bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stem damage in Swiss forests: incidence, causes and relations to crown transparency
Authors: Innes J. L. , Schwyzer A. 
Published: June 2007

AbstractIn the annual assessments of forest damage in Switzerland, the nature of any stem damage is recorded on the target trees. As the inventory is undertaken on a representative basis, the extent of stem damage should accurately reflect the extent of stem damage on trees in Switzerland. This paper examines the occurrence of stem damage by species, region and forest type and determines whether any relationship exists between stem damage and crown transparency.
The condition of the phloem in declining oaks
Authors: Schlag M. G. 
Published: June 2007

SummaryOaks (Quercus petraea, Q. robur) from several sites in eastern Austria affected by novel oak decline (NOD), as well as oaks (Q. robur) showing symptoms of oak yellows (OY), were tested for the presence of mycoplasma‐like organisms (MLOs). The samples, comprising roots, annual shoots, and branches, were examined using light‐, fluorescence‐, and electron‐nucroscopic techniques. Staining with the DNA‐fluorochrome DAPI provided no evidence for the presence of MLOs in any of the samples. Furthermore, no pathological sieve‐tube necrosis and no abnormal callose accumulation could be observed. An association of MLOs with‘novel oak decline’ or ‘oak yellows’ is, therefore, unlikely.
Histology of Pinus maximinoi cones infected by Cronartium conigenum1
Authors: Rayachhltry M. B. , Webb R. S. , Miller T. , Kimbrough J. W. 
Published: June 2007

SummaryApparently healthy and C. conigenum infected female strobili of Pinus maximinoi, collected in Guatemala, were histopathologically studied by light microscopy. Scales from infected cones were fused and fertile scales had aborted seeds. Infected cone scales lacked fibre cells in the cortex, which are abundant in healthy cone scales. Intercellular spaces of cortex contained abundant hyphae compared to phloem and xylem.The cell walls of infected tissues in the ovules were darkly stained, while those of comparable healthy tissue were colourless under Pianeze's IIIB stain. Infected ovules of different developmental stages with nucellus, or nucellus plus spongy tissue, were observed. The cells of each tissue type contained many haustoria and did not develop into female gametophyte and embryo. Ovule colonization by hyphae appeared after pollination and subsequently caused their early abortion.
Uni‐ and binucleate Rhizoctonia spp. co‐existing on the roots of Norway‐spruce seedlings suffering from root dieback
Authors: Hietala A. M. 
Published: June 2007

Summary Rhizoctonia fungi were isolated from the roots of 2‐year‐old nursery‐grown Norway‐spruce seedlings displaying root‐dieback symptoms. The most frequently isolated species, a uninucleate Rhizoctonia sp., was found to co‐exist with binucleate Rhizoctonia in the same root system of several seedlings. All the uninucleate isolates anastomosed with each other forming a single anastomosis group with common cultural characteristics. Binucleate Rhizoctonia isolates were divided into several, morphologically dissimilar anastomosis groups (AG‐I, R. spp.). In a pathogenicity test under sterile conditions, isolates belonging to the uninucleate Rhizoctonia sp. infected all root regions, particularly the root tips, resulting in a stunted root‐system morphology, as was also observed in the isolation material.Binucleate Rhizoctonia spp. colonized only basal root regions, occasionally infecting cortical cells with monilioid hyphae, and had no effect on root growth.
Immunocytochemical localization of pathogenesis‐related proteins in roots of Norway spruce infected with Heterobasidion annosum
Authors: Asiegbu F. O. , Denekamp M. , Daniel G. , Johansson M. 
Published: June 2007

SummaryThe occurrence and accumulation of β‐1, 3‐glucanase and chitinase in seedling roots of spruce (Picea abies) following challenge by the root‐rot pathogen Heterobasidion annosum were studied. Chitinase activity increased 2–3 fold following inoculation, whereas no significant increase in the activity levels of glucanase was recorded during infection. With TEM immunogold labelling, the enzymes were localized in protein aggregates in host tissues and in the cell walls of intercellular hyphae. Gold particles were sparse and irregularly distributed within host‐cell walls. Only minor labelling was observed on hyphal walls coated with electron‐dense materials. The labelling intensity increased with infection time and was always higher than in non‐infected seedling roots. When this experiment was repeated using root samples inoculated with the saprophyte Phlebiopsis gigantea, a similar labelling pattern was observed. The cross reactivity of antisera raised against sugar‐beet chitinase and glucanase with spruceroot enzyme extracts was demonstrated using dot‐blot assays and ELISA.
Transmission of hypovirulence agents among some Cryphonectria parasitica strains from Italy
Authors: Maresi G. , Giovannetti L. , Ventura S. , Turchetti T. 
Published: June 2007

