Xylella: EFSA evaluates new research

EFSA is assessing the results of experiments carried out in Apulia on the susceptibility of grapevine (Vitis) to Xylella fastidiosa CoDiRO, the strain of X. fastidiosa that has been spreading in southern Italy since 2013.

Vitis is known to be highly susceptible to the fastidiosa sub-species of the X. fastidiosa bacterium, which causes the deadly Pierce’s disease of grapes in California. However, because of uncertainty about the full host range of X. fastidiosa CoDiRO, Vitis is currently regulated and subject to EU emergency measures against X. fastidiosa.

The Italian authorities argue that the results of the research in Apulia have removed any uncertainty regarding susceptibility of Vitis to CoDiRO and have urged the Commission to remove Vitis from the list. Risk managers in Brussels have asked EFSA to evaluate the findings in order to help them respond to the request. The Authority’s Scientific Opinion will be published by the end of November.

Hot water treatment

The new evaluation follows an EFSA Scientific Opinion published in September which concluded that hot water treatment is an effective safeguard against all strains of X. fastidiosa in grapevine planting material.

What is the new information on grapevine and CoDiRO?

The dossier submitted to the Commission by the Italian authorities is based on the work of scientists from the Consiglio Nazionale delle Ricerche and University of Bari, who carried out three main research activities:

  • A series of inoculation experiments conducted on potted plants between 2014 and 2015, which showed that while X. fastidiosa CoDiRO spread rapidly in  olive plants, it did not spread in Cabernet Sauvignon vines.
  • A second group of experiments in which samples of grapevine, olive, oleander, citrus and control plants (periwinkle) were exposed to meadow spittlebugs (Philaenus spumarius), which are known transmitters (vectors) of X. fastidiosa and are common in the outbreak area of Apulia. The control plants were quickly infected whereas the grapevines showed no sign of infection throughout the three-month testing phase. The results for olive, oleander and citrus are not yet available.
  • Surveys of vineyards in the heart of the contaminated area of Apulia, where almost 100% of olive trees are infected by X. fastidiosa CoDiRO. Samples were collected from many grapevine varieties and rootstocks in 2013, 2014, and 2015. None of the samples showed any signs of infection by X. fastidiosa CoDiRO.

For more information about EFSA’s work on X. fastidiosa, please see our frequently asked questions.

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