Recovering of Olive Groves Infected by Xylella fastidiosa subsp. pauca in Apulia (Italy) Through a Sustainable Management Strategy

Abstract

Abstract Xylella fastidiosa subsp. pauca , listed as a quarantine bacterium in the European Union, has spread in Salento (Apulia, Southern Italy) landscape causing severe damage to the olive cultivation. X. fastidiosa is the causal agent of the “olive quick decline syndrome” (OQDS). Through a series of multidisciplinary studies, it has been possible to assess and set up an effective management strategy for maintaining the traditional olive germplasm of Salento. For this aim, a systemic biocomplex containing zinc (4%), copper (2%) and citric acid is sprayed to the tree canopy, once per month, from spring to early autumn. The strategy also includes sustainable vector control through agronomical techniques as well as the regular tree pruning and soil fertilization. Quantitative real-time polymerase chain reaction (PCR) assessments showed a significant reduction of X. fastidiosa subsp. pauca concentration in the xylem tissue of the leaves upon the treatments, thus allowing the olive trees to normally yield. Both 1 H-NMR metabolomic and mass-spectrometry lipidomic analyses of leaf extracts revealed the occurrence of biomarkers linked to the disease or tree restoration. After the spray treatment, a rapid re-programming in the metabolic tree activity has been observed. Multi-scale satellite imagery monitoring confirmed the robustness of the strategy for several years in both experimental and productive olive groves. Currently, the strategy is applied in many olive groves of Salento. Some aggressive fungal species belonging to the Neofusicoccum genus have been found to be associated with olive trees that show symptoms very similar to OQDS and that are also co-infected by X. fastidiosa subsp . pauca . Information © The Author 2024