SummarySix hypovirulent (H) strains of Cryphonectria parasitica collected in Italy were tested for dsRNA content, virulence, and conversion ability. Nine converts were also checked for dsRNA. In inoculation trials, H and converted (C) strains showed reduced pathogenicity. Most H and C strains were able to convert strains from various v‐c groups. DsRNA banding patterns were similar in five of the H strains and in their converts, while the last one and its converts showed no evidence of dsRNA. The broad conversion ability of H strains seems to be responsible for the natural recovery of Italian chestnut trees.
Differences in Agrobacterium infections in silver birch and Scots pine
Authors: Aronen T. , Häggman H. 
Published: June 2007

SummaryThe aim of this study was to investigate the differences in infections caused by Agrobacterium tumefaciens in a conifer, Scots pine (Pinus sylvestris), and in a non‐host deciduous species, silver birch (Betula pendula). All the Agrobacterium tumefaciens strains tested caused crown‐gall formation in both tree species, but the infection rates varied remarkably. In Scots pine, the development of galls was rare, and slower than in silver birch. Inoculation into the base of the stem were the most successful in gall induction. Silver‐birch galls were large, often surrounding the whole stem, in contrast to Scots pine galls, which were characterized by their small size and neck‐like connection with the host plant. In silver birch, no other morphological changes could be seen. In Scots pine, abnormal phenotypes with proliferating short shoots above the galls were observed during the second and third growing season. The results indicate that, of the two non‐host tree species, the deciduous one, silver birch, is more susceptible to an A. tumefaciens infection than the conifer, Scots pine. The matrix for A. tumefaciens infection in silver birch differs from that in Scots pine, since the terpene compounds of Scots pine seem either to kill the agrobacteria or to suppress their growth. The differences between the species could be partly caused by their difference in sensitivity to phytohormones. These features reflect evolutionary incompatibility between A. tumefaciens and a gymnosperm.
Occurrence of Persian (English) walnut blight and its control in the nursery
Authors: Belisario A. , Zoina A. 
Published: June 2007

SummaryObservations carried out over several years in walnut nurseries in Italy revealed bacterial walnut blight, induced by Xanthomonas campestris pv. juglandis, to be the most harmful disease; 4 years of field trials were performed. Infection level was shown to be related to the inter‐row distances. The inter‐row distances 0.6, 0.8, 1.0, and 1.4 m were tested. The 1.4‐m distance resulted in the best control of bacterial spread, even under high inoculum pressure due to artificial inoculations. Foliage flush was the stage most vulnerable to bacterial infection. Chemical control with Bordeaux mixture and mancozeb was tested, but only Bordeaux mixture showed some effect. Two copper treatments, at the beginning and at the end of the vegetative period, can be recommended for those areas that are heavily infested with X. c. pv. juglandis.
Vegetative compatibility and conversion to hypovirulence among Italian isolates of Cryphonectria parasitica
Authors: Causin R. , Frigimelica G. , Montecchio L. , Mutto Accordi S. 
Published: June 2007

SummaryA total of 850 virulent isolates of Cryphonectria parasitica were isolated from natural cankers on European chestnut trees growing in various Italian regions. Vegetative‐compatibility (v‐c) group membership was tested using the merge‐barrage method. In all, 19 vegetative‐compatibility groups were found, and, for each of these, a representative isolate (v‐c tester) was identified; 49% of the isolates were compatible with the tester of only one v‐c group, whereas 51% were compatible with the testers of more than one v‐c group; 3% of the isolates showed compatibility with seven v‐c groups. The coincidence between vegetative incompatibility and failure of conversion occurred in only a few cases; 42% of the converts were stable with respect to their morphological characteristics and presence of cytoplasmic ds‐RNA. The results obtained in Italy suggest that, for an efficient biocontrol programme, it is preferable to evaluate the tendency of a population to be converted rather than evaluating the v‐c group membership.
Effects of sulphuric acid and heavy‐metal deposition on frequency of asymptomatic infections of Gremmeniella abietina in Scots‐pine seedlings
Authors: Ranta H. , Neuvonen S. , Virtanen T. 
Published: June 2007

