| 1. |
- Arhipova, Natalija, et al.
(författare)
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Bark stripping of Pinus contorta caused by moose and deer: wounding patterns, discoloration of wood, and associated fungi
- 2015
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Ingår i: Canadian Journal of Forest Research. - : Canadian Science Publishing. - 0045-5067 .- 1208-6037. ; 45, s. 1434-1438
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess the extent of bark stripping wounds, subsequent wood discoloration, and associated fungi in 30-year-old Pinus contorta Douglas ex Loudon stems damaged by large game. In total, 90 trees were evaluated, and 170 bark stripping wounds of different ages (1-20 years) were measured. From each wound, wood samples were collected for subsequent fungal isolation. Thirty trees were cut to evaluate the length of the discoloration column. Of 170 injuries, 16 of them represented closed scars and 154 of them represented open wounds that exposed 4-4355 cm(2) of sapwood. The wound length had a strong impact on the length of decay (r = 0.716); however, the spread of discoloration beyond the wound margin was limited (0-20 cm). The most commonly isolated fungus was Sarea difformis (Fr.) Fr. and, among the Basidiomycetes, Peniophora pini (Schleich.) Boidin. The results suggest that when planning to grow P. contorta in areas of Europe, the population size of large game animals needs to be considered, in view of potential risk of bark stripping damage.
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| 2. |
- Arhipova, Natalija, et al.
(författare)
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Decay, yield loss and associated fungi in stands of grey alder (Alnus incana) in Latvia
- 2011
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Ingår i: Forestry. - : Oxford University Press (OUP). - 0015-752X .- 1464-3626. ; 84, s. 337-348
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Tidskriftsartikel (refereegranskat)abstract
- The significance of grey alder (Alnus incana (L.) Moench.) as a fast-growing renewable source for energy and wood production has increased during the last decade. The aims of this study were to: (1) estimate the incidence of stem decay in A. incana stands, (2) measure the extent of decay within individual stems, (3) estimate the impact of decay on wood yield and (4) identify decay-causing fungi. In total, 4344 recently cut A. incana stumps were examined on 46 clearfelled areas in different regions of Latvia. The incidence of decayed stumps varied from 1 to 54 per cent. In addition, 175 living trees were cut to measure the extent of decay within the stems. The length of decay columns varied from 0.4 to 20.6 m and that of spongy rot from 0 to 18.0 m. In total, 354 isolates representing 70 fungal taxa and 1129 isolates representing 131 fungal taxa were obtained from decayed stumps and living stems, respectively. The present study shows that decay and associated fungi are important factors determining biomass production and quality in A. incana stands and that their impact should be seriously considered when cultivating this tree species in the future.
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| 3. |
- Arhipova, Natalija, et al.
(författare)
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Growth rates of Heterobasidion annosum s.s. and H.parviporum in functional sapwood of Pinus sylvestris and Picea abies
- 2015
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 45, s. 437-439
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Tidskriftsartikel (refereegranskat)abstract
- Growth rates of H.annosum s.s. and H.parviporum were investigated in the functional sapwood of young Pinus sylvestris and Picea abies plants as an indicator of the relative susceptibilities of the hosts to these pathogens. The stems of 520 five-year-old P.abies and 321 four-year-old P.sylvestris plants were inoculated and the extent of infection determined 16weeks later. H.annosum s.s.grew further than H.parviporum in P.sylvestris sapwood, while in P.abies, no differences between the two Heterobasidion spp. were found. Both H.annosum s.s. and H.parviporum spread faster in the sapwood of P.abies than in P.sylvestris. There was high within-host species variation in growth rates for both P.sylvestris and P.abies suggesting it may be possible to identify tree genotypes with lower susceptibility.
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| 4. |
- Arhipova, Natalija, et al.
(författare)
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Heart-rot and associated fungi in Alnus glutinosa stands in Latvia
- 2012
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 327-336
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Tidskriftsartikel (refereegranskat)abstract
- The interest in Alnus glutinosa (L.) Gaertn. as plantation species has increased during last years, but its prospects should be evaluated from the perspective of forest health. The aims of the present study were to: (1) estimate the incidence of stem decay in Latvian A. glutinosa stands, (2) measure the extent of decay within individual stems and on a stand level and (3) identify decay-causing fungi. In four A. glutinosa stands, 450 trees were randomly sampled with an increment borer and the presence/absence of decay was recorded. As a result, 112 sound-looking and 338 decayed trees were detected, and a corresponding number of wood samples were collected for fungal isolations. A total of 34 stems with decay symptoms were cut to measure the extent of internal decay. The incidence of decayed stems in studied stands was 75.1% on average. The length of the decay column was 7.7 +/- 5.4 m on average, and that of spongy rot was 4.2 +/- 4.5 m on average, implying that yield losses for fully stocked 80-years-old A. glutinosa stand would comprise 49.2% of the total stand volume, and the losses from spongy rot alone -30.5%. In total, 1134 isolates representing 68 fungal taxa were obtained. The most common decay-causing fungi were Inonotus radiatus and Armillaria sp.
