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One day the olive trees began to die

Ever since I was a child, the son of a southern Italian father and a German-speaking mother, I knew about a certain line that is said to divide Europe into two different parts. This invisible border had no fences, was not marked on the maps and didn’t really exist, yet even a child like me understood that it was real: the olive oil-butter line.

I also knew that my region, Puglia, was south of this border, where people eat a lot of olive oil, while those to the north only have butter, which explained why they were so happy when, on our yearly road trips to visit my mother’s friends and relatives, my father brought them some of our olive oil, and they treated it like liquid gold. Personally, I used to find it too strong and rather boring, a bit like the job of making it, which mostly consisted of picking olives on cold, autumn Sundays. Yet already back then I knew olive oil was somehow important, and I couldn’t help noticing that when my mother’s friends and relatives came to visit us, they never brought us any butter.

Whether this line does indeed exist or not, the world it encloses shares many real things, and one of the most visible ones has, in fact, much to do with olive oil. While butter is produced mostly in closed spaces, the cows living in distant farms we often don’t want to know too much about, the trees that make the olive oil we eat can be seen everywhere among us, and all across the Mediterranean Sea. From Portugal to Syria, people and olive trees have established a relationship that has shaped the landscape of the entire region, as much as it has influenced our cultures and even our religions, and has endured for thousands of years. Knowing that some of these trees have been standing since long before our ancestors even came to these lands, we might be excused for believing that the olive trees will always be there, just as we will always prefer olive oil to butter.

Yet today our relationship to these trees, and therefore also the olive oil we eat, is threatened by a newcomer to our region: Xylella fastidiosa, a bacteria from Central America. To understand the seriousness of this threat, one has to look at the very heart of the Mediterranean Sea, where this relationship is maybe the strongest: Puglia, in Southern Italy, a land on which some four million people who eat a lot of olive oil live among more than fifty million olive trees.

Over the past ten years, vast numbers of these trees have died in Salento, the southern part of this peninsula that is known for its centuries-old, beautiful olive groves, many of which now look like eerie cemeteries of desiccated trees. “The disease began appearing in various places”, I was told by Antonio Matino, a farmer who lives right in the middle of the infected area, “and then exploded over a very short period of time”. He said he would take me to visit his olive grove, and after a short drive he stopped his car in the middle of an empty field, with a few wooden trunks standing in the middle. ”Here I used to harvest five tons of olives every day, and now look at it. This is our situation now.” While there is still much to learn about the exact causes of this disaster, scientists have established its connection to Xylella fastidiosa, a plant pathogen whose presence was detected in the olive trees of Salento in 2013.

This bacteria has a long relationship with human agriculture, and has been the scourge of wine, coffee and citrus growers in the Americas since the late 19^th century. Identified only in 1987, Xylella fastidiosa takes its name from the “xylem vessels” of the plants that it colonizes, sometimes growing until these vessels become clogged, causing the branches to wither and die. Beside the movement of infected plants, its only mean of transmission is through small insects that feed on sap, as for example the many species of spittle bugs and leafhoppers that can be found almost everywhere on this planet.

Every spring, the fields of Puglia are literally full of these bugs, and at some point one of them must have fed on an imported, ornamental coffee plant that was infected with a strain of Xylella fastidiosa found in Costa Rica, according to the scientists of the CNR (National Council of Research) and the University of Bari who were the first to find this bacteria in the affected olive trees while looking for the causes of the sudden die-off. Because of its capacity to mutate and colonize a wide range of cultivated plants, and of the fact that to this day, nobody has been able to find a cure to the many diseases it causes in these plants, Xylella fastidiosa is universally regarded as a “quarantine organism”, a pest that has to be contained because of the danger it poses to the world’s agriculture.

