First report of Ceratocystis platani in Albania

The fungus Ceratocystis platani was detected in various localities of the Gjirokastër prefecture in southern Albania, where it was causing widespread mortality on Platanus orientalis trees. The identification of the fungus was based on both morphological characteristics in culture and DNA sequencing. The pathogenicity of C. platani was confirmed in inoculations on seedlings of P. orientalis. To our knowledge, this is the first report of C. platani in Albania.     

Platypus cylindrus,a vector of Ceratocystis platani in Platanus orientalis stands in Greece

The ambrosia beetle Platypus cylindrus was very common in stands of Platanus orientalis trees in Greece, infesting trees already infected by Ceratocystis platani. The fungus C. platani was isolated from 59% of adult beetles of P. cylindrus collected on the wing in a heavily infected stand of P. orientalis. Transmission of C. platani was demonstrated in 80% of P. orientalis seedlings challenged with P. cylindrus beetles, which were previously fed in cultures of the fungus. In most of the cases, the beetles had bored tunnels in stems, where abundant perithecia of C. platani were observed. Platypus cylindrus adults regularly visited artificially wounded P. orientalis trees in a natural stand. Although this ambrosia beetle normally infests stressed or dead trees, it appears to play a role as a vector of C. platani, especially by visiting wounded trees.     

Volatile organic compounds (VOC) as biomarkers for detection of Ceratocystis platani

Ceratocystis platani causes canker stain of plane trees, and it represents a serious disease of Platanus spp. both in the United States and Europe. Current chemical or biological controls do not effectively manage C. platani, so new preventive methods need to be developed in order to limit this pathogen spreading. In this work, we have characterized the main volatile organic compounds (VOC) emitted in vitro from pure cultures of C. platani and other common pathogenic fungal species of hosts plants growing in the same ecosystems as plane trees. We found that C. platani emitted a similar blend of VOC compared with phylogenetically similar species C. populicola. In particular, C. platani was characterized by emission of isoamyl acetate and isobutyl acetate while C. populicola by ethyl acetate and isobutyl acetate, which were not released by any of the other out‐group fungal species grown on the same medium. Moreover, following a targeted approach based on the main VOC found in vitro, we have successfully validated in vivo that VOC uniquely emitted by C. platani (i.e. isobutyl acetate along with isoamyl alcohol) were released from the bark of plane trees following C. platani inoculation. Our results highlight the possibility to exploit VOC emitted specifically by C. platani as biomarkers to recognize Platanus x acerifolia plants infected by this pathogen.     

Natural infection of Fraxinus excelsior seeds by Chalara fraxinea

The occurrence of Chalara fraxinea, the fungus responsible for dieback of European ash (Fraxinus excelsior), was investigated in the current and previous seed years collected from symptomatic trees in Latvia and Sweden using molecular techniques (DNA extraction, ITS‐PCR, Sanger sequencing). Molecular analysis of seeds revealed the presence of 30 different fungal taxa. Chalara fraxinea was detected in 8.3% of seeds tested from the current year originating from Latvia. The presence of C. fraxinea in seeds of F. excelsior is of great concern to phytosanitary protection authorities in countries outside the current zone of infestation.     

Neofusicoccum parvum associated with pomegranate branch canker in Iran

Pomegranate (Punica granatum) is native to Iran and neighbouring countries and is negatively affected by a wide range of diseases. Canker and dieback diseases caused by Cytospora punicae and members of the family Botryosphaeriaceae are the main trunk diseases on pomegranate. In summer 2017, progressive dieback of branches on some young pomegranate trees was observed in orchards of the Gorgan Region (Golestan province, Northeast Iran). Fungal colonies with similar colony colour were isolated from symptomatic tissues. The identity of the causal agent was determined as Neofusicoccum parvum, based on a polyphasic taxonomic approach including morphological features of conidiomata and phylogenetic inference based on the ITS‐rDNA region and translation elongation factor 1 alpha (tef1‐α) gene. Koch's postulates were fulfilled using an excised shoot method. This study provides the first report on the occurrence of N. parvum as a cause of branch canker on pomegranate in Iran.     

