Xylella update: still no cure, control measures crucial
EFSA has updated its assessment of the risks posed by Xylella fastidiosa to plants and crops in the European Union. The new assessment provides new insights and conclusions on controlling existing outbreaks of this pest and preventing further spread in the EU.
Controlling the threat
EFSA’s Plant Health Panel (PLH) used computer modelling to simulate how X. fastidiosaspreads across short and long distances under different conditions. The modelling showed the importance of implementing control measures, such as those specified by the European Commission, to prevent further spread and even eradicate outbreaks. It illustrated the relative effectiveness of using different-sized buffer zones to control an infected area.
The simulations also demonstrated the importance of controlling the insects that are known to transmit the pathogen in Europe – such as the spittlebug Philaenus spumarius – and minimising the delay between detection and implementation of control measures such as removing infected plants and establishing demarcated areas.
Is there a cure?
The assessment confirms that there is still no known way of eliminating the bacterium from a diseased plant in field conditions. The effectiveness of chemical and biological control measures has been assessed in recent experiments. The results show that they may temporarily reduce disease severity in some situations, but there is no evidence that they could eliminate X. fastidiosa in field conditions over a long period of time.
Which countries are at risk?
Computer simulations showed that although most of the EU territory has climate types under which the pathogen is known to occur elsewhere in the world, the areas most at risk are in southern Europe (see map). However, the modelling showed some variation to this general rule according to the subspecies involved. For example, it suggested that X. fastidiosa subsp. multiplex had greater potential to establish in northern Europe than other subspecies.
The information on risk of establishment will be valuable in setting up surveillance and detection programmes in different Member States. EFSA is currently developing survey guidelines on X. fastidiosa with plant health organisations across the EU.
A hidden pest
The assessment contains a key section on variations in the asymptomatic period – the time from infection to expression of symptoms – of plants that can act as hosts for X. fastidiosa.
A literature review and data analysis revealed significant differences in the asymptomatic period for different combinations of host and subspecies. This information will assist in the design of tailored surveillance programmes as well as help risk managers to decide when it is safe to end demarcation of an outbreak area.
Stephen Parnell, Chair of the PLH Panel’s X. fastidiosa working group, yesterday said:
“This was a complex scientific challenge with many areas of uncertainty, but we have distilled some important conclusions that will assist risk managers, risk assessors and researchers.
“Computer simulations are at the core of this scientific opinion. The models we have developed are robust and, importantly, flexible so they can be adapted to explore a wide range of different scenarios and support emergency planning.”
Dr Parnell added:
“A wealth of new information has become available since our last opinion was published in 2015, much of it generated by EU-funded projects such as POnTE and XF-ACTORS. Our understanding of this dangerous plant pest is advancing all the time thanks to these initiatives, although much uncertainty remains, particularly at subspecies and sequence type level.
“It is vital that we continue to invest in research that can help us to not only control outbreaks but anticipate them.”
Xylella fastidiosa is one of the most dangerous plant bacteria in the world. It causes a wide range of diseases, with huge economic impact on agriculture, gardens and the environment.
The four most commonly reported subspecies are fastidiosa, pauca, multiplex and sandyi. The bacterium lives in the plant xylem tissue and is commonly spread by insect vectors feeding from the plant xylem.
X. fastidiosa was first detected in Europe in 2013, when an outbreak began in Apulia, southern Italy. Since then it has been reported in France (Corsica and Provence-Alpes-Côte d'Azur), Spain (Balearics, Valencia, Madrid), central Italy (Tuscany) and Portugal (Porto). EU emergency control measures are in place in all the outbreak areas.
- Update of the scientific opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory
- Effectiveness of in planta control measures for Xylella fastidiosa
- Collection of data and information on biology and control of vectors of Xylella fastidiosa
Latest News from
President Michel’s MFF proposal not acceptable for Parliament21/02/2020 09:25:00
Ahead of a special summit on 20 February, the EP’s negotiating team expresses its opposition to President Michel’s proposal for the next long-term budget.
Budgetary Control Committee asks for stronger measures to protect EU spending20/02/2020 15:25:00
On Wednesday, the Budgetary Control Committee signed off on the Commission’s 2018 budget, but rules to fight fraud and conflict of interest must be strengthened.
COVID-19 outbreak: Commission supports repatriation of EU citizens from cruise ship in Japan20/02/2020 12:25:00
The EU is co-financing the repatriation of EU citizens from the Diamond Princess cruise ship docked in Yokohama, Japan, thanks to flights from Italy mobilised through the EU Civil Protection Mechanism.
Shaping Europe's digital future: Commission presents strategies for data and Artificial Intelligence20/02/2020 11:38:00
The EC has unveiled its ideas and actions for a digital transformation that works for all, reflecting the best of Europe: open, fair, diverse, democratic and confident.
Fabio Panetta: Deepening & widening Economic and Monetary Union: finding the right speed19/02/2020 13:20:00
Introductory remarks by Fabio Panetta, Member of the Executive Board of the ECB, at the European Parliamentary Week.
"EU Budget risks being a failure for people & a gift to populism" warns CoR President19/02/2020 12:20:00
The European Committee of the Regions (CoR) asks to preserve funds for hospitals, schools, local transport, environment, universities and small businesses.
Council sets its priorities for the 2021 EU budget19/02/2020 11:20:00
The Council adopted the following conclusions setting out its priorities for the 2021 EU budget.
Human rights: EU adopts conclusions on EU priorities at UN Human Rights Fora in 202018/02/2020 13:25:00
On the occasion of the year marking the 75th anniversary of the entry into force of the UN Charter, the Council conclusions reaffirm EU's commitment to the rule-based international order – human rights protection being an important part of it.
Consultation on Air Quality - Executive Summary14/02/2020 12:20:00
The Secretariat of the Commission for Environment, Climate Change and Energy (ENVE) of the CoR is in the process of informing other EU institutional and non institutional actors about the Implementation Report of the consultation on Air Quality, whose Executive Summary is already available here.