From Costa Rica to Europe, hidden within nursery materials and coffee plants: this appears to be the journey that brought Xylella to us. The first outbreak, detected nearly ten years ago, appeared in the hinterland of Gallipoli. But that was only the beginning. A second wave in 2015 struck crops in the provinces of Lecce and Brindisi. Today, Xylella has reached Fasano and is advancing at a rate of approximately 2 kilometers per month.
What is Xylella?
Xylella, or Xylella fastidiosa to use its scientific name, is a bacterium that spreads within the plant’s lymphatic vessels (xylem) responsible for the supply of water and minerals. The bacterial colony creates a dense, gelatinous mucilage that obstructs the vessels, blocking the flow of sap and causing the desiccation of part or all of the leaf canopy. It is now scientifically established that this bacterium is responsible for OQDS (Olive Quick Decline Syndrome), a plague that has been affecting centuries-old olive trees in southern Italy for several years. The main insect vector for this bacterium has the curious common name “spittlebug” (sputacchina), due to the foam it produces and lives inside to protect itself from evaporation and predators.
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What is the economic impact of Xylella?
While it has been found in about fifteen varieties of plants—including almond, cherry, and oleander—Xylella’s primary target is the olive tree. And for olive trees, the consequences are often disastrous. According to Coldiretti, olive production plummeted by 73% in 2018. Considering that Puglia alone produces more than a third of “Made in Italy” oil and that the territory comprises approximately 300,000 farms, 43 PDO (DOP) oils, and 4 PGI (IGP) oils—with a heritage of 250 million plants covering 380,000 hectares—the devastating scale of this problem is evident. Partial data from the 2019/2020 campaign further highlights that production in the Lecce area has decreased by 90%. Finally, one must consider the secondary industries involving seasonal workers and oil mills, which suddenly find themselves without raw materials to process and faced with the prospect of not even starting up their plants. In fact, news broke a few months ago that some mills in Salento were dismantled and moved abroad to Morocco and Tunisia. Consequently, oil imports from these countries to our shelves have seen exponential growth, replacing up to 60% of local varieties.
What is the current situation regarding Xylella?
As highlighted, the situation is extremely complicated for oil production in our country. Unfortunately, while focus was diverted toward confused conspiracy theories—seeking political consensus among local communities and pointing fingers at agrochemicals while suggesting they be replaced by planting aromatic herbs—time passed and the bacterium spread. The situation was further aggravated by the legislator’s actions regarding controls, uprooting, and precautions, which did not encourage the search for a real solution against Xylella.
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Science and Xylella: What does the law establish?
Looking at the most recent decrees adopted by various Ministers of Agriculture—from the “Martina Decree” (2018) to the “Centinaio Decree” (2018) and Decree-Law No. 27 (2019)—we find, unfortunately, that they are all aimed at the uprooting of olive trees and the massive use of herbicides and insecticides, including neurotoxic ones effectively banned by the European Union.
The legislated remedies are essentially reduced to:
- The massive use of herbicides and insecticides to combat the spittlebug vector, even during full bloom. This not only harms pollinator populations but also risks altering the quality of the final product. Furthermore, since the agricultural area involved covers hundreds of thousands of hectares, the millions of hectoliters of chemicals used would heavily pollute the soil and groundwater.
- Fines for those who oppose uprooting, not only of infected trees but also healthy ones within a 100-meter radius of the diseased ones—an approach that is entirely unscientific. Moreover, the large compensations linked to uprooting discourage any preventive or precautionary environmental approaches.
In short, following these legal decisions, the scientific community is not only ignored but actively hindered. True scientific research is limited and shackled by the law itself (Art. 6 of the Martina Decree, confirmed by subsequent decrees and Law No. 44/2019), which prohibits “anyone from possessing or moving live material of Xylella fastidiosa or any infected material derived from it.” This forces anyone wishing to study it to give prior notice to the Phytosanitary Service of the Puglia Region, to whom researchers are required to promptly communicate scientific results “before public dissemination.”
In addition to bureaucratic difficulties, a complex web of entities and laboratories that seem to have a monopoly on research has discouraged others from contributing constructively. The worst consequence, however, is the public’s resignation to the idea that this plague is unstoppable. This attitude leads to the justification of large-scale uprooting and the indiscriminate use of chemicals, overlooking the lack of a diversified and pluralistic base of scientific research.
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What are the possible solutions against Xylella?
As early as November 2015, research conducted by the University of Foggia demonstrated that 120 infected trees, treated with specific products (fertilizers and bio-stimulants, but not insecticides), were able to overcome the presence of the bacterium and survive. In 2016, the first olive trees of the Leccino variety—which are not immune but are resistant to the bacterium—were planted. Recently, the first harvest took place with encouraging results.
At Nanomnia, we have also embraced this cause. We have designed a multi-pronged approach to strengthen the plant while simultaneously limiting or even eradicating the bacterium. This involves an integrated method of nanotechnology, natural products, and new antibacterial molecules. However, we have encountered bureaucratic hurdles that effectively limit experimentation. Nevertheless, we remain focused on the problem and hopeful of finding serious new partners to prove the validity of our idea. Xylella can certainly be stopped.