And this danger appears to have materialized in Salento, where trees that had stood for hundreds if not thousands of years have been getting sick, their leaves turning yellow and the branches withering one after the other, until the entire plant is nothing but desiccated wood. “For us the death of an olive tree was a taboo”, I was told by the president of one of the province’s main unions of farmers, Pantaleo Piccinno, “we did not understand that we were faced with a one-in-a-million-years event. We couldn’t accept, psychologically, that a tree that for us is a symbol of longevity, that we always thought to be eternal, could die. In our experience as farmers, olive trees don’t die, and even if they burn completely, we know that they will grow again”. In the area where the outbreak began, around the seaside town of Gallipoli, thousands of olive trees have died in this grim manner, throwing entire communities into despair and causing untold financial damage. “In my farm”, Piccinno continued, “I expect to loose 80% of the production by next year, and after that, I don’t think we will harvest any olives”. And this catastrophe does not only affect farmers, since the production of olive oil is a central element of the area’s entire economy: “when there is bad harvest, a farmer can wait it out. But the mills, the cooperatives, they can’t afford it, they took out loans, they have workers to pay, and many other expenses. We will loose the entire supply chain, and this will affect the entire territory. Paradoxically, the loss of the trees is the least worrying element. Trees can be replanted, but once you loose all the rest, there is no more olive sector.”

To make matters worse, the outbreak is also threatening the region’s flourishing tourism industry, whose appeal is also based on the olive trees and their special place in the landscape and the local culture, something that also played a role in slowing down the initial response. Giovanni Martelli, the professor of plant pathology of the University of Bari who suggested Xylella fastidiosa as the cause of the outbreak, remembers that “there was a plan to put up signs to warn people about the carrier insect, and to be careful when moving tractors and other materials from the infected zone, but the proposal was rejected because signs saying that there was an infection would scare tourists.”

According to international treaties such as the International Plant Protection Convention (IPPC), “quarantine organisms” must be prevented from spreading at all costs, which usually means destroying any newly infected plants or animals. Thousands of chicken and pigs are routinely slaughtered to contain diseases such as bird flu or swine fever, and similar measures where immediately planned by the Italian authorities, which declared a state of emergency and set up a monitoring program to find and eradicate the infected trees, together with any other plant that could host the bacteria within a radius of 100 meters, in order to prevent the infection from spreading.

However, these plans did not take into account the visceral attachment that the people of Puglia feel towards their olive trees, and the distrust towards both the authorities and mainstream science that pervades our contemporary societies. According to Martelli, “with other diseases, the infected plants or animals are immediately destroyed, and nobody says anything, because if I cut down a peach tree, nobody cares. But if one cuts down an olive tree, all hell breaks loose. It has a strong impact on the media, on the society, even on the psychology of people. And even I can understand it: looking at an olive tree and looking at a citrus tree is not the same thing.” Faced with the eradication of thousands of olive trees, most of which appeared to be perfectly healthy, vast sections of the population of Salento rejected the authorities’ containment plans and mobilized against what they saw as a plot to destroy their beloved olive trees and alter the landscape of their region.

Olive trees are protected by law in Puglia, and many saw the outbreak as an excuse to repeal this law, opening up the countryside to speculation and “land grabbing”. While much of this opposition was undoubtedly fuelled by a mix of denial and online conspiracy theories about the impending replacement of the region’s centuries-old olive groves with genetically-modified varieties, others simply challenged the science on Xylella fastidiosa, putting forward alternative explanations for the die-off which they sought to prove through several field experiments on different treatments to save the olive trees.

After eradicating a few hundred infected plants amid furious protests and acts of civil disobedience, in 2015 the entire management of the emergency was put under investigation by the judiciary, which also confiscated the trees marked for eradication and essentially froze the authorities’ containment plans. The accusations, based on countless appeals and complaints filed by tree-owners and activists, were somewhat bewildering: the scientists on whose work the authorities’ response was based were accused both of having invented the connection between Xylella fastidiosa and the die-off, and of having recommended measures that were useless to contain the bacteria. The prosecutors went as far as suggesting that it had been introduced to Puglia on purpose, with the goal of “altering the agricultural tradition and territorial identity of Salento by means of their replacement with super-intensive growing systems and new varieties of olive trees”.

