The legendary olive trees of Puglia produce some of the finest oil in the world. Thousands of farm families have pressed the fruits for generations. The trees’ twisted trunks — some radiocarbon-dated at more than 2,500 years old — are as fundamental to the landscape here as the castles and the sea. They have persisted through centuries of invasions, wars, droughts and depressions. No matter how bad things have ever gotten, the orchards have always provided promise for the future. That’s why the spontaneous death of these trees, presumably by a foreign bacterium called Xylella fastidiosa, feels like a black plague. Carried by insects, the bacterium has swept through grove after grove.

Authorities have reacted with extreme measures. On July 7, Giuseppe Silletti, head of the Puglia division of the State Forestry Corps and special commissioner in charge of eradicating Xylella, ordered two dozen of his men to sweep into an area with several small groves near Oria at 5 a.m. to cut down more than 40 olive-laden trees. They arrived, chain saws blaring, without warning any of the owners or the local mayor, Cosimo Ferretti. More than 30 special armed police, generally dispatched to control riots, arrived with them to hold back the farmers and their families and neighbors. The owners watched in horror while the uniformed men massacred the ancient trees and yanked the gnarled roots from the ground, as if to symbolize the destruction of the region’s deep-rooted heritage. Angry residents raised their fists and screamed, “Murderers!” Two women in their 50s — third-generation growers who were infuriated that their orchards were among those being razed — began to hit the police and were escorted away. ...