Almond trees are highly susceptible to xylella, but not all varieties. | Francesca Marí

Results from the first year of research into strategies for controlling the xylella fastidiosa bacterium highlight the "significant" resistance of certain varieties of almond tree.

The initial phase of the research project, which has drawn on tourist tax revenue funding, has focused on the study of resistance, tolerance and susceptibility of almond and olive trees and vines. Some 3,800 samples were analysed, and almond trees were shown to have high levels of variation. With vines, the variation was much lower, while with olive trees there was no difference between varieties.

Aerial imaging has been part of this research. This indicates that almond trees on land without irrigation are more susceptible to the xylella bacterium than trees where there is irrigation. Last July, a helicopter from the Spanish National Research Council's Institute for Sustainable Agriculture flew over 2,000 hectares in Majorca in obtaining images.

The study has also looked into insect vectors which transmit the bacterium. Philaneus spumarius, otherwise known as the meadow froghopper or spittlebug, was identified as being overwhelmingly responsible. This confirms what Italian research has previously found.

To date, there have been 1,027 positive cases of xylella in the Balearics; 611 of these have been in Majorca, 151 in Minorca, 265 in Ibiza, and none in Formentera