bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of the ligno‐suberized barrier zone and wound periderm in four species of European broad‐leaved trees
Authors: Woodward S. , Pocock S. 
Published: June 2007

SummaryThe development of wound periderm after mechanical wounding was examined in the barks of Acer pseudoplatanus, Betula pendula, Fagus sylvatica and Sorbus aucuparia. Following the initial necrosis of cells immediately surrounding the wounds, development of the ligno‐suberized barrier zone was detected within 7 days. Suberin deposition was observed in this tissue in A. pseudoplatanus, S. aucuparia and B. pendula 7 days after wounding, but not in F. sylvatica until day 14. By 28 days after wounding, extensive thickening of the walls of these cells had occurred. Differentiation of the wound periderm was detected immediately abutting the ligno‐suberized barrier‐zone tissues in all species, with extensive development by 28 days. Fifty‐six days after wounding, the wound periderm was fully formed and completely confluent with the original periderm. Development of the wound response was similar in all species, with differences only in the timing of first detection of suberin.
Gremmeniella‐infected Pinus contorta as raw material in the production of kraft pulp
Authors: Ahlqvist B. , Karlman M. , Witzell J. 
Published: June 2007

Summary Pinus contorta, logs with occluded cankers caused by the pathogen Gremmeniella abietina, as well as logs from unaffected trees were sampled from a 23‐year‐old plantation in Sweden and compared in terms of their paper properties. Damaged wood gave kraft pulp with poor paper properties: it required a larger amount of beating energy and resulted in paper with low tear strength, air permeability, tensile stiffness, burst strength, and poor light‐scattering properties. However, small amounts of damaged wood mixed in with a large amount of healthy wood can pass almost unnoticed. The use of trees with a larger content of damaged wood will lead to serious processing problems and give a pulp with poor paper properties. Thus, wood damaged by Gremmeniella should be sorted out and classed as low‐grade raw material.
Susceptibility of the Quercus rubra root system to Phytophthora cinnamomi; comparison with chestnut and other oak species
Authors: Marĉais B. , Dupuis F. , Desprez‐Loustau M. L. 
Published: June 2007

SummaryThe susceptibility of oak seedlings (Quercus palustris, Quercus robur, Quercus rubra) and chestnut seedlings (Castanea sativa) to Phytophthora cinnamomi was tested. The dynamics of infection was examined in plant material raised in a rhizotron. In the oak species, primary root tissues were susceptible whereas secondary cortical tissues showed some resistance to P. cinnamomi. Secondary cortical tissues of the tap root in C. sativa were susceptible. Inoculations with P. cinnamomi were performed both in situ and on excised roots of mature Q. rubra. In both cases, the resistance of Q. rubra roots and shoots was negatively correlated with diameter at the inoculation point. Small roots (l–5‐cm diameter) were resistant, whereas collar and trunk were susceptible. In contrast to oak, small excised roots of mature C. sativa (0.7–2‐cm diameter) were susceptible to P. cinnamomi. This may explain why P. cinnamomi does not induce a decline of the attacked oaks, but rather a trunk canker.
Antagonism of Acremonium mucronatum towards Diplodia mutila in tests in vitro and in situ
Authors: Ragazzi A. , Moricca S. , Vagniluca S. , Dellavalle I. 
Published: June 2007

SummaryTests in vitro and in situ showed that both mycelial and conidial suspensions of Acremonium mucronatum were antagonistic for Diplodia mutila, a common pathogen on the apical twigs of declining Quercus cerris, Quercus frainetto, Quercus pubescens and Quercus robur. Antagonism was greater with the mycelium than with the conidial suspensions, and was strongest at a test temperature of 20°C. The results suggest that pathogenicity of D. mutila on declining trees may be significantly reduced by the presence of A. mucronatum.
Influence of clonal susceptibility, leaf age and inoculum density on infections by Melampsora larici‐populina races E1 and E3
Authors: Giorcelli A. , Vietto L. , Anselmi N. , Gennaro M. 
Published: June 2007

