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Several natural compounds have been found to act as PPARγ agonists, thus regulating numerous biological processes, including the metabolism of carbohydrates and lipids, cell proliferation and differentiation, angiogenesis, and inflammation. Recently, Cladosporols, secondary metabolites purified from the fungus Cladosporium tenuissimum, have been demonstrated to display an efficient ability to control cell proliferation in human colorectal and prostate cancer cells through a PPARγ-mediated modulation of gene expression. In addition, Cladosporols exhibited a strong anti-adipogenetic activity in 3T3-L1 murine preadipocytes, preventing their in vitro differentiation into mature adipocytes. These data interestingly point out that the interaction between Cladosporols and PPARγ, in the milieu of different cells or tissues, might generate a wide range of beneficial effects for the entire organism affected by diabetes, obesity, inflammation, and cancer. This review explores the molecular mechanisms by which the Cladosporol/PPARγ complex may simultaneously interfere with a dysregulated lipid metabolism and cancer promotion and progression, highlighting the potential therapeutic benefits of Cladosporols for human health.

Environmental changes are occurring on a global scale, but their effects are most pronounced in climate change hotspot zones, such as the Mediterranean basin. Within this area Italy, extending from its southern coasts in the core of the Mediterranean Sea to its northernmost pre-Alpine and Alpine regions, is characterized by a variety of climatic conditions and vegetation types. Surveys conducted in 2018–2022 in forest formations of Central-Northern Italy revealed that the enhanced warming trend and irregular distribution of precipitations are strongly impacting the health of Fraxinus species, with some pathogenic fungi and oomycetes being important contributing factors to the decline of the three main ash species growing there: common ash (Fraxinus excelsior), flowering ash (Fraxinus ornus), and narrow-leaved ash (Fraxinus angustifolia). Isolation from symptomatic plant material collected countrywide under different site conditions and pathogenicity tests revealed a complex phytopathological framework, with several pathogenic species in addition to Hymenoscyphus fraxineus involved with a prominent role in the ash dieback etiology. Key microbial taxa included the fungal and oomycete pathogens Botryosphaeria dothidea, Diplodia fraxini, Diplodia subglobosa, Phytophthora acerina, and Phytophthora plurivora. The disease impact was higher on sites where ash trees grew under environmental stress (i.e., areas characterized by mild dry winters, hot summers with intense and prolonged drought) and exhibited reduced vigor, also as a consequence of anthropogenic interference (i.e., silvicultural management and fires). The identified causative agents are emerging pathogens that thrive under warmer conditions, their impact in the investigated areas being prevalent compared to H. fraxineus, which appears to be restricted on the Italian peninsula to the cooler and wetter valleys of the Alps and Central-Northern Apennines.

Gnomoniopsis castaneae is responsible for brown or chalky nut rot in sweet chestnut (Castanea sativa), causing heavy reductions in nut production. Controlling it is challenging, due to its inconspicuous infections, erratic colonization of host tissues and endophytic lifestyle. Fungicides are not applicable because they are prohibited in chestnut forests and strongly discouraged in fruit chestnut groves. Trichoderma species are safe and wide-spectrum biocontrol agents (BCAs), with a variety of beneficial effects in plant protection. This study tested selected strains of T. viride, T. harzianum and T. atroviride for their ability to suppress G. castaneae. Field experiments were conducted in four chestnut groves (two test plots plus two controls) at two sites with a different microclimate. As the size of the trees were a major drawback for uniform and effective treatments, the Trichoderma strains were delivered directly by trunk injection, using the BITE® (Blade for Infusion in TrEes) endotherapic tool. The BCA application, repeated twice in two subsequent years, significantly reduced nut rot incidence, with a more marked, presumably cumulative, effect in the second year. Our data showed the tested Trichoderma strains retain great potential for the biological control of G. castaneae in chestnut groves. The exploitation of Trichoderma spp. as biopesticides is a novelty in the forestry sector and proves the benefits of these microbes in plant disease protection.

