HomeIdeaXylella Fastidiosa, the solution at your fingertips

Xylella Fastidiosa, the solution at your fingertips

XyIlella Annoying, origin or symptom of one of the most serious crises in the Italian agricultural system. 5 years of battles including judicial and diatribes still in search of solutions. History, analysis and evidence of a solution that comes from scientific research Made in Italy:, already successfully tested but still underestimated. With a view to conserving olive trees and restoring depressed ecosystems.

Apulian olive growers, 5 years of battles

February 2019 will be remembered by agricultural communities in Italy for the sheep milk crisis in Sardinia, but also for that of olive growers in Puglia. The 'orange vests' have been trying for months to draw attention to the misfortunes that afflict them, Xylella Fastidiosa and missed reimbursements for the frosts of February 2018. In addition to the inefficiency, ca va sans dire, of the Rural Development Plan (PSR).

The battle of the Apulian olive growers has continued without respite since October 2013, when the Regional Phytosanitary Service was informed of the probable presence of Xylella Fastidiosa on some olive trees near Gallipoli (Le). The Puglia region immediately adopted the first measures, to try to eradicate the pathogen or at least stem its spread. The infected territory was divided into zones, establishing a calendar of interventions for the management of plants and land due to the proximity to the outbreaks. (1)

Minister Gian Marco Centinaio, with decree 14.2.19, adopted the 'Intervention plan for the relaunch of the agricultural and agri-food sector in the areas affected by Xylella'. With a total allocation of 100,65 million euros (48,05 from MiPAAFT, 52,60 from the Region) to compensate, at least in part, the damage caused by the plant disease that is damaging the olive trees. In addition to the 30 million euros assigned by the Interministerial Committee for Economic Planning (CIPE), on 9.2.19, to the new 'Emergency plan for the containment of Xylella Fastidiosa '. (2)

Xylella Fastidiosa, the symptom of the crisis

Xylella Fastidiosa it is a bacterium asporigenous gram-negative which colonizes the xylem vessels of plants and occludes them, preventing the sap from reaching every part of the plant. Symptoms are often similar to those deriving from water stress (leaf bruscation, drying of branches and portions of the canopy). And it is not easy to identify them at the first infection, as they manifest themselves even after a year.

The plant continues its biological cycle and produces healthy fruits (albeit in smaller quantities), until the bacterium reaches the roots, prevents it from absorbing nutrients and thus leads to its death. The bacterium has several sub-species (the ST53 strain, in Puglia) and spreads through different vectors. Like the Medium Spittoon, Philaenus spumarius, which feeds on the tender leaves of the olive tree and spreads the bacterium to other plants.

The spittoon it can travel up to 100 meters a week and thus spread the pathogen with potential rapidity (also due to possible passive journeys, by means of vehicles and wind). Precisely for this reason, a quick and incisive intervention would have been useful, which nevertheless suffered slowdowns due to scientific uncertainties on the bacterial strain and consequent disputes. (3)

The pathogenicity of the bacterium it is still doubted by some parts, although the scientific community has shown proof of it by demonstrating Koch's postulates. In fact, some consider the impoverishment of the soils due to the massive use of pesticides and herbicides (rather than the presence of wood fungi and moths Zeuzera Pyrina), as the primary cause of plant diseases.

Xylella, the Italian-European debate

The discordant positions they have collected the consensus of associations and politicians interested in protecting olive growers (or more likely their votes and favors), in the face of the more drastic prospect, the eradication of olive trees. The conspiracy theory inevitably arose, with the result that most olive growers felt 'safe' without having to do anything to try to stem the infection or to save their plants.

The European Commission intervened with two subsequent measures:

- in 2014 Brussels banned 'the movement of plants destined for planting out of the province of Lecce, Puglia region, Italy '. By ordering official annual inspections to ascertain the presence of the bacterium Xylella and ordering Member States to collect reports on areas at risk,

- in 2015 he then ordered the most drastic measure, the eradication. To be extended to all plants potentially host to the bacterium within a radius of 100 m from the infected olive tree, regardless of their apparent state of health. (4)

In 2016 the EU Court of Justice ended three years of debates. Affirming that the eradication obligation results'appropriate and necessary ' to ensure a high level of phytosanitary protection in the European Union. (5) Taking into account the scientific evaluations expressed by EFSA, according to which there is no cure for phytopathy. Although 'It is possible that changes made to the growing systems (e.g. pruning, fertilization and irrigation) have some impact on the disease, but this is generally not enough to cure the plants'. (6)

In 2017 the TARs of Lazio and Puglia they therefore rejected the innumerable administrative appeals against the orders for the uprooting of infected trees, affirming the priority of interest in safeguarding the health of plants and the duty to apply the precautionary principle.

