| 1. |
- Jönsson Belyazid, Ulrika, et al.
(författare)
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First records of soilborne Phytophthora species in Swedish oak forests
- 2003
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 33:3, s. 175-179
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-two oak stands in southern Sweden, 27 with predominantly declining trees and five with a higher proportion of healthy trees were investigated regarding the presence of soilborne Phytophthora species. Phytophthora quercina , an oak-specific fine root pathogen, was isolated from rhizosphere soil samples in 10 of the 27 declining stands. Additionally, P. cactorum and P. cambivora were recovered from one stand each. No Phytophthora species were isolated from the healthy oak stands. The soil conditions at the sites from which Phytophthora spp. were recovered ranged from mesic sediments to moraines, with clayey to silty textures and with soil pH (BaCl2) between 3.5 and 5.0. The results show that P. quercina is geographically widespread in oak stands in southern Sweden and indicate that this pathogen may be one of the factors involved in oak decline in Northern Europe as has already been shown for western, Central and parts of southern Europe.
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| 2. |
- Ahonen-Jonnarth, Ulla, et al.
(författare)
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Effects of nickel and copper on growth and mycorrhiza of Scots pine seedlings inoculated with Gremmeniella abietina
- 2004
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 34:6, s. 337-348
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine (Pinus sylvestris) seedlings were planted in soil originating from two localities with different background levels of nickel and copper. In addition, some of the seedlings were exposed to additional nickel (20.5 mg Ni/l of soil) or copper (63.5 mg Cu/l of soil), or a combination of both Ni and Cu, via soil without direct shoot exposure during their second growing period. The seedlings were either irrigated with spring water (pH 6) or got only natural rain during the whole field experiment. All seedlings were inoculated with conidia of a shoot-pathogen Gremmeniella abietina during their third growing season, and harvested the following spring. Lengths of shoots of different year-classes were used as growth estimates. In roots, the proportion of fungal (assumedly mycorrhizal) biomass was estimated by measuring ergosterol concentration. Guajacol peroxidase activity was measured. Short roots were classified into two groups according to their condition and the composition of the mycorrhizal community was expressed as a proportion of morphotypes in the roots. The seedlings exposed to additional Ni had higher shoot growth than the seedlings in the other treatments. The mean Ni concentration in the roots of seedlings exposed to additional Ni was 79 p.p.m. and in other seedlings 16 p.p.m. Additional Ni also decreased the frequency of clearly senescent short roots and the proportion of the mycorrhizal morphotype with the thinnest mantle. These results indicate that the Ni exposure levels used in this experiment had some positive effects on the seedlings. The relative fungal biomass was about 6% lower (p = 0.0981) in the fine roots of seedlings treated with additional Cu. The mean Cu concentration in the roots of seedlings exposed to additional Cu was 256 p.p.m. and in other seedlings 29 p.p.m. Peroxidase activity, which was used as a general stress indicator in this study, was not affected by any of the treatments. The shoot growth and the relative biomass of fungi in the fine roots were positively correlated in all seedlings, and this correlation was stronger in seedlings exposed to additional Ni that were not irrigated compared with seedlings not exposed to additional Ni that were irrigated. The frequency of asymptomatic infections of G. abietina was positively correlated with the proportion of senescent short roots in the irrigated seedlings but not in not-irrigated seedlings. The general condition of seedlings may be an important factor for infection by G. abietina when moisture is high enough for the fungi to infect seedlings by conidia.
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| 3. |
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| 4. |
- 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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| 5. |
- Cleary, Michelle
(författare)
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Pathogenicity and virulence of Armillaria sinapina and host response to infection in Douglas-fir, western hemlock and western redcedar in the southern Interior of British Columbia
- 2012
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 42, s. 481-491
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Tidskriftsartikel (refereegranskat)abstract
- The frequency of infection, lesion characteristics and anatomical changes in phloem and cambial tissues caused by Armillaria sinapina were studied on inoculated trees of Douglas-fir, western hemlock and western redcedar and compared with results of A. ostoyae inoculations previously reported on the same host species. Similar percentages of inoculations resulting in infection of roots on the three hosts indicate that A. sinapina and A. ostoyae are equally pathogenic. Armillaria ostoyae was more virulent than A. sinapina as demonstrated by fungal exudates from A. ostoyae inoculum blocks, which appeared to cause lesions on roots; the higher frequency at which lignified impervious tissue (IT) and necrophylactic periderm (NP) developed in bark and following cambial invasion, compartmentalization; the large proportion of roots that showed no visible host response; the large zones of IT formed under continuous stimulation by A. ostoyae advancing in inner bark; and the high frequency of breaching of NP barriers. Spread of A. sinapina mycelium in host species appeared slower than that of A. ostoyae, particularly in Douglas-fir and western hemlock. In western redcedar, A. ostoyae induced stronger host responses than those following invasion by A. sinapina, which included further expansion of the induced rhytidome response, traumatic phloem resin duct formation and higher numbers of polyphenolic parenchyma comprising its barrier zone. Where damage by A. sinapina ensued, it was always associated with high inoculum potential. The ecology of virulent and less virulent species of Armillaria in natural forests is discussed.