SummaryThe isolation frequency of Gremmeniella abietina was measured from asymptomatic 4‐year‐old Scots‐pine seedlings. The seedlings had been subjected to simulated sulphuric deposition (pH 3.1 or 4.1) or control treatments (irrigation with spring water (pH 6), or no irrigation) during the three previous growing seasons. The seedlings were planted in soil originating from two localities with different backround levels of copper (Cu) and nickel (Ni), and the soil was further amended with Cu (63.3 mg/1 of soil) and Ni (20.5 mg/1 of soil), or a combination of the two. The seedlings were inoculated with conidia of G. abietina during their third growing season in the field. Asymptomatic infections of G. abietina were recovered frequently from seedlings that had received water irrigation. The addition of sulphuric acid to the irrigation water, and/or the lowered pH (pH 3.1 and 4.1) resulting from this addition, mitigated the effect of water application. The effect of Ni‐treatment on the recovery of G. abietina depended on the irrigation treatment; with no irrigation, Ni‐treatment increased isolation frequency, but, in irrigated seedlings the response was the opposite. Only 10.6% of the seedlings had symptoms caused by G. abietina; most of the seedlings had become infected before the application of the various treatments.
Occurrence of Gremmeniella abietina damage on Scots pine along a pollution gradient from Monchegorsk nickel smelter to western Lapland
Authors: Kaitera J. , Fedorkov A. , Jalkanen R. , Krutov V. , Tsvetkov V. 
Published: June 2007

Summary Gremmeniella abietina damage was studied at stand and tree level on the Kola Peninsula and in northern Finland. At stand level, damage was recorded in four areas in Finland, while only individual damaged trees were found in Russia. According to the results of branch analysis, there was no sign of endemic epidemics in any of the areas. There was a significant negative correlation between the average G. abietina damage and modelled SO2 deposition and temperature sum along the gradient. The results suggest that G. abietina is distributed all over northern Finland and the Kola Peninsula in natural stands of Scots pine, and that the direct effect of SO2 deposition from the Monchegorsk nickel smelter on the damage may be minimal.
Inoculation of young pine seedlings with Peridermium pini from north‐east Scotland
Authors: Pei M. H. , Brodie J. 
Published: June 2007

SummarySeedlings of Pinus sylvestris, P. nigra ssp. laricio, and P. mugo vars mughus, rostrata and pumilio were inoculated at their cotyledon stage with aeciospores of Peridermium pini from north‐east Scotland. Infection was determined by the presence of both mycelia and haustoria in free‐hand or paraffin sections. In the second growing season, infected seedlings showed symptoms such as stem‐swelling, development of spermogonia and aecia, and death. In a second experiment, young P. sylvestris seedlings from seven seed sources collected in Great Britain were inoculated and the infection were examined after 6 weeks. In the samples of 50 seedlings from each source, 30–70% seedlings were infected.
Control of Dutch elm disease by induced host resistance
Authors: Sutherland M. L. , Mittempergher L. , Brasier C. M. 
Published: June 2007