A severe dieback of flowering ash (Fraxinus ornus L.) has been observed in north-central Italy in the last decades. Symptoms include typical sunken, light-brown cankers on the stem and branches; vascular discoloration; tip and shoot dieback; and foliage necroses. The disease was more evident at the beginning of the growing season, and more severe on young regeneration. Six Botryosphaeriaceae species were consistently isolated from symptomatic plant tissues: Botryosphaeria dothidea, Diplodia fraxini, Diplodia subglobosa, Dothiorella iberica, Dothiorella omnivora and Neofusicoccum parvum. B. dothidea and D. fraxini expressed higher aggressiveness and showed a widespread incidence, being the species most frequently associated with cankers; the other four species were less virulent and more erratic, occurring mainly on succulent branch tips and foliage. Isolates were characterized using morphological and molecular approaches (colony/conidial phenotyping and rDNA-ITS genotyping). Phylogenetic analysis provided congruent phylogenies depicting the relationships of the six taxa with the most closely related conspecifics. Pathogenicity tests on 2-year-old seedlings confirmed the higher virulence of B. dothidea and D. fraxini. Extensive, multi-year field surveys at different sites supported the hypothesis that climatic vagaries, mainly heat, water and drought stresses, impaired tree health and vigor, facilitating infection and pervasive colonization by these Botryosphaeriaceae species. Environmental stressors are thus the key factor bringing the six fungal pathogens together in a multitrophic interaction with F. ornus in a novel, lethal fashion.

Cypress Canker Disease (CCD) pandemic caused by Seiridium cardinale is the major constraint of many Cupressaceae worldwide. One of the main symptoms of the disease is the flow of resin from the cankered barks. While inducible phloem axial resin duct-like structures (PARDs) have recently been characterized from an anatomical point of view, their actual resin production is still being debated and has never been demonstrated. Although the involvement of polyphenolic parenchyma cells (PP cells) in the bark of Cupressus sempervirens after S. cardinale infection was revealed in one of our previous studies using light microscopy, their evolution from the phloem parenchyma cells is yet to be clarified. This study investigated functional and ultrastructural aspects of both PARD-like structures and PP cells by means of more in-depth light (LM) and fluorescence microscopy (FM) combined with histochemical staining (using Sudan red, Fluorol Yellow, NADI Aniline blue black, and Toluidine blue staining), in addition to Transmission Electron Microscope (TEM). Two-year-old stem sections of a C. sempervirens canker-resistant clone (var. “Bolgheri”), artificially inoculated with S. cardinale, were sampled 5, 7, 14, 21, and 45 days after inoculation, for time-course observations. FM observation using Fluorol yellow dye clearly showed the presence of lipid material in PARD-like structures lining cells of the cavity and during their secretion into the duct space/cavity. The same tissues were also positive for NADI staining, revealing the presence of terpenoids. The cytoplasm of the ducts' lining cells was also positive for Sudan red. TEM observation highlighted the involvement of plastids and endoplasmic reticulum in the production of terpenoids and the consequent secretion of terpenoids directly through the plasma membrane, without exhibiting vesicle formation. The presence of a high number of mitochondria around the area of terpenoid production suggests that this process is active and consumes ATP. The LM observations showed that PP cells originated from the phloem parenchyma cells (and possibly albuminous cells) through the accumulation of phenolic substances in the vacuole. Here, plastids were again involved in their production. Thus, the findings of this work suggest that the PARD-like structures can actually be considered PARDs or even bark traumatic resin ducts (BTRD).

Thousand cankers disease (TCD) is a new deadly disease in walnut trees (Juglans spp.), which is plaguing commercial plantations, natural groves, and ornamental black walnut trees (Juglans nigra) in their native and invasion areas in the US and, more recently, in artificial plantations and amenity trees in the newly-invaded areas in Europe (Italy). This insect/fungus complex arises from the intense trophic activity of the bark beetle vector Pityophthorus juglandis in the phloem of Juglans spp. and the subsequent development of multiple Geosmithia morbida cankers around beetles’ entry/exit holes. After an analysis of the main biological and ecological traits of both members of this insect/fungus complex, this review explores the options available for TCD prevention and management. Special focus is given to those diagnostic tools developed for disease detection, surveillance, and monitoring, as well as to existing phytosanitary regulations, protocols, and measures that comply with TCD eradication and containment. Only integrated disease management can effectively curtail the pervasive spread of TCD, thus limiting the damage to natural ecosystems, plantations, and ornamental walnuts.

