Unfortunately, the deadly pathogen Xylella fastidiosa currently poses a greater threat to olives trees, and other important plants, than ever. After several years of destruction in southern Italy, it has now been spreading relentlessly across further regions in Europe. These regions include parts of France, Portugal, Italy, Spain and other countries. As we posted recently, positive samples of Xylella have been confirmed for the first time in the French region of Occitanie, and local plant health authorities were, obviously, not pleased with this news. Their concern should come as no surprise: the Xylella fastidiosa pathogen is also known as the ‘olive tree killer’.
Today, Xylella fastidiosa is slowly advancing through regions in Italy and Spain which have incredible cultural heritage and value. Xylella is on the verge of spreading to areas which are home to numerous so-called ‘monumental’ olive trees, some of which can be more than a 1,000-years-old. It would, without a doubt, be tragic were the pathogen to reach these monumental lives trees, and potentially decimate these amazing and ancient plants.
What is Xylella fastidiosa?
Xylella fastidiosa is a plant pathogen, specifically a type of bacteria, that causes Quick Olive Decline Syndrome (QODS) in olive trees. It is carried by xylem-feeding insects, such as spittlebugs, which infect the host while they feed. Once the insect bites into the plant and starts to feed, the bacterium enter the tree’s xylem (the tissue that transports water and nutrients around the tree) and, there, they begin to multiply. Eventually these bacteria block the nutrient-carrying vessels causing the plant to essentially die from within.
Initial symptoms include dieback of the leaves, wilting, discolouration, etc. In fact, the symptoms very much resemble those which are typical of plant dehydration. For more concrete symptoms of the infection, see the top 9 Xylella fastidiosa symptoms. If your plant is demonstrating more of the listed symptoms, it might be time to worry.
Why is Xylella so dangerous?
At this stage, there is no cure for this plant pathogen. In fact, Xylella fastidiosa has been identified by the European Union as one of the top priority pests. It causes disease in a variety of plants, not just olives, and there is no cure for it. In addition, the disease spreads incredibly quickly. According to an article in Olive Oil Times, the ”disease has spread from 8,000 hectares estimated in 2013, to 8,000 square kilometres”. This is an alarming rate, considering the pathogen was first identified in southern Italy in 2013.
Xylella is on the verge of wiping out monumental trees
Xylella fastidiosa has already managed to infect monumental trees in Puglia, Italy. According to Olive Oil Times, two millenary olive trees have been tested positive for the presence of the pathogen. Unfortunately, the Monumental Tree Valley and its surrounding plateau are at extreme risk. It has been estimated that one third of the monumental olive trees (some of which have been there for more than 1,000 years) have been lost due to Xylella.
As such, farmers are worried that if the infection keeps spreading, the region might lose its cultural heritage as well as economic significance for tourism and olive oil production.
New areas at risk of Xylella infections in 2021
It’s not only in southern Italy where monumental trees are at risk. Mallorca (Spain) is also home to stunning monumental olive trees. Examples of such can be found in the Tramuntana Valley (known as Serra de Tramuntana in Spanish).
The pathogen has already been found to be present in Mallorca and it is spreading across the island. Some olive farmers fear that the Tramuntana Valley (a World Heritage site) is at high risk of being infected. Should the region be infected with the Xylella, the European regulations designed to prevent further spread of the harmful bacteria would apply. This means that, as there is currently no cure for the disease Xylella causes, the infected monumental trees would need to be uprooted or burned. Special buffer zones and infection zones would also need to be applied to the region as well.
One of the partners from the BIOVEXO project consortium, who has an olive farm in Mallorca, emphasised their concerns: ”The monumental trees within the Tramuntana Valley must be protected at all costs! They have been there for centuries and we cannot let them die”.
Special attention must be paid by all stakeholders to protect the vitality of EU agriculture as well as plant health. This is part of the reason that the European Commission, through the Circular Bio-based Europe Joint Undertaking, is funding projects such as BIOVEXO to search for novel bio-pesticides to help stop the spread of Xylella.
Top Xylella news in 2020
2020 was an eventful year as regards Xylella fastidiosa. The pathogen has been present in Europe since its identification 2013, however Xylella still poses a threat to global plant health. Take a quick look at the top 7 Xylella events that happened in 2020.
To learn more about Xylella and the latest EU research on this plant pathogen, visit www.biovexo.eu.
