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Species ofColletotrichumare considered among the most important plant pathogens, saprobes and endophytes on a wide range of ornamentals, fruits and vegetables. SeveralColletotrichumspecies have been reported in nurseries and public or private gardens in northern Italy. In this study, the occurrence, diversity and pathogenicity ofColletotrichumspp. associated with several ornamental hosts was explored. Survey were carried out during the 2013–2019 period in Piedmont, Italy. A total of 22Colletotrichumisolates were collected from symptomatic leaves and stems of twoCampanulaspp.,Ceanothus thyrsiflorus,Coreopsis lanceolata,Cyclamen persicum,Hydrangea paniculata,Liquidambar styraciflua,Mahonia aquifoliumandRhyncospermum jasminoides. A multi-locus phylogeny was established based on the basis of three genomic loci (gapdh,actandtub2). The pathogenicity of selected, representative isolates was tested.Colletotrichumisolates were identified as members of four important species complexes: Acutatum,Gloeosporioides,DematiumandDestructivum.Colletotrichum fioriniae,C. nymphaeaeandC. fuscumwere found in association with leaf lesions ofMahonia aquifolium,Campanula rapunculoidesandCoreopsis lanceolata, respectively.Colletotrichum lineola,C. grossumandC. cigarrowere isolated fromCampanula trachelium,Rhyncospermum jasminoidesandLiquidambar styraciflua, respectively.Colletotrichum fructicolawas found to be responsible of anthracnose ofCeanothus thyrsiflorus,Hydrangea paniculata,Cyclamen persicumandLiquidambar styraciflua. All the tested isolates were pathogenic and reproduced identical symptoms to those observed in private gardens and nurseries. The present study improves our understanding ofColletotrichumspp. associated with different ornamental hosts and provides useful information for an effective disease management programme.

Fusarium oxysporum, associated with wilt symptoms, has been reported in commercial nurseries in Northern Italy in several hosts of the Asteraceae family, such as chrysanthemum, Paris daisy, African daisy, and gerbera. Forma specialis chrysanthemi was assigned as the causal agent of this wilt disease. Severe wilting has recently been observed on the new Asteraceae host, orange coneflower (Rudbeckia fulgida). Morphological observations and sequencing of the translation elongation factor 1α (EF-1α) gene have indicated the involvement of F. oxysporum in this disease. The objective of this study was to identify the forma specialis of F. oxysporum isolated from orange coneflower. This was achieved by means of pathogenicity tests and phylogenetic analyses on the EF-1α and intergenic spacer (IGS) regions performed on single-spore isolates. The results of this study have characterized Fusarium oxysporum on orange coneflower for the first time. F. oxysporum f. sp. chrysanthemi was identified as the causal agent of the wilt disease. This represents the first report of this forma specialis on orange coneflower in Italy, as well as in the world.

Increases in carbon dioxide (CO2) and temperature are expected to induce complex effects on plant pathogens. The results of studies on the effects of climate change on a number of pathosystems, such as the downy and powdery mildew of grapevines, and on several pathogens of vegetable crops, such as rocket, basil, beet and zucchini, have been analysed in this review. In the reviewed works, plants were grown in controlled environment facilities (phytotrons) under six different simulated climatic conditions: a standard CO2 concentration (400–450 ppm) with a standard (ranging from 18 to 22/24 °C) and elevated temperature (5 °C higher than standard), and elevated CO2 (800–850 ppm) under a standard and elevated temperature. When the CO2 level and the temperature were increased, an increase was observed of powdery mildew on zucchini, Alternaria leaf spot on rocket salad, black spot and downy mildew on basil, Allophoma tropica on lettuce and Phoma leaf spot on garden beet. Variable effects were instead observed when individual climate parameters were taken into consideration. The effects of changed environmental values on some physiological parameters on the production of mycotoxins as well as on disease management were also considered on selected pathosystems. CO2 concentration and temperature proved to influence disease severity and mycotoxin production in different ways. As far as the application of biocontrol agents is concerned, the efficacy of Ampelomyces quisqualis against zucchini powdery mildew was found to be improved under higher temperature and CO2 conditions. The results obtained with different host/pathogen combinations will allow to develop adaptation strategies for disease management and to provide the seed industry with useful information in order to develop new cultivars that will be more adapted/adaptable to the changing conditions. The usefulness and limitations of studies carried out under controlled environment conditions are critically discussed.