Endophytische Pilze in Nadeln von gesunden und geschädigten Fichten (Picea abies [L.] Karsten)

Endophytic fungi in needles of healthy-looking and diseased Norway spruce (Picea abies [L.] Karsten). Endophytic fungi were isolated from surface-sterilized, 5 to 6 year old needles of healthy-looking and diseased trees. Two fungal species could be isolated frequently: Lophodermium piceae and Tiarosporella parca. At any site neither L. piceae nor T. parca could be isolated more frequently from needles of diseased trees. The possible types of relationship between these two fungi and Norway spruce are discussed.     

Detection of the endophyte Discula umbrinella in buds and twigs of Fagus sylvatica

Endophytic fungi have been isolated from buds and twigs of beech trees collected at four different sites in Switzerland. Discula umbrinella. was recovered at high frequencies from the bud scales and the twig pieces contiguous to the buds, but was virtually absent from the rolled up leaves enclosed by the scales. In addition to infection by air-borne inoculum, thalli of D. umbrinella may grow from the twigs into the leaf tissues.     

Endophytische Pilze in Blättern und Zweigen von Quercus petraea

Endophytic fungi in leaves and twigs of Quercus petraea . Surface sterilized leaf and twig samples taken in 1989 from sessile oak (Quercus petraea) in Austria yielded host-specific as well as unspecific ubiquistic endophytes. In leaves, Aureobasidium apocryptum and Apiognomonia quercina were the most frequent taxa, while Colpoma quercinum was the dominant species in twigs. The colonization rates of individual species were subjected to seasonal variation.     

The effect of bagging branches on levels of endophytic fungal infection in Japanese beech leaves

The species composition of the endophytic mycobiota in leaves of Japanese beech trees (Fagus crenata) and the sources for leaf infections were studied in a forest reserve situated in central eastern Honshu, Japan. To clarify the mechanism of infection of leaves, half of the branches were covered with polyethylene bags and species composition and levels of endophytic fungal infection were then compared with those of unbagged controls. Isolations were carried out from the leaves, petioles, and current‐year twigs of both, bagged and unbagged branches. Additionally, species composition was detected in overwintered terminal buds of beech trees and in the leaves of potted seedlings that had been placed in the field in different seasons. The species assemblage of the unbagged leaves, petioles, and current‐year twigs was dominated by Mycosphaerella buna, Ascochyta fagi, Periconiella sp., and Tritirachium sp. Other frequently recovered species were Xylaria sp., Phomopsis sp., and Tubakia dryina. Mycosphaerella buna and A. fagi were never isolated from leaves on bagged branches. A. fagi was, however, detected on both bagged and unbagged petioles and current‐year twigs at comparatively low isolation frequencies. The detection of Periconiella sp. on all occasions in both bagged and unbagged leaves was a characteristic feature that differs from those of the other three dominant endophytic fungi. The fungus was also detected without significant differences in bagged and unbagged petioles and current‐year twigs on most sampling dates. Furthermore, Periconiella sp. was isolated from immature twigs inside the bud scales. Tritirachium sp. was frequently detected in unbagged leaves and petioles and in both bagged and unbagged current‐year twigs, and rarely in bagged leaves and petioles, but was never recovered from terminal buds. The results of the potted seedling experiments revealed that all four dominant species had airborne inocula. The infection of leaves by M. buna occurs exclusively by airborne propagules, i.e. ascospores in spring and conidia in autumn. In Periconiella sp. hyphal growth of the fungus from immature twigs inside the buds into the leaf tissues was suggested in addition to infection by airborne inocula. Tritirachium sp. hyphae were suggested to grow from previous‐ to current‐year twigs. Ascochyta fagi was present in the outermost scales of overwintered terminal buds, but no systemic growth of the fungus into the petioles and current‐year twigs was observed. Our technique of covering the branches before new leaves unfolded was effective in preventing infection by airborne inocula of endophytic fungi.     