SummaryA range of fungi was screened for the ability to suppress symptoms of Dutch elm disease in European and hybrid elms under UK and Italian field conditions. The efficacy of the preventative inoculations varied Considerably between elm clones of differing resistance to the causal fungus Ophiostoma novoulmi. On susceptible English elm, Ulmus procera, preventative inoculations with conidia of Verticillium dahlias, Opbiostoma ulmi or Ophiostoma piceae (OPH form) caused no reduction in final disease levels. On U. x bollandica cv.‘Commelin’, pretreatment with V. dabliae or O. ulmi reduces final disease levels, but not significantly, On the elm clone Ca06 of U. carpinifolia, and on the hybrid clones FL025 and 196–6, significant (p0.05) symptom suppression occurred in trees pretreated with O. ulmi or V. dahliae. On the more resistant elm clones 3–14 and Lobel, only V. dahliae was an effective pretreatment (p0.05). Certain pretreatment fungi alone caused symptoms in some of the elm clones. Major difficulties in using this approach to control Dutch elm disease are discussed.The technical assistance by F. C. Baldwin, R. Brooker, S. A. Kirk and J. Rose at the Forest Research Station, Alice Holt, and by A. Fagnani and F. Ferrini at CNR, Florence, as well as statistical advice from A. J. Peace at Alice Holt, is gratefully acknowledged.The authors would like to thank the Pilkington Charitable Trust for funding the research in the UK and lsotron plc, Swindon, Berkshire, for gamma irradiating the conidial suspensions. The Italian contribution was supported by the National Research Council of Italy, special project RAISA, subproject no. 2, paper no. 2133. The authors also thank John GIBBS for helpful comments on the manuscript.
Befall der Fichte (Picea abies) durchHeterobasidion annosum in Abhängigkeit vom Baumalter
Authors: Rleger S. 
Published: June 2007

Summary Infection of Norway spruce (Picca abies) by Heterobasidion annosum in relation to tree age The presence of H. annosum in stems and roots of young Picea abies of different age classes was determined in four heavily infected stands in Southern Germany. The frequency of infected trees increased with age (0% in age class I (I‐10 years), 7,5% in class 2 (11‐20 years), 33,3% in class 3 (21‐30 years)). Only the S‐type was found. An additional investigation of 1‐10‐year‐old trees growing on stumps with H. annosum decay or tightly surrounded by carpophores yielded an infection rate of 20% (mainly S‐type). H. annosum was confined to very small regions in the host tissue in these cases.
Capability of the European and North American race of Gremmeniella abietina to hydrolyse polygalacturonic acid in vitro
Authors: Petäistö R‐L. , Lappi J. 
Published: June 2007

SummaryPolygalacturonase was found to be one of the first enzymes secreted by a pathogen during infection. The polygalacturonic‐acid hydrolysing activity was compared between the North American and the European race of Gremmeniella abietina in vitro. Isolates were grown in pure pectin media from which the enzyme activity was analysed. Altogether, 29 isolates were tested in five experiments (experimental runs in a growing chamber). The data were analysed using variance‐component models that included fixed‐race effects and random‐experiment, isolate, flask and measurement effects. The European race secreted more polygalacturonic‐acid hydrolysing enzyme than the North American race and the mycelial dry weight produced was smaller for the European race. The differences between races were of the same order of magnitude as the variation between isolates within races; variance components relating to experimental errors were quite large. No correlation was found between the activity and mycelial dry‐matter production within the races. Logarithmic transformation removed the apparent racial differences in the variability of the activity and mycelial dry weight. Results from the additionally tested A‐ and B‐type of Finnish isolates indicated differences in dry‐matter production.
Variation in Melampsoridium resistance among European white‐birch clones grown in different fertilization treatments
Authors: Poteri M. , Rousi M. 
Published: June 2007

SummaryResistance of 2‐year‐old plantlets of seven European white birch, Betula pendula, clones to birch rust, Melampsoridium betulinum, was studied in field experiments and in a leaf‐disc bioassay. In addition, rust resistance of plantlets growing in a nursery under three fertilization treatments was tested. The birch clones clearly varied in their levels of resistance. One of the clones was consistently the most resistant, and two were very susceptible. Plantlets growing in the lowest fertility treatment were the most resistant. Clone × fertilization interaction was small. The plantlets grown in the lowest fertilization treatment, in particular, deviated from the other treatments. Generally good rust‐resistance correlations were obtained between different experiments. The leaf‐disc bioassay was an effective way of determining the field rust resistance of birch clones. The possibility of trade‐offs between rust resistance and tree growth is discussed.
Seedling response of two trembling aspen (Populus tremuloides) families to infection by Hypoxylon mammatum
Authors: Enebak S. A. , Li B. , Ostry M. E. 
Published: June 2007

