bluuebunny/crossref_metadata_2025 huggingface dataset:
Black canker and leaf spot of Salix in New Zealand caused by Glomerella miyabeana (Colletotrichum gloeosporioides)
Authors: Spiers A. G. , Hopcroft D. H.
Published: June 2007

Two new diseases have been observed attacking willows in New Zealand. In the first instance black stem cankers formed on S. matsudana × S. alba × S. alba cultivars, eventually killing them. In the second instance foliage of S. gooddingii and S. amygdaloides was attacked and premature defoliation occurred. Morphological studies and host inoculations established that Glomerella miyabeana (Colletotrichum gloeosporioides anamorph) was the causal agent of both diseases. Foliage of cultivars exhibiting stem cankering was not attacked nor were stems of cultivars with foliar lesions. Electron microscope studies showed that conidia of Colletotrichum gloeosporioides formed phialidically within acervuli and comdial dimensions varied significantly with host.
Geographical distribution and ecology of the Armillaria species in western Europe
Authors: Guillaumin J.‐J. , Mohammed Caroline , Anselmi N. , Courtecuisse R. , Gregory S. C. , Holdenrieder O. , Intini M. , Lung Brigitte , Marxmüller Helga , Morrison D. , Rishbeth J. , Termorshuizen A. J. , Tirró A. , van Dam Barbara
Published: June 2007

Over 4000 records of the six EuropeanArmillariaspecies were compiled to give distribution maps and host lists for each species. Differences in geographical and altitudinal distribution, pathogenicity, dissemination and ecological role are discussed.
The effect of industrial air pollution on chlorophyll fluorescence and pigment contents of Scots pine (Pinus sylvestris) needles
Authors: Saarinen T. , Liski J.
Published: June 2007

Chlorophyll fluorescence induction of Scots pine needles was measured under field conditions in the vicinity of an oil refinery, and in the greenhouse after a recovery period of 20 h. Pigment content of needles was also determined. Sulphur dioxide is discussed as a potential factor affecting the light reactions of photosynthesis.
Effects of pruning young Scots pines on host vigour and susceptibility to Leptographium wingfieldii and Ophiostoma minus, two blue‐stain fungi associated with Tomicus piniperda
Authors: Långström B. , Solheim H. , Hellqvist C. , Gref R.
Published: June 2007

In a field experiment in central Sweden, the vigour of 25‐yr‐old Scots pines was manipulated by pruning, prior to inoculation with Leptographium wingfieldii and Ophiostoma minus, two blue‐stain fungi associated with Tomicus piniperda. Our main purpose was to correlate fungus invasion and host defence reactions with host vigour. Both fungi invaded the inner bark and the sapwood at the points of inoculation. L. wingfieldii caused larger lesions in the bark, but O. minus tended to grow faster in the sapwood. The flow of primary resin was related to tree vigour, whereas carbohydrates present in needles and stem phloem were not. Lesion formation and the content or composition of resin acids in lesions did not differ between fungi or pruning treatments.
Early interactions of Heterobasidion annosum and Stereum sanguinolentum with non‐decay fungi and bacteria following inoculation into stems of Picea abies
Authors: Hallaksela Anna‐Maija
Published: June 2007

Different combinations of two decay fungi (Heterobasidion annosum, Stereum sanguinolentum), two non‐decay fungi (Nectria fuckeliana, Ascocoryne cylichnium), a yeast‐like fungus and two bacteria (Bacillus pumilus, Enterobacter agglomerans) all of spruce origin, were inoculated into stems of 16 healthy‐looking Picea abies. Growth and survival of the microbes were followed over the subsequent five years. The rapid upward vertical spread of the decay fungi during the first two years was followed by a later regression and loss of these decay fungi by the fifth year.

The stems were effectively colonized by the bacteria, A. cylichnium and/or Neobulgaria premnophila which then persisted over the whole experimental period. The endophytic fungi, N. premnophila and A. cylichnium, were abundant in the stems of the experimental trees before inoculation.
Concentration of CO2 under snow cover and the winter activity of the snow blight fungus Phacidium infestans
Authors: Vuorinen M. , Kurkela T.
Published: June 2007

The winter activity of soil organisms and of the fungus Phacidium infestans inoculated on excised Scots pine shoots was monitored by measuring CO2 concentrations under the snow cover. Other variables measured, relating to respiration, were the temperature under the shoot heaps and the depth of snow cover. The concentrations were highest when the temperature under the snow remained at a relatively high level during the whole winter which also favoured respiration from P. infestans. When the soil was covered with a thin layer of snow, the conditions did not favor a high respiration rate until the snow melt period.
Evidence of resistance to hemlock dwarf mistletoe (Arceuthobium tsugense) in western hemlock (Tsuga heterophylla) clones
Authors: Smith R. B. , Wass E. F. , Meagher M. D.
Published: June 2007

Records from western hemlock (Tsuga heterophylla) trees naturally exposed to infection by hemlock dwarf mistletoe (Arceuthobium tsugense) and controlled inoculations of grafted branch scions from a selection of these trees indicated a repeatability of the levels of resistance to the disease in the clonal material. Evidence pointed to a resistance mechanism operating within, rather than outside, the host branch.
Effect of auxin, cytokinin, and glutamine on mycelial growth of Phaeolus schweinitzii
Authors: HřIB J. , Vooková B. , Fľak P.
Published: June 2007

The effect of naphthaleneacetic acid (NAA), benzylaminopurine (BAP), L‐glutamine (L‐gln), and combinations of these substances on mycelial growth of Phaeolus schweinitzii was studied in vitro.