Temporal variations in endophytic fungal assemblages of Ginkgo biloba L.

We isolated endophytic fungi from living healthy leaves, petioles, and current-year twigs of Ginkgo biloba L. from April to November 2004 with the objective of identifying the dominant endophytic fungal taxa, and monitoring their occurrence and frequency. A total of 9 fungal taxa were identified to the genus level. Diversity measures inferred from the Shannon–Wiener, Morisita–Horn, and S?rensen indices indicated that leaves and petioles harbored more diverse endophytic fungal assemblages than twigs, and that fungal taxa involved in twigs shared less with those in leaves and petioles. Among the organs, the occurrence pattern of overall endophytic fungi differed significantly, and two taxa, Phomopsis sp. and Phyllosticta sp., were the most frequently isolated and thus regarded as the dominant endophytic fungi. Phomopsis sp. was isolated frequently from twigs (84.8%) but rather few from leaves (16.1%) and petioles (24.3%). Phyllosticta sp. was isolated frequently from leaves (72.9%) and petioles (65.7%) but was never isolated from twigs. Temporal changes in relative frequency of total endophytic fungi tended to differ among sampling dates for all three organs. The occurrence of Phyllosticta sp. in both leaves and petioles was first detected in August and peaked in October. Phomopsis sp. was detected in twigs throughout the growing season. These results suggest that the distribution of the two dominant endophytic fungi was organ-specific and differed within seasons.     

La variabilité de la sensibilité du Hêtre (Fagus sylvatica L.) à Nectria coccinea,un des agents de la maladie de l'écorce

Variability of Fagus sylvatica susceptibility to Nectria coccinca, one of the agents of beech bark disease . N. coccinea was inoculated into wounds of young beeches raised from seeds of 6 bark diseased trees and 6 healthy ones in the same stand of the forest of Lyons. Classifieation of the progenies, according to the size of the necrosis, is in good agreement with the health of the mother trees. N. coccinca susceptibility of beech has a genetic origin.     

Fungi in leaves,twigs and stem bark of Populus tremula from northern Spain

Fungal species were recorded from Populus tremula leaves, twigs and bark (trunk) at eight sites in the northern region of Spain, with the aim of evaluating the effect of sampling site, sampling tissue and isolation method on the frequency and species distribution of the fungi recovered from necrotic and healthy tissues. Two different isolation methods were used: the first consisted of finding fruitbodies on plant tissues after incubating them in wet and warm conditions, and the second included growing mycelia from plant fragments plated on potato dextrose agar (PDA). A total of 48 fungal species were isolated from 960 plant fragments. Cytospora chrysosperma, previously reported to be a pathogen of poplar, was recovered very frequently and was recorded as much in healthy as in dead or dying tissues. Cladosporium maculicola, Elsinoe veneta, Alternaria alternata, Aureobasidium pullulans and Pollaccia radiosa were also frequently isolated. The isolation frequencies from necrotic and healthy plant tissues were significantly different between sites and isolation methods. The incubation in moist chambers revealed significantly more fungal isolates and a higher species richness (38 species) than isolations on PDA. However, 16% of the fungal species were exclusively recorded from cultures. Therefore, a combination of several isolation methods is recommended for surveys of fungal communities associated with trees.     

Osmotic potential of spruce,fir and beech as a contribution to water budget in connection with forest decline (“Waldsterben”)

Osmotic cell sap potentials of diseased and healthy spruce, fir and beech leaves, fine roots and cortes were determined with the aid of capillary cryoscopy. With one exception (fir needles) the diseased trees showed no reduction in osmotic potential compared to healthy trees.     

