Fungal Species Causing Canker and Wilt of Ficus carica and Evidence of their Association with Bark Beetles in Italy.

Field surveys conducted during 2021 and 2022 in Western Sicily, Italy, revealed the presence of common fig trees severely affected by trunk and crown root canker and bark cracking. Moreover, in conjunction with the symptomatic tissues, the same surveyed plants showed the presence of bark beetle holes and internal wood galleries. The predominant beetle Criphalus dilutus was previously reported attacking figs in Sicily. Phylogenetic analyses based on multi-locus DNA data showed the presence of different fungal taxa associated with disease symptoms, including Botryosphaeria dothidea, Ceratocystis ficicola, Diaporthe foeniculina, Neocosmospora bostrycoides, N. perseae and Neofusicoccum luteum. Pathogenicity tests conducted on potted fig plants showed that all the species were pathogenic to fig, with C. ficicola and Neocosmospora spp. as the most aggressive fungal species. Moreover, isolations conducted from the bodies of emerging adult insects recovered from disease samples confirmed the presence of C. ficicola and Neocosmospora spp., suggesting the potential involvement of C. dilutus in their dissemination.

Characterization and Pathogenicity of Fungal Species Associated with Dieback of Apple Trees in Northern Italy.

Severe dieback symptoms were recently observed on apple (Malus × domestica) trees in Northern Italy, representing a growing concern for producers. Surveys were conducted over a 3-year period (2019 to 2021), and five apple orchards, from 5 to 12 years old, were monitored. A total of 33 fungal isolates isolated from symptomatic plants was selected for characterization. The species identification was achieved through multilocus phylogenetic analyses performed on sequences of three genomic loci (ITS, tub2, and tef1). Morphological features were assessed, and the average growth rate at different temperatures was determined. Seven species were identified in association with dieback of apple trees: Botryosphaeria dothidea, Cadophora luteo-olivacea, Diaporthe rudis, Diplodia seriata, Eutypa lata, Kalmusia longispora, and Paraconiothyrium brasiliense. All the species were pathogenic when inoculated on healthy apple plants. B. dothidea resulted in the most aggressive infections. This study provides an insight into the fungal species diversity associated with apple dieback and provides basis for further investigations to assess the phytosanitary status of plant materials to recommend and implement effective management strategies.

Diversity and Pathogenicity of Fusarium Species Associated with Stalk and Crown Rot in Maize in Northern Italy.

The genus Fusarium includes several agronomically important and toxin-producing species that are distributed worldwide and can cause a wide range of diseases. Crown and stalk rot and grain infections are among the most severe symptoms that Fusarium spp. can cause in maize. Disease development usually occurs during germination, but it may also affect the later phases of plant growth. The purpose of this study was to investigate the diversity and pathogenicity of 41 isolates recovered from symptomatic seedlings collected in Northern Italy and seeds of five different geographical origins in 2019 and 2020. The pathogenicity was tested and confirmed in 23 isolates causing rotting in maize seedlings, with disease indexes from 20% to 90%. A multilocus phylogeny analysis based on four genomic loci (tef1-α, rpb2, calm and tub2) was performed on 23 representative isolates. Representative isolates were identified as species belonging to three species complexes (SC), including Fusarium verticillioides and F. annulatum in the F. fujikuroi SC. Fusarium commune was identified in the F. nisikadoi SC, and three different lineages were found in the Fusarium oxysporum SC. This study reports F. annulatum and two lineages of the Fusarium oxysporum SC as maize pathogens for the first time in Italy.

Molecular Characterization and Pathogenicity of Alternaria spp. Associated with Black Rot of Sweet Cherries in Italy.

Black rot is limiting the production of sweet cherries in Italy. Dark brown to black patches and sunken lesions on fruits are the most common symptoms of Alternaria black rot on sweet cherry fruits. We isolated 180 Alternaria spp. from symptomatic cherry fruits 'Kordia', 'Ferrovia', and 'Regina' harvested in Northern Italy, over three years, from 2020 to 2022. The aim was to identify and characterize a selection of forty isolates of Alternaria spp. based on morphology, pathogenicity, and combined analysis of rpb2, Alt-a1, endoPG and OPA10-2. The colonies were dark greyish in the center with white margins. Ellipsoidal or ovoid shaped conidia ranging from 19.8 to 21.7 µm in length were observed under a microscope. Based on the concatenated session of four gene regions, thirty-three out of forty isolates were identified as A. arborescens species complex (AASC), and seven as A. alternata. Pathogenicity was evaluated on healthy 'Regina' sweet cherry fruits. All the tested strains were pathogenic on their host. This study represents the first characterization of Alternaria spp. associated with black rot of cherries in Italy and, to the best of our knowledge, it is also the first report of AASC as an agent of black rot of sweet cherries in Italy.