NAA (1 mg × 1−1), L‐gln (500 mg × 1−1) and a combination of NAA with L‐gln inhibited the growth of fungal mycelium. BAP (1 mg × 1−1) enhanced the inhibitory effect of NAA while in combination with L‐gln it reduced the inhibitory effect of L‐gln.
Influence of water stress on susceptibility of red oak (Quercus rubra) to Phytophthora cinnamomi
Authors: Marçais B. , Dupuis F. , Desprez‐Loustau M.L.
Published: June 2007

Influence of water status of oak trees (Quercus rubra) on the development of Phytophthora cinnamomi lesions was studied. On agar media or excised inner bark, growth of P. cinnumomi was reduced by low water potentials. In contrast, on voung saplings or mature oak trees the development of P. cinnamomi lesions was not affected during a period of water stress. But after the end of the water stress treatment, susceptibility of the young saplings to P. cinnamoni increased.
Ganoderma root‐rot in an Acacia arboretum
Authors: HARSH N. S. K. , SONI K. K. , TIWARI C. K.
Published: June 2007

Ganoderma lucidum
caused root rot in an Acacia arboretum. Stumps colonized by the fungus were the source of infection. Among 18 species. Acacia albida, A. aneura, A. decurrens, A. murrayana and A. victoriae were the most susceptible to the disease whereas A. greggii and A. verek showed resistance.
Histopathology of Pinus elliottii var. elliottii needles infected by Ploioderma hedgcockii
Authors: Jewell F. F.
Published: June 2007

The ascomycete Ploioderma hedgcockii is unique in speculating; on living, as well as on dead needle tissues. The fungus was examined in green and dead needles of Pinus elliottii var. elliottii using light microscopy. Teleomorph and anamorph stromata originated from sub‐hypodermal host tissue. In green needles, the hypnae where restricted to tissues outside the endodermis. The mesophyll cells adjacent to stromata showed abnormalities; the mesophyll distal to the stromata showed no symptoms despite heavy colonization by intercellular hyphae. In dead needles, all tissues, with the exception of vascular tissues, where colonized by inter‐ and intracellular hyphae.
Decline symptoms on roots of Quercus robur
Authors: Blaschke H.
Published: June 2007

A comparative study by light and scanning‐electron microscopy of fine and coarse roots from healthy and declining oaks demonstrated a progressive deterioration of fine roots and mycorrhizal systems on mature trees in decline. Histopathological events such as infection of cortical and vascular root tissues by parasitic fungal hyphae leading to the impairment of woody roots are described. Distinct disease symptoms such as necrotic lesions on small diameter roots and callussing wounds on coarse roots are documented, supporting the hypothesis that Phytophthora spp. are involved in oak decline.
Aerial photographs reveal chestnut‐blight foci
Authors: Bisseggerand M. , Heiniger U.
Published: June 2007

Infrared photographs of a chestnut (Castanea sativa) stand of northern Switzerland which was severely infested by Cryphonectria parasitica were evaluated to document disease progress. Two original infection foci were identified in the photographs. These foci were strongly correlated with the distribution of the two vegetative compatibility groups of C. parasitica strains found there, suggesting that two independent introductions of the fungus occurred within this stand.
Une méthode d'inoculation pour l'évaluation précoce du comportement du Mélèze vis a vis du Lachnellula willkommii
Authors: Sylvestre G. , Pâques L. , Delatour C.
Published: June 2007

An inoculation method for early assessment of Larch resistance to Lachnellula willkommii. Efficiency of inoculation with mycelium and ascospores was compared on 4–13‐year‐old Larix decidua. Only mycelium induced high infection rates. Mycelial inoculum was contained in colonized sorghum‐straw pieces and was introduced in 1 mm diameter holes drilled through the bark in April/May. The main infection was detectable as early as 18 months after inoculation and infection rate increased only until the 28th month after inoculation. The susceptibility of the branches did not depend on their age, their position in the trees, the age of inoculated shoots or the management of the trees. Susceptibility was even for the 1–2‐yr‐old parts of the stems and branches but the oldest parts of the stems were less susceptible. The inoculation method was effective for detecting differences in susceptibility among trees. One seedling from the Alps, and clone 3001–00035, which is the mother of resistant hybrids, were the least susceptible.
Association of the pine‐top weevil with Endocronartium pini on Scots pine
Authors: Pappinen A. , von Weissenberg K.
Published: June 2007

It has been suggested that the pine‐top weevil (Pissodes piniphilus) could be a vector of resin‐top disease caused by Endocronartium pini. The association of this weevil with trees and stands infected with the fungus was studied. The number of pupal chambers around cankers and in trapping bolts indicated an association. Mobility studies with flight traps and sticky rings, however, gave inconclusive results as to the possible role of the weevil as vector of the disease.
Stem cankers on Swedish biomass willows caused by Cryptodiaporthe salicella and other fungi
Authors: ÅStröm B. , Ramstedt M.
Published: June 2007

Field surveys and inoculation experiments were carried out in order to determine the most important stem‐canker fungi on willows planted for energy production. The pathogenicity of different fungal isolates and factors influencing infection were studied in the field and in greenhouse experiments, where canker extension was measured after inoculation either on dormant plants or on plants undergoing active growth.
Vascular modifications in Platanus acerifolia seedlings inoculated with Ceratocystis fimbriata f. sp. platani
Authors: Clerivet A. , El Modafar C.
Published: June 2007