In January 2019 the Public Prosecutor of Bari ordered the seizure of an infected olive tree found in Monopoli. Gathering the harsh criticism of the spokesmen of the 'orange vests' and of Confagricoltura, who instead invoke the green light for the eradication of any plant that is positive for the analyzes. Already in 2015 the Lecce Public Prosecutor's Office obtained the preventive seizure of some plants, indicting Commissioner Giuseppe Silletti (delegate for the management of the Xylella emergency) and 9 other experts.

Xylella, the traveling bacterium

Phytopathy advances towards the North, where the Puglia Region gradually redefines the boundaries of the 'delimited' areas (infected areas and buffer zones). From 2013 to today, the affected area has expanded from 8 hectares (in the province of Lecce alone) to 715 hectares. The entire provinces of Lecce and Brindisi, a large part of that of Taranto and some municipalities in the Bari area. 36% of the Region, about 21 million trees (out of a total of 60).

One third of Italian olive oil it is produced in Puglia (40-45% extra virgin, 30-35% virgin, 25-30% lampante), where the olive production expresses 15% in value of the regional agricultural production. Phytopathy would have contributed to the cessation of activity of about 400 mills in the last 5 years. The Centinaio decree will now be implemented through the assignment of roles and responsibilities, simplification of process of eradication and incentive for replanting of cultivar that tolerate the bacterium (eg. Leccino, Fabulous FS17).

Other outbreaks however, of different sub-species have already been reported in Spain, as well as in France. Stopping the spread of the bacterium therefore appears unrealistic, if not entirely utopian. Without losing hope, we must rather stimulate the resilience of those same plants that already feed the economy of the two leading world producers of olive oil, Spain and Italy. Respecting i cultivar originating, maybe even.

Olive trees in Salento, the underlying problem

The olive tree in Salento it is a poor tradition crop, with very low margins, historically destined to produce lamp oil (lampante, in fact). Saving on management has always been an imperative, to the point that the olives were collected from the nets thrown on the ground and brought to the mill after several days, without haste or care for the oxidation of the drupes.

The earth though it was worked, at least under the plants. Until systematic chemical weeding took over human work. (7) With the result of eliminating the organic substance in the soils. The olive growers believed they were saving money (the harder the earth, the better it worked) and instead caused the pre-desertification of the land (below which limestone rock is often found). Water and systemic stress.

The biologist and phytopathologist Margherita D'Amico, project manager 'Ecocompatible fight systems against the Codiro', found that the dominant plant species in Salento are those resistant to glyphosate. Therefore proposing to verify if and to what extent the broad-spectrum herbicide has afflicted the roots, which in the diseased olive trees of Salento have often turned out to be rotten.

Scientific researches conducted in Puglia following the emergency, according to the researcher, they never considered the root system. Although international studies conducted on the bacterium, as early as 2004, have shown the deterioration of the xylema of trees. That is to say the tissue of vascular plants, from roots to leaves, used for the conduction of the raw sap (ie water and the solutes dissolved in it).

The study on olive groves conducted by the University of Basilicata over a period of 15 years highlights in turn the need for analysis on the soils and roots (of the plants infected by the bacterium as well as those exposed to the relative risks, for the purpose of an exact diagnosis of the problems to be faced. Where the lack of organic substances already in itself constitutes the premise of various pathologies and unproductivity, with respect to which an intervention to restore lost balances is indispensable. (8)

Mycorrhiza, the solution Made in Italy: handy

'Biodiversity of an agricultural soil, Xylella cause or consequence?'Giusto Giovannetti - brilliant biologist of the Experimental Cultures Center (CCS) of Aosta, which the writer has had the honor of knowing already in distant times - has been working for decades on microbial bacteria to promote health, resilience and plant growth. In fact, microbial communities intervene on the rhizosphere (from the Greek rhìza, root e sphaira, sphere), i.e. the portion of soil around the roots from which plants absorb the nutrients and water needed to grow. Through mycorrhizae.

The mycorrhizae (from the Greek mikos, mushroom and rhìza, root) are symbiotic associations between soil fungi and non-lignified roots of plants. The host plant transfers organic materials (sugars, proteins, vitamins) to the fungus and obtains a better absorption of nutritional elements. Where mycorrhizae develop (as in nature, near 90% of the trees in the woods) the plants are healthier, more vigorous and less subject to environmental stress. (9)

The experimentation conducted on 1350 olive trees in Presicce (LE) with a group of farmers from 'Sustainable Salento'was based on an intervention to recover the microbial heritage of the land, through the inoculation of a high concentration of microbial biota. The metabolic function of the olive trees was thus reactivated, with more than positive results. After the treatments, in fact, sprouts on the main and secondary branches were highlighted, as well as basal suckers also on already dry sections.

