Back to the Balearics: Xylella updates from Mallorca and BIOVEXO's new field testing site
The BIOVEXO Project has been fortunate enough to visit the Balearic Island of Mallorca twice before: in December 2021, when we visited our initial testing sites and met with local experts to better understand the situation in Mallorca; and in November/December 2022, when we held a consortium meeting and spent time exploring some of the ways in which olives are used locally and contribute to the local economy and culture. From July 3rd to July 5th 2023 the BIOVEXO Project returned to Mallorca. Read on to find out about the work we did and what we learned this time!
A New BIOVEXO Test Site
Previously, we have written about the threat that Xylella fastidiosa poses to the Almonds in Europe. We are therefore happy to have agreed to expand our testing on BIOVEXO’s innovative biopesticides to a new testing site in Mallorca with the help of Maria Antonia Tugores, an Agricultural Engineer from Grup Fruits Secs, a group of cooperatives of almond and carob producers that has more than 1,000 members and 6,000 hectares dedicated to almond and carob crops, mainly on the island of Mallorca. The new testing site comprises over 160 individual almond trees. Experts from the BIOVEXO Project, specifically Pasquale Saldarelli from Consiglio Nazionale delle Ricerche (CNR) in Italy and Stéphane Compant, BIOVEXO’s Scientific Coordinator, from the AIT Austrian Institute of Technology, were able to provide Maria Antonia with special training on the detection of Xylella symptoms.
This sort of knowledge sharing and exchange is one of the many benefits of BIOVEXO’s close collaboration with local partners, but also of European Union-funded research projects more broadly.
We were fortunate enough to interview Maria Antonia and she explained the status of Xylella in Mallorca, its devastating impacts, especially on almond farming, with many thousands of almond trees already destroyed – only suitable to be used as firewood. Check our interview with Maria Antonia below.
Also with us in Mallorca was Jose Manuel Garcia Madero, from BIOVEXO project consortium partner DOMCA. He had previously explained to us the role of DOMCA in the BIOVEXO project and the work DOMCA is doing to ensure the innovative biopesticides being developed by the BIOVEXO project are safe for the environment. He explained that, once it was realised that the strain of Xylella fastidiosa present on Mallorca had greater impacts on almonds than on olives, it was agreed that a new orchard, containing only almonds, would be included in the project.
The BIOVEXO team collected samples from the trees in the new orchard, as well as selected specimens from our existing test site, to test them for Xylella and provide the base measurement for the new growing season and a reference against which the efficacy of the biopesticides will later be assessed. But how exactly do you test a tree for the presence of Xylella fastidiosa? Good question!
Quantitative PCR Testing Trees
The COVID pandemic has made almost everybody familiar with Quantitative Polymerase Chain Reaction (commonly known as PCR) testing – you’ve no doubt been tested many times and remember the routine of gargle tests or throat swabs. But did you know that we can also test trees using the same process? That’s right, exactly the same procedure that is used to detect COVID in humans can be used to detect Xylella in plants! We took a trip to the Official Plant Health Laboratory of the Balearic Islands and met with its Director, Dr. Diego Olmo, to give him our samples, but also to learn a bit more about the testing procedure.
It was the busiest time of the year for the Plant Health Laboratory, which typically receives 200 samples per week for testing during the summer months (compared to 50-100 samples per week during the autumn/winter), so we were especially grateful for his time.
Dr. Olmo kindly explained the whole procedure for qPCR testing: watch and find out all about how the testing is done:
Dr. Olmo went on to explain to us that Xylella has been found in around 1500 samples so far in Mallorca, belonging to 38 different hosts, including almond trees, olive trees, grapevines, fig trees, and walnut trees, among cultivated plants; and Polygala, rosemary, wild olive trees, Acacia, and lavender among ornamental and forest plants. There are 4 Xylella genotypes presents in the Balearic Islands: Xylella fastidiosa subsp. fastidiosa ST1 (Mallorca), Xylella fastidiosa subsp. multiplex ST81 (Mallorca and Menorca), Xylella fastidiosa subsp. multiplex ST7 (Mallorca) and Xylella fastidiosa subsp. pauca ST80 (Ibiza).
Collaboration with the FreePoc Project
The drawback with quantitative PCR testing is that it is relatively expensive. This means quantitative PCR testing is unaffordable for many farmers (if you imagine testing each tree/plant in a large field, you can quickly see how costs add up…).
The BIOVEXO Project was pleased to welcome an expert from the FreePoc project, Dr Angelantonio Minafra, to its new almond test site so that Dr Minafra could give us a demonstration of their experimental system for Xylella testing which, it is hoped, will save researchers and farmers time and money in the future by allowing them to test for Xylella cheaply. It should be noted that FreePoc’s testing system only give qualitative information about whether the tree is infected with Xylella or not. BIOVEXO’s own expert, Dr Ana Falcon from DOMCA, was given a crash course on how to use the FreePoc system!
Understanding Eco-system services provided by Almond Trees
If almond trees and olive trees were to disappear as a result of Xylella, most people would not think much beyond the fact that we’d no longer have olives or almonds to eat. However, for farmers like Pilar Puig, who is a member of the BIOVEXO consortium and on whose farm the biopesticides have been under assessment for the last two years, the trees have a much greater significance.
She has previously explained the impact of Xylella on her farm and why she chose to participate in the BIOVEXO project. This time we spoke to her about other products she produces on her farm, in particular, her award winning honey, mel equilibri. She explained to us the importance of balance (from which her honey takes its name) and biodiversity on her farm, describing how paying close attention to the health of her bees has taught her the interconnectedness of nature.
“Honey is like tasting the landscape of each season.” – Pilar Puig
As an example, she mentioned how it is important to pay attention to the different times at which different plants flower and provide food for pollinators. The almond trees in Mallorca produced many millions of flowers, these are increasingly disappearing due to the impact of Xylella. The decrease in flowers directly affects the biodiversity by removing a source of food to pollinators, forcing them to seek out less-preferred or more distant options. This impacts on honey production – the taste of the honey changes if the pollinators feed on different plants, and the health of the bees can be affected by stresses caused by food scarcity or competition. With this example, she helped us understand how the effects of Xylella go far beyond the mere availability of olives or almonds for human consumption.
This interconnectedness between different parts of the ecosystem also reminds us why the BIOVEXO project is being so careful to ensure its innovative biopesticides will be save for the environment, especially pollinators.
Final words
BIOVEXO is fighting Xylella and protecting olive and almond trees in different locations across Europe. The project is, at the time of writing (July 2023), almost two-thirds of the way through its 60-month duration. If you’ve found this blog interesting and you’d like to follow the work of the BIOVEXO project and stay up to date on the fight against Xylella, please sign up to our Newsletter or and follow us on Twitter, Instagram, Linkedin, or Facebook.