Vascular modification of plane tree seedlings inoculated withCeratocystis fimbriataf. sp.platani, the canker stain disease agent, were characterized using histochemical and scanning electron microscopy methods.
Effect of Melampsora rust on the growth and development of Salix burjatica‘Korso’in Northern Ireland
Authors: Dawson W. M. , McCracken A. R.
Published: June 2007

The impact of Melampsora rust on the growth of Salix burjatica‘Korso’was assessed. Comparisons were made between untreated plants and those where the disease had been partially controlled using fungicides. Fungicides delayed the onset of the disease and its effects on growth. Leaf loss was reduced whilst shoot growth and dry matter yields increased. The effect of secondary organisms was also reduced resulting in lower levels of shoot death in the following season.
Butt‐rot of Scots pine in Thetford Forest caused by Heterobasidion annosum: a local phenomenon
Authors: Greig B. J. W.
Published: June 2007

Heterobasidion annosum was found to be the main cause of decay in 50–60‐year‐old Scots pine in Thetford Forest in East England. On some sites, up to 15% of the trees could be suffering from H. annosum rot, with decay occasionally extending 2 m or more up the stem. Prior to this study, Scots pine had been considered as resistant to H. annosum butt‐rot in Britain, except in overmature trees.
Haustorial morphology of Cronartium conigenum in naturally infected cones of three Pinus species from Guatemala1
Authors: Rayachhetry M. B. , Webb R. S. , Kimbrough J. W. , Miller T.
Published: June 2007

Haustorial morphology of the cone‐rust pathogen, C. conigenum, was investigated among naturally infected female strobili of three Guatemalan pines, P. maximinoi, P. pseudostrobus, and P. oocarpa. Among the three pine species, haustorial shapes and sizes were more variable in P. maximinoi and P. oocarpa than in P. pseudostrobus. The haustorial shapes and sizes were more variable in parenchyma cells of the cortex, xylem, and pith than in the cells in the phloem, xylem rays, and tracheids. The haustoria were also present in larger numbers in the parenchyma cells of the cortex, xylem, and pith than in phloem parenchyma cells and tracheids. In living cells, the tips of some haustoria were appressed to the host nuclei.
Identification of European Armillaria species by restriction‐fragment‐length polymorphisms of ribosomal DNA
Authors: Schulze S. , Bahnweg G. , Tesche M. , Sandermann H.
Published: June 2007

Identification of European Armillaria species using ribosomal DNA (rDNA) restriction‐fragment‐length polymorphisms (RFLPs) was studied. A total of 44 Armillaria isolates representing five European biological species were examined. Whole‐cell DNAs were digested with one or two (double digest) restriction endonucleases and probed with a cloned plasmid carrying one complete rDNA repeat copy of Saccharomyces carlsbergensis. Applying the restriction endonuclease Bgl II in combination with either Eco RI, Bam Hl or Hin dIII, it was possible to detect rDNA RFLPs allowing differentiation between all five European Armillaria species investigated in the study. The most conclusive results were obtained in the rDNA/Ava II RFLP pattern. All biological species showed unique Ava II banding patterns. Generally speaking, the interspecific similarities were around 42% and lower, indicating a distinct species separation.

The analysis of rDNA RFLP patterns by a restriction‐enzyme‐rDNA‐probe combination (for instance, Ava II or Bgl II/Hin dIII; probe pMY 60) is a practical means of identifying European Armillaria species for further taxonomic, phylogenetic and host‐pathogen interaction studies.
Response of maple sapwood to injury and infection
Authors: Shortle W. C. , Smith K. T. , Dudzik K. R. , Parker S.
Published: June 2007

In sapwood challenge experiments in Acer rubrum, columns of discolouration initiated by wounding and inoculation with pioneer fungi (Cephalosporium sp., Phialophora sp.) were similar in size to untreated wounds. Inoculation with decay fungi (Pleurotus ostreatus, Trametes versicolor) produced larger columns of wound‐initiated discolouration. The removal of bark around a bore wound caused a significantly larger column to form compared to the sum of the columns inititiated by separate wounds. Stage‐I discoloured wood, not associated with obviously rotted wood, had concentrations of mobile cations and soluble phenols similar to sapwood. Stage‐II discoloured wood, spatially associated with rotted wood, was frequently bounded by a chemically distinct boundary layer and the discoloured wood contained significantly greater concentrations of mobile cations and soluble phenols than stage‐I discoloured wood.
Short‐term variation in ascospore release by Phacidium infestans on the needles of Pinus sylvestris
Authors: Kurkela T. T.
Published: June 2007

Ascospore release by Phacidium infestans was monitored with volumetric‐recording spore traps in Finland. Detached branches of Scots pine infected naturally during the previous winter were used as a spore source. Spores were trapped during two autumns with simultaneous recording of weather factors. Free water from rain or thawing of rime or snow on the needles was required to initiate the spore release. After the onset of rain, the number of spores reached its maximum in 4–6 h, while heavy rain decreased the liberation of spores into the air. The number of spores had a higher correlation both with relative humidity and with precipitation delayed 3–7 h than with current precipitation. Temperature did not directly affect the ascospore release. Only a few spores were trapped at temperatures below 0°C. The effect of wind on the release of spores was mainly negative, and indirect through decreasing humidity. No diurnal periodicity was detected in the spore release.
Wood‐rotting fungi on Nothofagus pumilio in Patagonia, Argentina
Authors: Cwielong P. P. , Rajchenberg M.
Published: June 2007