Molecular Characterization and Pathogenicity of Diaporthe Species Causing Nut Rot of Hazelnut in Italy.

Hazelnut (Corylus avellana), a nut crop that is rapidly expanding worldwide, is endangered by a rot. Nut rot results in hazelnut defects. A survey was conducted in north-western Italy during 2020 and 2021 to identify the causal agents of hazelnut rots. Typical symptoms of black rot, mold, and necrotic spots were observed on hazelnut nuts. The prevalent fungi isolated from symptomatic hazelnut kernels were Diaporthe spp. (38%), Botryosphaeria dothidea (26%), Diplodia seriata (14%), and other fungal genera with less frequent occurrences. Among 161 isolated Diaporthe spp., 40 were selected for further analysis. Based on morphological characterization and multi-locus phylogenetic analysis of the ITS, tef1- α, and tub2, seven Diaporthe species were identified as D. eres, D. foeniculina, D. novem, D. oncostoma, D. ravennica, D. rudis, and D. sojae. D. eres was the main species isolated from hazelnut rots, in particular from moldy nuts. Pathogenicity test performed on hazelnut nuts 'Tonda Gentile del Piemonte' using a mycelium plug showed that all the Diaporthe isolates were pathogenic on their original host. To our knowledge, this work is the first report of D. novem, D. oncostoma and D. ravennica on hazelnut nuts worldwide. Diaporthe foeniculina, D. rudis, and D. sojae were reported for the first time as agents of hazelnut nut rot in Italy. Future studies should focus on the comprehension of epidemiology and climatic conditions favoring the development of Diaporthe spp. on hazelnut. Prevention and control measures should target D. eres, representing the main causal agents responsible for defects and nut rot of hazelnuts in Italy.

First Report of Gnomoniopsis fragrariae causing leaf spots on strawberry in Italy.

Strawberry (Fragaria × ananassa Duch.) is widely cultivated in Italy. During May-June 2022, mild symptoms of an unknown leaf spot disease appeared on 5-10% of June-bearing strawberry (cv. Elodì) plants transplanted in July 2021 in a commercial farm located in the province of Cuneo, North Italy. During September-November 2022, the symptoms appeared also on 10-15% of the plants transplanted in July 2022. The disease was scattered throughout the field, large 600 m2, both on new and senescent leaves. Fungicides (sulphur, Tiovit Jet; penconazole, Topas 10 EC) were applied to the plants according to integrated pest management during the growing period. The disease symptoms were purplish to brown necrotic leaf spots up to 1-3 mm in diameter and chlorotic leaf margins. Black lesions were occasionally observed on the petioles, appearing as small necrotic or larger elongated lesions causing leaf death. Peritechia were observed in planta after about 4 months from sampling and measured (144 to 239 µm and 200 to 291 µm, n = 10). Diseased leaves and petioles from about 10 plants were surface disinfested for 1 min in 1% NaClO, rinsed with sterile water and plated on potato dextrose agar (PDA) amended with 25 mg streptomycin sulphate/liter. A fungus with white cottony colonies was repeatedly recovered and maintained in pure culture on PDA. Biguttulate conidia with rounded ends were measured (4.3 to 8.0 µm and 1.2 to 2.9 µm, average 6.1× 2.3 µm, n = 50) from 21-day old colonies grown in PDA at 22°C and 12 h photoperiod. According to colony and conidia morphology, the isolate was identified as Gnomoniopsis sp. (Walker et al., 2010). The fungal DNA was extracted from a pure culture of one isolate selected as a representative (code FR2-22), by using the E.Z.N.A. Fungal DNA Mini Kit (Omega Bio-Tek, Darmstadt, Germany). The identification was carried out by amplifying and sequencing the internal transcribed spacer (ITS) region and the partial translation elongation factor 1-α (TEF) gene using the primers ITS1/ITS4 and EF-728F/EF2 (Udayanga et al., 2021), respectively. The purified PCR products were sequenced at the BMR Genomics Centre (Padova, Italy) obtaining 551bp (ITS) and 652bp (TEF) sequences deposited in GenBank (Accession nos. OQ179950 and OQ190173, respectively). A BLASTn search of both sequences revealed to be 100% identical to the ITS and TEF loci of Gnomoniopsis fructicola sequences of the isolates VPRI_15547 and CBS 275.51 deposited in GenBank with accession Nos. MT378345 and MT383092. The pathogenicity of the isolate FR2-22 was assessed in two trials by biological tests (3 replicates with 1 plant per replicate/pot) in two greenhouse compartments, kept at temperature 20-24°C and at humidity 80-90%. Healthy leaves of forty-day-old strawberry plants (cv. Elodì) were sprayed with 1-5 x106 conidia/ml obtained from the FR2-22 isolate grown on PDA at 25°C for 20 days. The control (water-sprayed plants) was kept in the same conditions. Small leaf spots similar to the symptoms previously observed in the farm were observed 15 days post inoculation. Furthermore, 30 to 40% of leaves developed symptoms similar to those observed in the field after 25-40 days, while the control remained health. The same fungal isolate was repeatedly reisolated from the affected leaves and petioles and identified based on TEF sequencing. Gnomoniopsis fragariae comb. nov., designed as new name for Gnomoniopsis fructicola (Udayanga et al., 2021), has previously been reported on Fragaria × ananassa plants in Australia and in the USA (Farr and Rossman, 2023). To the best of our knowledge, this is the first report of G. fragariae on strawberry in Italy. The impact of the disease caused by this pathogen could be of high importance in the future of strawberry production in Italy. Healthy propagation material and strict disease management practices in nurseries is a requirement to avoid disease epidemics.