Differences in composition of endophytic mycobiota in twigs and leaves of healthy and declining Quercus species in Italy

The composition of the endophytic fungal assemblages in Quercus cerris, Q. pubescens and Q. robur, three oak species most susceptible to decline, was investigated in Fagarè (Padova), Ulignano (Pisa), and Radda in Chianti (Firenze). The endophytic assemblages were studied as a function of health status of the whole tree and of twigs and leaves. The effect of station altitude was tested on Q. cerris. Samples were gathered from healthy and declining trees. In April (bud opening time) 20 twigs and 10 leaves were collected from each tree. Fungi were isolated from twig segments and leaf portions. A total of 23 fungal genera with 27 different species were isolated, in addition to a few sterile mycelia. Eleven species were found to be common to all three oak species, while other species were found only on one oak species, suggesting host specificity. Among the fungal species isolated, some were known to be pathogenic (Apiognomonia quercina, Colpoma quercinum, Diplodia mutila, Phomopsis quercina). The colonization frequency (CF) of pathogenic species varied between 0.9% for A. quercina in Q. cerris and 60.2% for P. quercina in Q. robur. Analysis of variance showed a statistically significant difference among the oak species tested. The CF was higher in declining trees in comparison with healthy trees, and also in twigs vs. leaves. The CF was found to be higher for Q. cerris trees growing at sea level as compared with those situated at an elevation of 350–400 m. In stands where, on account of particular ecological conditions, pathogenic behaviour is displayed simultaneously by more than one endophytic fungal species, trees accentuate their decline.     

Pathogenicity of fungi associated with ash dieback symptoms of one‐year‐old Fraxinus excelsior in Montenegro

In addition to Hymenoscyphus fraxineus, two fungi identified as Diaporthe eres aff. and Fusarium sambucinum aff. were also isolated from necrotic bark lesions on declining one‐year‐old Fraxinus excelsior in a forest stand in Montenegro. To examine their involvement in ash decline, a pathogenicity test was performed using under bark inoculations on one‐year‐old Fraxinus excelsior. Hymenoscyphus fraxineus was included as comparison. All three fungal species proved highly pathogenic towards one‐year‐old seedlings although lesion sizes differed significantly between the different species. Hymenoscyphus fraxineus was most aggressive, followed by F. sambucinum aff., while D. eres aff. caused the smallest lesions. This study demonstrates for the first time the ability of isolates in the D. eres and F. sambucinum species complexes to cause decline on one‐year‐old common ash seedlings.     

A twig blight of understorey European beech (Fagus sylvatica) caused by soilborne Phytophthora spp.

During and after prolonged periods of rainfall in late spring, blighted young twigs of European beech (Fagus sylvatica) were frequently observed in several beech stands in south‐western and southern Germany. Long and short shoots of young understorey trees or lower branches up to 1.5 m above the soil level were affected. Symptoms also occurred regularly on twigs in heights up to 2 m and more above the ground. Necroses usually expanded within the current year’s tissue and often also reached into the previous year’s wood. Ponding rain water in the stands or along forest roads or open soil seemed to promote the disease. Of a total of 54 symptomatic twigs collected in four stands, 37 revealed Phytophthora isolates, of which 33 were P. plurivora and four were P. cambivora. Both species caused extensive lesions on beech twigs in laboratory pathogenicity tests. Patterns of the disease indicated that these pathogens, generally considered soilborne species, in most cases are transmitted from the soil to above‐ground parts of the trees via rain splash. In larger heights, however, other vectors such as snails might be responsible for transmission. Although Phytophthora spp. are well known as causal agents of seedling blight as well as root and cambium rot and aerial bleeding cankers of mature beech, to our knowledge this is the first report of a twig blight in beech associated with soilborne Phytophthora spp. In particular in periods of high precipitation, this disease might pose an additional threat to Central European beech forests, especially endangering the success of artificial and natural regeneration of beech in affected stands.     

