Paul Keller
Massive olive trees are dying in southern Italy. The reason: an aggressive bacterium that has already infected more than 20 million olive trees. So far there is no antidote.
The sight of southern Italian olive oil groves is a sad thing in some places: Where silver leaves used to shine in the sun, more and more dried up olive trees can now be seen. First individual leaves turn brown, then whole branches wither until the whole tree dies.
One of the most dangerous plant diseases
The reason why the olive trees, some of which are over 1,000 years old, are dying is a bacterium called Xylella fastidiosa, also known as the fire bacterium. The extremely aggressive bacterium is transmitted by insects. It ensures that the tree’s pathways become clogged and the transport of water and nutrients inside the plant no longer works, so that the trees practically die of thirst.
The European Commission has classified the disease as one of the most dangerous plant diseases. According to the Italian farmers’ association Coldiretti, the bacterium has now infected 21 million trees.
Disease threatens agriculture in southern Italy
The insidious plant disease has been known since 2013. In recent years it has spread further and further north from southern Italy. Meanwhile, X. fastidiosa has also been diagnosed in olive trees and on vines in Spain.
Italian olive oil farmers are complaining about a massive slump in their oil production. The bacterium, which originally comes from America, not only threatens Italy’s agriculture, but also causes immense economic damage. The farmers’ representation estimates the damage already incurred at 1.2 billion euros.
Diseased olive trees: no antidote in sight
So far there is no known means of ridding infested trees of the bacterium. The only measure to prevent further spread is cutting down and burning infected trees. But even that often comes too late, because infested plants often show no symptoms for months. Research is currently being carried out into resistant olive tree species that the fire bacterium cannot harm.