Walnut species (Juglans spp.) are multipurpose trees, widely employed in plantation forestry for high-quality timber and nut production, as well as in urban greening as ornamental plants. These species are currently threatened by the thousand cankers disease (TCD) complex, an insect–fungus association which involves the ascomycete Geosmithia morbida (GM) and its vector, the bark beetle Pityophthorus juglandis. While TCD has been studied extensively where it originated in North America, little research has been carried out in Europe, where it was more recently introduced. A key step in research to cope with this new phytosanitary emergency is the development of effective molecular detection tools. In this work, we report two accurate molecular methods for the diagnosis of GM, based on LAMP (real-time and visual) and SYBR Green qPCR, which are complimentary to and integrated with similar recently developed assays. Our protocols detected GM DNA from pure mycelium and from infected woody tissue with high accuracy, sensitivity, and specificity, without cross-reactivity to a large panel of taxonomically related species. The precision and robustness of our tests guarantee high diagnostic standards and could be used to support field diagnostic end-users in TCD monitoring and surveillance campaigns.

The ascomycete fungus Geosmithia morbida (GM) and the walnut twig beetle (WTB), Pityophthorus juglandis, constitute a recently discovered fungal–insect complex responsible for the harmful Thousand Cankers Disease (TCD) in walnut trees. Key aspects of the epidemiology and ecology of the fungus and its insect vector were investigated in a disease outbreak found in central Italy, currently the southernmost introduction area of TCD on the Old Continent. Walnut trees with symptoms of crown dieback and epicormic branching with beetle galleries were sampled for pathogen isolation, while funnel traps were used to catch beetles and obtain adult flight curves. Growth-temperature relationships were determined for the fungus; optimum growth temperature for GM was 25°C, but it thrived up to 37°C. The phloem-boring bark beetle showed a longer flight period than in northern Italy. The beetle haplotype identified in Tuscany (H1) differed from haplotypes H2 and H21 found in northern Italy, suggesting possible multiple anthropogenic introductions. The substantial high temperature tolerance shown by the two organisms suggests they will not be constrained by the high temperatures of warmer areas. As a consequence, the impact of TCD in southern Europe, where the native Juglans regia is widely cultivated for its nuts and wood, would potentially be disastrous to local economies. In fact, although J. regia is not considered as susceptible as J. nigra, it can nevertheless be attacked in conditions of high bark beetle population density, a harbinger of high fungus’ propagule pressure.

Lindgren funnel traps were used to monitor Pityophthorus juglandis occurrence. Traps were placed directly on walnut trees, with the top tied to one of the lower branches (about 2m high). An 8-funnel model was used instead of a 4-funnel trap, with the specific pheromone bait positioned between the fourth and the fifth funnel. Traps were customized with a 5mm metal mesh which was placed inside the bottom funnel so that debris (mainly foliage) and larger non-target insects would not end up inside the collecting jar. Geosmithia morbida was isolated from beetle adults, larvae and necrotic woody tissue around beetle galleries. Contaminant-free colonies were subcultured in purity and identified by: a) colony phenotyping [morphology, texture and pigmentation; margin type (regular/irregular; lobed/non-lobed); mycelium compactness; surface bumpiness; growth/temperature relationships]; b) micromorphology: type, morphology and ontogeny of conidiophores, metulae and phialides; conidiogenesis; shape, dimension and pigmentation of conidia; c) DNA fingerprinting. • Our protocol was customized to prevent traps from swinging in the wind and to optimize beetle catches by transversely fixing the bottom of funnel traps to the tree trunk with wooden shafts for stability. • To enhance fungus isolation in purity, a semi-selective Potato Dextrose Agar (PDA) medium, enriched with the antibiotics Ampicillin (Policillin-N) and Rifampicin (Rifamycin), was devised to prevent contamination by Gram-positive and Gram-negative bacteria and by mycobacteria.