At the heart of the controversy there is a disagreement on the nature of the disease affecting the olive trees of Salento. The automatic, mandatory measures prescribed by the international regulations on “quarantine organisms” clashed with the degree of uncertainty that inevitably accompanies scientific research, especially on a complex issue such as the connection between a pathogen and a certain pathology. Research projects on plants, and especially on slow-growing plants like olive trees, can take years to yield results, as shown by the fact that more than thirty years after its identification, no definitive cure has yet been found to the any of the many diseases caused by this bacteria. “We known that there things that are bad for the bacteria”, professor Martelli explained me, “but the problem is bringing them inside the plant, where the bacteria lives.”

Before the scientists working in Bari could prove the primary role of Xylella fastidiosa in causing the death of the trees, other possible explanations were investigated, leading to the initial definition of the disease as “Co.Di.R.O.”, an Italian acronym referring to a “complex” of causes of the die-off, which also included other pathogens such as harmful insects and fungi that were found on the affected trees. “Olive trees are very vulnerable to fungi”, according to plant pathologist Antonia Carlucci, “and this vulnerability can be increased by poor soil conditions.” She went on listing the countless pathogens she encountered in her research on the die-off in Salento, explaining how in her laboratory at the University of Foggia, she has an entire refrigerating room full of unknown fungi she found all across Puglia, waiting to be identified. “I work on the Xylella fastidiosa outbreak and I can personally confirm that the bacteria exists”, she concluded, “but I can also tell you that when we examined the affected trees, we always found the whole plant to be in bad conditions, with fungi and plenty of other pathogens. How can we say that they don’t also play a role in the disease?”

These investigations then expanded into a wider look at the general condition of Salento’s olive trees, looking at the effects of the monocultural and intensive nature of olive growing in the region. Because of the low price of olive oil, most farmers in Salento harvest their olives from the ground, and use herbicides such as Monsanto’s Roundup to make this operation easier, a practice that produces low-quality olive oil and has impoverished the soil, reducing its organic matter and destroying its microbial flora. “In many areas of Salento we found less than 1% of organic matter in the soil”, Roberto Polo, who is researching ways to restore this destroyed microbial flora, “and keep in mind that according to FAO, a soil with less than 2% of organic matter is at risk of desertification. This is especially bad for the microbes that live on the trees’ roots, which cannot survive without organic matter to eat, and are just as important as the microbes that live in our intestines, without which we cannot survive.” Combined with a general decline in fundamental agricultural techniques such as pruning, also caused by the low price of oil, the olive trees of Salento appeared to be in very poor health, which could explain the proliferation of well-known pathogens, and also the trees’ vulnerability to the newly arrived Xylella fastidiosa. This wider approach was immediately embraced by activists and concerned tree-owners as proof that something could still be done to restore the health of the trees, and possibly to allow them to withstand the bacteria, making their eradication unnecessary.

At the same time, both the European regulations and the growing calls for drastic and immediate measures by the rest of the region’s olive oil producers, whose sector employs thousands of people and generates more than half a billion euros of value every year, led the authorities to immediately focus their efforts on the bacteria and on finding resistant varieties of olive trees, in a way confirming the opposition’s worst suspicions that the authorities had already given up on their trees, or had always been bent on their replacement with other cultivations.

These two approaches generated two radically opposed camps, and their disagreements quickly degenerated into open hostility, with each side accusing the other of endangering the future of the entire region. As a result, accepting any part of the opposite view, no matter how self-evident or supported by scientific research, became totally impossible, preventing a meaningful debate about a controversy that goes much beyond a disease of plants, and should concern all the people who eat a lot of olive oil, wherever they live on the shores of the Mediterranean Sea.

Immediately after the detection of Xylella fastidiosa in the olive trees of Salento, all countries in the region began monitoring the presence of the bacteria. While most countries declared to be Xylella-free, such as Israel in 2015, other strains of the bacteria were detected in France, Spain, Portugal and even in Germany. Only a few of these new outbreaks affected olive trees, yet they indicate that infected plants continue to be brought to Europe, and that Xylella fastidiosa is capable of spreading much beyond Puglia.