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| 5. |
- Bakys, Remigijus, et al.
(författare)
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Investigations concerning the role of Chalara fraxinea in declining Fraxinus excelsior
- 2009
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Ingår i: Plant Pathology. - : Wiley. - 0032-0862 .- 1365-3059. ; 58, s. 284-292
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Tidskriftsartikel (refereegranskat)abstract
- A study was carried out to clarify the role of the fungus Chalara fraxinea in decline of Fraxinus excelsior, which is observed on a large scale in central and northern Europe with high incidence of tree mortality. The aims of this work were: (i) to check for the presence of C. fraxinea in various tissues of declining F. excelsior by agar culture isolations and by direct analysis of plant tissues using molecular techniques (DNA extraction, ITS-PCR, cloning, ITS sequencing and T-RFLP); (ii) to study fungal communities inhabiting tissues with symptoms; and (iii) to test the pathogenicity of C. fraxinea to F. excelsior. Chalara fraxinea was isolated from 93% of stem cankers, 91% of necrotic leaf stalks, 27-28% of bark wounds and 30% of visually healthy leaf stalks. Molecular analyses of necrotic leaves, leaf stalks and bark revealed the presence of 25 different fungal taxa, 14 of which were detected in all three types of tissue sample. Chalara fraxinea was the second most common species (61% of samples), and only Cryptococcus foliicola occurred more often (70%). All eight of the tested C. fraxinea isolates induced necroses in bark and cambium on each of 86 inoculated trees, and all controls remained healthy. Average length of necroses caused by different C. fraxinea strains varied from 4.2 to 8.9 cm, but the differences were statistically insignificant. Instead, differences in resistance of individual trees to C. fraxinea were observed.
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| 6. |
- Bakys, Remigijus, et al.
(författare)
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Occurrence and pathogenicity of fungi in necrotic and non-symptomatic shoots of declining common ash (Fraxinus excelsior) in Sweden
- 2009
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Ingår i: European Journal of Forest Research. - : Springer Science and Business Media LLC. - 1612-4669 .- 1612-4677. ; 128, s. 51-60
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Tidskriftsartikel (refereegranskat)abstract
- Currently, massive dieback of Fraxinus excelsior is observed in countries of eastern, northern and central Europe, and the reasons for it are unclear. The aims of the present work were (a) to study fungal communities in declining F. excelsior crowns; (b) to clarify role of fungi in the decline. Shoots from symptomatic crowns were collected in four localities in central Sweden, and distributed into the following categories: (a) visually healthy; (b) initial necroses; (c) advanced necroses; (c) dead tops. The most frequently isolated fungi were Gibberella avenacea, Alternaria alternata, Epicoccum nigrum, Botryosphaeria stevensii, Valsa sp., Lewia sp., Aureobasidium pullulans and Phomopsis sp., and these taxa were consistently found in shoots of all four symptomatic categories. Forty-eight taxa of other fungi were isolated, and fungal diversity was not exhausted by the sampling effort. The same taxa of fungi were dominant in F. excelsior shoots of different symptomatic categories, and moderate to high similarity of fungal communities was observed in shoots despite the symptoms. Forty-four isolates from 24 fungal taxa were used for artificial inoculations of 277 1-year-old F. excelsior seedlings in bare root nursery. After 2 years, only four fungi caused symptomatic necroses of bark and cambium: A. alternata, E. nigrum, Chalara fraxinea and Phomopsis sp. The most pathogenic was C. fraxinea, inducing symptoms on 50% of inoculated trees, while three other fungi caused necroses on 3-17% of inoculated trees. Infection biology of C. fraxinea and environmental factors determining susceptibility of F. excelsior to decline deserve future investigations.
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| 7. |
- Bakys, Remigijus, et al.
