Cipollini, a biology professor, is careful to not overstate the alarm to olive growers, but the ash borer is now found to have naturally infested another ash relative, the white fringetree, an ornamental that grows in Ohio and elsewhere. That revelation came as a surprise when Cipollini made that discovery in 2014, he said.
In the Mediterranean, fruit fly blight and “olive tree leprosy” sent 2014 production down 35 percent in Italy — the second largest producer after Spain. A drought that same summer in Spain caused a disastrous harvest there. Due to the shortage from the two countries that together produce 70 percent of the world’s olives, Europeans paid on average 19.8 percent more for olive oil during much of 2015, according to analysts. Prices are still volatile now that the “leprosy,” Xylella fastidiosa, is wreaking havoc in Spain.