An unwanted byproduct of European free trade: Foreign pests

A bacterium called Xylella fastidiosa was first noticed in Italy in 2013. Since then, it has killed tens of millions of olive trees and there is no known cure. With Italy's annual olive oil harvest significantly down and the European Union dedicated to an open import system, what is to be done? Marco Werman speaks with Wopke Van der Werf who is a professor of agricultural ecology at Wageningen University in the Netherlands.