SummaryA study was conducted on the influence of clonal susceptibility, leaf age and inoculum density on the incubation and presporulation periods, and on the intensity of attack of Melampsora larici‐populina races El and E3, under controlled conditions, on artificially inoculated poplar leaf discs. Both races were more virulent on susceptible clones and on 5‐ to 15‐day‐old leaves. On susceptible clones the intensity of attack increased progressively with the increase of inoculum density. Where there was complete coverage of the leaf surface, uredia were smaller in size as a result of the increase in density. The incubation period and, above all, the average presporulation period of susceptible clones proved to be longer with 1‐ to 3‐day‐old leaves and, generally, with the oldest. The epidemiological consequences of these results are discussed.
Characterization of Canadian isolates of Chondrostereum purpureum by protein content, API ZYM and isozyme analyses
Authors: Shamoun S. F. , Wall R. E. 
Published: June 2007

SummarySeventeen isolates of Chondrostereum purpureum, collected from New Brunswick, Vancouver Island, and south‐eastern British Columbia, Canada, were compared to determine the degree of genetic variation among isolates from different host species and different biogeographic locations. Several characteristics, including mycelial protein content, fungal biomass, API ZYM profile (semi‐quantitative assay to detect the presence of 19 different enzymatic activities in an organism), and isozyme patterns were measured in these isolates. All 17 isolates shared similar API ZYM profiles, with only minor variation observed in the level of expression of specific enzymes. Of the 13 isozyme systems examined, eight (acid phosphatase, alkaline phosphatase, β‐esterase, β‐glucosidase, malate dehydrogenase, peroxidase, phosphoglucomutase, and polyphenoloxidase) produced measurable activity. No qualitative differences were observed between the isolates for all of these enzymes. There appeared to be limited variation between the isolates collected from across Canada and there was no correlation between specific API ZYM, and isozyme patterns and either host plant or geographical source of the isolates.
Detection of phytoplasma infections in declining Populus nigra ‘Italica’ trees and molecular differentiation of the aster yellows phytoplasmas identified in various Populus species
Authors: Berges R. , Cousin M.‐T. , Roux J. , Mäurer R. , Seemüller E. 
Published: June 2007

SummaryA disease of Populus nigra‘Italica’ associated with foliar yellowing, sparse foliage, stunting, dieback, and decline was observed in south‐western Germany; a witches’ broom disease of Populus alba that is known in other countries was also detected in Hungary and Germany. The aetiology of the diseases was studied by fluorescence microscopy and polymerase chain reaction (PCR) amplification. Using fluorescence microscopy, phytoplasmas could be detected only in P. alba. However, most diseased trees of P. nigra‘Italica’ tested phytoplasma‐positive by PCR. In some of the trees the phytoplasma numbers were so low that nested PCR was required to detect the infection. Very low phytoplasma numbers were also observed in diseased Populus tremula. The identity of phytoplasmas from P. nigra‘Italica’ sampled in Germany and France, P. alba and also P. tremula was examined by restriction fragment length polymorphism (RFLP) analysis of PCR‐amplified ribosomal DNA. In all poplars, phytoplasmas of the aster yellows group were detected. However, three different RFLP groups were identified that consisted of (1) French strains from P. nigra‘Italica’, (2) German strains from P. nigra‘Italica’ and (3) strains from P. alba and P. tremula. The profile observed in the last group was probably the result of sequence heterogeneity in the two 16S RNA genes.
First report of Sphaeropsis canker on cypress in South Africa
Authors: Linde C. , Kemp G. H. J. , Wingfield M. J. 
Published: June 2007

SummaryIn this study a Sphaeropsis sp. is recorded as causing cankers on cypress in South Africa. These cankers are either found alone or on trees which are infected with the well‐known cypress canker pathogen, Seiridium unicorne. When the two fungi occurred together, lesions could not be distinguished from each other, although the greater number of lesions were caused by the Sphaeropsis sp. The fungus appears to be identical to that described as Sphaeropsis sapinea f.sp. cupressi, in Israel, which is a fungus very different from the pine pathogen, Sphaeropsis sapinea. Pathogenicity tests showed that the Sphaeropsis sp. is significantly more pathogenic to Cupressus lusitanica than to Pinus roxburgii and Pinus elliottii. S. sapinea was pathogenic only to the Pinus spp. tested, and not to C. lusitanica. In contrast, the cypress pathogen Seiridium unicorne, was pathogenic to C. lusitanica and also to the two Pinus spp. tested.
Histological and histochemical detection of defence responses in pine embryos challenged in vitro with Heterobasidion annosum
Authors: Nsolomo V. R. , Woodward S. 
Published: June 2007