The cultivation of walnuts (Juglans sp.) in Europe retains high economic, social, and environmental value. The recent reporting of the Thousand Cankers Disease (TCD) fungus, Geosmithia morbida, and of its vector, Pityophthorus juglandis, in walnut trees in Italy is alarming the whole of Europe. Although Italy is at present the only foothold of the disease outside North America, given the difficulties inherent in traditional identification of both members of this beetle/fungus complex, a rapid and effective protocol for the early detection and identification of TCD organisms is an absolute priority for Europe. Here we report the development of an effective and sensitive molecular tool based on simplex/duplex qPCR assays for the rapid, accurate and highly specific detection of both the bionectriaceous fungal pathogen and its bark-beetle vector. Our assay performed excellently, detecting minute amounts of target DNA without any non-specific amplification. Detection limits from various and heterogeneous matrices were lower than other reported assays. Our molecular protocol could assist in TCD organism interception at entry points, territory monitoring for the early identification and eradication of outbreaks, delineation of quarantine areas, and tracing back TCD entry and dispersal pathways.

Tree pathogens and pests are fundamental components of forest ecosystems. By killing and decomposing susceptible trees, they regulate the cycle of nutrients and energy flow, thus shaping the structure and composition of forest stands. However, ecosystems can be seriously disrupted when the population density of these parasites increases beyond their tolerance level. Ascertaining the origin of pathogen and pest outbreaks, recognizing their causal agents in a precise and unequivocal way, while understanding their reproductive and dispersive dynamics are all crucial for the implementation of effective control measures. The studies collected in this special issue cover a wide range of topics in the field of forest pathology and entomology. Investigations range from molecular diagnosis of pathogens and pests to their monitoring and quantification in the field, from measurements of their proliferation rate to the analysis of their genetic variability, from the assessment of the role of plant diversity and ecosystem heterogeneity on pathogen and pest impacts to disease and pest management. Specific case studies show how applied research conducted with innovative methods is key to solving taxonomic issues that were, until now, controversial. The variety of experimental approaches and the range of scientific issues addressed document the trends and topicality of modern forest health protection science.

Paulownia species are fast growing trees native to China, which are being grown in managed plantings in several European countries for the production of wood and biomasses. In 2018, wilting, stunting, leaf yellowing, and collapse, as a consequence of root and crown rot, were observed in around 40% of trees of a 2-year-old planting of Paulownia elongata × P. fortunei in Calabria (Southern Italy). Two species of Phytophthora were consistently recovered from roots, basal stem bark, and rhizosphere soil of symptomatic trees and were identified as Ph. nicotianae and Ph. palmivora on the basis of both morphological characteristics and phylogenetic analysis of rDNA ITS sequences. Koch’s postulates were fulfilled by reproducing the symptoms on potted paulownia saplings transplanted into infested soil or stem-inoculated by wounding. Both Phytophthora species were pathogenic and caused root rot and stem cankers. Even though P. palmivora was the only species recovered from roots of naturally infected plants, in pathogenicity tests through infested soil P. nicotianae was more virulent. This is the first report of Phytophthora root and crown rot of a Paulownia species in Europe. Strategies to prevent this emerging disease include the use of healthy nursery plants, choice of well-drained soils for new plantations, and proper irrigation management.

Forest health worldwide is impacted by many invasive alien pathogens and pests (IAPPs) that cause significant harm, with severe economic losses and environmental alterations. Destructive tree pathogens and pests have in the past devastated our forests, natural landscapes and cityscapes and still continue to represent a serious threat. The main driver of pathogen and pest invasions is human activities, above all global trade, which allows these invasive species to overstep their natural distribution ranges. While natural transport occurs according to a regular, expected colonization pattern (based on the dispersive capacity of the organism), human-mediated transport takes place on a larger, unpredictable scale. In order for a pathogen or pest species to become invasive in a new territory it must overcome distinct stages (barriers) that strongly affect the outcome of the invasion. Early detection is crucial to enabling successful eradication and containment. Although sophisticated diagnostic techniques are now available for disease and pest surveillance and monitoring, few control and mitigation options are usable in forestry; of these, biological control is one of the most frequently adopted. Since invasion by pathogens and pests is an economic and ecological problem of supranational relevance, governments should endorse all necessary preventive and corrective actions. To this end, establishing and harmonizing measures among countries is essential, both for preventing new introductions and for diminishing the eventual range expansion of IAPPs present at a local scale. Research is fundamental for: (i) developing effective and rapid diagnostic tools; (ii) investigating the epidemiology and ecology of IAPPs in newly introduced areas; and (iii) supporting policymakers in the implementation of quarantine regulations.

