Federico Manni first noticed something was wrong with his family's olive trees about six years ago.
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 Italy's boot.
They noticed some trees looked burnt.
"Dead branches, brown leaves," Manni says. "Terrible, really terrible."
They pruned and washed the trees but it didn't help. Soon more trees shriveled. Today nearly all are dead.