First report of Diaporthe eres causing stem blight and dieback on highbush blueberry (Vaccinium corymbosum) in Italy.

Vaccinium corymbosum L. is a woody deciduous shrub belonging to the Ericaceae family. During the last decade, Northern Italy has become a major area for blueberry cultivation and production in Europe, supplying other countries with high quality fruit (FAOSTAT 2020). In June 2020, plant stem and branch wilting with brownish necrotic internal lesions were observed on 20% of around 250 plants of the cultivar (cv.) Draper cultivated in a soilless culture system located in Peveragno (Piedmont, Cuneo Province, 44°21'05.6''N, 07°37'23.2''). Dieback and death of the plants also occurred. Fifteen symptomatic plants were collected. Wood pieces (5-10 mm) excised from diseased stems and branches were sterilized in 1% sodium hypochlorite for 1 min, rinsed in sterile distilled water and dried on sterile absorbent paper. Small fragments (2-3 mm), obtained from the edge of the necrotic tissues, were plated on potato dextrose agar (PDA) amended with 25 mg/L of streptomycin sulfate. Plates were incubated at 25 ± 1°C under a 12 h photoperiod and, five days after, colonies with the same characteristics of Diaporthe spp. were established from single hyphal tip transfers. Two representative strains (CVG1130 and CVG1131) were grown on PDA from single hyphal-tip transfers. After 7 days, white colonies with fluffy, aerial, mycelium reaching 8.3 cm were observed. colonies turned gray after three weeks producing dark brown pycnidia. Aseptate, hyaline, fusiform to ellipsoidal, measuring 6.3 to 8.4 × 2.2 to 3.0 µm alpha conidia were produced. No beta conidia were observed. The DNA of the same strains was extracted and a polymerase chain reaction (PCR) was performed for the ITS (primer set: ITS1-ITS4) (GenBank Accession no. ON834528; ON834529), tef (EF1-728/EF1-986) (GenBank Accession no. ON843715; ON843716) and tub2 (T1/Bt2b) (GenBank Accession no. ON843713; ON843714) regions, in accordance with previous studies (Gomes et al. 2013, Bezerra et al. 2021). Sequences analysed with BLASTn algorithm (Altschul et al. 1997) exhibited 98% identity with the ex-type strain CBS 138594 of Diaporthe eres for ITS (GenBank Accession no. KJ210529), 100% identity for tub2 (GenBank Accession no. KJ420799) and 99% identity for tef (GenBank Accession no. KJ210550). The maximum likelihood method based on combined sequences of ITS, tef and tub2 loci was performed, and the isolates CVG1130 and CVG1131 clustered with several reference strains of D. eres (Supplementary figure). To fulfil Koch's postulates, pathogenicity tests were performed on 1-year-old blueberry potted plants cv. Draper and Duke. A small piece of the bark tissue was removed with a sterile-bladed scalpel to expose the cambium. Mycelium plugs (5 mm diameter), obtained from 10-day-old cultures of the strains CVG1130 and CVG1131, were placed with the mycelium in contact with the internal plant tissues. Three plants were used for each isolate and the inoculation points were sealed with Parafilm®. The same number of plants treated with sterile PDA plugs were used as control. Plants were placed in a growth chamber at 25°C for 3 weeks. After this period, symptoms similar to those observed in the field appeared on the inoculated plants, while control plants remained healthy. A fungus with the same morphological characteristics of D. eres was reisolated from inoculated plants and identified by sequencing the tub2 gene to confirm Koch's postulates. Diaporthe eres was previously reported on different Vaccinium spp. in Chile, Lithuania, the Netherlands and the U.S.A. (Farr and Rossman, 2022). To our knowledge, this is the first report of D. eres associated with stem blight and dieback of highbush blueberry in Italy. Duke and Draper are among the most cultivated blueberry cultivars in Piedmont, where the spread of D. eres could represent a serious threat.

Endophytic Diaporthe Associated with Morinda officinalis in China.

