Bad news for lovers of tapenade and pesto. Olive trees are succumbing to a new disease. Tom Heap reports from Puglia on the ultimate foodie nightmare.

The heel of Italy is currently gripped by an outbreak of Xylella fastidiosa, a voracious tree disease that is systematically devastating olive groves in the main areas of production for olive oil.

95% of the world's olive trees are in the Mediterranean, and Italy is the world's second largest exporter of oil, behind Spain.

Rural communities risk being torn apart as the disease threatens the livelihoods of farming families that have grown olives in the region for centuries. The whole environment is set to change as trees die, leaving the landscape totally bare.

Tom meets the scientists about to wage war on the bacteria: Professor Giovanni Martelli and Dr Donato Boscia from the University of Bari. They are working to find a way of stopping the disease from spreading. If they are unsuccessful, olive production in the whole of the Mediterranean basin could be at risk.

Producer: Martin Poyntz-Roberts.