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Xylella fastidiosa and Candidatus liberibacter (which causes Huanglongbing-HLB disease) are gram-negative bacteria, spread by vectors (cycadellids, cercopids and cicadas in the case of Xylella, and Trioza erytreae and Diaphorina citri in the case of Candidatus). Both affect the vascular system of plants (xylem in the case of Xylella and phloem in the case of Candidatus).
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These are two global pests that cause losses valued at billions of dollars/euros in several strategic crops as vines, olives, almods, fruit and citrus trees.
So far, despite global research efforts, there is no commercial solution for either of the two bacterial pests. Climate change, with global temperature increases, facilitates both their development kinetics in plants and their spread to areas not yet affected. Therefore, the forecasting of Xylella expansion in Europe and Australia, for example, point to annual losses of up to 100 million euros in some dramatic scenarios, while in North African countries this figure would double.
AFECTED CROPS
01. Olive wood.
The Olive Quick Decline Syndrome is caused by Xylella fastidiosa. In Apulia, Italy, considering the average number of working hours that olive trees require to maintain and harvest, about 33,000 jobs have been lost since the bacteria onset. European Union have estimated about 300.000 jobs in risk in case of wide spread of Xylella.
02. Grapevine.
​Xylella fastidiosa cause the bacterial disease in grapevine called Pierce’s disease. The affliction can deliver a devastating economic blow. Only in California, Pierce’s disease costs the wine industry more than $100 million annually.
03. Citrus.
​Huanglongbing (HLB), caused by Candidatus liberibacter, is considered one of the main citrus diseases; it spreads quickly through orchards, reducing the production and quality of the fruit of affected plants, and causes significant economic losses. In Florida, since 2005, the 80% of citrus production have been got lost. In Brazil, the world's leading citrus producer, HLB causes the loss of 30% of production.
04.Almonds.
​Together with olive trees, almond trees were found to be infected by Xylella fastidiosa with typical leaf scorch symptoms of ALSD. Only in Alicante, Spain, Xylella shrunk the almond production in 800 tons during 2023, with more than three million of euros in losses.
05. Otros cultivos