Xylella is caused by a bacterium.

Also known as:
Olive quick decline syndrome (OQDS)
Oleander leaf scorch
Phony peach disease
Pierce’s disease (grapes) – not in Europe

recognize Xylella on citrus
Xylella on orange tree, photo: Alexander Purcell - CC BY 3.0

Xylella (Xylella fastidiosa) is caused by a bacterium. The disease initially occurred only in the United States but has been found in Europe since 2013. By now, millions of olive trees (especially in Italy) have been affected. The disease interferes with water uptake, causing the trees to slowly dry out (with all the associated symptoms: growth stops, yellowing leaves) and eventually die. The disease is highly contagious to plants. Meadow froghoppers (Philaenus spumarius) and other insects transmit the disease.
Field weeds such as nettle and spurge are host plants of Xylella. Other host plants include: grape, myrtle-leaf milkwort (Polygala myrtifolia), hebe, lavender, rosemary and periwinkle.
No chemical plant protection products are available against Xylella. Biological control of the bacterium or its carrier offers potential in the long run.
Breeding programs are underway to make grape and citrus resistant.

Where to find


There is no treatment against Xylella. Felling of affected trees and all others in the wider area should prevent further infection.


Satellite images detect infected trees before they show visible signs of infection and are then cleared. And by felling all the olive trees and other susceptible plants (grape, peach, almond, oak, among others) in the wider area, buffer zones are created.