SummaryEmbryos of Pinus sylvestris, Pinus nigra var. maritima and Pinus contorta were inoculated in vitro with Heterobasidion annosum and the histology and histochemistry of the host response determined. Three days after challenge, intercellular penetration of hyphae through the epidermis and into the cortex of the host species had occurred. In cells close to the invading hyphae, cell walls became thickened in all three pine species. Lignification and suberization of cell walls in the cortex was detectable in P. nigra var. maritima and P. contorta, but not in P. sylvestris. Moreover, cells in the cortex of P. nigra var. maritima and P. contorta became occluded with dense deposits staining positively for phenolic and lipidic materials. Starch grains had accumulated in host cells close to sites of penetration by day 3, and levels appeared to increase by day 6, except for tissues where heavy invasion by H. annosum had occurred. Host responses intensified between 3 and 6 days after challenge. By day 6, however, the pathogen had penetrated as far as the stele and into the developing xylem vessels. Nine days after challenge, host tissues contained abundant intra‐ and inter‐cellular hyphae, causing severe disruption and disintegration of all tissues. The utility of such in vitro systems in studies on the resistance responses of conifers to challenge with fungal pathogens is discussed.
Secondary metabolites from dual cultures of genetically different Armillaria isolates
Authors: Sonnenbichler J. , Guillaumin J.‐J. , Peipp H. , Schwarz D. 
Published: June 2007

SummaryToxic secondary metabolites are synthesized for attack or defence in competing cultures of different basidiomycete species. In combination with incompatibility reactions changes in the pattern of secondary metabolites were also detected in dual cultures of diploid isolates of different Armillaria species (Armillaria gallica, Armillaria borealis and Armillaria cepistipes) on agar. In dual cultures the response in A. cepistipes was most pronounced and occurred combined with increasing growth inhibition of the fungus. The toxic metabolites which were formed in monocultures disappeared and the newly arising metabolites showed no antibiotic activity. The chemical structures of the compounds have been elucidated (two are described for the first time) as sesquiterpene esters of orsellinic acid derivatives. The augmenting metabolites of A. cepistipes are dehydroxylation products. A new facet of the role of secondary metabolites in the ecological interactions of fungi is described, namely, the detoxification of toxins by a competitor.
Liberation of Heterobasidion annosum conidia by airflow
Authors: Möykkynen T. 
Published: June 2007

SummaryThe effect of speed and humidity of the airflow and the míst sprayed with airflow on the liberation of conidia of Heterobasidion annosum from pure cultures was studied in a small windtunnel. The conidia were liberated more easily in humid than in dry airflow. Liberation was most abundant when mist was added to the airflow. Threshold speed for the liberation of conidia was calculated to vary between 1.8 m/s and 3.9 m/s. According to the results, conidia of H. annosum may be liberated into the air by wind gusts associated with high humidity or mist and thus the conidia may have a role in aerial dispersal, although this is probably small compared with basidiospores.
Accumulation of airborne fluorides in forest trees and vegetation
Authors: Horntvedt R. 
Published: June 2007

SummaryThe accumulation of fluoride in natural vegetation exposed to emissions from five aluminium smelter plants in Norway was studied during the years 1990–93. About 2000 leaf, bark and twig samples of 60 plant species, collected mostly during the growing season, were analysed. Rowan (Sorbus aucuparia) was widespread and common in the areas studied, and was used as a reference species. Fluoride concentrations in monthly samples of rowan leaves were linearly related to fluoride exposure (average fluoride concentration in ambient air × days since leaf emergence). The accumulation coefficient for rowan was estimated to be 1.7 m3/g dry wt. day. Most other species had values between 0.3 and 1.5; the median for all species was 0.8. The fern Dryopteris filix‐mas was exceptional, containing on average three times greater fluoride concentrations man rowan. High background levels indicated that soil uptake contributed significantly to the fluoride accumulation in this species. The fluoride concentrations in bark and shoots of trees were mostly low compared with leaves, but the bark of Betula pendula and B. pubescens had very high concentrations.
Laccase isoenzyme patterns of European Armillaria species from culture filtrates and infected woody plant tissues
Authors: Robene‐Soustrade I. , Lung‐Escarmant B. 
Published: June 2007