Oaks are dominant and key tree species in Mediterranean forest ecosystems. However, in recent decades, oak forests have been heavily impacted by oak decline, a worldwide phenomenon exacerbated by climate change. The charcoal disease agent Biscogniauxia mediterranea is involved in the decline of Mediterranean oak formations in a variety of contexts. Here, we investigated the impact and role of B. mediterranea in the decline of oaks in Castelfidardo Forest, a relict wood of the late Holocene and a Site of Community Importance. We established five plots within which we recorded tree positions, any symptoms and signs of decline, association of B. mediterranea to declining trees, and deadwood and associated mycota. Of 471 oaks inspected, 7.0% showed brownish exudates on the stems, 46.9% showed epicormic shoots along the main trunk, and 24.4% showed black carbonaceous stromata on diseased branches and trunks. The decline was most severe for Quercus cerris, which comprised plots #4 and #5, at 50.0% (81/162 trees) and 29.0% (33/114), respectively; then for Quercus robur for plot #3, at 40.0% (38/95); and finally for Quercus pubescens for plots #1 and #2, at 13.7% (7/51) and 12.3% (6/49), respectively. Bark tissues were collected from trees with charcoal cankers and taken to the laboratory for microscopic examination and identification by mycological and molecular methods. This investigation revealed a close association between oaks with pronounced reduction of vitality and incidence of B. mediterranea. Deadwood was equally distributed among the five plots, and was heavily colonized by Basidiomycota. The high incidence of the charcoal canker pathogen B. mediterranea appeared to be related to environmental stresses. However, the absence of silvicultural management, high competition among physiologically mature trees, and the geographic isolation of this residual forest may have predisposed oaks to decline.

In this work, we rechecked, using species-specific Loop mediated isothermal AMPlification (LAMP) diagnostic assays followed by sequencing of fungal isolates at the beta-2-tubulin (tub2) gene region, a historical and never confirmed report of Dothistroma needle blight (DNB) in the introduced Monterey pine (Pinus radiata D. Don) in the mountains in the extreme tip of southern Italy. The report dates back to the mid-1970s, and predates the molecular-based taxonomic revision of the genus Dothistroma that defined the species accepted today. In the fall of 2019, symptomatic needles of Monterey pine and Corsican pine (Pinus nigra subsp. laricio (Poir.) Palib. ex Maire) were sampled in the area of the first finding. The applied diagnostic methods revealed the presence of Dothistroma septosporum (Dorogin) M. Morelet on both pine species. In this way, we: (i) confirmed the presence of the disease; (ii) clarified the taxonomic identity of the causal agent now occurring at that site; (iii) validated the species-specific LAMP diagnostic protocol we recently developed for Dothistroma for use on a portable field instrument, and (iv) showed that the pathogen now also attacks the native P. nigra subsp. laricio, a species particularly susceptible to the disease, indigenous to the mountains of Calabria, which is one of the very few areas where the species’ genetic resources are conserved. Comparative genetic analysis of the rare populations of D. septosporum found in the central Mediterranean region and in the native range of P. nigra subsp. laricio could help to clarify the history of the spread of the pathogen in southern Europe and better evaluate the risk it poses to the conservation of native pine species.

Melampsoridium hiratsukanum is an alien rust fungus which has spread pervasively throughout several European countries following introduction into North Europe at the end of the 20th century. The authenticity of several records of the Melampsoridium species infecting alder (Alnus spp.) in the northern hemisphere is questionable, due to the misidentification and confusion that surround many of the older reports. Given this complicated taxonomic history, and since a M. hiratsukanum-like rust is strongly impacting Alnus incana stands in the Alps, probably affecting the bank protection role of this species along rivers, the unambiguous identification of this pathogen was a pressing epidemiological and ecological issue. In this study, field surveys, light (LM) and scanning electron microscopy (SEM), and molecular characterization were put together in an attempt to solve the conundrum. Field monitoring data, LM and SEM analyses of key taxonomic traits (length of ostiolar cells of uredinium, uredinio-spore shape and size, spore echinulation, number and position of germ pores) and ITS-rDNA sequence-based identification, convergently and unambiguously connected the rust that is causing the current epidemic to the non-native M. hiratsukanum. We documented the completion of the M. hiratsukanum life cycle on its two taxonomically unrelated broadleaf/conifer hosts. This is the first report of M. hiratsukanum from naturally infected Larix decidua in Europe.