Fungi in foliage and shoots of Fraxinus excelsior in eastern Ukraine: a first report on Hymenoscyphus pseudoalbidus

In eastern Ukraine, the first symptoms of dieback on common ash (Fraxinus excelsior) were observed in 2010, as sparse flushing of leaves, bark necrosis and wood discoloration of shoots. The aim of this study was to assess possible causal agents of the damage by studying fungal communities in both symptomatic and healthy‐looking shoots, and leaf petioles. Field sampling was carried out in 2010 in Kharkiv and Sumy regions in eastern Ukraine and included 68 segments of symptomatic shoots, 68 segments of healthy‐looking shoots and 240 segments of petioles. DNA isolation from individual segments and direct sequencing of fungal ITS rRNA resulted in 430 fungal sequences representing 29 distinct taxa. Results showed that Hymenoscyphus pseudoalbidus – the primary causal agent of ash dieback in Europe – was present at low proportion (5.6%) in symptomatic shoots. Other more frequently detected fungi were Epicoccum nigrum, Venturia fraxini, Colletotrichum truncatum, Aureobasidium pullulans, Alternaria alternata, Alternaria sp. and Lophiostoma corticola. In conclusion, the study reports on the first incidence of ash decline in the Ukraine and other possible causal agents of damage which may help to evaluate and forecast the future situation with F. excelsior stands in the region.     

The canker stain disease of plane tree in Marseilles and in the south of France

Platanus accrifolia Hyb. is attacked by a serious disease: the canker stain. The responsible agent is an Ascomycete, Ceratocystis fimbriata f. platani which is extremely virulent. During the last twelve years, it has killed more than 1,800 plane trees in the streets of Marseilles. This disease was until now strictly localized in north America.     

Characterization,pathogenicity and host range studies of Paecilomyces formosus associated with dieback of Christ's thorn trees (Paliurus spina-christi Mill.) in Iran

Christ's thorn (Paliurus spina-christi Mill.) tree is an important and valuable forestry species and has significant potential in afforestation and reforestation systems. In recent years, dieback symptoms were observed on Paliurus spina-christi trees in Gilan-e Gharb region of Kermanshah province, west Iran. During 2020 to 2021, Christ's thorn trees that exhibit branch dieback symptoms were sampled for fungal isolations. The pathogenicity tests, biochemical assay of growth, acid production on creatine sucrose agar (CREA) medium and morphological and molecular investigations (ITS and β-tubulin regions) identified Paecilomyces formosus as a dieback causal agent. This is the first report of P. formosus pathogenicity on Paliurus spina-christi trees. Furthermore, disease severity was assayed on 11 tree species under three different temperatures 15, 25 and 35°C. Disease severity caused by all isolates on detached branches was greater at 35°C than at 15 and 25°C. This study presents the host range of this pathogen and showed that these potential hosts are prone to this pathogen under high temperatures, which forest trees experienced in recent decades.     

Une méthode simple de recherche de Ceratocystis fimbriata f. platani sur arbre en place

A simple method of diagnosing Ceratocystis fimbriata f. platani in standing trees. Bluish or purple streaks are found at the margins of lesions caused by Ceratocystis fimbriata f. platani. These contain the fungus systematically. Cores may be taken with an augur from any such streaks, the core then being cut into discs which are kept in a humid chamber at 20–25°C. C. fimbriata, if present, produces diagnostic endo-conidia after 2–4 days of incubation in 50–90 % of the samples.     

First report of Ceratocystis huliohia causing mortality of Metrosideros polymorpha trees on the Island of Kauaʻi,Hawaiʻi USA

The fungus Ceratocystis huliohia was detected for the first time in dead and dying Metrosideros polymorpha trees on the Island of Kaua?i, Hawai?i, U.S.A. Fungal isolates were recovered from diseased trees into culture, and identities were confirmed by diagnostic qPCR assay and DNA sequencing. Growth chamber inoculations confirmed C. huliohia pathogenicity on M. polymorpha seedlings and subsequently the same fungus was recovered, completing Koch's postulates. DNA sequence analysis revealed a unique ITS haplotype for Kaua?i isolates of C. huliohia that has not been found on Hawai?i Island.     

