**6. Conclusions**

Globalization has led to intensified movement of people, plants, and plant products, and an increase in the unintentional introduction of non-native fungal species into new ecosystems. Many plant pathogens are biological opportunistic invaders causing several billion dollars in losses to crops, pastures, and forests annually, worldwide. Consideration needs to be given to building resilience in the new environments, from the perspective of pathogen introductions. In particular, the monitoring of plants and plant products, plus early identification-detection of pathogen risks are key steps towards ensuring successful regulation to exclude potential disorders caused by pathogens. This review demonstrated the broad fungal diversity recovered from a small group of ornamental plants that have been relatively unexplored as fungal hosts. Even if the reviewed plant genera are not recognized as sources of significant forest diseases, that have had an ecosystemic impact on a continental scale in the past, we highlight the risk represented by plants as inoculum sources of potentially harmful organisms. Overall, many other species not listed by the EU have represented or may cause important impact in many ecosystemic, environmental, and ecological issues. Our literature search revealed that fungal species may also be introduced through a few hundred plants and invade new ecosystems. In this context, it is important to underline that the amount of imported plant material may not be related to a specific risk, but needs to be considered and evaluated to estimate the negative impacts on agriculture, forestry, and public health, associated with non-indigenous species in European ecosystems. For example, little is known about the effects of invasive species on ecosystem services, although some historic pest invasions (e.g., chestnut blight from North America to Europe) have destroyed host tree species in their locations. The true challenge lies in preventing further damage to natural and managed ecosystems. For this reason, preventative policies need to take into account the means through which pathogens gain access to the EU. The accidental introduction of potentially harmful pathogens also links to other issues of major policy concern (i.e., biotechnology, human health, climate change, etc.) that should be addressed through improved international cooperation and a holistic approach. We should expect that some strategies should be continued or further established to prevent or monitor future introductions, especially at airports, seaports, and other ports of entry, to reduce risks to an acceptable level and preserve natural and agricultural ecosystems.

**Author Contributions:** Conceptualization, L.G., G.d., F.V. and S.L.W.; literature investigation L.G., G.d., M.S. and M.R.; writing—original draft preparation, L.G. and G.d.; writing—review and editing, project administration, F.V. and S.L.W.; funding acquisition, F.V. and S.L.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the following projects: MIURPON (Grant number Linfa 03PE\_00026\_1; Grant number Marea 03PE\_00106); POR FESR CAMPANIA 2014/2020-O.S. 1.1 (Grant number Bioagro 559); MISE CRESO (Grant number Protection n. F/050421/01-03/X32); PSR Veneto 16.1.1 (Grant number Divine n. 3589659); PSR Campania 2014/2020 Misura 16-Tipologia di intervento 16.1–Azione 2 'Sostegno ai Progetti Operativi di Innovazione (POI)'—Progetto 'DI.O.N.IS.O.', C.U.P. B98H19005010009; European Union Horizon 2020 Research and Innovation Program, ECOSTACK (Grant agreement no. 773554); PRIN 2017 (Grant number PROSPECT 2017JLN833).

**Conflicts of Interest:** The authors declare no conflict of interest.

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