Acute oak decline (AOD) is a multifactorial disease that affects European oaks and represents a growing threat to forests. The disease results from a complex interaction between biotic and abiotic factors: the various environmental stresses, which vary depending on the area in question, and generally increased by climate change, predispose trees to attack by opportunistic pathogens. Among them, we focused on a bacterial consortium associated with AOD, consisting mainly of Brenneria goodwinii, Gibbsiella quercinecans, Rahnella victoriana, and Lonsdalea britannica, which produce degrading enzymes that contribute to phloem necrosis and the development of stem bleeds and bark cracks. However, the role of other pathogens, such as fungi, cannot be ruled out, but instead could be contributory. The potential involvement of xylophagous insects is also being studied, particularly Agrilus biguttatus, which, although, frequently associated with the disease, has not been conclusively demonstrated to act as an active vector of the bacteria. Currently, disease management requires integrated approaches, including monitoring and other forestry strategies to increase forest resilience. Given the phenomenon’s complexity and the risk of the future expansion of that bacterial consortium, further research is necessary to understand the dynamics and to develop effective containment strategies of AOD-associated bacteria.

Flavescence dorée (FD) is a major grapevine disease in Europe with significant economic consequences. The objective of this review is to provide as much information as possible on the documented susceptibility or tolerance of different cultivars, both international and local within individual countries. Additionally, spontaneous recovery has been observed as a viable option for replanting injured vines, but its efficacy varies by cultivars. In this regard, a broad categorization was developed for several cultivars, particularly those examined in Europe, describing their higher or lower susceptibility and aptitude to recover. Future research, however, should not only address the geographic spread of FD, but also investigate how pathogen–host interactions may differ across cultivars. Such insights could be crucial for assessing the risk of FD introduction in new regions and understanding cultivar-specific susceptibility and epidemic dynamics, because present studies remain mostly concentrated in regions suffering significant FD pressure, resulting in a focus on a small number of cultivars that are often specific to a certain geographical area. Furthermore, the implementation of innovative strategies has the potential to give a comprehensive and long-term approach to managing and containing FD.

Xylella fastidiosa (Xf) is a Gram-negative bacterium responsible for severe diseases in several commercially significant crops, including olive, grapevine, citrus and almond. Its management is particularly challenging due to its transmission via widespread vector insects, its ability to form biofilms, its high genetic diversity and, sometimes, latent symptoms. Current control strategies focus on integrated and preventive approaches, including the use of resistant varieties, agronomic practices, and vector control through chemical and biological methods. Direct control of the bacterium has always been a complex challenge that includes strategies to limit vector presence and activity in the field; however, several compounds have recently been evaluated that are able to inhibit biofilm formation and Xf growth. This review provides an up-to-date summary of studies investigating the efficacy of various treatments based on organic compounds, synthetic molecules and salt- or metal-based formulations. By evaluating the results of in vitro and in vivo experiments, the most promising solutions were identified that address the main challenges and limitations of chemical control strategies. These include N-acetylcysteine and zinc- and copper-based formulations, which are effective and potentially transferable to the field for crops such as citrus and olive trees. Antimicrobial peptides and nanoparticles, on the other hand, have demonstrated high efficacy in vitro, although further studies directly in the field are required. The evidence emerging from the analyzed studies offer insights to guide future research towards more effective and sustainable management approaches to mitigate the spread and impact of Xf.

Acute Oak Decline (AOD) is a complex and rapidly progressing disease affecting several Quercus species across Europe. While previously reported in Quercus ilex in Italy, this study provides the first evidence of AOD symptoms and associated bacterial infection in Quercus coccifera (kermes oak). Symptomatic trees were identified in a Mediterranean forest in southern Italy, and bacterial isolation, qPCR detection, and 16S rRNA sequencing confirmed the presence of Brenneria goodwinii and Gibbsiella quercinecans. Phylogenetic analyses clustered the isolates closely with known AOD-related strains. Pathogenicity tests on excised Q. coccifera branches demonstrated that both bacteria induced wood necrosis and external exudates consistent with natural symptoms, confirming their virulence. These findings expand the known host range of AOD-related bacteria and highlight the potential threat to Mediterranean oak ecosystems. Early detection and monitoring of Q. coccifera decline are essential to inform conservation strategies and forest management practices aimed at mitigating AOD spread.

Oak decline, in acute and chronic forms, is an emerging challenge in the forest and urban environments of Europe and the Mediterranean basin. Oak trees have central ecological and cultural roles: they support diverse organism communities, are involved in hydrological and biogeochemical cycles, and provide ecosystem services in natural and anthropised landscapes. Populations of Quercus species are increasingly threatened by combined effects of extreme weather events, soil degradation, hydrological imbalance, and increasing numbers of emerging pathogens. These factors interact in complex ways, often accelerating decline processes and complicating diagnoses and management. Advances in visual assessment, remote sensing, and molecular tools are improving early decline diagnoses, and accurate assessments of severity. Integrated management approaches, incorporating vegetation management, adaptive silviculture, and soil and water conservation, offer promising pathways to improve oak tree resilience. Attention is required in urban settings, where chronic abiotic stress and site constraints amplify tree vulnerability. Long-term monitoring networks and multidisciplinary approaches are essential for understanding disease progression, anticipating risks, and guiding effective interventions. This review synthesises current knowledge on oak decline dynamics, diagnostic approaches and management strategies, providing a framework to support sustainable, science-based strategies, to mitigate the disease and ensure long-term viability of oak-dominated landscapes.