(författare)
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Patterns and Severity of Crown Dieback in Young Even-Aged Stands of European Ash (Fraxinus excelsior L.) in Relation to Stand Density, Bud Flushing Phenotype, and Season
- 2013
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Ingår i: Plant Protection Science. - 1212-2580. ; 49, s. 120-126
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Tidskriftsartikel (refereegranskat)abstract
- The extent and temporal pattern of crown damage (attributed to Hymenoscyphus pseudoalbidus) in even-aged stands of Fraxinus excelsior in relation to bud flushing phenotype, stand density, and season was investigated. Data were collected in 2007 in four statistically designed thinning experiments located in 12-15-years old plantations of ash in Denmark. The study included 21 plots of four contrasting, residual stand densities: (1) 1700-5500 trees/ha (unthinned control plots), (2) 1500 trees/ha, (3) 500 trees/ha, and (4) 100-150 trees/ha. Assessments included estimation of flushing phenotype in May, followed by evaluation of severity of crown damage (percentage of crown killed) in June and September. Simultaneously, for each tree, the presence or absence of crown wilt and dead tops were recorded. The seasonal pattern of disease severity (average crown damage) was similar in all stands, and disregarding stand density the extent of tree crown damage increased significantly towards the end of the growing season (P < 0.005). Disease severity was the worst in unthinned plots, but otherwise unrelated to stand density. Late-flushing trees were most severely affected (P < 0.001). The observed patterns of disease severity are probably associated with ecological features of the pathogen that still remain largely unknown.
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| 8. |
- Bakys, Remigijus, et al.
(författare)
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Root rot, associated fungi and their impact on health condition of declining Fraxinus excelsior stands in Lithuania
- 2011
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 26, s. 128-135
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Tidskriftsartikel (refereegranskat)abstract
- Dieback of Fraxinus excelsior L. associated with Chalara fraxinea is observed in Europe, and in some areas dying trees exhibit symptoms of root and butt rot. Our study was conducted (1) to estimate the impact of the rot on F. excelsior dieback severity; (2) to identify fungi colonizing roots of dieback-affected trees; (3) to check their pathogenicity to F. excelsior; and (4) to estimate sprouting incidence and sprout health condition in relation to presence/absence of rot. The extent of rot was measured in 33 trees with different dieback intensity, 150 fungal isolations were attempted from roots of 50 trees, 26 fungi were tested for pathogenicity to 286 saplings, and sprouting was evaluated for 328 stumps on three clear-felled sites. Root rot was mainly caused by Armillaria cepistipes, and the extent of rot correlated positively with dieback severity although it played a secondary role in tree decline. Four years after tree felling, root rot had a negative impact on sprouting frequency, yet rot did not enter sprouts from stumps, and when experimentally inoculated, fungi associated with root rot in mature ash had no visible impact on tree vigor, showing that after formation of sprouts, rot does not affect the subsequent phytosanitary condition. Sprouts on investigated sites exhibited Chalara dieback symptoms on leaves and bark irrespectively of presence/absence of rot, indicating that vigorous natural regeneration of F. excelsior in dieback-affected areas could not be expected.
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| 9. |
- Bengtsson, Stina, et al.
(författare)
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Detection of Chalara fraxinea from tissue of Fraxinus excelsior using species-specific ITS primers
- 2010
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 40, s. 111-115
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Tidskriftsartikel (refereegranskat)abstract
- P>Chalara fraxinea (teleomorph: Hymenoscyphus albidus) is known as a serious pathogen of Fraxinus excelsior, causing massive dieback of trees in Europe. The fungus is able to cause latent infections, and has been previously detected as an endophyte in asymptomatic tissues. Chalara fraxinea is a slow grower in culture, and is thus likely to be overgrown by faster growing fungi whenever pure culture isolations are being attempted. This study reports species-specific ITS primers allowing fast and reliable detection of the pathogen directly from infected tissues of F. excelsior.
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| 10. |
- Bengtsson, Stina, et al.
(författare)
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Population structure of Hymenoscyphus pseudoalbidus and its genetic relationship to Hymenoscyphus albidus
- 2012
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Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048 .- 1878-0083. ; 5, s. 147-153
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Tidskriftsartikel (refereegranskat)abstract
- The ascomycete fungus Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea) is responsible for ash dieback currently expanding over large parts of Europe. Our objective was to investigate the genetic structure of H. pseudoalbidus and to examine its relationship to the species H. albidus, known as a saprotroph. The study comprised 181 isolates of H. pseudoalbidus collected within the diseased area, 17 H. albidus isolates from six apothecia, collected outside the diseased area in Norway, and nine apothecia of H. pseudoalbidus collected in Sweden. By analysis of microsatellite markers developed for this study, combined with AP-PCR using the M13 primer, we demonstrated sexual heterothally in H. pseudoalbidus, detected high gene flow and low geographic structure of the H. pseudoalbidus population and found indications of a founder effect. Also, substantial genetic differences were detected between the two species of fungi; only four of seven microsatellite markers developed for H. pseudoalbidus were amplified for H. albidus, and no alleles were shared among the species. Furthermore, AP-PCR banding patterns were distinctly different for the two species. We conclude that even though the two fungi have a similar habitat and are morphologically virtually identical, they do not share a recent common ancestor. (C) 2011 Elsevier Ltd and The British Mycological Society. All rights reserved.
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