SummaryPolyacrylamide isoelectric focusing with specific staining for laccase activity was used to characterize laccase from European Armillaria species (Armillaria ostoyae, Armillaria mellea, Armillaria gallica, Armillaria cepistipes). The enzyme was extracted from culture media either supplemented, or not, with pine sawdust, and also from Pinus pinaster naturally infected by A. ostoyae, or artificially inoculated with A. mellea and A. ostoyae. Some differences in banding patterns were found for Armillana isolates according to the species and the culture media, but a common band at pI = 3.4 was found in all the extracts tested, independently of their origin (culture filtrate or wood).
Detection and partial characterization of extracellular proteases of the pathogenic fungi Endocronartium pint, Gremmeniella abietina and Heterobasidion annosum
Authors: Pappinen A. , Von Weissenberg K. 
Published: June 2007

SummaryProtease activities from 10 homokaryotic isolates of Heterobasidion annosum., two isolates of Grem‐meniella abietina and six isolates of Endocronartium pini were studied. All the fungi showed in vitro protease activity with denatured casein. The greatest caseinolytic activity was at acidic pH, but Heterobasidion annosum and Gremmeniella abietina showed caseinolytic activity at basic pH also. Protease preparations from Heterobasidion annosum were able to degrade proteins from total phloem extracts of Pinus sylvestris, Picea abies, Betula pendula and Juniperus communis. At basic pH the artificial substrates hippuryl arginine (HA) and hippuryl phenylactic acid (HPLA), were hydrolysed most rapidly by Heterobasidion annosum at pH 8.1, indicating high exopeptidase activity at this pH. According to inhibitor studies with EDTA (ethylenediaminetetraacetic acid), E64 (L‐trans‐epoxy‐succinyl‐leycylamide‐(4‐guanidino)‐butane‐agmatine) and pin2 (potato trypsin/chymotrypsin inhibi‐tor) both cysteine and serine proteases were present in proteases secreted by these pathogens, although only very low protease activity at basic pH was detected with Endocronartium pini.
Development of Leptographium wageneri on root surfaces and other substrata
Authors: Diamandis S. , Epstein L. , Cobb F. W. , Popenuck T. , Hecht‐Poinar E. 
Published: June 2007

SummaryConidia of Leptographium wageneri var. ponderosum, Leptographium wageneri var. pseudotsugae and Leptographium wageneri var. wageneri germinated on wounded roots of ponderosa pine (Pinus ponderosa), Douglas fir (Pseudotsuga menziesii), and pinyon (Pinus edulis), but not on unwounded roots. On wounds, germination occurred regardless of the combination of pathogen variety and plant species. When wounded roots of ponderosa pine and Douglas fir seedlings were inoculated with conidia of L. w. var. ponderosum and L. w. var. pseudotsugae, respectively, 87‐100% of the seedlings became infected. When unwounded roots were inoculated with wooden blocks colonized with L. wageneri, 60‐66% of the seedlings became infected.The development of L. w. var. ponderosum and L. w. var. pseudotsugae on agar was compared with their development on agar overlaid with either cellophane or Nucleopore membranes. Undulating hyphae were found commonly in and on the agar, but less frequently on the membranes. On both membranes, mycelia formed mats which were tightly appressed to the surface; mats were not formed on the agar. On both agar and the membranes, two or more hyphae often formed a strand. When L. w. var. ponderosum mycelia were allowed to colonize the surface of an unwounded pine root, strands, undulating hyphae and poorly formed mats were seen.
Intersterility groups of Heterobasidion annosum and their host specificity in Bulgaria
Authors: Porta N. La , Apostolov K. , Korhonen K. 
Published: June 2007

SummaryThe occurrence of 46 strains of Heterobasidion annosum from four forest areas in Bulgaria is reported. Three intersterility groups, P, S and F, were identified for the first time in populations of this pathogen in Bulgaria. A strict host specificity of different intersterility groups was observed even in mixed stands. The P group was isolated from Pinus sylvestris and Pinus nigra and occasionally from stumps of Abies alba. It was rare in artificial pine plantations on dry sites, whereas it was more common on more moist sites. The F group caused severe damage on Abies alba but was not found, even as a saprotroph, on admixed pines. This is the first report of the F group on Abies alba in the Balkans. The S group was found only on Picea abies.
Stimulation of Armillaria ostoyae vegetative growth by tryptophol and rhizomorph produced by Zygorhynchus moelleri
Authors: Kwaśna H. , Lakomy P. 
Published: June 2007

