Carlo Bregant

Chestnut ink disease, caused by Phytophthora spp., represents one of the main threats to the productivity and sustainability of sweet chestnut ( Castanea sativa ) in southern Europe. Early diagnosis is an essential step to develop appropriate management strategies. Therefore, this study investigates the potential of dogs' olfactory abilities to detect pathogen‐specific volatile organic compounds (VOCs) emitted by infected roots, offering a promising, non‐invasive approach for rapid and reliable disease detection in forest ecosystems. Hulk, a 7‐year‐old Labrador retriever, was trained through a multiphase protocol using GETXent polymer tubes soaked with Phytophthora VOCs under controlled conditions. His performance was then evaluated in greenhouses with artificially inoculated seedlings and in chestnut orchards under natural conditions. Statistical analyses showed that Hulk demonstrated positive Phytophthora detection skills throughout the training phases, both with polymer tubes and in the greenhouse and his performance remained consistently superior to random expectations. In chestnut orchards, Hulk revealed high sensitivity, showing signs of alert for 86% of trees displaying specific ink disease symptoms and for 75% of trees displaying nonspecific symptoms. Furthermore, the dog was shown to be efficient in intercepting early root infection on apparently asymptomatic trees, validated by laboratory analyses. In addition, VOCs related to Phytophthora infections were chemically identified as o ‐cymene, camphor and borneol. To our knowledge, this is the first application of canine detection using GETXent polymer tubes to train a dog for Phytophthora cambivora surveillance in chestnut orchards, which could have application in nursery stock to limit anthropogenic spread on a wide scale.

Landscape and land-use are potential factors influencing the presence of insect pests and fungal pathogens, which can drive the onset of decline and mortality events. However, the impact of different types of landscapes on the community of insect-associated fungal pathogens still remains to be thoroughly understood. This study aimed to investigate the effect of landscape on plant-pathogenic fungi occurring in cork oak trees infested by Coraebus florentinus. Field surveys were conducted in 14 cork oak stands in Sardinia (Italy), classified as forest or woodland on the basis of the tree cover density. Fungi were isolated from wood materials sampled across various compartments of the gallery systems excavated by mature larvae of C. florentinus and identified based on morphological characteristics and DNA sequence analyses. Differences in fungal diversity between landscapes, as well as between gallery compartments and wood material types, were evaluated using ecological diversity indices and both non-parametric and ordination statistical methods. A total of 172 fungal isolates belonging to fourteen families and 26 species were obtained. Fungi in the Botryosphaeriaceae (41.28%), Nectriaceae (15.12%) and Cryphonectriaceae (12.79%) were the fungal families most frequently isolated from the infested branches. Diplodia corticola was the most frequently isolated species, representing 24.5 and 40.6% of total isolations in the forest and woodland areas, respectively. Multivariate analyses indicated that the presence and frequency of plant-pathogenic fungi were significantly associated with the predominant landscape. Results from this study emphasizes the importance of considering landscape types to facilitate risk assessment of the presence and spread of pathogenic fungi such as D. corticola and other members of the Botryosphaeriaceae family mainly involved in oak decline.

1. Species of Lasiodiplodia are cosmopolitan plant pathogens responsible of dieback and canker in a broad range of plants, including Theobroma cacao L., Vitis vinifera L., and Mangifera indica L. (...

Magnolia grandiflora is an important ornamental tree in urban areas. In 2025, leaf spot symptoms were observed on M. grandiflora leaves in Viterbo, Italy. The causal agents were isolated and identified through morphological characterization and multilocus phylogenetic analysis of EF1-α, RPB1 and RPB2 gene sequences, and were identified as Fusarium venenatum and F. clavum. Pathogenicity tests on healthy M. grandiflora leaves produced characteristic brown leaf spots within 3 d post-inoculation. Re-isolations of the inoculated fungi confirmed Koch’s postulates. This study demonstrated that F. venenatum and F. clavum caused the leaf spot symptoms on Magnolia, and is the first report of this disease in Italy. These results provide the basis for developing targeted disease management strategies for emerging diseases caused by these fungi in urban areas.

