The threat of Xylella on the Balearic Islands

From 29 November to 1 December 2022, the team behind the BIOVEXO project gathered in Mallorca for another in-person consortium meeting. The aim of the meeting was to review project progress and share opinions on planning the way forward. The BIOVEXO partners used this opportunity not only to discuss the project progress and biocontrol solutions to fight the Xylella fastidiosa pathogen, but also to visit orchards with almond and olive trees affected by this disease and observe the progress of the preventive and curative treatments being applied to the trees.

Why is it important to treat olive trees in the Balearic Islands? 

To remind our readers, the threat of Xylella was first detected on the Balearic Islands back in 2016. As sudden and unknown a threat as it was at the time, it soon became a severe phytosanitary challenge for the region, and later, the wider Mediterranean. The detection of Xylella fastidiosa was followed by containment measures and eradication, as per the requirements of EU Decision 2015/789. The detection of Xylella posed not only a great immediate threat to the production of olive oil and the economy of the region, but it also became a threat to the cultural heritage of the region, where many monumental olive trees that are hundreds of years-old were affected and showed symptoms of rapid decline.

BIOVEXO project Consortium at the AIMERIT farm, Mallorca

Saving olive trees – saving family tradition 

While the main purpose of the meeting was to discuss project progress and continuation of the journey towards exploration of innovative biopesticides to combat the disease, we must not forget about the socio-cultural aspect of the problem. Preserving cultural heritage is a ‘sine qua non‘ for every society, therefore during this trip to Mallorca the BIOVEXO team also decided to pay a visit to the ancient olive oil factory Can Det in Sóller, Spain, whose lineage dates back to 1525. 

After settling in the 16th century in Soller, the family has been engaged in activities related to olive production, as well as production of citrus fruits. Nowadays, ‘Can Det‘ is an olive oil factory that uses outstanding raw materials to produce excellent olive oil using olives from the ancient trees. Having said that, it is no wonder that the Can Det estate received an award in 2020, even having one of its olive trees recognised as the ‘Best Monumental Olive Tree in Spain‘. 

‘Can Det‘ olive oil factory, Photo: RTDS Group

Arriving at the Can Det property, BIOVEXO team received a warm welcome from Mr Tomeu Deia, followed by an introduction explaining the process of olive oil making. Mr Deia also answered some of our questions on challenges and advantages of olive oil production in Soller. We learned that the greatest challenge of last year was the drought they were facing, and (luckily) not Xyllela. Tomeu is at Serra de Tramuntana where they say Xylella hasn‘t arrived yet. The threat is, however, still there. 

Tomeu Deia at ‘Can Det‘, Photo: RTDS Group
 

A challenge to the protection of cultural heritage

Serra de Tramuntana was declared a World Heritage Site by UNESCO in 2011, given its breathtaking scenic and cultural values. The richness of Serra de Tramuntana lies also in the number of rare olive trees, which therefore require extra care and protection. However, protection of  those trees is not an easy task. The problem in Sierra de Tramuntana is the tiny terraces and stonewalls that make it difficult for machines and new tractors to get in. Everything has to be done by hand. This makes it inefficient and unprofitable. Since the cost of tackling the problem in such a situation is so high, there is a major threat of abandonment – both of the area and the problem.

It goes without saying that, by managing the Xylella outbreaks in Europe and finding innovative and sustainable solutions, we could save centuries of family traditions like these; save astonishing, hundreds-of-years-old, monumental trees; ease the lives of farmers who heavily rely on production; contribute to the sustainability of an important component in the healthy diet of millions of people around Europe; and, finally – save and protect our forever home, planet Earth, for future generations to come. 

So, an important question is raised here – what can the farmers at Serra de Tramuntana do? 

Our BIOVEXO partner from AIMERIT, Pilar Puig says ‘We know that young trees are more productive than monumental olive trees so, these trees deserve care just like sequoias.. These trees are so rare that they should be protected, and we should find ways to help owners take care of them.’

One of the ways to keep the trees healthier and more productive is the pruning process. The trees are usually pruned in order to allow more light to reach the tree, resulting in healthier and more productive trees. Why is this important? Trees that are not pruned are more prone to illness since they receive less sunlight, water, and other important nutrients. Over time, the branches also become very dry. Consequently, this allows illnesses like Xylella to attack the trees with ease.

At the AIMERIT farm, the BIOVEXO partners had the unique opportunity to witness and carefully observe the pruning process of a few olive trees. Pruning usually takes around 20 minutes and requires a very skilled and experienced worker. 

Pilar Puig, AIMERIT Farm. Photo: RTDS Group

Providing extra care for the trees, early detection and contacting the local authorities could be some of the crucial steps in attempts to minimize the threat and prevent the spread of Xylella.

Do we have organic solutions on the market to counteract the devastation?

It is saddening and devastating to see many trees in the Mediterranean affected by this disease, including hundreds-of-years-old monumental olive trees. To date, there is no organic solution available on the market to battle the devastation caused by Xylella fastidiosa. Effectively, this places the economic and socio-cultural sustainability of Europe at high risk. At BIOVEXO, we hope to make a positive contribution towards mitigating the spread of Xylella and its effects by developing innovative biopesticides to combat this pathogen.  

Photo: Shutterstock

BIOVEXO is not the only project attempting to find strategies and solutions to the outbreak of Xylella in Europe. We would like to use this opportunity to introduce you to the BeXyl, a Xylella-focused project under the Horizon Europe Programme aimed at finding new strategies to mitigate the impact of the Xylella fastidiosa outbreak in the EU. For more information on BeXyl, we strongly encourage you to visit BeXyl official website. You can find valuable insight on Xylella fastidiosa in a recently published paper by researchers of the BeXyl consortium on the ‘Evaluation of Control Strategies for Xylella fastidiosa in the Balearic Islands‘.

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