The presence of basidiomes of wood‐decay fungi on living lenga (Nothofagus pumilio) was investigated in seven forest stands in Patagonia (Argentinia). The following species accounted for 85% of the rots: Postia pelliculosa, Phellinus andinopatagonicus, Piptoporus portentosus, Aurantioporus albidus, and Serpula himantoides. Ph. andinopatagonicus and A. albidus cause characteristic white rots, while the other tree species cause unspecific, cubical brown rots. S. himantoides was associated with cords among the decayed wood fragments. One stand was investigated in detail. The volume of decayed timber on this plot was 75%. Postia pelliculosa and Ph. andinopatagonicus probably infected the trees through the roots as well as through the canopy, and accounted for 70% of the wood‐rots. Piptoporus portentosus probably infected only through the canopy, while A. albidus and S. himantoides did so through the roots. Only 12% of the trees showed no decay. From trees with decay, 36% were attacked by one fungal species, 35% by two species.
Veränderungen des Monoterpenspektrums in verletzten Fichtenwurzeln und ihre potentielle Bedeutung für die Resistenz gegenüberHeterobasidion annosum
Authors: Rieger S.
Published: June 2007

Changes in composition of the monoterpene fraction in damaged roots of Norway spruce and the potential significance for resistance against Heterobasidion annosum

The composition of monoterpenes in undamaged and wounded roots of Norway spruce (Picea abics) was investigated, α‐ and β‐Pinene comprised at least 85%. of the total content in undamaged roots. The variation of the monoterpene fraction within roots and between roots of an individual tree was relatively small. Variations of the monoterpene fraction between trees were found. There were no qualitative differences between stem and roots except for sabinene, which was found in small amounts in the stem. Large quantitative differences between stem and roots were found in α‐ and β‐pinene content. In almost all trees, damaging the sapwood of roots caused an increase in the α‐pinene content combined with a decrease in the relative content of β‐pinenc and limonenc/β‐phellandrene. Two different types of traumatic reaction in heartwood could be distinguished. The possible significance of the traumatic reaction in the roots of spruce with respect to their resistance to H. annosum is discussed.
Long‐term damage on Scots pine caused by Gremmeniella abientina near a nickel smelter in the Kola peninsula
Authors: KAitera J. , Isaenva L. , Jalkanem R.
Published: June 2007

The history of damage caused by Gremmeniella abietina on 10 Scots‐pine trees (Pinus sylvestris) was studied near a nickel smelter in Tsuna, Russia. The most severely damaged area was located alongside a river. According to the results of branch analysis, the first sign of G. abietina infection occurred in 1937. During the following 4 decades, annual signs were few and they occurred at random. Most of the damage had appeared during the 1980s and the early 1990s. In terms of cankers, the peak occurred in the mid‐1980s, and in terms of scars and leader changes, the peak was in the late 1980s and early 1990s. Branch mortality and secondary Tomicus spp. attacks increased in the late 1980s and were at their highest level in the early 1990s. The high number of mature G. abietina pycnidia on shoots formed in the years 1989–1991 suggests that the epidemic will continue in the near future.
Modelling rubber‐tree root diseases, simulations of various inoculum rates and methods of control
Authors: Nandris D. , Chadoeuf J. , Pierrat J. C. , Joannes H. , Geiger J. P. , Nicole M.
Published: June 2007

Two root‐rot fungi,Rigidoporus lignosusandPhellinus noxiusare the causal agents of severe damage in Ivory Coast rubber tree (Hevea brasiliensis) plantations. Mathematical investigations were made using data from a previous 6 year long epidemiological survey. Modelling of spatial spread of the pathogens and mortality of the infected trees, lead to simulations of the quantitative evolution vs. time of root diseases. The theoretical kinetics obtained revealed intra‐ and interspecific variability among the studied stands with respect to the damage caused. Using this model, different phytosanitary scenarios were simulated in relation to the density of the initial inoculum, the control measures, the specificity of the fungicide, the efficiency of the treatment, and the optimal time for application. Their influence on root‐disease dynamics was quantified. The characteristics of the model, its applicability in plantations and its use in predicting disease or stand development are discussed.
RAPD variation in Gremmeniella abietina attacking Pinus sylvestris and Pinus contorta in northern Sweden
Authors: Hansson P. , Wang X‐R. , Szmidt A. E. , Karlman M.
Published: June 2007

Genomic DNA from 81 isolates of Gremmeniella abietina collected from eleven plantations each of Pinus sylvestris and Pinus contorta in northern Sweden was studied using RAPD markers. The DNA variation between and within populations and the race and type distribution of G. abietina populations, causing symptoms similar to those of the North American race, were studied. The degree of genetic similarity was greater among G. abietina isolates from the same geographical areas than among isolates from different geographical areas, regardless of whether they were isolated from P. sylvestris or P. contorta. RAPD variation was greatest in the central parts of northern Sweden, suggesting that sexual reproduction has been somewhat more important there than further north or south. Only the RAPD fragments characteristic of the EU race of G. abietina were found in the material tested. The RAPD pattern described as characteristic of the northern type within the EU race was identified in 62% of the isolates. Divergence from the expected profile was due to differences in occurrence of fragments OPA12‐1400 and 12‐1500. This indicates that this part of the RAPD profile cannot be treated as diagnostic for the northern type. A conclusion of practical importance is that there is a considerable risk of G. abietina spreading from infected P. contorta plantations to adjacent areas with indigenous P. sylvestris regeneration, and vice versa, owing to the indicated lack of host‐specificity of the pathogen. It is possible, however, that host‐specific strains exist, but do not differ in their RAPD profiles.
Detection of genetic variation between Ophiostoma ulmi and the NAN and EAN races of O. novo‐ulmi in Switzerland using RAPD markers
Authors: Hoegger P. J. , Binz T. , Heiniger U.
Published: June 2007

