells, distributes or provides for the introduction or release of a species specified in the third schedule.

I am informed that the delay in enacting section 50 relates to Ireland’s membership of the EU, and specifically to concerns regarding free trade. It is unclear whether section 50 can or will be enacted.

As regards penalties, section 67 provides that a person found guilty, on summary conviction, is liable to a class A fine or imprisonment for a term not exceeding six months, or both.

Currently, a class A fine amounts to €5,000. For more serious transgressions – that is, on conviction on indictment – the penalty may be a fine of €500,000 or imprisonment for a term not exceeding three years, or both.

Section 40 of the Wildlife Act 1976 (as amended by section 46 of the Wildlife (Amendment) Act 2000) states: “It shall be an offence to cut, grub, burn or otherwise destroy during the period beginning on 15 April and ending on 31 August in any year, any vegetation growing on land not cultivated or in the course of cultivation for agriculture or forestry.”

Section 52(7) and (8) (as amended) make it an offence to plant or otherwise cause to grow in a wild state exotic species of plant.

Section 40 of the 1976 Wildlife Act was indirectly amended by section 12 of SI 355/2015 (the European Communities (Birds and Natural Habitats) (Amendment) Regulations 2015), which amended SI 477 of 2011 and which permits the minister to issue a licence for the destruction of a species where it “poses a threat to any of the objectives of the Birds and Habitats Directives” and “and that the destruction of that population is a practical, appropriate and proportionate measure to reduce that threat”.

Local authorities have no direct enforcement role, though most local authorities are now aware of the problem and are endeavouring to control outbreaks within their districts.

Readers may have seen notices along roadsides warning people that a specific plant stand is undergoing control and to avoid cutting, etc (for fear of spreading the problem species).

The National Parks and Wildlife Service is the primary regulatory and enforcement authority but, due to limited recourses, lacks the capacity to investigate outbreaks on private land.

Attack of the killer tomatoes

The issue of invasive species has not, insofar as I am aware, been litigated in Ireland. In law, control of invasive species is a matter for the landowner. There have been, however, two significant cases to date in Britain.

In Williams v Network Rail Infrastructure Ltd (B20YX969) and Waistell v Network Rail Infrastructure Ltd (B34YJ849) (together ‘Waistell’), the claimants each owned half of a pair of adjoining semi-detached houses.

Network Rail owned an active railway line behind those houses, as well as an access path and an embankment between the houses and the railway line. Japanese knotweed had existed on the embankment for upwards of 50 years.

The claimants alleged nuisance in two ways: by physical encroachment onto the claimants’ land, and by the presence of Japanese knotweed on the defendant’s land. In the Court of Appeal, Etherton MR disagreed with the court of first instance, which had rejected the claim in nuisance based on the spread of the knotweed rhizomes on the claimants’ properties.

The court held that Japanese knotweed and its rhizomes can be described as a ‘natural hazard’: “They affect the owner’s ability fully to use and enjoy the land.

They are a classic example of an interference with the amenity value of the land.” While the claimants succeeded in damages, the Court of Appeal also disagreed with the court of first instance and was careful to state that the tort of nuisance “is not to protect the value of the property as an investment or a financial asset”.

In other words, there was not an actionable nuisance “simply because it diminished the market value of the claimants’ respective properties, because of lender caution in such situations”.

Beachside land

In Smith and Another v Line (November 2017), the defendant owned a large tract of beachside land. She sold a house on it to the claimants in 2002 for £200,000 and retained the majority of the land for grazing and, in summer, public car parking.

The claimants discovered Japanese knotweed on their land in 2003 and complained to Ms Line, who suggested that it had encroached from the claimants’ land onto hers.

By 2013, the claimants had successfully treated the Japanese knotweed on their land and requested Ms Line to take steps to remove it from hers, where it grew close to the boundary.

Ms Line refused and repeated her assertion that it was encroaching from the claimants’ land. The claimants issued a nuisance claim and successfully obtained a mandatory injunction requiring Ms Line to enter into a contract with a reputable contractor to treat the Japanese knotweed on her land.

A quia timet injunction was sought and granted (where no wrong has yet been committed, although it is threatened). The court also ordered her to pay the claimants’ costs.


Judge Carr, giving judgment, said that he could not improve on the judgment in Waistell and so, unsurprisingly, found that the claimant’s land had not been damaged but (having additionally found that Ms Line had failed to comply with her measured duty of care) that the Japanese knotweed on Ms Line’s land interfered with the claimants’ enjoyment of their land.

While neither Waistell nor Smith v Line are binding authorities in Ireland, any claim in nuisance based on encroachment of Japanese knotweed will not succeed in the absence of physical damage to a claimant’s land.

Therefore, potential claimants may have to rely on the loss-of-amenity approach based on the diminution in value of their land by reason of a reduced market.


The spread of invasive species is monitored and recorded by Biodiversity Ireland, which maintains a website detailing the spread and distribution of a given species (see maps.biodiversityireland.ie).

Likewise, the EU provides a species-mapping tool: (alien.jrc.ec.europa.eu/SpeciesMapper).


EU Regulation 1143/2014 envisages three distinct types of measures: prevention, early detection and rapid eradication, and management. In 2017, the EU published its List of Invasive Alien Species of European Concern, which details 49 plant species.

This is to be reviewed every six years. I understand that, in order to comply with European regulations, national regulations dedicated to invasive species have been drafted by the department. These have not yet been published or implemented. These will likely replace sections 49 and 50.

Most planning authorities in Ireland are now aware of the problem and will often bring up the matter of invasive species in a further information request for the applicants to put in place a plan of eradication.

An Bord Pleanála likewise regularly imposes conditions dealing with invasive species.

An Bord Pleanála imposed such a condition on to the Aldi site in Trim, Co Meath, that read: “Prior to commencement of development, details of spraying over a minimum of three successive years to result in the eradication of invasive alien species on-site, specifically Japanese knotweed, shall be submitted to and agreed in writing with the planning authority … If an alternative method of control is proposed, then a detailed method statement shall be submitted to, and agreed in writing with, the planning authority prior to commencement of any works.”

Structural damage

In Britain, lending institutions are well aware of the structural damage that Japanese knotweed causes – and so the presence of this plant on a property is a well-known cause for refusal of a mortgage.

The TA6 form of the Law Society of England and Wales require sellers to state whether the property is affected by Japanese knotweed.

It would be prudent for the Law Society Conveyancing Committee to consider the insertion of appropriate clauses in the contract for sale and requisitions on title documents to establish for the purchaser’s benefit whether there are any invasive species present on the subject property.

Invasive species – Look it up


  • Network Rail Infrastructure v Williams & Waistell [2018] EWCA Civ 1514
  • Smith and Another v Line (CTR00216) WL 09565854, 6 November 2017)