This risk was predicted long ago by one of the world’s greatest experts on Xylella fastidiosa, Alexander Purcell. In a paper published in 1997, he analysed the correlation between climate and the disease that this bacteria causes in grapes, known as Pierce’s Disease, and concluded that “tropical and subtropical climates, including Mediterranean climates, are probably most at risk to X. fastidiosa”. Aware of this risk, once the bacteria was detected in Puglia, the various regional and national plant protection organizations of the region, such as the European and Mediterranean Plant Protection Organization (EPPO) and the Near East Plant Protection Organization (NEPPO) began cooperating and held several conferences and workshops at the International Center for Advanced Mediterranean Agronomic Studies of Bari (CIHEAM-IAMB) whose results are collected in a publication, “Xylella fastidiosa & the Olive Quick Decline Syndrome (OQDS). A serious worldwide challenge for the safeguard of olive trees”.

Throughout these research papers and reports, these organizations “strongly expressed their concern and the need to get information and training for setting up efficient measures for preventing the introduction and spread of this pathogen and its vector”, with the delegates from the FAO Regional Office for the Near East and North Africa noting that the strain of the bacteria found in Puglia “poses an enormous threat to olive production in all the Mediterranean countries”.

And the climate is not the only element in the region that is favourable to Xylella fastidiosa: this pathogen is capable of infecting more than 350 different plants, with at least 20 affected by the specific strain found in Puglia. Among this remarkably wide range of hosts, one can find many of our most important cultivations: grapes, almonds, peaches, plums, citrus and many others, making this bacteria a threat not only to olive growers, but the our entire agriculture, a concern shared by most plant protection organizations, whose respective Pest Risk Analyses (PRA) all confirmed this high degree of vulnerability. According to doctor Ofir Bahar, a researcher from the Agricultural Research Organization – Volcani Center of Rishon LeZion, this bacteria “is a threat to practically any country that grows these plant species”, and while the specific insects that transmits it in Puglia and in America are not known to be in Israel, “this does not rule out the possibility that there may be other insects that could serve as vectors. Israel grows a lot of olives, citrus, grapevine, almonds and more susceptible crops, so these crops are under threat of Xylella fastidiosa.”

Since there is still no known cure to the diseases caused by this pathogen, there are only three available Pest Management strategies at the moment: exclusion, preventing it from entering a new area; eradication, which means its elimination from any newly infected area; and containment, aimed at preventing it from spreading out of an infected area. The experience of Puglia proves how difficult the last option can be, and most scientists agree that “there is no record of successful eradication of X. fastidiosa once established outdoors due to its broad range of host plants and vectors”, leaving exclusion as the only certain way to neutralize this threat. However, the long series of new outbreaks detected since monitoring began seem to indicate that, in our globalised and inter-connected world, not even this option is truly realistic, especially within the context of free trade agreements or regional common markets such as the European Union. The report by Valencia’s Institute for Agrarian Research takes the example of Puglia as “the paradigm of how the plant pathogenic bacteria have been able to overcome the European legislation that protects the international trade without taking into account the phytosanitary risks”, adding that while the EU “reacted fast against this pathogen”, there is still a vast amount of host plants imported in previous years that were never analysed, such as “35000 t of potted plants imported every year since 2010 to 2014 from Costa Rica, Guatemala, Honduras and other countries where this pathogen is present”.

Since it is even possible that Xylella fastidiosa might already be present throughout the Mediterranean region, the experts agree that every country should prepare for the worst, and immediately set up contingency plans. In doing so, it might be useful to look at what happened in Puglia, where all three Pest Management strategies failed one after the other, allowing the bacteria to spread essentially unchecked. The infected area now stretches over more than 100 km and encompasses the whole of Salento, where the vast majority of olive groves are affected, olive mills are closing down after centuries of activity and entire swathes of the countryside have turned into a desert. “Over the coming harvest seasons we will witness a terrifying decline in production”, Piccinno made sure to tell me in 2017, and his prediction seems to be coming true. According to reports from his farmers’ union, the production of olives in the affected province was 50% below the average in 2016, 75% in 2017 and 90% in 2018, leading to similar drops in the numbers of people employed by the sector and causing damages for more than 1.2 billion euros.