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| 6. |
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| 7. |
- Menkis, Audrius
(författare)
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Distribution and genetic diversity of the root-rot pathogen Neonectria macrodidyma in a forest nursery
- 2012
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 42, s. 79-83
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess genetic diversity and spatial distribution of 123 strains of the root-rot pathogen Neonectria macrodidyma isolated from fine living roots of bare-root nursery cultivated Pinus sylvestris. We found that ITS rDNA sequences were 100% identical for all strains. Arbitrary primed PCR fragment analysis showed the presence of two distinct N. macrodidyma types (Type 1 and Type 2), which included respectively 11 and 14 genotypes composed of 129 strains. Results of this study indicate that N. macrodidyma is commonly associated with fine living roots of pine seedlings, is largely disseminated by asexual means of local genotypes and has even distribution in the forest nursery soils. In living roots, N. macrodidyma is likely present as dormant propagules but under favourable conditions, it may develop rapidly and have a significant negative effect on plant health and productivity.
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| 8. |
- Oliva Palau, Jonàs
(författare)
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Epidemiology of Heterobasidion abietinum and Viscum album on silver fir (Abies alba) stands of the Pyrenees
- 2010
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 40, s. 19-32
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Tidskriftsartikel (refereegranskat)abstract
- In the last two decades, stand decline and increased mortality has affected silver fir (Abies alba) forests in the Spanish Pyrenees. Simultaneously severe occurrences of the root rot fungus Heterobasidion annosum s.l. and of the mistletoe Viscum album have been reported. We aimed to improve the understanding of the epidemiology of both pathogens in our region. All H. annosum isolates found on silver fir were typed as H. abietinum. H. abietinum was more frequently observed where cuttings had targeted fir trees rather than other species. H. abietinum fruiting bodies were observed in the most recently cut stumps. V. album was more abundant on more dominant fir trees, and in southern aspect stands. The number of V. album colonies in the stand correlated (R(2) = 0.40) with silver fir mortality. Stands with a high level of V. album infection tended to have a smaller percentage of basal area in species other than silver fir, and they tended to be located on more south-facing slopes. H. abietinum was widespread in silver fir forests of the Pyrenees. Our data suggest that, in the Pyrenees, the observed H. abietinum incidence may represent a combination of both primary and secondary spread of the pathogen. Favouring mixed forests should be tested as a potential control method for V. album. The correlation between silver fir mortality and V. album infection warrants further study, as the observed tree mortality could have occurred due to other factors than V. album, such as drought damage.
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| 9. |
- Ramstedt, Mauritz
(författare)
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Rust severity in bioenergy willow plantations treated with additional nutrients
- 2009
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 39, s. 28-34
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Tidskriftsartikel (refereegranskat)abstract
- A 3-year field study was carried out to determine the effect of wastewater irrigation and previous differences in mineral fertilization on the occurrence of willow leaf rust (Melampsora epitea). The experiment was conducted in two energy forest plantations: one designed for wastewater purification and the other as a mineral fertilization experiment. The severity of leaf rust on different clones and sites with different treatments was assessed by counting the number of uredinia per leaf unit area. Generally, plants irrigated with wastewater consistently had more leaf rust, irrespective of the study years or willow clones. Previous mineral fertilization had mixed effects on different clones 2 years after the last application. Three years after the last fertilizer application, however, no impact of the treatment on rust disease development was detected. In general, the rust levels differed from year to year probably due to climate. In this study, no correlation was detected between shoot age and rust severity, whereas climate and treatments strongly influenced leaf rust levels on some willow clones.