The culturable leaf mycobiome of Viscum album subsp. austriacum

In Poland's pine forests, mistletoe (Viscum album subsp. austriacum) abundance has increased over the past 20 years. This mistletoe infestation has decreased the growth and vigour of Scots pine trees. In this study, we surveyed the culturable fungi from healthy and diseased V. album subsp. austriacum leaves from two stands in Poland. In total, 63 distinct species were identified, 99.8% of which belonged to the phylum Ascomycota. The community compositions of fungi in mistletoe leaves were similar in healthy and diseased leaves as Alternaria alternata, Aureobasidium pullulans, Botryosphaeria visci, Fusarium paeoniae and Microsphaeropsis olivacea were consistently found in leaves of all symptom types. The most frequently isolated fungus from asymptomatic leaves was M. olivacea, followed by A. alternata, A. pullulans and Hypoxylon rubiginosum. In comparison, the most frequently isolated fungi from leaves with rusty-brown necrotic spots were (in decreasing order) M. olivacea, B. visci, F. paeoniae and A. alternata, while the most frequently isolated fungi from leaves with black or dark brown spots were M. olivacea, A. alternata, A. pullulans, Epicoccum layuense and F. paeoniae. This study was the first comprehensive report showing that certain fungal species may be pathogens of V. album subsp. austriacum in Poland. This study was also the first report of F. paeoniae, F. juglandicola, Diaporthe vacuae and Heterotruncatella spartii from V. album, and the first report of D. vacuae and H. spartii in Poland.     

Characterization of Cylindrocarpon‐like species associated with litter in the old‐growth beech forests of Central Europe

Cylindrocarpon‐like fungi are globally distributed plant pathogens and have a wide range of host species. However, very little is known about the species that live in the topsoil of forests and their potential role in reducing the natural regeneration of tree species, particularly of forest trees that produce abundant fruit only once every few years. To enhance our understanding of the species that inhabit the topsoil, we studied the diversity and pathogenicity of Cylindrocarpon‐like fungi inhabiting the litter in old‐growth mixed‐beech forests in the Carpathians (Poland) and in the Alps (Austria), and in a managed beech stand in the Krakowsko‐Cz?stochowska Highland (Poland). The fungi inhabiting the beech litter were investigated using beechnuts and pine seedlings as bait. Isolates were identified based on morphology and DNA sequencing. The pathogenicity of the most common species was investigated by inoculating beech germinants. A wide range of Cylindrocarpon‐like fungi were associated with the beech litter: 718 cultures representing 12 species were isolated. Five taxa were identified down to species level: namely Ilyonectria crassa, I. pseudodestructans, I. rufa, Neonectria candida and N. obtusispora, and seven species were identified to genus level (Neonectria or Ilyonectria species). Ilyonectria destructans, which is considered to be the sexual morph of ‘Cylindrocarpon destructans’, was not found. There were qualitative and quantitative differences between the different forest sites in terms of Neonectria and Ilyonectria species composition in beech litter. The isolation frequency and species richness of Cylindrocarpon‐like fungi were greatest in beech litter taken from old‐growth mixed‐beech forests. Neonectria and Ilyonectria species were capable of killing beech germinants, suggesting that they may play a negative role in natural beech regeneration.     

Wundfäule in Fichtenwaldungen mit alten Schälschäden

Wound decays in spruce stands following bark stripping . 2083 trees in 91 sample plots on four trial areas (24 ha) were examined for bark stripping and decay. Only 25% of trees showed no injury. Of the injured trees, 73% showed some degree of decay, 10% discoloration. and 17% neither decay nor discoloration. Of the wood destroying fungi isolated Fomes annosus was dominant and appeared to be the most important and widespread of the wound inhabiting fungi in the test area. Besides the Basidiomycetes a considerable number of other fungi was isolated. The most frequent was Cylindrocarpon cylindroides var. tenue.     

Auswaschung phytotoxischer Substanzen aus Blättern kranker und gesunder Buchen - Schäden an der Bodenflora

Leaching of phytotoxic substances from foliage of diseased and healthy beeches - damage to ground vegetation. Damage to vegetation under declining beeches gave rise to test the effects of simulated aqueous leachate of beech leaves on 7 wild flower species. In biotests under aseptic conditions leachate of declining beeches affected germination and plant development more than leachate of healthy ones.     