With the rapid expansion of avocado cultivation in southern Italy, growers have had to deal with the emergence of new diseases often caused by invasive and polyphagous pathogens responsible for leaf spot, branch cankers, dieback and fruit and root rot. Given the severity of these emerging diseases, a study was conducted in the main avocado growing areas in Sardinia and Sicily (Italy) to isolate and characterize the causal agents. Specifically, a total of 430 symptomatic leaf, fruit, branch, stem and root samples were collected and examined. Isolations performed on both non-selective and selective growth media yielded 22 species (fungi and oomycetes) belonging to the genera Botryosphaeria, Colletotrichum, Diplodia, Dothiorella, Macrophomina, Neofusicoccum and Phytophthora, including 14 new host–pathogen records in Italy. Notably, Neofusicoccum australe, Phytophthora cinnamomi and Phytophthora palmivora emerged as the main pathogens involved in the emerging avocado diseases. The identified pathogens were often isolated simultaneously from the same plants, which exhibited a complex of symptoms. Pathogenicity bioassays have helped to clarify the differences in aggressiveness among the different species and their specificity towards the different plant organs. The results achieved suggest that avocado orchards’ productivity and profitability is threatened by a plethora of unrelated pathogens whose control represents a major challenge for the success of this crop in Italy.

Monitoring surveys, conducted in four Italian regions (Apulia, Marche, Sardinia and Veneto), revealed the widespread occurrence of young and mature fig trees ( Ficus carica ) showing sudden death, crown thinning, shoot blight, branch dieback, cankers and root rot symptoms. Given the widespread distribution and severity of these symptoms, a study was conducted to identify the main causal agents. To achieve this goal, 86 samples including fine roots with rhizosphere (11) and branches with bleeding and sunken cankers (75) were collected from 11 symptomatic fig trees. Isolations performed on universal and selective growth medium yielded colonies belonging to three families: Botryosphaeriaceae , Diaporthaceae (Ascomycetes) and Peronosporaceae (Oomycetes). Based on morphobiometric data and DNA nucleotide sequences, seven species, namely Botryosphaeria dothidea (14 isolates), Diaporthe cinerascens (10), Neofusicoccum australe (9), Neofusicoccum mediterraneaum (10), Neofusicoccum parvum (28), Phytophthora citricola (3) and Phytophthora plurivora (6) were identified. In addition, two isolates of a new putative Phytophthora species obtained from the rhizosphere including symptomatic fine roots of fig trees in Apulia region are described here as Phytophthora messapica sp. nov. For Phytophthora species, N. australe and N. mediterraneaum (reported here for the first time on fig trees worldwide), Koch's postulates were satisfied by inoculating 5‐year‐old fig trees under controlled conditions. Sixty days after inoculation, all inoculated plants showed the same symptoms as those observed in the field. Overall, the data obtained highlights the involvement of multiple Botryosphaeriaceae and Phytophthora species in the aetiology of the emerging diseases affecting fig trees in Italy.

Gnomoniopsis castaneae has become an important pathogen of European chestnut (Castanea sativa), affecting fruits and colonizing shoots and branches, as well as galls caused by the oriental chestnut gall wasp (Dryocosmus kuriphilus). On apparently asymptomatic fruits, G. castaneae can colonize the endosperms, causing quality issues, especially in post-harvest. Given the alarming spread of G. castaneae infections in Italy and the current knowledge gaps regarding aspects of G. castaneae biogeography and virulence, research was addressed to: 1) evaluate occurrence of G. castaneae in chestnut nuts and branches in different Italian regions; 2) study occurrence and distribution of the two known G. castaneae haplotypes throughout Italy; and 3) evaluate their virulence on chestnut under different water regimes. Fungal isolation from representative chestnut branch and nut samples consistently yielded colonies that were morphologically consistent with G. castaneae, the identity of which was confirmed by analysis of ITS sequences. Analysis of β-tubulin sequences confirmed the presence of two distinct genetic lineages (Gc-haplotypes A and B). To assess pathogenicity, G. castaneae isolates were inoculated onto chestnuts, chestnut cuttings and 3-year-old young plants grown under two water regimes. All assessed isolates were pathogenic on chestnut, and water-stressed plants exhibited more extensive necrosis than well-watered plants when inoculated with the Gc-haplotype A, highlighting the influence of environmental conditions on disease expression. This study expands current knowledge on the distribution, genetic diversity, and effects of water stress on the pathogenic potential of G. castaneae on chestnut.