The walnut twig beetle Pityophthorus juglandis is a phloem-boring bark beetle responsible, in association with the ascomycete Geosmithia morbida, for the Thousand Cankers Disease (TCD) of walnut trees. The recent finding of TCD in Europe prompted the development of effective diagnostic protocols for the early detection of members of this insect/fungus complex. Here we report the development of a highly efficient, low-cost, and rapid method for detecting the beetle, or even just its biological traces, from environmental samples: the loop-mediated isothermal amplification (LAMP) assay. The method, designed on the 28S ribosomal RNA gene, showed high specificity and sensitivity, with no cross reactivity to other bark beetles and wood-boring insects. The test was successful even with very small amounts of the target insect’s nucleic acid, with limit values of 0.64 pg/µL and 3.2 pg/µL for WTB adults and frass, respectively. A comparison of the method (both in real time and visual) with conventional PCR did not display significant differences in terms of LoD. This LAMP protocol will enable quick, low-cost, and early detection of P. juglandis in areas with new infestations and for phytosanitary inspections at vulnerable sites (e.g., seaports, airports, loading stations, storage facilities, and wood processing companies).

The Authors have analyzed the interactions between insects and fungal pathogens of chestnut, cypress, elm, oak and pine trees in the natural environment and in urban areas. A brief description of the insect's life cycle is provided by relating some of its phases with the vectored fungus. The purpose of this work is to relate the different insect/pathogen associations with their environment in order to bring out the role of such symbioses in determining, together with abiotic factors, the destabilization of forest and urban ecosystems. The ascertained and possible interactions, as well as the ones that might occur in the future between immigrant and resident insects and fungal pathogens as a consequence of new introductions, are treated separately, taking into account the available control strategies, in particular those that are feasible in human-frequented areas.

Phytophthora ramorum is a quarantine pathogen that causes leaf blight and shoot dieback of the crown, bark cankers and death on a number of both ornamental and forest trees, especially in North America and northern Europe, where it has produced severe outbreaks.In Italy it was first reported in 2002, on Rhodondendron yakushimanum in a Piedmont nursery; after that it seemed to have disappeared, only to re-emerge in 2013 when numerous isolates were detected on batches of Viburnum tinus plants growing in some nurseries in the Pistoia area (Tuscany), which is an important district in the trade of nursery plants world-wide. This work reports on a number of laboratory tests that were carried out on isolates from infected plant samples. The micromorphological and macromorphological characteristics of the pathogen growing on carrot agar (CA), corn meal agar (CMA), malt extract agar (MEA) potato dextrose agar, and V8 agar with added PARPNH (see text) were determined, as was the growth rate at 10º, 15º, 20º, 25°, 30º, 32º and 35ºC. Molecular analysis was employed to identify the isolates more precisely. Inoculation trials under the bark were also carried out to ascertain the isolate virulence and the Koch’s Postulates.The Plant Protection Service of the Tuscan Region (SFR, Servizio Fitosanitario Regionale) was alerted as soon as the pathogen infection was detected and it took the prescribed steps to eradicate the infection in the field and prevent the recurrence of an epidemic.