Diaporthe species are endophytes, pathogens, and saprobes with a wide host range worldwide. However, little is known about endophytic Diaporthe species associated with Morinda officinalis. In the present study, 48 endophytic Diaporthe isolates were obtained from cultivated M. officinalis in Deqing, Guangdong Province, China. The nuclear ribosomal internal transcribed spacer (ITS), partial sequences of translation elongation factor 1-α (tef1-α), partial calmodulin (cal), histone H3 (his), and Beta-tubulin (ß-tubulin) gene regions were sequenced and employed to construct phylogenetic trees. Based on morphology and combined multigene phylogeny, 12 Diaporthe species were identified, including five new species of Diaporthe longiconidialis, D. megabiguttulata, D. morindendophytica, D. morindae, and D. zhaoqingensis. This is the first report of Diaporthe chongqingensis, D. guangxiensis, D. heliconiae, D. siamensis, D. unshiuensis, and D. xishuangbanica on M. officinalis. This study provides the first intensive study of endophytic Diaporthe species on M. officinalis in China. These results will improve the current knowledge of Diaporthe species associated with this traditional medicinal plant. Furthermore, results from this study will help to understand the potential pathogens and biocontrol agents from M. officinalis and to develop a disease management platform.

Impact of Calonectria Diseases on Ornamental Horticulture: Diagnosis and Control Strategies.

Diseases caused by fungi in the genus Calonectria pose a significant threat to the ornamental horticulture industries in Europe and the United States. Calonectria spp. are particularly challenging pathogens to manage in ornamental production systems and the urban landscape for multiple reasons. A high level of species diversity and poorly resolved taxonomy in the genus makes proper pathogen identification and disease diagnosis a challenge, though recent molecular phylogenetic studies have made significant advances in species delimitation. From a disease management perspective, Calonectria spp. produce long-lived survival structures (microsclerotia) that contaminate nursery production systems and can survive multiple years in the absence of a susceptible plant host. Latent infection of plant material is poorly understood but likely contributes to long-distance dissemination of these fungal pathogens, including the clonal Calonectria spp. responsible for the global emergence of boxwood blight. Breeding for disease resistance represents a sustainable strategy for managing Calonectria diseases but is challenging due to the perennial nature of many ornamental plants and high levels of susceptibility in commercial cultivars. Ultimately, long-term sustainable management of Calonectria diseases will require an improved understanding of pathogen biology as well as integration of multiple disease management strategies.

First report of Fusarium commune causing root and crown rot on maize in Italy.

Maize (Zea mays L.) is a cereal crop of great economic importance in Italy; production is currently of 62,587,469 t, with an area that covers 628,801 ha, concentrated in northern Italy (ISTAT 2020). Fusarium species are associated with root and crown rot causing failures in crop establishment under high soil moisture. In 2019 maize seedlings collected in a farm located in San Zenone degli Ezzelini (VI, Italy) showed root and crown rot symptoms with browning of the stem tissues, wilting of the seedling, and collapsing due to the rotting tissues at the base of the stem. The incidence of diseased plants was approximately 15%. Seedlings were cleaned thoroughly from soil residues under tap water. Portions (about 3-5 mm) of tissue from roots and crowns of the diseased plants were cut and surface disinfected with a water solution of NaClO at 0.5% for 2 minutes and rinsed in sterile H20. The tissue fragments were plated on Potato Dextrose Agar (PDA) amended with 50 mg/l of streptomycin sulfate and incubated for 48-72 hours at 25oC. Over the 80 tissue fragments plated, 5% were identified as Fusarium verticillioides, 60% as Fusarium spp., 35% developed saprophytes. Fusarium spp. isolates that showed morphological characteristics not belonging to known pathogenic species on maize were selected and used for further investigation while species belonging to F. oxysporum were discarded. Single conidia of the Fusarium spp. colonies were cultured on PDA and Carnation Leaf Agar (CLA) for pathogenicity tests, morphological and molecular identification. The colonies showed white to pink, abundant, densely floccose to fluffy aerial mycelium. Colony reverse showed light violet pigmentation, in rings on PDA. On CLA the isolates produced slightly curved macronidia with 3 septa 28.1 - 65.5 µm long and 2.8-6.3 µm wide (n=50). Microconidia were cylindrical, aseptate, 4.5 -14.0 µm long and 1.5-3.9 µm wide (n=50). Spherical clamydospores were 8.8 ± 2.5 µm size (n=30), produced singly or in pairs on the mycelium, according to the description by Skovgaard et al. (2003) for F. commune. The identity of two single-conidia strains was confirmed by sequence comparison of the translation elongation factor-1α (tef-1α), and RNA polymerase II subunit (rpb2) gene fragments (O'Donnell et al. 2010). BLASTn searches of GenBank, and Fusarium-ID database, using the partial tef-1α (MW419921, MW419922) and rpb2 (MW419923, MW419924) sequences of representative isolate DB19lug07 and DB19lug20, revealed 99% identity for tef-1α and 100% identity to F. commune NRRL 28387(AF246832, AF250560). Pathogenicity tests were carried out by suspending conidia from a 10-days old culture on PDA in sterile H2O to 5×104 CFU/ml. Fifty seeds were immersed in 50 ml of the conidial suspension of each isolate for 24 hours and in sterile water (Koch et al. 2020). The seeds were drained, dried at room temperature, and sown in trays filled with a steamed mix of white peat and perlite, 80:20 v/v, and maintained at 25°C and RH of 80-85% for 14 days with 12 hours photoperiod. Seedlings were extracted from the substrate, washed under tap water, and observed for the presence of root and crown rots like the symptoms observed on the seedlings collected in the field. Control seedlings were healthy and F. commune was reisolated from the symptomatic ones and identified by resequencing of tef-1α gene. F. commune has been already reported on maize (Xi et al. 2019) and other plant species, like soybean (Ellis et al. 2013), sugarcane (Wang et al. 2018), potato (Osawa et al. 2020), indicating that some attention must be paid in crop rotation and residue management strategies. To our knowledge this is the first report of F. commune as a pathogen of maize in Italy. References Ellis M L et al. 2013. Plant Disease, 97, doi: 10.1094/PDIS-07-12-0644-PDN. ISTAT. 2020. http://dati.istat.it/Index.aspx?QueryId=33702. Accessed December 28, 2020. Koch, E. et al. 2020. Journal of Plant Diseases and Protection. 127, 883-893 doi: 10.1007/s41348-020-00350-w O'Donnell K et al. 2010. J. Clin. Microbiol. 48:3708. https://doi.org/10.1128/JCM.00989-10 Osawa H et al. 2020. Journal of General Plant Pathology, doi.org/10.1007/s10327-020-00969-5. Skovgaard K 2003. Mycologia, 95:4, 630-636, DOI: 10.1080/15572536.2004.11833067. Wang J et al. 2018. Plant Disease, 102, doi/10.1094/PDIS-07-17-1011-PDN Xi K et al. 2019. Plant Disease, 103, doi/10.1094/PDIS-09-18-1674-PDN.

