Biology

Xylella fastidiosa, the Ebola of the olive tree

Xylella fastidiosa is a bacterium that causes a lethal disease for different plant species of economic interest, such as the olive tree or the vine. Hence, its introduction in Europe is triggering all the alerts.

The “Ebola of the olive trees”

The scientific name of this species, Xylella fastidiosa , has a rational explanation. The bacterium causes an incurable disease in several plant species, affecting their xylem. The xylem is the set of vascular bundles that transport water from the roots to the leaves of plants. On the other hand, it is called annoying because it is difficult to handle in the laboratory.

The "Ebola of the olive trees"
The “Ebola of the olive trees”

The disease caused by plants is called “Pierce’s disease” in honor of the first scientist who investigated it, specifically in California in the 19th century. The disease continues to affect fruit trees in the US more than a century later, causing about $ 100 million of damage each year in California alone.

This species affects the vine, the olive tree, the almond tree, the plum tree, the peach, the lemon tree and some plants without edible fruit, such as the laurel . There is no known treatment and the only way to prevent its spread is to cut down the affected trees. The problem with Ebola in olive trees is that until the first symptoms are detected, it can take a while, so the bacteria could spread undetected.

The plague was detected in Italy in 2013, specifically in Puglia (the southeast corner of the Italian peninsula). Since then it has spread to infect some 230,000 hectares and already affects millions of olive trees. Interestingly, no cases of citrus affected by the disease have been detected, so it is speculated that this strain only attacks olive trees.

In Italy, a quarantine zone has been established between affected crop fields and the rest of the country. Two containment zones had previously been established that were bypassed by the disease between 2015 and 2016. On this occasion, a protocol has been established to cut down all olive trees located 100 meters from any infected plant that is detected.

Presence of Ebola from olive trees in Spain

At the end of 2016, the disease was detected in olive trees on the Balearic Islands. Due to the virulence of the plague, periodic analyzes were carried out to detect the presence of the bacteria, and thus could be detected before the effects were disastrous.

For now, the only affected olive trees are the older ones, as young individuals tend to be more resistant to the plague . This could be positive for the olive oil industry but disastrous from a heritage point of view, as the blight devastates centuries-old olive trees.

Recently, in June 2017, the first case of the disease was detected in the Iberian Peninsula . Specifically in the town of Guadalest , in Alicante. If the authorities take action quickly and establish a quarantine zone like in Italy, the disease could be stopped and prevent it from spreading to the rest of Spain.

For now, a campaign has been carried out to make farmers aware of the problems associated with this disease. Traps have also been placed to capture sap-sucking insects, which are the vector of disease transmission between infected and healthy trees.

Conflict with environmentalists in Italy

Measures such as cutting down trees in the containment zone in Italy have not sat well with farmers, who have protested vigorously against the authorities. Rumors began to appear that the bacterium Xylella fastidiosa was not the cause of the plague, that the bacterium is easy to control without having to cut down the trees and even that the scientists themselves had introduced the plague into the country.

These rumors gained traction until they reached the ears of politicians and judges, who in some cases sided with environmental groups that were dissatisfied with the official version of events. In an unexpected twist, researcher Donato Boscia, from the institute of the Institute for Sustainable Plant Protection in Bari, was formally charged with causing the disease and an investigation was opened .

As a consequence, the institute’s computers were confiscated and the work of scientists trying to figure out how to stop the plague was stopped. The measures proposed by these environmental groups, which are not based on any scientific study, have not been shown to be of any use to date and the disease continues to kill affected trees.

Hopefully in Spain the disease is contained in time and environmental groups do not prevent trained researchers from carrying out their work.

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