Xylella Fastidiosa. archive photo. | Quico


At least 79% of Mallorca’s almond trees have been killed or damaged by the Xylella fastidiosa plague which a new study shows has been present on the Island for more than 25 years.

The study was carried out by a multi-disciplinary team made up of Researchers from the UIB, the CSIC Tragsa and the Ministry of Agriculture and published in the Communications Biology journal.

Biologist and Researcher Eduardo Moralejo estimates that more than 80% of almond trees in Mallorca are infected and that the plague was originally mistaken for wood fungus.

Researchers have made a retrospective analysis of the development of Xylella fastidiosa symptoms showing the progressive death of tree branches infected with wood fungi. The research combined dendrochronology and molecular biology techniques, which have shown Xylella infections in almond trees as far back as 1998.

According to UIB researcher, Marga Gomila, these same techniques have helped analyse DNA of the two Xylella strains (fastidiosa and multiplex) in the growth rings of the wood of the almond trees, which enabled them to track the date of the first infection.

"I have analysed the DNA of the rings and we have found symptoms from 1998," added Moralejo who added that it has been deduced that Xylella must have arrived in Mallorca with imported plant materials in 1993.