The structure of the Ophiostoma ulmi and Ophiostoma novo‐ulmi population of Switzerland was analysed. 79 Swiss isolates were compared to reference strains from various countries. A dendrogram from RAPD profiles was produced. O. ulmi and O. novo‐ulmi were clearly separated into two major clusters. O. novo‐ulmi was further divided into the EAN and NAN races. This classification is consistent with subgroups by taxonomic parameters (growth rate, culture aspect, fertility barriers). The variation detected within the EAN and NAN races indicates a post‐epidemic situation in Switzerland. A clonal population is present only in a restricted area in mid‐eastern Switzerland, indicating a still active disease front.
Stem lesions on Betula pendula seedlings in Finnish forest nurseries and the pathogenicity of Phytophthora cactorum
Authors: Lilja A. , Rikala R. , Hietala A. , Heinonen R.
Published: June 2007

Phytophthora cactorum was isolated from necrotic stem lesions on 20–80% of diseased Betula pendula seedlings sampled from three nurseries in Finland. Fusarium avenaceum and Godronia sp. were also found in all nurseries. Inoculation of P. cactorum on B. pendula seedlings caused necrotic lesions and the spread of these lesions around the stem was detrimental. Neither the timing of N application nor two different PK‐levels applied to the seedlings the previous year significantly affected the size of lesions caused by P. cactorum.
Identification of multiple Endocronartium pini infections in Scots pine with PCR
Authors: Pappinen A. , Kasanen R. , Weissenberg K.
Published: June 2007

Rust susceptibility in pine is known to be heritable, which means that the disease risk remains in a stand. Also, if the climate becomes warmer and more humid, as expected, the risk of rust disease will increase. The main trait of interest and importance in an obligate parasite, such as Endocronartium pini is the variation in pathogenicity. However, to test the variation in pathogenicity the fungal population in a stand must be described. In this study it was possible to partly describe an E. pini population at stand level with RAPD‐PCR and identify multiple infections in a single infected tree (Pinus sylvestris). Some RAPD phenotypes detected were more common than others. This suggests some mechanism by which some phenotypes spread more effectively. The E. pini population structures in the two Pinus sylvestris stands studied were also significantly different, even when the stands shared some equally common RAPD phenotypes. The most common phenotype was not always present in a tree with multiple infections, as would be expected. Thus, some specific resistance interaction may occur. Further research is needed to prove this assumption.
The spreading of the S type of Heterobasidion annosum from Norway spruce stumps to the subsequent tree stand
Authors: Piri Tuula
Published: June 2007

The occurrence of Heterobasidion annosum in stumps and growing trees was investigated on 15 forest sites in southern Finland where the previous tree stand had been Norway spruce (Picea abies) infected by H. annosum, and the present stand was either Scots pine (Pinus sylvestris), lodgepole pine (Pinus contorta), Siberian larch (Larix siberica), silver birch (Betula pendula) or Norway spruce 8–53 years old. Out of 712 spruce stumps investigated of the previous tree stand, 26.3% were infected by the S group and 0.3% by the P group of H. annosum. The fungus was alive and the fruit bodies were active even in stumps cut 46 years ago. In the subsequent stand, the proportion of trees with root rot increased in spruce stands and decreased in stands of other tree species. On average, one S type genet spreading from an old spruce stump had infected 3.0 trees in the following spruce stand, 0.5 trees in lodgepole pine, 0.3 trees in Siberian larch, 0.05 trees in Scots pine and 0.03 trees in silver birch stand. Although silver birch generally was highly resistant to the S type of H. annosum, infected trees were found on one site that was planted with birch of a very northern provenance.
Pathogenitätstests mit Bursaphelenchus mucronatus an Kiefern und Fichtensämlingen in Deutschland
Authors: Braasch Von H.
Published: June 2007

Pathogenicity tests with Bursaphelenchus mucronatus on pine and spruce seedlings in Germany

Inoculation tests on Pinus sylvestris seedlings with a German, a Siberian and a French isolate of Bursaphelenchus mucronatus and on Picea abies seedlings using only the German isolate have clearly shown, under German field conditions, that the nematode can cause wilt symptoms on the apex of about 60% of the inoculated P. sylvestris plants. The nematodes in all these tests mostly remained near the inoculation site. However, further spread of the nematodes and wilt symptoms occured when a climate chamber, at 25°C, was used or when the French isolate was used outdoors. At 25°C, 10% of the inoculated plants with at least 1000 nematodes per seedling died. Seedlings' apices wilted if more than 50 nematodes per trunk were present, whereas smaller numbers of nematodes could cause partial wilting. Nevertheless, a few pine seedlings did tolerate high nematode‐population densities, up to 966 per plant. No further progress of wilt of plants with symptoms was observed the following year. Inoculations of P. abies with a German isolate resulted in population development near the site of inoculation. Spruces largely tolerated nematode infestations without any development of wilt symptoms.
Weevil feeding on Scots pine affects germination of Endocronartium pini
Authors: Pappinen A. , Weissenberg K.
Published: June 2007

