Efsa: There is still no cure to Xylella fastidiosa

  • EFSA has updated its assessment of the risks posed by Xylella fastidiosa to plants and crops in the European Union. 

EFSA’s Plant Health Panel (PLH) used computer modelling to simulate how Xylella fastidiosa spreads 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.

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 Xylella fastidiosa in field conditions over a long period of time.

Which countries are at risk?

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 Xylella fastidiosa subsp. multiplex had greater potential to establish in northern Europe than other subspecies.