SummaryTryptophol (an indole‐3‐ethanol analogue which is a major secondary metabolite produced by Zygorhynchus moelleri) stimulated the growth of 13 out of 18 isolates of Armillaria ostoyae in culture. Rhizomorph production of 16 out of 18 isolates of A. ostoyae was enhanced by the presence of Z moelleri in oak branch segments. Tryptophol can be considered as a growth‐promoting substance stimulating the vegetative growth of A. ostoyae in culture, and Z. moelleri as a fungus stimulating the rhizomorph formation on oak wood.
Die Bedeutung von Krankheitserregern beim gegenwärtigen Eichensterben in Europa – eine Literaturübersicht
Authors: Donaubaur E. 
Published: June 2007

SummaryThe decline of oaks (Quercus spp.) has been reported in literature for more than two centuries. The symptoms of this syndrome seem to be the same at different sites ‐ with the exception of oak with’ in North America, the geographic range of declines coincides more or less with the natural range of oaks, but most of the reports from the past few decades deal with the European situation and less With such syndromes in America and Asia. So far, the decline of oaks is not yet fully understood. Pathogens play’ a role as predisposing and aggravating factors, but in general are not the primary cause of the decline.
Tree mortality risk of oak due to gypsy moth
Authors: Gottschalk K. W. , Colbert J. J. , Feicht D. L. 
Published: June 2007

SummaryWe present prediction models for estimating tree mortality resulting from gypsy moth, Lymantria dispar, defoliation in mixed oak, Quercus sp., forests. These models differ from previous work by including defoliation as a factor in the analysis. Defoliation intensity, initial tree crown condition (crown vigour), crown position, and species grouping classes were highly significant in categorical analysis of variance for mortality. Heavy defoliation intensity was shown to have a strong, consistent influence in increasing the probability of tree mortality. Classification and Regression Tree (CART) analysis, a binomial decision tree procedure, was used to develop prediction models of mortality risk for use by forest managers. The best decision tree had 65 groups that correctly classified 75% of the live trees and 76% of the dead trees. Models were run separately by defoliation class and provided correct classifications between 63 and 78% of the trees. Forest land managers can use these models to assign probabilities of death for moderate and heavy defoliation intensity levels and compare predicted mortality to mortality of undefoliated trees to determine how gypsy moth defoliation will affect their stands. The probabilities can be used to develop marking guides Lased on projected defoliation levels for implementing silvicultural treatments to minimize gypsy moth effects in forest stands prior to infestation.
The distribution of Phratora vulgatissima (Coleoptera: Chrysomelidae) on cultivated willows in Britain and Ireland
Authors: Sage R. B. , Tucker K. 
Published: June 2007

SummaryInsect samples were collected from the canopy of 24 willow short rotation coppice (SRC) sites on farmland in Britain and Ireland in 1995. The blue willow beetle Phratora (= Phyllodecta) vulgatissima (L.) (Coleoptera: Chrysomelidae), previously identified as the main defoliating pest of this crop, was recorded from 13 of these at varying levels of abundance. Data describing aspects of the environment at each site were also collected. These data were used to create potential explanatory variables for a regression analysis of beetle abundance. This analysis indicated that P. vulgatissima were most likely to occur and were more abundant at older willow sites on clay soils and at sites that bad certain free‐living willow species growing nearby. Within sites, most willow clones sampled contained P. vulgatissima, although two, Salix burjatica‘Germany’ (‘Aquatica Gigantea’) and Salix mollissima‘Q83’ (Salix triandra × Salix viminalis), were avoided. Chrysomelid pest avoidance and clonal resistance could form part of an integrated pest management strategy for SRC crops.
A rapid, apple‐based test for virulence in Cryphonectria cubensis isolates
Authors: De Lange W. J. , Wingfield B. D. , Wingfield M. J. 
Published: June 2007

SummaryThe presence of the Eucalyptus canker pathogen Cryphonectria cubensis in South Africa is of concern to the local forestry industry. Quantification of the virulence of this fungus through the inoculation of trees, is both time consuming, and expensive. In this study, the potential to use apples in screening for virulence of isolates of C. cubensis, was tested using different apple cultivars and inoculation procedures. The best indication of virulence was given on Golden Delicious apples incubated at 25°C for 14 days. Here, the lesion size associated with inoculations of C. cubensis, was found to correlate significantly with the virulence of the isolates, as determined by inoculations on trees.