First Report of and Associated with Cankers and Necrosis of Holm Oak () in Declining Stands in Southern Italy.

The emergence of new plant diseases is an increasingly important concern. Climate change is likely to be among the factors causing most of the emerging diseases endangering forest and tree heritage around the world. Such diseases may be caused by latent pathogens or microorganisms cryptically associated with plants. The shift from a non-pathogenic to a pathogenic stage may depend on physiological alterations of the host, environmental changes, and/or stress factors. In some woods of the Salento Peninsula (Apulia Region, Italy), sudden declines of holm oak plants ( L.) have been observed since 2016. The morphological and molecular characterization of representative fungal isolates associated with cankers and necrosis in declining plants indicated that these isolates belong to the family, and the most frequent species were and , followed by . In artificially inoculated young holm oak plants, both and species produced intense and severe subcortical and leaf margin necrosis. , although less aggressive, induced the same symptoms. Our research, in addition to confirming the involvement of in olm oak decline, represents the first report of as a new pathogen of in Italy. Furthermore, to the best of our knowledge, we also found as a new pathogen of .