FILE - An olive tree is seen silhouetted in an olive plantation in Amelia, central Italy, June 13, 2017.
FILE - An olive tree is seen silhouetted in an olive plantation in Amelia, central Italy, June 13, 2017.

ROME - After the 24-hour storm dumped more rain on his olive trees than 55-year-old Gianluca can recall having seen in a September, the part-time farmer shook his head as he inspected his forlorn crop. 

"This is the third year I have not seen much to harvest," he lamented. "Last year was even worse, mind you. But look at this," he said, pointing to trees with few olives and many threadbare branches. 

FILE - Damaged olives hang in a grove in Nerola, 50 kilometers (31 miles) from Rome, Nov. 13, 2014.

In the distance, Lago di Bolsena shimmered and the Italian countryside just north of Rome seemed picture perfect. The sun had returned after Monday's extreme storm and with it warm autumnal temperatures. But for all the surrounding bucolic beauty, farmers and smallholders in northern Lazio, as in much of rural Italy, are becoming alarmed at the increasingly fickle weather with erratic rainfall, spring frost, tempestuous wind and summer drought.

Farmers say the change in climate patterns across Italy is causing poor olive harvests, which are leaving in their wake predictions that the country could become dependent on olive oil imports.

That's a remarkable turnaround for a country that many see as synonymous with olive oil — although olive trees weren't natural to Italy and first arrived in Italy from Greece, thanks to Greeks who settled in Sicily.

By early in the first century AD, the Roman historian Pliny could brag that Italians produced more olives than the Greeks and the quality was superior.

FILE - Olive oil comes out of a tap in an oil mill in the Tuscan village of Montepuclciano, Oct. 6, 2007.

Last year, Italy saw a 57 percent plunge in the country's olive harvest, sparking protests by thousands of Italian farmers who descended on Rome wearing orange vests, calling for climate action. 

According to Riccardo Valentini, a professor in forest ecology at the University of Tuscia in Viterbo, the development of olive trees can suffer greatly when there are sudden extremes in weather.

"Three or four days of 40 (degree Celsius) temperatures in summer, or 10 days without rain in spring — even two days of freezing temperatures in spring — are important," he said in a recent interview with Italian media. "The alarm bell is ringing loud and clear: If we do not limit emissions and pollution levels, the land that we all know is in great danger."

Climate change, disease and insects are reducing Italy's production of homegrown olive oil, say scientists and farmers. Last year's unusual weather patterns inflicted an estimated $1 billion worth of damage on the olive-oil sector, according to the national farmers' association Coldiretti. The sharp drop in production was the worst the country has witnessed in a quarter-century. 

Insects, disease

The weather is also hurting the trees by helping insect infestations — especially of a species of fly that lays eggs in the trees after burrowing into them.

FILE - Olive trees infected with a disease called Xylella fastidiosa are seen near Gallipoli in the Salento peninsula, in Apuglia, southern Italy, June 20, 2019.

Of even greater threat is a bacteria called Xylella fastidiosa, thought to have come from Costa Rica and spread by the meadow spittlebug. The bacteria starts in the leaves, turning them a rusty brown color, then proceeds into the trunks, disrupting arteries that allow the tree to absorb water. 

The disease first broke out around 2013 in the southern region of Puglia, in the heel of the Italian boot. Until recently, Puglia was responsible for more than half of Italy's olive oil production but it has slipped as a result of hundreds of thousands of olive trees dying. Last year, the region's production plunged by 65 percent. 

Altogether, an estimated one million Italian trees have died as a result of the disease, and farmers in Lazio are fearful that they will soon see what they dub "tree cemeteries." While climate change isn't being held responsible for the appearance of the bacteria in Italy, it is thought to have helped its quick spread. 

The EU has called on Italy to create a buffer zone by cutting down diseased trees, but the work has been patchy and trees elsewhere — in Lazio and Tuscany — are showing early signs of the disease.