Il cocktail of microbiota used has been produced by CCS in the Aosta Valley for several decades and is regularly used to improve soil health. The vascular system of the plant is in turn rich in biota, which is in fact absorbed by the soil in good health. Microorganisms, for millions of years, have been a living part of plants and animals and therefore activate a sort of 'positive epidemic'. The 'super-organism' tends to recover the functions weakened by stressful conditions thanks to the rebalancing of the symbiotic activity. With an intervention in some ways similar to what can be achieved with the prebiotics on the microbiome human.

Conclusions. System or brain crisis?

Since the mid-twentieth century microorganisms (considered pathogens) were considered enemies. And it seemed reasonable, at the time, to plan for its elimination. However, the mistake that is repeated - and is no longer justifiable, in the current state of research - is instead that of continuing to destroy indispensable microorganisms, under the pretext of destroying harmful ones. This approach is already under review in medicine, where i Probiotics they are often more effective than antibiotics, on which it has matured widespread resistance. And it is time for it to be reconsidered also in agronomy.

'To fight the bacterium it is necessary to look at the olive grove as a whole and improve its "immune system", adopting sustainable agronomic practices that increase the ability of plants to counteract biotic and abiotic stresses. By doing so, it is possible to live with the bacterium, limiting its spread and recovering infected plants'. (10)

The eradication of millions of olive trees - today in Puglia, tomorrow who knows - will benefit the economy of the sectors concerned in the short term. It is therefore no wonder that the vultures financed by seed monopolies and pesticides praise rainfalls, to devastate and rebuild. The question remains whether it is right for us and for our children to persist in destroying thehabitat and its unique landscapes. Instead of looking after the ecosystem and the biodiversity, developing a healthy economy free from standardized seeds, herbicides and pesticides.

Dario Dongo

(with the collaboration of Marina De Nobili and Guido Cortese. Cover photo by Alberto Mileti)


(1) In the face of the immediate danger of the spread of harmful organisms such as the one under consideration, Member States must indeed take provisional protective measures. See dir. 2000/29 / CE, 'concerning protective measures against the introduction into the Community of organisms harmful to plants or plant products and against their spread within the Community'

(2) In addition to the Agricultural Operational Plan, with use of the residuals of the Fund for Development and Cohesion 2014-2020

(3) Xylella Fastidiosa it had been extensively studied in other areas of the planet (especially in the USA, where Pierce's disease caused by it has affected the vines) but not so much in Europe

(4) See decisions (EU) 2014/497 and 2015/789, both relating to 'measures to prevent the introduction and spread within the Union of Xylella fastidiosa (Wells et al.)'. The European Commission, after notifying the Italian government, in December 2015 referred Italy to the Court of Justice. And the sentence is still awaited (of conviction, in all probability)

(5) ECJ, joined cases C 78/16 and C 79/16, judgment 9.6.16

(6) See EFSA opinions 6.1.15 and 20.3.15. Margherita Ciervo, geographer of the University of Foggia, notes how both documents of the European Food Safety Authority lack scientific evidence on hypothetical successes of eradication

(7) The provinces of Lecce and Brindisi reached the podium for the consumption of herbicides (Istat data, 2003-2008)

(8) See Cristos Xiloyannis, Adriano Sofo, Assunta Maria Palese (2015). 'Against olive Xylella, good agronomic practices'. The Agricultural Informer, 19-2015, https://www.scribd.com/document/378573314/Xylella-articolo-Xiloyannis#download

(9) On mycorrhizae and the works of CSS, see also https://www.arsacweb.it/wp-content/uploads/2016/07/Opuscolo-funghi-micorrizici.pdf

(10) See note 8

Computer scientist and professional beekeeper. A former conscientious objector, he served and then volunteered in a canteen for the homeless in Turin. He deals with the right to food, food policy, food sovereignty and biodiversity. He founded the association of Metropolitan Pollinators with the aim of defending biodiversity through specific projects of social and environmental regeneration. He represents the Slow Food Community of Metropolitan Pollinators. He promoted the birth of the national network of urban beekeepers. He directs an independent agricultural market, collaborates and writes for Egalitè (Onlus Rome) which deals with defending the rights of disadvantaged people, and with the newspapers Great ItalianFood Trade, Qualiformaggio, L'apicoltore Italiano and minor magazines.


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