Xylella bacteria was first observed in Puglia in 2013, and through genomic sequencing has been traced back to Central America, likely Costa Rica. The bacterium is believed to have been introduced via the importation of infected ornamental plants.

Xylella originated in Lecce and has since spread to Brindisi and Taranto. Ostuni, located in Brindisi, lies within the infected zone. The bacterium is spread by insects, for example the meadow spittlebug.

Latest research shows that alongside vector control through pesticides, the key protection method is through grafting - merging resistant varieties of olive branch, to protect the tree from the bacteria.