GAGLIANO DEL CAPO, Italy — Working in an arid Italian field of crumbly soil, agronomists are battling a rampant bacterium that has already infected millions of olive trees and could threaten the entire Mediterranean basin.
Xylella fastidiosa, which has no known cure, has devastated ancient olive trees in Italy's southern Apulia region and beyond, causing $1.3 billion of damage to the world's second olive oil exporter after Spain.
Since 2013, the disease has torn through Apulia's olive groves, leaving thousands of skeleton-like trees in its wake, and little hope for farmers.
Once Xylella fastidiosa bacteria — carried by tiny sap-sucking insects known as spittlebugs — take hold, blocking the tree's ability to absorb water, the plant is doomed.
Bureaucracy and 'mafia'
The only way to fight the spread of the disease, known as "olive tree leprosy", is to destroy diseased trees, but farmers must seek special permission and say the authorities are not always forthcoming.
Doubtful of conspiracy theories that the mafia are killing trees to make way for hotel construction, agronomist Pierfederico La Notte noticed that some trees seemed not to become infected, standing tall and green in otherwise devastated fields.
Suspecting that they may be resistant varieties that can develop the disease to a small degree but continue to grow and flower, the soft-spoken researcher rapidly identified two that appeared to suffer little from Xylella.
"The Leccino and Favolosa varieties are a starting point, not the finish line," said La Notte, who works for Italy's National Research Council.
"We hope, and we're working on it, to find a much bigger number of resistant varieties," said La Notte, teaching visiting Egyptian agronomists in a research field outside the ancient town of Gallipoli.
Results so far are promising.
Branches from resistant varieties that are grafted onto the trunks of sick trees are growing perfectly and even producing fruit, offering a glimmer of hope to the devastated region in the heel of Italy's boot
Immunity?
Down the road in the heavily agriculture-dependent region, agronomist and olive oil producer Giovanni Melcarne has lost 90% of his plants since Xylella arrived, and he is seeking an even better solution: immune varieties of olive tree.
While much of his machinery for olive cultivation now lies dormant, he has built an improvised greenhouse, filled with dozens of small olive saplings, among which he hopes to find at least one immune variety.
"We will infect them with the illness, we will contaminate them with the insects that transmit the illness so we have scientific proof that this plant, this indigenous variety that we could cultivate, doesn't catch the disease and so is immune," Melcarne said, carefully labelling a batch of olive saplings.
