Close up image of an olive tree

Xylella fastidiosa is a species of bacteria that can kill infected plants. It is not known to be in the UK, but the Government is concerned about how to prevent the disease being accidentally brought into the country on imported plants. On 8 July 2020, Lord Framlingham (Conservative) is due to ask the Government what representations it has received from the European Union about the Government’s plans to prevent the importation of Xylella fastidiosa.

What is Xylella?

Xylella fastidiosa is a species of bacteria that infects the xylem (water transport tissue) of plants. It can disrupt or block water transport in infected plants leading to symptoms including wilting and tissue dieback. Xyllella can kill infected plants. An estimated 200 plus species of plants are susceptible to Xylella fastidiosa (and its sub-species), including oak, plane, and sycamore trees. It also infects plants such as lavender and rosemary. Xylella is spread by insects that feed on plant fluids drawn from xylem tissue. Forest Research has said that there are a number of insect species in the UK that could spread Xylella, including the common froghopper (Philaenus spumarius). It also stated that whilst these insects normally only fly up to 100m, winds can carry them further.

Xylella is not known to be in the UK. However, there have been outbreaks of the disease in mainland Europe, including in France, Italy, and Spain. Portugal confirmed its first case in 2019, on lavender. In 2019, the UK Government stated that Xylella fastidiosa’s damage to olive trees alone had caused a loss of €390 million over three years in Italy. Up until 2013 Xylella was only known in the Americas and in Taiwan.

The Government has argued that any outbreak of the disease would “lead to widespread destruction of plants and trees, the restriction of horticultural trade and the use of pesticides to control the insects which spread the disease”. Xylella species have a wide range of hosts but the Department for Environment, Food and Rural Affairs (Defra) has said that Xylella fastidiosa sub-species multiplex is of most concern to the UK. This sub-species can survive in cooler climates and can affect many UK native broadleaved trees such as oak.

Xylella is a notifiable disease, which means that occurrences of it must be reported to relevant authorities in England and each of the devolved nations.

UK’s regulations on Xylella

Under the terms of the withdrawal agreement between the UK and the EU, the UK must continue to apply EU law during the transition period, apart from specific exceptions set out in the agreement. The transition period is due to last until 31 December 2020. The UK has confirmed that it is applying the EU Plant Health Regulation (EU 2016/2031) and the Official Controls Regulation (EU 2017/625) during the transition period. The EU Plant Health Regulation entered into force on 13 December 2016 and was applicable from 14 December 2019. It aims to “modernise” the EU’s plant health regime and ensure safe trade.

On 31 March 2020, the Government laid the Official Controls (Plant Health and Genetically Modified Organisms) (England) Regulations 2020 before Parliament (the 2020 regulations). The 2020 regulations updated previous regulations from 2019 and came into force on 21 April 2020. Similar but separate legislation operate in Scotland, Wales, and Northern Ireland.

The Government has explained that the 2020 regulations introduced measures to strengthen the protection of plants from certain pests and diseases, including Xylella. They were made under article 52 of the EU Plant Health Regulation. This allows member states (or the UK during the transition period) to take additional temporary national measures if they inform the European Commission and put forward a “technical case to request EU measures against a specific pest, and those measures have not or will not be introduced in time to mitigate the risk concerned”. The explanatory memorandum to the UK’s 2020 regulations explained that the Commission may undertake a review of the risk put forward by the member state and that “an Implementing Act may be adopted by the Commission to repeal or amend the national measures in the event they are considered to be disproportionate or not adequately justified”.

The UK Government has argued that current EU emergency measures on Xylella do not address risks highlighted in the UK’s pest risk analysis on the disease:

In particular, it is not clear if or when the EU emergency measures will be reviewed to address these risks and ensure a greater degree of assurance of disease freedom in relation to plants of those species being moved in the EU and introduced from third countries. As such, there remains an unacceptable level of pest risk and this instrument introduces national measures under article 52, in the absence of EU requirements.

Regarding Xylella, the 2020 regulations prohibited the importation of olive, Coffea, Polygala and almond plants unless they could meet a series of requirements. It also introduced additional import requirements for other host plants such as lavender and rosemary. Alongside Xylella, the regulations introduced further provisions relating to emerald ash borer (Agrilus planipennis) and canker stain of plane (Ceratocystis platani).

What has the European Commission said about the UK’s regulations on Xylella?

In a decision on 4 June 2020, the European Commission said that it informed the UK on 28 April 2020 that the new national measures “go beyond the existing requirements, are not supported by most recent scientific justification and are disproportionate”. In its decision, it stated that the UK “should amend the UK Official Controls Regulations of 2019, by removing the amendments concerning Xylella fastidiosa and Ceratocystis platani which were made to those regulations by the UK Official Controls Regulations of 2020”. It stated that the UK should comply with the decision by 20 June 2020. The decision discusses the European Commission’s objections to the specific provisions of the 2020 regulations in more detail. European Commission decisions are legally binding on those they are addressed to.

What has been the Government’s response?

On 19 June 2020, Defra stated that the UK disagreed with the European Commission’s conclusions and that it was disappointed that “the opportunity has not been taken to extend the UK measures across the EU, providing enhanced protections for the EU’s member states”.

Defra argued that the biosecurity threat regarding the pests had not changed and the rationale for introducing stronger requirements remained. The department said it continued to encourage stakeholders and industry to “employ risk management practices which maintain the robust protection and assurance that the Defra regulations provide”. Defra also stated that:

[The Animal and Plant Health Agency] and the devolved administrations will continue to carry out intensive inspections of imported plants, taking account of risk factors such as origin, presence of insect vectors, suspect symptoms etc.

The implications of a confirmed finding of Xylella are substantial, including felling of plants within a 100m radius and trade restrictions across a 5km radius.  A finding of plane canker would also cause substantial impacts.

We will keep the need for any further actions under review in light of the ongoing risk situation, including developments in the EU and the results of our own surveillance.

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Image by Alex Holyoake from Unsplash.