Federico Manni first noticed something was wrong with his familys olive trees about six yearsago.

It was summer, the cicadas were singing, and Manni and his father, Enzo, were weaving through their olive groves in Puglia, the southern region forming the heel of Italysboot.

They noticed some trees lookedburnt.

Dead branches, brown leaves, Manni says. Terrible, reallyterrible.

They pruned and washed the trees but it didnt help. Soon more trees shriveled. Today nearly all aredead.

The Mannis now call the field worked by generations of their family an olive-treecemetery.

These olive trees survived wars and bad weather. They almost gave us a sense of immortality, Enzo says. Now I hold back my tears when I see these extraordinary beauties replaced by lifelesstrunks.

The tree-killer is a bacterium called xylella fastidiosa. Since 2013, it has killed millions of olive trees in Italy and is now threatening those in Spain and Greece. Together, these countries produce 95% of Europes olive oil. A recent study projects that southern Europe, already crushed by the coronavirus pandemic, could lose at least $22 billion over the next 50 years, if xylellaspreads.

There is no cure, says Maria Saponari, a plant virologist at the Institute for Sustainable Plant Protection in Italy, and the disease spreadsquickly.

Saponari compares xylella to the coronavirus. Just as COVID-19 keeps oxygen from reaching our vital organs, she says, xylella clogs the inside of olive trees so they cant absorbwater.

On the outside, you see the leaves desiccate, you see the wood turn gray or brown, and the tree dies, shesays.

Saponari, who has studied xylella for years, says the bacterium came to Italy from the Americas, where it ravaged citrus trees and vineyards. She says Italy likely imported ornamental coffee plants infected with xylella. Because it flourishes in warm weather, unfortunately it found a very suitable condition to establish here, shesays.

The pathogen is spread by sap-sucking insects like the spittlebug. Because theres no cure, Saponari says farmers must focus on prevention, which includes keeping spittlebugs away from trees. One method involves weeding and tilling olive groves to kill insect larvae. Scientists have also suggested trying insect-repellingclays.

Olive farmers in Puglia have tried it all. They have cleaned infected branches with copper sulphate and fertilized the soil with cow manure. They have quarantined sick trees and uprooted healthy onesnearby.

But Gianni Cantele, a winemaker, who is part of the local farmers association, says the supply of olive oil has nearly rundry.

The production in this area is no more than 10% of the original, hesays.

Cantele says that the disease has also hurt local tourism built around those olivetrees.

We lost a huge historical and cultural treasure, he says. Olive trees define the landscapehere.

In Spain, xylella has mainly affected almond trees and vineyards. But Blanca Landa, a plant pathologist at the Spanish National Research Councils Institute for Sustainable Agriculture, warns Spains olive farmers to stayvigilant.

You never know what can happen, she says, if farmers import unvetted plants and introduce something that can be really dangerous and destroy completely the economy of acountry.

If I drive through Andalusia (in southern Spain), I cannot imagine not seeing olive trees there, she says. Olive oil is on every table. Olives are offered to visitors in everyhome.

Xylella has so far spared Greece. But we are all on high alert, says Antonis Marakakis, head agronomist for olive farmers at Terra Creta, an olive-oil company on the island ofCrete.

He tells farmers to call him immediately if their trees looksick.

I tell them to get samples from the trees so they can be tested right away for signs of xylella, he says. We have to catch it before itspreads.

Back in southern Italy, Federico and Enzo Manni are now struggling to farm potatoes during apandemic.

Federico shares old videos of the family harvesting and pressing olives into earthy, slightly spicy olive oil, before xylella turned their trees into scorched-graycorpses.

When we lost the trees, he says, its like we lost ourhouse.

He says he hasnt given up on olives justyet.

Xylella infects the two best-known olive varieties in Puglia Cellina di Nard and Ogliarola salentina but scientists believe other varieties might be resistant to thedisease.

Manni wants to try farmingthose.

If we plant 20% of what we lost, its a good number, he says. Olives are our story here, and this story is not over.

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Southern Europe Could Lose $22 Billion Fighting Deadly Olive Tree Disease - OPB News