Progress towards Sustainable Control of <i>Xylella fastidiosa</i> subsp. <i>pauca</i> in Olive Groves of Salento (Apulia, Italy)

• Main Authors: Marco Scortichini, Stefania Loreti, Nicoletta Pucci, Valeria Scala, Giuseppe Tatulli, Dimitri Verweire, Michael Oehl, Urs Widmer, Josep Massana Codina, Peter Hertl, Gianluigi Cesari, Monica De Caroli, Federica Angilè, Danilo Migoni, Laura Del Coco, Chiara Roberta Girelli, Giuseppe Dalessandro, Francesco Paolo Fanizzi
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Pathogens
• Subjects: olive quick decline syndrome; real-time PCR; NMR metabolomic; endotherapy; sustainable development goals of the United Nations
• Online Access: https://www.mdpi.com/2076-0817/10/6/668

<i>Xylella fastidiosa</i> subsp. <i>pauca</i> is the causal agent of “olive quick decline syndrome” in Salento (Apulia, Italy). On April 2015, we started interdisciplinary studies to provide a sustainable control strategy for this pathogen that threatens the multi-millennial olive agroecosystem of Salento. Confocal laser scanning microscopy and fluorescence quantification showed that a zinc-copper-citric acid biocomplex—Dentamet^®—reached the olive xylem tissue either after the spraying of the canopy or injection into the trunk, demonstrating its effective systemicity. The biocomplex showed in vitro bactericidal activity towards all <i>X. fastidiosa</i> subspecies. A mid-term evaluation of the control strategy performed in some olive groves of Salento indicated that this biocomplex significantly reduced both the symptoms and <i>X. f.</i> subsp. <i>pauca</i> cell concentration within the leaves of the local cultivars Ogliarola salentina and Cellina di Nardò. The treated trees started again to yield. A ¹H-NMR metabolomic approach revealed, upon the treatments, a consistent increase in malic acid and γ-aminobutyrate for Ogliarola salentina and Cellina di Nardò trees, respectively. A novel endotherapy technique allowed injection of Dentamet^® at low pressure directly into the vascular system of the tree and is currently under study for the promotion of resprouting in severely attacked trees. There are currently more than 700 ha of olive groves in Salento where this strategy is being applied to control <i>X. f</i>. subsp. <i>pauca</i>. These results collectively demonstrate an efficient, simple, low-cost, and environmentally sustainable strategy to control this pathogen in Salento.