Agricultural Biodiversity Weblog

The NY Times is the latest media outlet to freak out about Italian olives. There’s quite a lot to freak out about. Xylella fastidiosa, the bacterium that is believed to have caused serious damage to perhaps a million trees in Puglia, Italy’s heel, can be spread widely by insects and attacks a wide range of hosts, including citrus and grapevines, where it causes Pierce’s disease. It was recently discovered on a coffee plant near Paris. The French Minister of Agriculture proposed a ban on imports of olive-related products from Puglia. The BBC has reported that the European Commission has urged Italy to step up efforts to “destroy infected trees and restrict any trade in species vulnerable to the disease”. It also says that Italian officials believe the disease entered the country in “ornamental plants imported from Costa Rica”. Meanwhile, our information is that the pugliesi are saying it is nothing to do with some foreign bacteria, but rather a fungus, which has just happened to flare up now, and it will all blow over, and don’t you dare try and control it by cutting down our trees. In any case, that may not be enough:

Scientists say a buffer zone may be useful but warn that simply cutting down infected trees will not solve the problem in southern Salento. “The only feasible option is coexistence — and to create an open sky laboratory in that area,” said Donato Boscia, a scientist at Italy’s National Research Council.

That’s what happening with Pierce’s disease in Brazilian citrus, for example. Nobody seems to be talking much about resistant varieties, at least in citrus and olives. Resistance in grapes seems to be in the pipeline, but quite far away. Not a short-term solution, clearly, but it might be worthwhile starting to screen the larger collections, surely.