Genetic Diversity and Pathogenicity of Botryosphaeriaceae Species Associated with Symptomatic Citrus Plants in Europe.

This study represents the first survey studying the occurrence, genetic diversity, and pathogenicity of Botryosphaeriaceae species associated with symptomatic citrus species in citrus-production areas in five European countries. Based on morphological features and phylogenetic analyses of internal transcribed spacer (ITS) of nuclear ribosomal DNA (nrDNA), translation elongation factor 1-alpha (TEF1) and ß-tubulin (TUB2) genes, nine species were identified as belonging to the genera Diplodia, Dothiorella, Lasiodiplodia, and Neofusicoccum. Isolates of Neofusicoccum parvum and Diplodia pseudoseriata were the most frequently detected, while Dothiorella viticola had the widest distribution, occurring in four of the five countries sampled. Representative isolates of the nine Botryosphaeriaceae species used in the pathogenicity tests caused similar symptoms to those observed in nature. Isolates assayed were all re-isolated, thereby fulfilling Koch's postulates. Isolates of Diplodia pseudoseriata and Diplodia olivarum are recorded for the first time on citrus and all species found in our study, except N. parvum, are reported for the first time on citrus in Europe.

Calcium oxide, potassium phosphite and a Trichoderma enriched compost water suspension protect Capsicum annuum against Phytophthora capsici by priming the immune system.

BACKGROUND: Proper management of Phytophthora capsici in pepper cultivation is extremely important, since Phytophthora blight is the main disease of this crop worldwide. In the past, the main strategy adopted had been the use of fungicides, causing, in some cases, the development of P. capsici resistant strains. In this work three different treatments selected from previous studies (potassium phosphite, calcium oxide and a water suspension from Trichoderma sp. TW2 enriched compost) were tested to prove their ability to activate the systemic acquired resistance (SAR) in pepper against P. capsici; acibenzolar-s-methyl was used as positive control. Two independent growth chamber pot experiments were performed, spatially dividing the site of treatments application (as radical drench) and the site of inoculation (as agar plug on the third leaf). RESULTS: Leaf lesions were measured, showing a significant reduction on all treated plants compared to the untreated control. To further confirm this hypothesis, the expression levels of three SAR key genes (CaPBR1, CaPO1 and CaDEF1) were evaluated though RT-Real Time PCR at the three end-point times: T0, T6 and T24. A significant increase of target genes expression at least in one end-point time in each treated plant was observed. Eventually, statistical overaccumulation of salicylic acid was observed in the upper leaves at the same end-point times, through HPLC-MS/MS analysis. CONCLUSION: This work confirmed the hypothesis that the three treatments tested have the ability to prime the plant immune system, leading pepper to an alert status able to confer a better defence against P. capsici. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bedding Plant Production and the Challenge of Fungal Diseases.