Feeling vindicated by reality, and with the judiciary investigation shelved for lack of evidence, scientists and politicians now point the finger at environmentalists and tree-owners as one of the causes of the catastrophe, denouncing their irrational attachment to olive trees and calling for harsh penalties on those who refuse to follow the containment plans. “Look at what happened in Oria”, Martelli said in regard to the first hotspot detected far from the initial infected area, “we detected it very early, and then what happened? The judiciary confiscated the trees, before we could eradicate them. And now the entire countryside is infected, and everybody can go there and see it.” The alternative explanations for the die-off are described as pseudo-science, and are accused of having created a false hope that the trees could be saved, pushing the population to oppose the containment plans of the authorities.

While it is true that most of those who struggled to save their olive trees, whether by appealing the eradication orders or by experimenting with alternative treatments, eventually saw them succumb to the bacteria, and that the widespread refusal to accept the reality of Xylella fastidiosa was irrational and unlikely to occur in places where people have less of a personal relationship to their trees, it is also true that similar protests are also taking place in Spain, where the government is planning to eradicate some 100,000 almond trees in order to contain their own outbreak, and that the opposition to the authorities’ containment plans has evolved over time, as did the plans themselves. Since eradication is no longer possible, the focus has shifted on slowing the spread of the infection while scientists look for a cure, which is proving just as controversial.

Unable to act against the bacteria itself, the authorities are now attempting to eliminate its carrier insect though “compulsory phytosanitary measures” meant to destroy its habitat and reduce its population. These measures involve both agricultural techniques such as ploughing and milling the soil, and the use of large amounts of herbicides and pesticides, all at the expense of the tree-owners themselves. Also because of the precarious financial situation of most farmers in Italy, with the prince of olive oil well below profitability, these measures are being implemented in a scattered manner, and come into direct conflict with the growing trend towards organic agriculture and an equally growing amount of scientific research on the negative effects of the use of chemical substances in agriculture and on the importance of biodiversity. Some of the pesticides proscribed by the authorities are known to be harmful to bees and possibly to people, and will soon be banned by the European Union, yet all opposition to their use is once again being branded as irrational environmentalism, pointing at a continued failure to take into account the views of the population.

“Communication is an essential, but too often forgotten, strategic component in responding to a phytosanitary outbreak”, two experts from FAO and CIHEAM commented in their analysis of what happened in Puglia, concluding that a “communication plan would strive to unite all stakeholders by informing them on how they are impacted by the outbreak both separately and together”, in order to engage them “to conduct activities that will facilitate the implementation of the contingency plan”. Yet while most reports in this publication by CIHEAM stress the need to disseminate correct information and to make sure that it reaches all those involved, the complete breakdown of trust that we have witnessed in Puglia suggests that instead of a lack of communication, the problem might have been the approach of the authorities, which has treated the Xylella fastidiosa outbreak simply as a phytosanitary problem, ignoring the social and environmental aspects of the relationship between people and olive trees. In this approach, issues such as the absurdly low price that we pay for the olive oil we eat, the worryingly poor state of Salento’s soil and the negative side effects of containing the bacteria’s carrier insect are brushed aside, all in the name of science. This not only replicates the opposition’s obsession with saving the olive trees at all costs, but also turns scientific research into a zero-sum game in which the fact that Xylella fastidiosa is the main cause of the death of the olive trees of Salento automatically negates the role of any other factor in contributing to the outbreak.

Just as the bacteria is real, and is here to say, the absurdly low price that we pay for the olive oil we eat and the effects of our modern intensive agriculture are real, and will continue to affect our relationship to olive trees in the future. We do not know whether the scientists will ever find a cure to Xylella fastidiosa, or we will be forced to watch our centuries-old olive trees wither and die, as the bacteria spreads all across Puglia and possibly beyond, until only the resistant varieties are left. What we do know is that we will continue to eat a lot of olive oil, and that our relationship to olive trees will continue, as it has done for thousands of years. What form it will take in the future is up to us to decide, and in doing so we should not repeat the mistakes of the past, ignoring the social and environmental aspects of the relationship between people and olive trees.

Published on the weekend magazine of Ha’aretz