During a monitoring survey carried out in a park in Aveiro, Portugal, typical Phytophthora symptoms of root rot, stem bleeding cankers and extensive canopy dieback were observed on mature ornamental glossy privet trees (Ligustrum lucidum). A study carried out in spring 2022 aimed to isolate the causal agents, as there is was no available knowledge on potential root pathogens of this host. Thirty-two Phytophthora isolates were obtained from inner bark tissues and/or rhizosphere samples (soil and fine roots) collected from 27 declining glossy privet trees. Based on morpho-biometric data and phylogeny of concatenated ITS and cox1 sequences, Phytophthora isolates were identified as P. hibernalis (14 isolates), P. multivora (12) and P. lacustris (6). Pathogenicity tests confirmed the virulence of the three species on glossy privet. Phytophthora lacustris was the most aggressive species, while P. hibernalis was most abundant. These results give new insights into emerging Phytophthora-related tree diseases in urban areas, and highlight the importance of enhancing biosecurity measures against these invasive pathogens.

In recent years, severe decline and mortality events have been observed in holm oak (Quercus ilex L.) ecosystems in different Italian regions, including Puglia (southern Italy). Given the landscape and ecological relevance of holm oak forests in Apulia, a study was conducted to identify the causal agents related to this complex disease syndrome. The surveys, conducted in winter 2024 in three different woodlands, revealed the widespread occurrence of mature holm oak trees showing sudden death, crown thinning, shoot and branch dieback, sunken cankers, and root rot symptoms. Isolations performed from symptomatic samples collected from both stem and small roots yielded fungal and fungal-like colonies representing two distinct families: Botryosphaeriaceae and Peronosporaceae. Analysis of morphological and DNA sequence data allowed us to identify six distinct species, including Diplodia corticola and D. quercivora (Botryosphaeriaceae), Phytophthora cinnamomi, P. multivora, P. psychrophila, and P. asparagi (Peronosporaceae). For P. asparagi and P. psychrophila, isolated for the first time from declining holm oak trees in Italy, Koch’s postulates were satisfied by inoculating 1-year-old seedlings at the collar in controlled conditions. Thirty days after inoculation, all plants showed the same symptoms observed in the field. Overall, the data obtained highlights the co-occurrence of multiple Botryosphaeriaceae and Phytophthora species on declining holm oak trees and the discovery of a new haplotype of Diplodia quercivora.

Fraxinus angustifolia, the main ash species in Croatia in terms of economic and ecological importance, is affected by a severe dieback initially attributed to the fungal pathogen Hymenoscyphus fraxineus. Recently, another pathogen, Diplodia fraxini, has been shown to play a key role in ash dieback in several European countries. Therefore, because the dieback symptoms of ash trees observed in Croatia are typical of Botryosphaeriaceae attacks, the aim of this study was to define the etiology of F. angustifolia dieback. To this end, symptomatic shoots and branches and cross-sections of the main stem were sampled from 20 symptomatic trees at eight locations and analyzed for the presence of D. fraxini and other possible fungal pathogens. Diplodia fraxini was the fungus most frequently associated with branch cankers and dieback; it was isolated from 17 trees in all sites monitored, and its pathogenicity towards F. angustifolia was confirmed. The fungus was also associated with wood necrosis at the base of the trunk in two trees. Other fungi, namely H. fraxineus, Diaporthe eres, Diplodia seriata, Botryosphaeria dothidea, Armillaria gallica, and Lentinus tigrinus, were isolated sporadically.