Bedding plants are a major group of ornamentals produced in greenhouses or nurseries worldwide and planted outdoors. Their economic importance has increased continuously in the last four decades in both the United States and the European Union. These plants are subject to a broad number of diseases that can negatively impact their production and cultivation. The initial steps of production strongly influence the health status of these plants and, consequently, their aesthetic appeal, which is a strong requisite for consumers. Seeds, cuttings, and other forms of propagative material, along with production systems and growing media, can influence the phytosanitary status of the final product. In this article, case studies of soilborne and foliar diseases are presented together with preventive measures to achieve innovative disease management strategies. Quarantine restrictions and eradication measures are also discussed, in consideration of the high likelihood for ornamental plants to be long-distance vectors of new pathogens and pests.

Presence of Powdery Mildew Caused by Erysiphe corylacearum on Hazelnut (Corylus avellana) in Italy.

Hazelnut (Corylus avellana) is widely grown in Italy, which is the second largest producer worldwide with 132,700 tonnes harvested from 78,593 hectares (FAOSTAT, 2018 ). Powdery mildew caused by Phyllactinia guttata has been reported in Italy and in other European countries, but recently in Austria, Switzerland and in central Europe a new species was discovered (Voglmayr et al., 2020; Beenken, 2020). During summer 2020, in Villar Fioccardo (Torino province, Piedmont, Italy) on hazelnut (cv. 'Tonda Gentile') growing on the edges of private gardens and parks, an extensive colonization of the adaxial side of the leaves with white powdery mycelium covering more than 80% of the surface was observed. Also, the abaxial side of the leaves showed the scattered presence of powdery, white, and thin mycelium. The powdery fungal pathogen collected from leaves had amphigenous, hyaline, branched, septate 1.5 to 3.7 µm wide mycelium; lobed, solitary hyphal appressoria; vertically elevated above the mycelium 53 to 82 µm long and 5 to 12 µm wide conidiophores (n = 30); hyaline, ellipsoid, ovoid to doliform conidia, solitary on conidiophores, 21 to 36 µm long, 15 to 21 µm wide (average 28 to 18 µm) (n = 50). Chasmothecia appeared in late September 2020 and they were spherical, single or in groups, 83 to 138 (average 100) µm in diameter (n = 50); 7 to 15 aseptate appendages were straight, sometimes flexuous, 55 to 111 (average 73) µm long (n = 50), with four to five times dichotomous branched apexes and recurved tips. In each chasmothecium, there were three to five ellipsoid, ovoid to subglobose asci with a length of 41 to 60 µm and a width of 28 to 56 µm (average 52 to 44 µm) (n = 30). Asci contained four to eight ascospores, 15 to 26 µm long and 10 to 17 µm wide (average 19 to 12 µm) (n =50). Mycelia were carefully scraped from the leaves with a scalpel and DNA was extracted by using the E.Z.N.A. Fungal DNA Mini Kit (Omega Bio-Tek, Darmstadt, Germany). Partial rDNA internal transcribed spacer region (ITS) of two isolates (DB20SET01, DB20SET01) was amplified using specific primers PMITS1/PMITS2 (Cunnington et al. 2003) and sequenced. Obtained sequences were deposited in GenBank (Accession Nos. MW045425, MW045426). BLAST analysis of the obtained 749-bp fragments showed 100% identity to ITS rDNA sequences of Erysiphe corylacearum from Switzerland (MN822721) and Azerbaijan (LC270863). One-year-old plants of C. avellane cv. Tonda Gentile were artificially inocuated by dusting conidia from infected leaves. Inoculated plants were incubated under controlled conditions at 23°C ± 1 and 70 to 80% relative humidity. Typical symptoms (white bloom) appeared on the upper surface of the leaves at 8 to 10 days after inoculation. No symptoms were found on control plants treated with sterile water. The fungus isolated from inoculated leaves was morphologically identical to the original isolates from diseased plants collected from Villar Fioccardo. Erysiphe corylacearum causes a new and aggressive form of powdery mildew. Since the first observation in north-eastern Turkey in 2013, it has spread rapidly throughout the Black Sea region, causing significant economic losses (Sezer et al., 2017). It has also been reported in Iran, Azerbaijan, and Ukraine (Arzanlou et al. 2018; Heluta et al., 2018). The disease has been observed sporadically in Piedmont, Italy, during summer 2020 (Regione Piemonte & Agrion, 2020) in some hazelnut growing areas, but presently, doesn't appear to impact yield. This is the first report of E. corylacearum, causing an aggressive powdery mildew on hazelnut in Italy, and as such, may more severely affect hazelnut groves in Italy and cause considerable yield losses. Literature cited Arzanlou M et al. 2018. Forest Pathology, 48:e12450. https://doi.org/10.1111/efp.12450. Beenken L et al. 2020. New Disease Reports 41, 11. http://dx.doi.org/10.5197/j.2044-0588.2020.041.011. Cunnington JH et al. 2003. Australasian Plant Pathology, 32, 421-428. Food and Agriculture Organization (FAO). 2018. http://www.fao.org/faostat/en/#home Heluta V.P. et al.2019. Ukrainian Botanical Journal, 2019, 76(3), 252-259. Regione Piemonte SFR & Agrion. 2020. https://www.regione.piemonte.it/web/sites/default/files/media/documenti/2020-10/mal_bianco_nocciolo_da_erysiphe_corylacearum.pdf Sezer AD et al. 2017. Phytoparasitica, 45, 577-581. Voglmayr H et al. 2020. New Disease Reports, 42, 14 http://dx.doi.org/10.5197/j.2044-0588.2020.042.014.