The aim of this study was to assess the effect and importance of the feeding of the pine top weevil (Pissodes piniphilus) on the germination of Endocronartium pini (syn. Peridermium pini) in Scots pine (Pinus sylvestris), and thus to establish the possibility of the E. pini infection via insect woundings. Germination tests were therefore carried out on current and previous year needle and phloem extracts. Elucidation of the importance of pathogen infection for the insect's feeding preference was also required; for this purpose feeding preference tests were carried out with healthy and infected pine branches using the pine top weevil as a test insect. Weevil feeding increased the germination of E. pini aeciospores on pine extracts. Germination on previous year annual‐shoot extracts was lower than that on current year annual‐shoot extracts. The advance of the growing season increased this trend, but weevil feeding increased germination on extracts from older annual shoots to the levels found on extracts from current annual shoots. Spores germinated equally well on needle extracts and on phloem extracts. The weevils ate more often on infected branches than on healthy branches. E. pini infections may occur via woundings on branches and weevil feeding may facilitate this.
Sexual behaviour of Armillaria heimii and A. mellea isolates from Africa
Authors: Abomo‐Ndongo S. , Mohammed C. , Guillaumin J.‐J.
Published: June 2007

Thirty isolates ofArmillaria heimiifrom western, eastern and southern Africa were cultured for fruit body production in the laboratory. Most isolates fruited easily. Investigation of single‐spore progenies revealed that all the isolates do not have the same sexual behaviour: some are heterothallic and unifactorial while others are homothallic. Two African isolates belonging to the speciesArmillaria melleaalso appeared homothallic. Unifactorial heterothallism has not previously been described inArmillaria, species. Homothallic behaviour has been reported only in a rare European speciesArmillaria ectypaand in the Japanese subspeciesArmillaria melleassp.nipponica.
Variability of virulence of Nectria galligena towards northern hardwoods
Authors: Plante F. , Bernier L.
Published: June 2007

The variability of virulence within a Québec population of the fungal pathogen Nectria galligena was studied under greenhouse conditions. Preliminary, small‐scale inoculation of Betula alleghaniensis saplings confirmed that wounds have to be present for successful infection by N. galligena and showed that saplings held at 10°C exhibited a broader range in necrotic zone length than saplings held at 24 °C for 6 weeks. Results from the inoculation of B. alleghaniensis saplings with eight full‐sib progeny sets of four siblings each of N. galligena showed a wide range of virulence in this pathogen. The observed variability was probably of genetic origin since, in seven cases out of eight, one of the four siblings of a given family was significantly different from at least one other sibling of the same family. Inoculation of B. alleghaniensis saplings with a population of 43 isolates originating from different host species and geographical locations further confirmed the variability of virulence within N. galligena but failed to indicate a relationship between virulence and host or geographic provenance. Inoculation of six additional deciduous tree species with a subset of nine isolates showed the polyphagous character of the pathogen, as lesions of comparable length were generally observed on five of the species tested. None of the nine isolates tested induced any necrosis on Fraxinus americana whereas Quercus macrocarpa tended to be slightly more resistant than the four remaining true species.
Pathogenicity of A and B morphotypes of Sphaeropsis sapinea confirmed on American larch (tamarack) and European larch
Authors: Stanosz G. R. , Smith D. R. , Guthmiller M. A.
Published: June 2007

Fungi identified as Sphaeropsis sapinea (or synonyms) have been reported from Larix. Lack of pathogenicity tests, confusion about the identity of isolates mentioned in previous literature, and existence of distinct populations (A and B morphotypes) of the pathogen indicated the need to evaluate the ability of S. sapinea to cause disease of larch. Elongating snoot tips of Larix decidua, Larix laricina, and known hosts of the pathogen, Pinus banksiana and Pinus resinosa, were inoculated with water‐agar plugs colonized with an A or a B isolate, or sterile plugs (controls). Each of five replications included five seedlings for each treatment‐species combination. After 6 weeks, no symptoms had developed on control seedlings, but two‐way analyses of variance revealed significant effects of isolate morpnotype and host on both incidence and severity of disease (values of p ≤ 0.01). The A isolate killed almost all shoot tips, but the B isolate killed from no P. resinosa shoots to 56% of L. laricina shoots. The average length of shoot killed by the A isolate was also greater than that killed by the B isolate. Response to the B isolate again varied among species, with greater average lengths of shoot killed on the larches (compared with the pines). Both A and B morphotypes of 5. sapinea should be considered among the fungi encountered on L. decidua and L. laricina.
Differences in the rust resistance of greenhouse and outdoor‐grown white birch species, Betula spp.
Authors: Poteri M. , Rousi M. , Gao Zhi‐He
Published: June 2007

The 2‐year‐old seedlings of five different white birch species (Betula platyphylla, Betula papyrifera, Betula pubescens, Betula pendula (two types) and Betula resinifera x Betula pendula) grown both in a greenhouse and outdoors, were inoculated in a leaf disc assay with two different birch rust (Mel‐ampsoridium betulinum) isolates from B. pendula and B. pubescens. The resistance of these birch species varied significantly. Resistance to the B. pubescens rust isolate was not related to the resistance of the B. pendula rust isolate. The behaviour of a birch genotype grown in the greenhouse did not correspond to the behaviour of the same genotype grown outdoors.

