Citrus is one of the most important crops in Italy, especially in the southern regions. Field surveys conducted in the main production areas of southern Italy, regulated by the EU geographical indications system, revealed the presence of symptomatic citrus trees (lemon, mandarin, sweet orange, bergamot, and grapefruit) showing severe trunk and branch canker and gummosis. This disease, formerly known as “Dothiorella gummosis,” has been reinvestigated in light of the new advances of fungal taxonomy. A total of 120 fungal isolates were characterized, and representative ones were tested for their pathogenicity. Multilocus phylogenetic analyses revealed the presence of different species including Boeremia exigua, Diaporthe foeniculina, Didymella nigricans, Dothiorella viticola, Fusarium caatingaense, F. citricola, F. falsibabinda, F. juglandicola, F. salinense, F. sarcochroum, Lasiodiplodia mediterranea, Neocosmospora metavorans, Neofusicoccum parvum, and Neoscytalidium dimidiatum. Pathogenicity tests were conducted by inoculating mycelial plugs on healthy potted citrus plants. Symptoms were evaluated 30 days after the inoculation. Results showed that the following species were pathogenic: B. exigua, D. foeniculina, D. viticola, L. mediterranea, N. metavorans, N. parvum, and N. dimidiatum. Among the fungal species identified in this study, N. parvum proved to be the most widespread across all the surveyed areas, and B. exigua, N. metavorans, and N. parvum were the most aggressive. This study represents a new update on the diversified etiology of citrus trunk and branch canker and gummosis in Italy.

Alternaria brown spot (ABS), caused by Alternaria alternata, is one of the main citrus diseases that causes heavy production losses and reductions in fruit quality worldwide. The application of chemical fungicides has a key role in the management of ABS. In this study, 48 isolates of A. alternata collected from citrus orchards since 2014 were tested in vitro for their sensitivity to pyraclostrobin and fludioxonil, the latter being temporarily registered in Italy since 2020. Pyraclostrobin sensitivity was determined using spore germination and mycelial growth assays. The effective concentration inhibiting 50% of fungal growth (EC₅₀) was determined for each isolate. The sensitivity assays showed that the majority of A. alternata isolates tested were sensitive to pyraclostrobin. EC₅₀ values of fludioxonil in a mycelial growth assay indicated that 100% of isolates were sensitive to this fungicide. The analysis of the cytochrome b gene showed that none of the 40 isolates with a different sensitivity profile had the G143A mutation, and the subgroup of 8 isolates analyzed by real-time PCR did not carry the G137R and F129L mutations. A subset of four more sensitive and two reduced-sensitive isolates was chosen to assess sensitivity on detached citrus leaves treated with pyraclostrobin at the maximum recommended label rate. Disease incidence and symptom severity were significantly reduced, with a small reduction reported in leaves inoculated with the reduced-sensitive isolates. Furthermore, there was no correlation between sensitivity and fitness parameters evaluated in vitro (mycelium growth and sporulation rate). These findings help the development of monitoring resistance programs and, consequently, set up effective anti-resistance strategies for managing ABS on citrus orchards.

Fungal diseases represent one of the major threats to citrus production, such as anthracnose caused by Colletotrichum gloeosporioides and Fungal Trunk Diseases (FTDs) associated with Botryosphaeriaceae, with Neofusicoccum parvum being the most prevalent species. In response to the need to reduce chemical fungicide use, this study evaluated the antifungal activity of essential oil-based nanoemulsions (N-EOs) as alternative management methods. Seven N-EOs (citronella, clove, fennel, garlic, laurel, lavender and peppermint) were first screened in vitro against multiple isolates of both pathogens through mycelial growth and conidial germination assays. Based on estimated EC₅₀ and EC₉₀ values, clove and garlic N-EOs exhibited the highest inhibitory activity, while lavender displayed intermediate but promising efficacy, particularly against N. parvum. These N-EOs were subsequently evaluated in vivo on lemon fruits inoculated with C. gloeosporioides and on detached lemon twigs inoculated with N. parvum. In vivo assays largely confirmed the in vitro trends, with clove and garlic significantly reducing lesion development. In contrast, lavender displayed limited efficacy under in vivo conditions. The phytotoxic effects at higher concentrations limited the range of applicable doses. Overall, the results suggest that N-EOs, particularly those based on clove and garlic, may offer potential as alternative tools for citrus disease management. However, host tissue interactions, formulation stability, volatility, and validation under field conditions remain critical aspects requiring further investigation.

Botrytis cinerea, the causal agent of gray mold or Botrytis rot on many vegetable and fruit crops worldwide, is ranked among the main limiting factors for strawberry production, being able to strongly compromise the quality, shelf life, and commercial value of fruit. UV-C is considered an environmentally friendly strategy for postharvest protection for several commodities. In this regard, this research evaluated the performance of short-wavelength UV-C radiation in reducing postharvest Botrytis decay, extending or maintaining the shelf life and quality of strawberry fruit, and detecting possible negative effects. The topic is of growing interest, as it falls within the strategic priorities of so-called “Green Technologies” to pursue a sustainable agriculture and safe food supply by minimizing fungicide use as much as possible. UV-C exposure (at a rate of 1428 J m⁻²) by means of a UV-C lamp (15 W) at a source distance of 25 cm for just 1 min provided significant reductions (from 41 up to almost 80%) depending on the artificial or natural decay pressure of gray mold caused by B. cinerea on strawberry fruit without phytotoxic effects. Analyses performed under both refrigerated and room-temperature storage conditions at different day intervals showed that postharvest UV-C does not significantly affect key chemical parameters, including the ascorbic acid content, total sugars, pH, and titratable acidity of strawberry fruit. Thus, UV-C exposure for a brief time, especially if combined with a low temperature, can be effectively considered for sustainable protection of strawberry fruit at the postharvest stage, providing a theoretical basis for further elucidation of the action modes for this and other targets, and potential large-scale application.