Phyllosticta citricarpa and sister species of global importance to Citrus.

Several Phyllosticta species are known as pathogens of Citrus spp., and are responsible for various disease symptoms including leaf and fruit spots. One of the most important species is P. citricarpa, which causes a foliar and fruit disease called citrus black spot. The Phyllosticta species occurring on citrus can most effectively be distinguished from P. citricarpa by means of multilocus DNA sequence data. Recent studies also demonstrated P. citricarpa to be heterothallic, and reported successful mating in the laboratory. Since the domestication of citrus, different clones of P. citricarpa have escaped Asia to other continents via trade routes, with obvious disease management consequences. This pathogen profile represents a comprehensive literature review of this pathogen and allied taxa associated with citrus, focusing on identification, distribution, genomics, epidemiology and disease management. This review also considers the knowledge emerging from seven genomes of Phyllosticta spp., demonstrating unknown aspects of these species, including their mating behaviour. TAXONOMY: Phyllosticta citricarpa (McAlpine) Aa, 1973. Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Botryosphaeriales, Family Phyllostictaceae, Genus Phyllosticta, Species citricarpa. HOST RANGE: Confirmed on more than 12 Citrus species, Phyllosticta citricarpa has only been found on plant species in the Rutaceae. DISEASE SYMPTOMS: P. citricarpa causes diverse symptoms such as hard spot, virulent spot, false melanose and freckle spot on fruit, and necrotic lesions on leaves and twigs. USEFUL WEBSITES: DOE Joint Genome Institute MycoCosm portals for the Phyllosticta capitalensis (https://genome.jgi.doe.gov/Phycap1), P. citriasiana (https://genome.jgi.doe.gov/Phycit1), P. citribraziliensis (https://genome.jgi.doe.gov/Phcit1), P. citrichinaensis (https://genome.jgi.doe.gov/Phcitr1), P. citricarpa (https://genome.jgi.doe.gov/Phycitr1, https://genome.jgi.doe.gov/Phycpc1), P. paracitricarpa (https://genome.jgi.doe.gov/Phy27169) genomes. All available Phyllosticta genomes on MycoCosm can be viewed at https://genome.jgi.doe.gov/Phyllosticta.

High diversity of Diaporthe species associated with dieback diseases in China, with twelve new species described.

Diaporthe species have often been reported as important plant pathogens, saprobes and endophytes on a wide range of plant hosts. Although several Diaporthe species have been recorded in China, little is known about species able to infect forest trees. Therefore, extensive surveys were recently conducted in Beijing, Heilongjiang, Jiangsu, Jiangxi, Shaanxi and Zhejiang Provinces. The current results emphasised on 15 species from 42 representative isolates involving 16 host genera using comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), calmodulin (cal), histone H3 (his3), partial translation elongation factor-1α (tef1) and ß-tubulin (tub2) gene regions, as well as their morphological features. Three known species, D.biguttulata, D.eres and D.unshiuensis, were identified. In addition, twelve novel taxa were collected and are described as D.acerigena, D.alangii, D.betulina, D.caryae, D.cercidis, D.chensiensis, D.cinnamomi, D.conica, D.fraxinicola, D.kadsurae, D.padina and D.ukurunduensis. The current study improves the understanding of species causing diebacks on ecological and economic forest trees and provides useful information for the effective disease management of these hosts in China.

Liberomycespistaciae sp. nov., the causal agent of pistachio cankers and decline in Italy.

