A voice from the field here (Puglia, southern Italy). I can assure you that the landscape has changed drastically in a decade. Where a few years ago you could see immense expanses of green, now you see a ghostly landscape. It's incredible. Years and years have been spent inconclusively, both by politicians and by investigators, who have also wasted time with conspiracy theories.
Only a few people have replanted olive trees using species resistant to Xylella.
We also had anti scientific movements that opposed to the destruction of olive trees in a radius big enough to prevent the bacteria to spread to other plants. Farmers also tried to delay the process of trees eradications by packing the judicial courts with appeals. Some singers (such as Al bano, I think caparezza as well) also expressed to listen to the farmers and to not touch the olives, when scientists has been saying for years "listen, we don't have a cure, we can't cure the plants, we can only contain it before it spreads to wider areas".
This anti scientific behavior and this thinking of "farmers might know better than scientist" that is not only false, but dangerous when expressed by a public figure such as a famous singer, are what I were complaining about in a different comment about people being ignorant in scientific fields in italy and almost being proud of it [1]
I wonder what the legal implications are of ignoring a disease until it spreads to your neighbour's farm. Can the neighbour sue for negligence or something?
Only a few people have replanted olive trees using species resistant to Xylella.