Détection par piégeage du Ceratocystis fimbriata f. platani

Application of the technique of trapping Ceratocystis fimbriata f. platani for the study of the persistance in affected trees . The study of the persistance of Ceratocystis fimbriata f. platani in affected trees is achieved by trapping of the fungus which is carried out on small branches of London plane, stripped of their bark. If C. fimbriata is present in samples of wood to be tested, it becomes visible after a few days when numerous perithecia form on the trap. Trapping the fungus by this method has been systematically achieved with young, artificially inoculated trees: in many cases, C. fimbriata persists in the wood after a period of about 19 to 22 months.     

Fusarium equiseti is associated with the wilt and dieback of Aquilaria malaccensis in Northeast India

Aquilaria malaccensis, categorized by IUCN as globally vulnerable, is in high demand in the Middle East and Asian markets for its unique resinous agarwood. In August 2015, symptoms of dieback were observed on A. malaccensis trees planted in the Medicinal and Aromatic Plant Garden, Panbari, Golaghat of the Assam Forest Department. The entire crowns of 70 trees showed complete leaf loss and severe dieback. Rotting at the collar region and of roots was also observed. Isolation from the infected roots consistently yielded Fusarium equiseti identified following standard laboratory procedures and analysis of the internal transcribed spacer (ITS) sequence of the ribosomal DNA. Symptoms of wilt, dieback and root rot were observed on 5‐month‐old Aquilaria seedlings 25 days after inoculation with the isolated fungus. This paper is the first report of F. equiseti causing wilt and dieback of A. malaccensis.     

Vascular modifications in Platanus acerifolia seedlings inoculated with Ceratocystis fimbriata f. sp. platani

Vascular modification of plane tree seedlings inoculated with Ceratocystis fimbriata f. sp. platani, the canker stain disease agent, were characterized using histochemical and scanning electron microscopy methods.     

First report of Cryptosphaeria pullmanensis as causal agent of Cryptosphaeria canker of Populus nigra in Iran

A diatrypaceous fungus was isolated consistently from cankers on Populus nigra trees showing dieback symptoms in Kohgiluyeh Boyer‐Ahmad, Zanjan and Esfahan provinces in Iran. Morphological characteristics and phylogenetic analyses of the ITS region of the rDNA identified the taxon as Cryptosphaeria pullmanensis. Pathogenicity tests conducted in potted 3‐month‐old cuttings of P. nigra confirmed Koch's postulates and revealed that C. pullmanensis caused canker on this host. This is the first report of C. pullmanensis causing a canker disease on P. nigra in Iran.     

Ceratocystis fimbriata of plane trees in Italy: biological aspects and control possibility

The biology of the pathogenic agent of plane tree canker (Ceratocystis fimbriata f.platani), the vectors of the disease and the results of some preventive and curative treatments are described in detail.     

Xyleborus glabratus attacks and systemic colonization by Raffaelea lauricola associated with dieback of Cinnamomum camphora in the southeastern United States

Laurel wilt, caused by Raffaelea lauricola, is responsible for extensive mortality of redbay and other American members of the Lauraceae in the southeastern United States. Raffaelea lauricola is a mycangial symbiont of the redbay ambrosia beetle (Xyleborus glabratus), and the beetle and fungus were accidentally introduced from Asia. Branch dieback of camphortree (Cinnamomum camphora), an Asian member of the Lauraceae, has been occasionally observed in areas where laurel wilt has decimated redbay populations, and R. lauricola was isolated from such camphortrees. However, the role of X. glabratus and R. lauricola in this branch dieback remains unclear. Examination of camphortrees on Jekyll Island, Georgia showed that healthy‐appearing trees and those with branch dieback had been attacked by X. glabratus, but the trees with branch dieback had four times as many beetle attacks. Raffaelea lauricola was routinely isolated from discoloured xylem near beetle tunnels in healthy trees and those with dieback. Single‐point inoculations with R. lauricola on stems of mature, healthy camphortree trees failed to induce wilt‐like symptoms or branch dieback, although areas of discoloration were scattered throughout the xylem, and R. lauricola was reisolated irregularly at various heights in some inoculated trees. In growth chamber experiments, single‐point inoculations with R. lauricola resulted in systemic colonization but no wilt symptoms or branch dieback in camphortree saplings. In contrast, inoculations at multiple points along the stem (simulating multiple attacks by the vector) caused branch dieback and wilt‐like symptoms, including a brownish, diffuse discoloration of the xylem. Camphortree appears to be more resistant than American species of Lauraceae to the vascular wilt caused by R. lauricola. The fungus does colonize camphortrees systemically, however, and can apparently cause branch dieback. This suggests that the fungus may provide brood material for X. glabratus in Asia as it does in the southeastern United States.     