The outdoor growth environment greatly increased the contents of soluble proteins, rubisco, chloro‐phyll and nitrogen in the leaves of diploid birch species (B. platyphylla, B. pendula and B. resinifera x B. pendula). For tetraploid and pentaploid species (B. pubescens and B. papyrifera, respectively) there was no such clear difference in the leaf physiological status between the seedlings grown outdoors and in the greenhouse. The C:N ratio was higher for the greenhouse‐grown seedlings in all the birch species, but the difference was significant only with the diploid species. The incidence of rust in the birch species did not correlate with any of the leaf physiological parameters studied. The adaptability of birch genotypes to the environment in relation to their resistance to birch leaf rust is discussed.
Vegetative compatibility and pathogenicity of Diplodia mutila isolates on oak
Authors: Ragazzi A. , Moricca S. , Dellavalle I.
Published: June 2007

Forty isolates of Diplodia mutila, a dieback agent on oaks were characterized by their capacity to produce heterokaryons, by their vegetative compatibility, and by their pathogenicity tests on Quercus cerris. The forty isolates were collected from Quercus cerris, Quercus frainetto, Quercus ilex, Quercus pubescens, Quercus robur and Quercus suber in different regions in Italy. Three nit mutants (nitt, nit and nitM) were identified with different nitrogen sources: sodium nitrite, sodium nitrate, uric acid, ammonium tartrate and hypoxanthine. On the two nutrient media employed, a potato dextrose agar (PDA) medium with chlorate (PDC), and a minimal agar medium with chlorate (MMC), isolates obtained from Q. cerris yielded the greatest number of mutants: 254 on PDC (out of a total of 583) and 190 on MMC (out of a total of 440). Nine vegetative compatibility groups (VCGs) were identified. There was a strong association between these VCGs and host species. All isolates tested except one from Q. cerris were pathogenic.
Isozyme and RAPD polymorphisms in Heterobasidion annosum in Italy
Authors: Goggioli V. , Capretti P. , Hamelin R. C. , Vendramin G. G.
Published: June 2007

Isozyme and random amplified polymorphic DNA (RAPD) polymorphisms were used to study variability in a group of 41 isolates from the Italian population of Heterobasidion annosum. The isolates belonged to the intersterility groups P and S, and particularly to the group that is most widely distributed in Italy, group F. Isozyme analysis was effective in identifying the three intersterility groups and revealed a high degree of genetic divergence within the P group isolates; the mannose phosphate isomerase (MPI‐2) locus was diagnostic in the attribution of isolates to the more correlated F and S groups. RAPDs were detected following amplification by the polymerase chain reaction (PCR). 74 RAPD fragments, obtained through amplifications with eight primers, were scored. Isolates from the 3 intersterility groups were clearly divergent based on analysis of RAPD markers. However, a similarity index calculated for the isolates within the F population indicated a high uniformity of the isolates collected throughout the Italian peninsula.
Genetic variation in three Ceratocystis species with outcrossing, selfing and asexual reproductive strategies
Authors: Harrington T. C. , Steimel J. , Kile G.
Published: June 2007

Nuclear and mitochondrial markers were used to examine variation within three closely related species of tree pathogens with differing reproductive strategies. Ceratocystis eucalypti is obligately outcrossing; Ceratocystis virescens is capable of selfing due to unidirectional mating type switching; and Chalara australis is an asexual species, comprised of a single mating type. When the nuclear DNA fingerprinting markers (CAT)5 and (CAG)5 were used as probes against Pst I‐restricted DNA, isolates of C. eucalypti were found to be highly polymorphic, and Ch. australis showed very little polymorphism. The selfing C. virescens showed an intermediate level of variation in the nuclear fingerprint markers, and much of the variation appeared to be due to differences between two forms of the species, one pathogenic to Acer and Liriodendron and another less‐pathogenic form on Fagus and other hardwoods. Mitochondrial DNA (mtDNA) polymorphisms were examined by digesting total DNA with Hae III or CfoI, and C. eucalypti showed somewhat more variation in mtDNA than did C. virescens. The only polymorphism seen in the mtDNA of Ch. australis was associated with a plasmid. Selfing in C. virescens may be common and could explain an intermediate level of diversity when compared to the obligately outcrossing C. eucalypti and the asexual Ch. australis.
Rust scorings in a plantation of Salix viminalis clones during ten consecutive years
Authors: ÅHman I.
Published: June 2007

Among pests and diseases occurring in coppiced willow plantations established to produce biofuel, Melampsora rust is the most widespread and severe. In the present study, the variation in rust attacks in a set of Salix viminalis clones was investigated. The aim was to look for trends possibly arising from changes in rust genotype composition, to get some idea about the risks of rust overcoming resistance bred into new willow varieties. Rust levels on 92 S. viminalis clones belonging to 18 different families were scored once each year during 1987–96 in a plantation in southern Sweden. Rust scorings in 1993 deviated most from the average scoring pattern of the clones. Furthermore there was a successive change, such that the longer the time interval between scorings the lower was the correlation between rust scores. Willow families were identified that deviated from the others over time. Various explanations for inconsistency in rust scores over time are discussed.
Effects of host plant hybridization on resistance to willow leaf rust caused by Melampsora sp.
Authors: Roche B. M. , Fritz R. S.
Published: June 2007