A new canker and decline disease of pistachio (Pistaciavera) is described from Sicily (Italy). Observations of the disease and sampling of the causal agent started in spring 2010, in the area where this crop is typically cultivated, Bronte and Adrano (Catania province) and later extended to the Agrigento and Caltanissetta provinces. Isolations from the margins of twig, branch and stem cankers of declining plants resulted in fungal colonies with the same morphology. Pathogenicity tests on 5-year-old potted plants of Pistaciavera grafted on P.terebinthus reproduced similar symptoms to those observed in nature and the pathogen was confirmed to be a coloniser of woody plant tissue. Comparison of our isolates with the type of the apparently similar Asteromellapistaciarum showed that our isolates are morphologically and ecologically different from A.pistaciarum, the latter being a typical member of Mycosphaerellaceae. Asteromellapistaciarum is lectotypified, described and illustrated and it is considered to represent a spermatial morph of Septoriapistaciarum. Multi-locus phylogenies based on two (ITS and LSU rDNA) and three (ITS, rpb2 and tub2) genomic loci revealed isolates of the canker pathogen to represent a new species of Liberomyces within the Delonicicolaceae (Xylariales), which is here described as Liberomycespistaciae sp. nov. (Delonicicolaceae, Xylariales). The presence of this fungus in asymptomatic plants with apparently healthy woody tissues indicates that it also has a latent growth phase. This study improves the understanding of pistachio decline, but further studies are needed for planning effective disease management strategies and ensuring that the pathogen is not introduced into new areas with apparently healthy, but infected plants.

Emerging citrus diseases in Europe caused by species of Diaporthe.

Species of Diaporthe are considered important plant pathogens, saprobes, and endophytes on a wide range of plant hosts. Several species are well-known on citrus, either as agents of pre- or post-harvest infections, such as dieback, melanose and stem-end rot on fruit. In this study we explored the occurrence, diversity and pathogenicity of Diaporthe species associated with Citrus and allied genera in European orchards, nurseries, and gardens. Surveys were carried out during 2015 and 2016 in Greece, Italy, Malta, Portugal, and Spain. A total of 79 Diaporthe strains were isolated from symptomatic twigs, branches and trunks. A multi-locus phylogeny was established based on five genomic loci (ITS, tef1, cal, his3 and tub2), and the morphological characters of the isolates determined. Preliminary pathogenicity tests were performed on lemon, lime, and orange plants with representative isolates. The most commonly isolated species were D. foeniculina and D. baccae, while only four isolates of D. novem were collected. Two new Diaporthe species, described here as D. limonicola and D. melitensis spp. nov. were found associated with a new devastating dieback disease of lemon plants. Furthermore, one cluster of sterile Diaporthe isolates was renamed as D. infertilis. Pathogenicity tests revealed most of the Citrus species as susceptible to D. baccae, D. foeniculina, and D. novem. Moreover, D. limonicola and D. melitensis caused serious cankers affecting all the Citrus species tested. This study is the first report of D. baccae and D. novem on citrus in Europe, and the first detection of a new Diaporthe canker disease of citrus in Europe. However, no isolates of D. citri were found. The study improves our understanding of the species associated with several disease symptoms on citrus plants, and provides useful information for effective disease management.

Tomato susceptibility to Fusarium crown and root rot: effect of grafting combination and proteomic analysis of tolerance expression in the rootstock.

Grafting can enhance the tolerance of vegetable crops to soilborne diseases. The aim of this study was to investigate whether different tomato scion-rootstock combinations may affect the plant susceptibility to Fusarium oxysporum f. sp. radicis-lycopersici (FORL), the causal agent of crown and root rot. A proteomic approach was used to investigate whenever the protein repertoire of the rootstock can be modified by FORL infection, in relation to cultivar susceptibility/tolerance to the disease. To this purpose, plants of tomato hybrids with different vigor, "Costoluto Genovese" (less vigorous) and "Kadima" (more vigorous), were grafted onto "Cuore di Bue" and "Natalia" hybrids, sensitive and tolerant versus FORL infections, respectively. Disease symptoms, plant biomasses, and protein expression patterns were evaluated 45 days after FORL inoculation. The extent of vascular discoloration caused by FORL in tomato plants grafted on "Natalia" rootstock (0.12-0.37 cm) was significantly lower than that of plants grafted on sensitive "Cuore di Bue" (1.75-6.50 cm). FORL symptoms significantly differed between "Costoluto Genovese" and "Kadima" scions only when grafted on sensitive rootstock. Shoot FW of non-inoculated "Kadima"/"Cuore di Bue" combination was 35% lower than "Kadima"/"Natalia", whereas no difference was manifested in inoculated plants. Shoot FW of inoculated "Costoluto Genovese"/"Cuore di Bue" combination was decreased of 39%, whereas that of "Costoluto Genovese"/"Natalia" of 11%, compared to control plants. Proteomic results showed a higher representation of proteins associated with pathogen infection in the tolerant rootstock, compared to the sensitive one, meaning a direct involvement of plant defence mechanisms in the tomato response to the pathogen challenge.