Fungal colonization patterns in necrotic rootstocks and stem bases of dieback‐affected Fraxinus excelsior L.

European ash (Fraxinus excelsior) trees currently face the major threat of ash dieback caused by an invasive fungus, Hymenoscyphus fraxineus. Collar rots in F. excelsior have been increasingly associated with infections by this pathogen. However, the aetiology of the collar rots is still unclear and remains heavily debated. In contrast to most studies of this kind, entire rootstocks of four diseased ash trees were dug out to examine necrotic tissues in these rootstocks and stem bases in detail and to sample necrotic wood for fungal isolation. With the aid of morphological and molecular identification techniques, five to twelve fungal taxa were detected per tree. Members of the Nectriaceae family and Botryosphaeria stevensii, the causal agent of stem and branch cankers on many tree species, were frequently isolated from outer xylem. In contrast, H. fraxineus was the dominating species in interior wood layers. Microsatellite genotyping of 77 H. fraxineus isolates helped to identify up to six different genotypes per tree. The role of H. fraxineus and other isolated fungi in the aetiology of ash collar rots are discussed.     

Phytophthora species associated with dieback of sweet chestnut in Western Turkey

Sweet chestnut (Castanea sativa) is an important tree species in the Marmara and Aegean regions of Turkey as these two regions produce the great majority of edible nuts, especially those used for marron glacé production. Chestnut forests and orchards in these regions showing severe dieback symptoms not associated with chestnut blight were investigated to determine the role of Phytophthora spp. in the decline syndrome. Soil samples were collected from around 108 symptomatic chestnut trees at 29 sites and Phytophthora spp. isolated using soil baiting technique and selective medium. Species isolated were identified by cultural characteristics and ITS sequencing. Phytophthora x cambivora was the dominant species detected in 13 sites, followed by P. cinnamomi (5 sites), P. plurivora (3 sites) and P. cryptogea (1 site). Phytophthora x cambivora was present in both regions, while P. cinnamomi was found only in the Marmara region in coastal areas around Istanbul. When inoculated at the stem bases of 3‐year‐old chestnut saplings, P. cinnamomi produced significantly longer necrotic lesions (7.8–12.0 cm) than P. x cambivora (2.6–6.3 cm) by 12 days after inoculation. Phytophthora plurivora was the least aggressive species causing only small lesions. Phytophthora cryptogea, which represents the first record on chestnut in Turkey, produced intermediate sized lesions in between P. x cambivora and P. plurivora. These results indicate that P. x cambivora and in some areas P. cinnamomi play major roles in the observed dieback of sweet chestnut in western Turkey.     

The destructive invasive pathogen Phytophthora lateralis found on Chamaecyparis lawsoniana across the UK

In 2010–2011, Phytophthora lateralis was isolated from diseased Chamaecyparis lawsoniana exhibiting dieback and mortality at eight geographically separate forest, parkland and shelterbelt locations in England, Scotland and Northern Ireland. In 2011, P. lateralis was also isolated from young symptomatic nursery plants of C. lawsoniana and Thuja occidentalis recently imported into Scotland from mainland Europe. These are the first findings of P. lateralis in the UK. At six of the field sites, only collar and root lesions were observed. However, at two sites, large stem and branch lesions unconnected to the collar region were also observed. Phytophthora lateralis was readily isolated from both aerial and basal lesions. In artificial inoculation experiments, two Scottish isolates of the pathogen caused lesions on C. lawsoniana shoots and were readily reisolated from the lesions, their pathogenicity being comparable to that of P. lateralis isolates originating from outside the UK. Isolates from six field sites and the two nursery interceptions exhibited ITS and cox II sequences identical to published sequences of French and North American isolates. However, the isolates from two field sites shared an ITS sequence with Taiwanese isolates and differed from North American, French and Taiwanese isolates by a single‐base substitution in cox II, suggesting a separate evolutionary history. It is clear that P. lateralis now presents a significant threat to C. lawsoniana in Britain. The main source of the outbreaks is likely to be imported infested nursery stock.