Mysteries of Xylella Fastidiosa

Real or virtual threat for the olive trees?


Since 2013, when Italy, announced a new and mostly unknown disease, Xylella fastidiosa, the European olive trees are threatened. Today, we publish an exclusive documentary, a book of 1789 (the year of the French Revolution and the fall of Bastille!), which forces us to revisit this case under a different angle.

Back to 1789

A book written in Naples, in 1789 by Cosimo Moschettini, professor of Medicine and Philosophy, was dedicated to a tree disease which expanded in Otranto and was called “Brusca”.  On the page 15, is referred epigrammatic: “Brusca, is an illness our olives suffer from and the most vivid greenish crowns, sometimes together with softer shoots, “die” and dry rapidly, detach from it and fall, leaving the burnt tree.”

In other words, Brusca of 1789, looks the same with Xylella fastidiosa of 2013 and breaks out in approximately the same area. From now on we have to answer to some difficult questions.


First of all: 2013

In October of 2013, Italy informed the European Commission and the other Member States about the presence of the disease Xylella fastidiosa in the province of Lecce (Apulia Region, South Italy), mainly in olive trees, almond trees and oleanders.

Actually, it is the first time that this disease appeared in the EU. The European Commission has adopted the Decision 2014/87 (13.02.2014) which has taken mild protection measures, prohibiting the uncontrolled movement of plants from Lecce to elsewhere.

Measures are tightened: 2014-2016

Xylella Fastidiosa is spreading in new areas affecting other plant species (ornaments in Corsica, in France, crops in Spain and olive trees in Taranto and Brindisi). In response, the European Commission scales with Decision 2015/789 and its amendments, with a series of measures, among others:

  • Initially Lecce is considered an “affected (demarcated) area” which includes all plants that are infected or simply symptoms, even those which may have been infected.
  • Around the affected area is determined a “safety (buffer) zone” of at least 30 km.
  • It orders the removal (cutting and destruction) of all plants that have been infected.
  • Broadens the initial plant catalogue that are susceptible to infection, which reach the number of 359(!); almost anything that grows.
  • Obliges nurseries to maintain the rules of traceability for material handling.
  • The expansion in southern Italy, led to new data. As for the province of Lecce the elimination of Xylella fastidiosa, is no longer possible, hence reduction measures must be followed, the eradication of at least the proven affected trees. The provinces of Taranto and Brindisi are characterized as containment zones with the obligation to be eradicated within a range of 100m from the affected plants, even the plants-hosts, regardless of their health. In other words, the creation of a huge “dead-zone” where almost nothing must grow. The absurdity is that in the center area (Lecce) the measures are softer than the surrounding regions.xylella-fastidiosa2

European Court of Justice

These EU decisions will lead, if applied, to a huge disaster (economic, ecological, social) of olive growers of southern Italy, who, as is logical, reacted and appealed demanding their annulment.

Finally, in June 2016, the European Court rejected completely the Italian appeals considering the decisions of the European Commission as absolutely valid. However, the prosecutor has noted that the olive growers, whose olive trees have been damaged, should take compensation, laying the blame to the Italian government.

It is better to predict

This case (should) concerns directly Greece, and not only, because if there is such a disease as Xylella fastidiosa, the threat for the Greek olive trees is going to be real. And then…

It is certain that the bacterium Xylella fastidiosa has endemic in America and in the end of 19th century has affected seriously the vineyard of California. But until October of 2013, when detected in Apulia of Southern Italy, Xylella f. had never gone on EU soil or tree (see annex of Directive 2000/29). So Xylella f. makes a jump of 120 years, hundreds of thousands of kilometers by an insect that supposedly transmits the contamination/infection within a radius of 100 meters, according to EU scientists.

Here it comes the document that we are publishing today that refers to a disease, Brusca that has similar characteristics with Xylella fastidiosa. Brusca has been detected 224 years before, in 1789, at the same region and to the same trees of Southern Italy.

EFSA’s opinions have been undergone to amendments the last two years and also they diverge from other scientific views by Italian side. There are critical and ambiguous “details” as, if there is a causal relationship between the bacterium Xylella fastidiosa and fast drying symptoms of olive trees, if the dry olive trees germinate again, what are the geographical limits of the action of the insects, which are the vulnerable trees, if Xylella fastidiosa is enough to infect olives and who and why are the other reasons that should help.

The European court, although recorded- albeit indirectly- the ambiguity that surrounds the scientific data and facts, finally has decided based on the “precautionary principle” (so not to extend the Xylella fastidiosa in the rest of the EU territory):

  • To rejected the Italian objections
  • To insists on the full implementation of the measures
  • To shifts to the Member State(Italy) the compensation of olive growers

Both are, therefore, the main views and versions:

  1. According to the first, Xylella fastidiosa came from America, with a delay of about 120 years, with host rather some ornamental plants and oleanders. For unknown reasons (and coincidences), it settled in Lecce, a southern Italy region, and it keeps spreading from there, threatening to even greater losses.
  2. According to the second, what we call Xylella fastidiosa has the same symptoms and therefore speculate that it is the same disease that had been recorded since 1789 as Brusca, which had appeared in the same region of southern Italy. So, it is not a new problem, but an old one, which reappeared today, possibly due to lack of olive cultivation, as growing olive trees (pruning, fertilization, irrigation, plowing) does not allow the appearance of the bacterium.

Regarding to which of these two versions is correct, at the moment the science of agronomy is unable to give a complete and certain answer. The question is not academic, as many powerful interests, which many articles and books have reported, intervene:

• Olive cultivation is affected in the capital olive oil producing region in Italy. The blow is not only productive and economical, but even ecological, cultural and detrimental to agrotourism, as it affects the whole image of Italy.

• The creation of this “buffer zone” by the eradication of olives and other plants, favors the interests of those who wish to change the land use or producers who want to “get rid of” perennial olive trees, or/and those planning urban expansion, hotels, etc.

In conclusion, guard and look after your olive trees so they will not be afflicted by Xylella fastidiosa / Brusca, especially if lack of olive cultivation is a key reason for the emergence and growth of the bacterium. Besides, the Professor of Philosophy and Medicine and author of the book refers to the wise words of Virgil on its cover: “Fortunate is he, who is able to know the causes of things”.

Finally, I would like to thank the agronomist George Kostelenos for the valuable document and the useful discussion.


How it works

The bacterium colonizes the plant’s woody vessel and normally transmitted by insects belonging to the families Cicadellidae and Cercopidae and they are feeded by the plant’s woody vessel. The insect of the family Cercopidae, with the scientific name Philaenus spumarius, which is a very common polyphagous insect and abounds in trees is considered the responsible sector for the spread of the bacterium in Apulia. Symptoms associated with the presence of Xylella fastidiosa in plants vary widely and can cause full necrosis of the plants within a few years, depending on the kind of the host plant, the severity of the infection and weather conditions.

  • Vasilis Zampounis