Olive oil, staple of the much-ballyhooed Mediterranean diet, is about to get a little more expensive. 

The world’s top producers, Spain and Italy, have faced a series of plagues that led one Italian newspaper to refer to 2014 as “the black year of Italian oil.” Ninety-five percent of the world’s olive trees are in the Mediterranean. Italy’s woes have knocked it down to third place in production, behind Spain and Tunisia, but it remains the world’s largest olive oil exporter. (A quirk in Italian labeling laws allows Italy to sell oil produced elsewhere but bottled in Italy as “Italian,” making it the second biggest importer of olive oil as well.)

“We’ve seen big reductions in key