Zusammenhänge zwischen Kronenschäden und dem Stärkegehalt der Wurzeln bei Fagus sylvatica L.

Correlation between root starch content and crown damage of European beech (Fagus sylvatica L.). During a research project on forest decline in European beech stands the starch content of woody roots apparently of healthy and trees with dieback symptoms were examined by a histochemical method developed by Wargo . A comparison of affected and apparently healthy trees indicated no correlation between starch content of coarse roots and damage class derived from crown symptoms. However, results of these preliminary studies on distribution of starch in the root system of European beech confirmed the data reported in the literature.     

<Emphasis Type="Italic">Ophiostoma</Emphasis> species associated with bark beetles infesting three <Emphasis Type="Italic">Abies</Emphasis> species in Nikko,Japan

Ophiostoma species were isolated from bark beetles and Abies mariesii, A. veitchii and A. homolepis attacked by the beetles in Nikko, Tochigi, central Honshu, Japan. One to two Ophiostoma species were frequently isolated from each species of bark beetle. Ophiostoma subalpinum was the most common associate of Cryphalus montanus. Ophiostoma sp. B as well as O. subalpinum was a common fungus associated with Polygraphus proximus. Ophiostoma europhioides was isolated from Dryocoetes hectographus and D. autographus as one of the common associates. Ophiostoma sp. J and Ophiostoma sp. S were frequently isolated from D. autographus and D. striatus, respectively. These fungi seem to have specific relationships with particular bark beetles. Ophiostoma sp. B, Ophiostoma sp. J and Ophiostoma sp. S have unique morphological characteristics and appear to be new species. Five trees of A. veitchii, approximately 43 years old, were inoculated with five Ophiostoma species to assess the relative virulence of the fungi. Ophiostoma subalpinum, Ophiostoma sp. B, and O. europhioides had relatively higher virulence than the other species studied.     

Scale insects,decay and canker fungi in American beech

Tripartite interactions among phytophagous insects, pathogens and their host plants provide insight into the role of host physiology in determining susceptibility to attack. American beech (Fagus grandifolia) often is simultaneously attacked by beech scale (Cryptococcus fagisuga), one or more Neonectria pathogens and Xylococculus betulae that can result in beech bark disease (BBD). Additionally, beech is frequently infected by heartrot‐decay fungi. Cursory observations in 2011 suggested that beech scale and Neonectria lesion densities were lower and greater, respectively, on trees with decay. In 2012, digital image analysis was used to quantify densities of these organisms on 123 beech from the Adirondack region of New York. Three groups of study trees (n = 41) were used: Inonotus glomeratus‐infected, Phellinus igniarius‐infected and non‐decay trees. Trees infected by decay pathogens supported lower densities of beech scale and higher densities of Neonectria. Densities of X. betulae did not significantly vary among decay groups. These results may be explained by decay‐induced changes in host physiology. Additional work is needed to elucidate the potential role of host bark chemistry in the BBD complex.     

Canker and dieback on Platanus x acerifolia caused by Diaporthe scabra

Cankers and dieback on London plane caused by Diaporthe scabra have been observed in urban plantings in Catania, Italy. Symptoms were delayed spring flush, trunk cankers, small chlorotic leaves associated with dead terminal or lateral branches and an early defoliation. Isolations from infected wood on PDA led to the isolation of the anamorph Phomopsis scabra with α‐conidia production. The infected wood placed in a moist chamber developed pycnidia with α and β conidia and perithecia of the teleomorph D. scabra. Sequence analysis of the internal transcribed spacers ITS1 and ITS2, the ribosomal intragenic spacer beta‐tubulin 1 and beta‐tubulin 2 genes, congruently indicated that the D. scabra isolate is phylogenetically related to two strains of D. helianthi isolated in Italy from sunflower and to strains of D. eres. Inoculations on young plants of London plane growing in pots confirmed the pathogenicity of the isolated fungus. To our knowledge, this is the first report of the disease in Italy.