Research Highlights: Protected natural areas are a reservoir of Phytophthora species and represent the most suitable sites to study their ecology, being less disturbed by human activities than other environments. Background and Objectives: The specific objective of this study was to correlate the diversity and distribution of Phytophthora species with the vegetation in aquatic, riparian and terrestrial habitats within a protected area in Eastern Sicily, Southern Italy. Materials and Methods: Environmental samples (water and soil) were sourced from two streams running through the reserve and six different types of vegetation, including Platano-Salicetum pedicellatae, the Sarcopoterium spinosum community, Myrto communis-Pistacietum lentisci, Pistacio-Quercetum ilicis,Oleo-Quercetum virgilianae and a gallery forest dominated by Nerium oleander (Natura 2000 classification of habitats). Phytophthora species were recovered from samples using leaf baiting and were classified on the basis of morphological characteristics and sequencing of internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA). Results: As many as 11 Phytophthora species, within five different ITS clades, were identified, including P. asparagi, P. bilorbang, P. cryptogea, P. gonapodyides, P. lacustris, P. multivora, P. nicotianae, P. oleae, P. parvispora, P. plurivora and P. syringae. No Phytophthora species were found in the Sarcopoterium spinosum comm. Phytophthora asparagi, P. lacustris and P. plurivora were the prevalent species in the other five plant communities, but only P. plurivora was present in all of them. Overall aquatic species from clade 6 (100 out of 228 isolates) were the most common; they were recovered from all five types of vegetation, streams and riparian habitats. Phytophthora populations found in the Platano-Salicetum pedicellatae and Oleo-Quercetum virgilianae show the highest diversity, while no correlation was found with the physicochemical characteristics of the soil. Conclusions: The vegetation type and the aquatic or terrestrial habitat were identified as major environmental factors correlated with the diversity of Phytophthora communities in this reserve.

Successful infection by a tree pathogen depends both on species-specific traits, related to its infection biology, and on external factors, i.e. the biotic and abiotic components of the ecosystem. Among species-specific traits, virulence, biomass (propagule) production and dispersal ability all contribute to pathogen establishment and spread. Among the external factors, two crucial roles are played by an environment conducive to disease and by vector occurrence. We investigated the endophytic fungi and xylophagous beetles associated with declining oaks in a natural stand of central Italy, particularly focusing on the fungi isolated from insects’ body. This paper extends and reinterprets the outcome of a previous study, which looked into the whole mycota (pathogenic/neutral/beneficial) found on these oaks. A rich assemblage of fungi was found on declining trees on which a number of wood-boring beetles (Buprestidae and Cerambycidae) also occurred. In the laboratory two-thirds of the insects proved to convey propagules of prominent fungal pathogens (Botryosphaeriaceae, Pestalotiopsidaceae, Plectosphaerellaceae, Pleosporaceae); this confirms pathogen pervasiveness in oak stands is enhanced by their association with xylophagous insects. The outcome of this research will benefit forest manager and other stakeholder efforts to manage stands and species invasions, also in the light of climate change. Keywords: Oak decline, Endophytic fungi, Xylophagous beetles

The present-day phytosanitary disasters caused by biological invasions are afflicting urban and peri-urban forest stands worldwide, as well as the varied services they normally provide. In Europe, we are witnessing an alarming situation due to an increasing introduction of infectious diseases and pests. The authors present an up-to-date list of alien microbial pathogens and insect pests affecting urban greening that have been accidentally imported in Italy or that are likely to be introduced. Information about the biology, epidemiology, ethology, and control of these invasive organisms is provided. For each species, the current geographical distribution, including newly-colonized areas, is also given, as well as the chronological progression of its occurrence. Particular detail is used for describing symptoms—the key diagnostic elements for appropriate and timely phytosanitary management. This paper will benefit urban forest management, which is a crucial factor in maintaining the social and ecological viability of urban green spaces, as well as ecosystem services. The importance of engaging citizens in community-based monitoring of urban greenspaces for tracking the location, abundance, and pathways of invasive pathogens and pests will also be touched upon.

The specificity of fungal endophytes to trees has generally been investigated on allopatric populations. In the present study, specificity was investigated on Quercus cerris and Quercus pubescens growing in sympatry at the same site, to examine host-endophyte interactions without interference from habitat-specific selective pressure. In a two-year study, 4800 samples were obtained from photosynthetic and non-photosynthetic tissue (leaves and twigs) both of healthy and declining trees. Endophytes were isolated from surface-sterilized samples and identified by traditional or molecular methods. Twenty-two endophyte species in 19 genera were identified. Some taxa in the Sordariomycetes, Dothideomycetes and Leotiomycetes colonized both species, but quantitative differences were evident. Water shortages and extended droughts may have impacted more severely on Q. cerris, which exhibited a more diverse endophytic assemblage and greater infection levels than Q. pubescens. In both species, more isolates were recovered from twigs than from leaves, and more from declining than from healthy trees. Endophytes tended to be specific to each host, and to the organs of that host. Interaction between plant species and the environment and continued competitive interaction between endophyte species may have led to niche diversification, with selection favouring host-specific and organ-specific endophytes. This study advances understanding of the role of some pathogenic fungal endophytes in Mediterranean oak forests.