Patterns of resistance to willow leaf rust caused by Melampsora sp. were measured on Salix eriocephala, Salix sericea, and their interspecific hybrids in natural field populations in 1991–94 and on potted plants in common garden experiments in 1994 and 1995. Testing was carried out to establish if the resistance of hybrids was intermediate between pure parental species (additive), equal to one of the parents (dominant), lower than both parents (susceptible), higher than both parents (resistant), or not different than either parent (null hypothesis). Support was generally found for hybrid susceptibility in the field and common garden experiments, with the null hypothesis of no difference having some support. The results from the common garden study suggest that the susceptibility of hybrids seen in the field is due to genetic differences. Hybridization between these species of willows results in increased susceptibility to this pathogen. The variation among years in the relative susceptibility of hybrid and parental willows may be due to environmental effects on the willows or to shifts in the abundance of Melampsora races.
Life‐cycles and ecology of willow beetles on Salix viminalis in England
Authors: Kendall D. A. , Wiltshire C. W.
Published: June 2007

The life‐cycles of three willow beetle pests, Phratora (= Phyllodecta) vulgatissima, Phratora (=Phyllodeeta) vitellinae and Galerucella lineola (Coleoptera, Chrysomelidae), were investigated during 1994–95 in a plantation of short‐rotation coppiced willows (Salix viminalis cv. Bowles Hybrid) at Long Ashton, Bristol, UK. The P. vulgatissima had one generation during the year. Overwintered adults emerged from hibernation in April and after a short feeding period, copulation and egg‐laying occurred. Larval stages were found from May–July. The new generation of adult beetles appeared in July–August and fed for a while before hibernating. Hibernating adults were found in hedgerows around the site and in the plantation on willow stools and ground vegetation. Dispersal of adult beetles between feeding and overwintering sites appeared to be fairly localized. Hence, crop management strategies that reduce the potential for overwintering in and around plantations may help to minimize spring re‐invasion and damage. Although based on limited observations, the biology of P. vitellinae and G. lineola appeared similar to that of P. vulgatissima. However, there is evidence in the literature that both these species, unlike the latter, can have a partial second generation in some years. The potential effect of insect herbivory on the growth and biomass yield of S. viminalis cv. Bowles Hybrid was investigated experimentally by artificial hand‐defoliation of pot‐grown plants. Yield losses were strongly correlated with the amount and time of defoliation. Results indicated that even slight or moderate damage by insect herbivores could have a significant impact on the biomass productivity of coppiced willows.
Rapid living crown reduction caused by Gremmeniella abietina affects foliar nutrient concentrations of Scots pine
Authors: Nuorteva H. , Kurkela T. , Lehto A.
Published: June 2007

The foliar chemistry of diseased and healthy trees was studied one growing season after severe reduction in living crown caused by Gremmeniella abietina in four young Scots pine (Pinus sylvestris) stands. Sample trees were chosen pairwise on the basis of the living crown length: a diseased tree with about 50% live crown reduction and a healthy tree in each pair. Fifteen elements were determined in the youngest healthy needles on the lateral top shoots of each sample tree. Diseased trees had higher foliar boron, manganese and sodium concentrations and lower magnesium, iron, zinc, copper, potassium, nitrogen and sulphur concentrations compared to the healthy trees. Foliar calcium, aluminium, phosphorus, carbon and hydrogen concentrations did not differ between the diseased and healthy trees, except for P and A1 in two of the stands when the stands were analysed separately. Significant correlations between the needle element concentrations and crown ratio (length of the living crown/tree height) were found especially for B (increasing B with decreasing crown ratio) and for Mg, Fe and Zn (decreasing concentrations with decreasing crown ratio). The effect of G. abietina‐induced living crown reduction on tree nutrient status and the role of these mineral nutrients in the susceptibility are discussed.
Genetic variation of the resin top fungus in Finland as determined by random amplified microsatellites (RAMS)
Authors: Hantula J. , Niemi E. Maarit , Kaitera J. , Jalkanen R. , Kurkela T.
Published: June 2007

The analysis of random amplified microsatellite (RAMS) markers among aecia of the causal agent of the resin top disease (Peridermium pini) on Scots pine (Pinus sylvestris) suggested that the genetic variation between the populations of this rust fungus is low in Finland. The method used allowed the identification of heterozygotic aecia in two loci, where the degree of heterozygosity was, however, low. The RAMS patterns of the Finnish aeciospores, other aeciospores from Thetford, UK and Cronartium flaccidum from Italy were highly similar suggesting that the autoecious and heteroecious forms of these rust fungi would be genetically closely related.
Snow‐packing as a potential harmful factor on Picea abies, Pinus sylvestris and Betula pubescens at high altitude in northern Finland
Authors: Jalkanen R. , Konocpka B.
Published: June 2007

Snow‐packing, a combination of ice, hoarfrost and snow on trees, and the subsequent tree damage by snow, were estimated on Norway spruce (Picea abies), Scots pine (Pinus sylvestris), and pubescent birch (Betula pubescens) in the winter of 1993‐94 in southern Lapland, northern Finland, near the local alpine timberline around 400 m a.s.l. Snow‐packing on each fully sized tree increased from a few hundred kilograms at 150–250 m a.s.l. to a maximum of 3290 kg at 300–350 m a.s.l. At 300 m a.s.l., snow‐packing per metre of stem increased from 30 to 50 kg on trees < 5 m in height up to 180–200 kg on 20‐m trees. There was 300 000‐480 000 kg/ha of snow accumulated on tree crowns. No stem breakage by snow‐packing occurred at or below 250 m a.s.l., whereas at 290–350 m a.s.l., 0‐46%, 39‐100%, and 0–33% of the spruce, pine and birch trees, respectively, had broken tops. Birch appeared to be the most resistant and pine the most susceptible to snow breakage.