SummaryOpen‐pollinated progenies from two trembling aspen (Populus tremuloides) families with a 30‐year field history of 91% (putatively susceptible, PS) and 45% (putatively resistant, PR) mortality, respectively, caused by Hypoxylon mammatum, were grown in a greenhouse for 3 and 9 months. Seedlings were inoculated with two isolates of H. mammatum, representing high and low aggressiveness, through a stem wound. Beginning 4 days after inoculation, host responses were examined on 312 seedlings per family for a period of 5 weeks on 3‐ and 9‐month‐old seedlings. Significant differences in host responses were observed between the two isolates, with the more aggressive isolate allowing less callus formation, causing more tissue necrosis and producing longer cankers than the less aggressive isolate on both aspen families. Between‐family difference was much greater than within‐family difference for tissue necrosis, callus formation and canker length for both seedling ages. When the 3‐month‐old seedlings were challenged with H. mammatum, the PR family showed greater tissue necrosis, longer cankers, and less callus formation than the PS family. However, when the more lignifìed 9‐month‐old seedlings of the same families were inoculated, the PR seedlings had much less tissue necrosis, shorter cankers, more callus formation and less seedling mortality than the PS family. The results indicate that artificial inoculation of seedlings in a greenhouse can differentiate two aspen families at the seedling stage, but their correlation to field performance is highly dependent upon the seedling age. Host responses of older seedlings may be a better indicator of field performance.
Seedborne fungi in Norway spruce: testing methods and pathogen control by seed dressing
Authors: Motta E. , Annesi T. , Balmas V. 
Published: June 2007

SummaryItalian seed lots of Norway spruce (Picea abies) were analysed by agar plate tests and seedling symptom test. Fusarium spp., Phoma spp. and Sirococcus conigenus were present on seeds, together with some saprophytes, but only S. conigenus and Fusarium spp. caused mortality in the seedling symptom test. Pathogenicity tests with 19 isolates belonging to nine Fusarium species showed that only some were pathogenic. Fusarium dlamini, reported for the first time in Italy, caused only some pre‐emergence mortality. Pathogenicity tests with S. conigenus indicated that the isolate was pathogenic and that temperature can greatly affect the results. Seed dressing with prochloraz was suitable for controlling the seedborne pathogens. Agar plate tests are effective and practicable methods for the detection of spruce seed mycoflora.
Quantitative assessment of fungal colonization in Norway spruce after green pruning
Authors: Metzler B. 
Published: June 2007

SummaryIn July and in October of 1978, 1979, 1980 five Picea abies stands in Baden‐Württemberg, Germany were green‐pruned up to a tree height level of c. 10 m. In 1993–94, 30 pruned trees and five control trees from each stand were harvested for investigation. The quality of pruning proved to be excellent because only few branch collar, bark injuries or too long branch stubs were detected. Based on isolations from more than 6000 wood specimens of c. 20 mm3 obtained from 175 trees, specific infection rates are given for different tree compartments. Wood decay fungi as well as important blue stain fungi were only rarely present. Tolerable discolourations were limited to the stub containing core of a few trees. Wood formed after pruning showed neither more fungal infections nor other related disadvantages compared with the respective increment from unpruned control trees. Nectria fuckeliana, proved to be the most abundant fungus in pruned trees especially in the branch stubs. Respective infection rates in and close to dry branches were compared. Bacteria could be found in the pruned branch stubs, however, they did not penetrate into the heartwood or sapwood of the stems. Both summer and autumn pruning involve only very low risk of wood deterioration. However, summer pruning shows some advantages with respect to lower infection rates by N. fuckeliana.
Responses of Cupressus and Chamaecyparis callus tissues to inoculations with Seiridium cardinale
Authors: Spanos K. A. , Woodward S. 
Published: June 2007

SummaryInoculations of callus generated from micropropagated shoots of Cupressus sempervirens, Cupressus macrocarpa, Cupressus torulosa and Chamaecyparis lawsoniana showed that callus of species resistant or relatively resistant to Seiridium cardinale supported significantly less surface growth of the pathogen than callus of susceptible species. In dual cultures of Cupressus sempervirens or Cupressus torulosa callus with S. cardinale, inhibition of fungal growth towards the callus was correlated with known field resistance of these host species. Lignification, accumulation of polyphenolics and possible suberization of cell walls were detected in inoculated callus. This response was also correlated with known field resistance of the tested host species.