The ecological and economic sustainability of agricultural and forest systems of many advanced and underdeveloped Countries are strongly threatened by the increasing introduction of exotic plant pathogens. This article provides an overview of the main causes behind these invasions. Some important diseases caused by non native phytopathogens, whose arrival in the past century had a disastrous impact on the environment and economy of vast rural areas of our Country are reported. Some dangerous, emerging pathogens, which are literally destroying whole territories in various parts of the Planet, with severe damage to agricultural crops, landscape, economy and local tourism are also reported. Action strategies to prevent immigration of unwanted pathogens, and mitigation strategies, aimed at the development of various measures to mitigate the negative effects of plant parasites already established in the territory are then discussed. Finally, it is highlighted how such a far-reaching problem can be properly tackled only with the active contribution of governments, institutions responsible for plant health monitoring (warning services), research, and agricultural, tourism and transport operators.

The relationship between the growth increments of declining and healthy Quercus robur and monthly rainfall and temperature data was explored in a Q. robur stand situated near Fagarè (Padova) in north-eastern Italy. As part of the same study, Q. robur growth rings were examined for gum deposits associated with Fusarium eumartii, an anamorphic fungus previously found on declining Q. robur individuals from the same area. The growth rings showed that over the period 1961–1994, declining trees had an average growth increment of 2.24 mm, while for healthy trees the increment was 3.57 mm. The mean monthly temperatures recorded between 1961 and 1994 were normal for the Po-Veneto basin. Mean monthly precipitation in March and April, the months in which resumption of vegetative growth occurs in Q. robur, was 100 mm or less in 1961, 1966, 1968, 1969, 1973, 1976, 1982, 1987, 1988, 1993 and 1994. It is precisely during these months that the rainfall needs of Q. robur exceed 100 mm/month, however. The lower growth recorded in those years was therefore to be attributed to drought in the months of March and April. At the same time F. eumartii was always isolated from the growth rings corresponding to the years 1962, 1967, 1969, 1970, 1977, 1983, 1988, 1989 and 1994. Each of these years followed a year characterised by reduced growth. It is concluded that the decline of the Q. robur population occurring at Fagarè may be due to periods of drought acting as an inciting factor to reduce growth, followed one year later by activity of the pathogen F. eumartii and its metabolites, as a contributing factor.

The isolation frequency of endophytic fungi in Quercus cerris was determined in relation to sampling data, the health state of the tree, and the tree organ affected. Sampling was carried out at three times, in April (budbreak), June (full vegetation) and October (leaf fall), on trees that were either healthy or in decline, and on three organs: current-year twigs, with a diameter less than 2 cm, buds, and leaves. The experiment was done in an approximately 20-year-old oak forest at an altitude of 350-400 m above sea level. Three healthy and three declining trees were sampled annually in 1999 and 2000. From each tree 20 current-year twigs, 20 buds and 10 leaves were harvested. Tissue fragments, after sterilization with 10% H2O2, were incubated on potato-dextrose-agar amended with streptomycin, at 20°C in the dark for 7 days, and the isolated mycelia maintained at 4°C on malt-extract agar. A total of 15 fungal species were isolated. All organs yielded fungal species but the greatest number of endophytic species came from current year twigs. Individual species were isolated more often from declining trees than from healthy trees, and more fungi were isolated in June (full vegetation) than in April or October. Diplodia mutila, Discula quercina and Phomopsis quercina, which are known to be pathogenetic on oaks, were present on oaks for a large part of the year. These fungi are both saprophytes (as endophytes) and parasites and are, therefore, probably a serious contributing and inciting factor in the oak decline syndrome.