Scientists Map Risk of Exposure to Xylella

The Xylella fastidiosa bacterium that has wreaked havoc in Italy’s olive groves could also spread to Spain and other countries with a temperate climate, according to a study from Spain’s University of Málaga.

The university had developed the first multi-scale and multi-factor model evaluating the potential regional and global reach of the bacteria, Olive Oil Times reported on 3 April.

Regions with the highest risk of exposure included southern Brazil, Central America, southern Europe and the USA.
Australia and southern Africa could also be at risk but zones beyond 40-50 degrees latitude appeared to be in less danger.
In Spain, the study showed that the Iberian Peninsula was at a particularly high risk to the entrance and spread of xylella, which was already widespread in the Balearic islands, Olive Oil Times wrote.
The Mediterranean coast and southwest Spain, with high temperatures and a lot of winter rain, were the areas at highest risk.
Oliver Gutiérrex Hernández, a professor at the university’s geography department, Luis García, from Spain’s National Research Council, wrote that geography played a crucial role in the management of biological risks.

“The success in the management of [these risks] depends, to a large extent, on our ability to predict the potential geographic ranges of invading organisms and identify the factors that promote its spread.”

However, Hernández and García acknowledged that their model only used data from areas where Xylella was known to be present, potentially leaving out information from areas where the bacterium may be viable but not yet detected.

Xylella fastidiosa attacks a plant’s water transporting xylem vessels, blocking water movement and causing symptoms that resemble water stress.