Fungal Trunk Pathogens of Fruit and Nut Tree Crops: Identification, Characterization, Detection, and Perspectives for a Critical Global Issue

Abstract

Fungal trunk pathogens are a growing global issue, significantly affecting fruit and nut tree crop cultivation. These pathogens, mainly ascomycetes, belong to several families, including Botryosphaeriaceae, Calosphaeriaceae, Cytosporaceae, Diaporthaceae, Diatrypaceae, Nectriaceae, and Togniniaceae. The large number of species involved represents a challenge in clarifying the etiology of trunk diseases, further complicated by frequent coinfections by different fungi. Typically, these pathogens enter plants through wounds and natural openings, and some can persist in a latent phase, switching to pathogenicity under favorable conditions. This aspect represents a significant concern for both nurseries and orchards. Moreover, the current climatic conditions and the intensification of cropping systems are likely exacerbating the spread and development of these pathogens, making their management more difficult. This review provides an overview of the main ascomycetes causing trunk diseases, discussing their identification, characterization, and detection methods. Accurate identification and characterization are crucial to increase the knowledge on these pathogens and to develop effective management strategies. An insight on the current preventive and curative strategies is provided as well to explore sustainable crop protection strategies, including agronomic practices, biological control, the use of new active ingredients, and tolerant and/or resistant cultivars, and to address this escalating problem.

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