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| 10. |
- Rönnberg, Jonas, et al.
(författare)
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Presence of Heterobasidion infections in Norway spruce stumps after treatment six years earlier with Phlebiopsis gigantea
- 2012
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 42, s. 144-149
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Tidskriftsartikel (refereegranskat)abstract
- Natural colonization by the root and butt rot causing fungi Heterobasidion spp. on Norway spruce (Picea abies) stumps following thinning and treatment with the biological control agent Phlebiopsis gigantea was investigated on three sites in southern Sweden 6 years after treatment. The fully treated stumps and control stumps were excavated and sampled to compare the survival of Heterobasidion spp. in the long term. Six years post-treatment, 47 and 11% of untreated and treated stumps, respectively, had Heterobasidion infection. There was no difference in the relative infected area in discs collected from the butt and the roots for the different treatments. Control efficacy was 83% for treated stumps. After 6 years, there were no apparent differences between the remaining infections in treated compared with those in untreated stumps regarding the number of colonies, their size or relative infection area. Although infections, 3 months after treatment with P. gigantea, were significantly fewer and smaller than in untreated stumps, Heterobasidion inoculum can survive for at least 6 years in the stump and, when it does, constitute a risk for neighbouring trees.
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| 11. |
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| 12. |
- Stenlid, Jan, et al.
(författare)
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Gene flow and inter-sterility between allopatric and sympatric populations of Heterobasidion abietinum and H. parviporum in Europe
- 2011
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 41, s. 243–252-
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Tidskriftsartikel (refereegranskat)abstract
- The tree pathogenic fungi Heterobasidion parviporum and H. abietinum are recently described sibling species that show marked host preference for Picea abies and Abies alba, respectively. H. parviporum shows a higher reproductive character displacement (i.e. higher intersterility) towards H. abietinum in sympatry than in allopatry. We inspected whether this pattern was also present in H. abietinum by studying the inter-sterility and gene flow amongst sympatric central European populations of H. abietinum and H. parviporum, and two isolated allopatric populations, Pyrenean H. abietinum and Scandinavian H. parviporum. Inter- and intra-specific fixation index values were calculated from DNA sequence data of the GST-1 locus and four microsatellite loci. Present allopatric and sympatric populations of H. abietinum were equally inter-sterile towards H. parviporum, not suggestive of relaxed reinforcement. Several hypotheses explaining the observed pattern are presented. Genetic differentiation was observed between H. abietinum in the Pyrenees and in the Alps, suggesting geographical structure of H. abietinum in Europe.
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| 13. |
- Vasaitis, Rimvydas, et al.
(författare)
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Discoloration and associated fungi in stems of silver birch (Betula pendula Roth.) following logging damage
- 2012
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 42, s. 387-392
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Tidskriftsartikel (refereegranskat)abstract
- Study aim was to investigate discoloration and associated fungi in 50- to 70-year-old stems of Betula pendula damaged by logging. Investigated wounds (on 70 stems) were inflicted 418 years previously, and all of them had discoloration with mean radial spread (+/- SD) 2.9 +/- 2.9 cm and longitudinal spread 50.3 +/- 24.0 cm. Both wound area and length had a strong impact on a total length of discoloration (r = 0.665 and r = 0.745, respectively; p < 0.001), but had no influence on its spread beyond wound margins (r = -0.035 and r = -0.079). There was no correlation between the age of an injury and spread of the discoloration neither in vertical (r = -0.110) nor in radial (r = -0.280) direction. Average wound closure rate was 1.2 +/- 0.5 cm year -1. The difference between discoloration length in stems with open and occluded injuries was insignificant (t-test, p = 0.769). The principal fungi isolated from the wounds were ascomycetes (Epicoccum, Cadophora, Neonectria, Alternaria spp.) that were able to cause discoloration of wood with little effect on its mechanical properties and capable only for limited spread inside a stem of a living tree. In conclusion, results of the present study demonstrate that the amount of discoloured wood beyond logging wounds in B.similar to pendula is mainly restricted to the damaged portion of a stem and that the associated loss of wood production remains low during about 10 years since the damage.
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| 14. |
- Wang, Liying, et al.
(författare)
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The effect of Phlebiopsis gigantea and urea stump treatment against spore infection of Heterobasidion spp. on hybrid larch (Larix eurolepis) in southern Sweden
- 2012
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 42, s. 420-428
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy of stump treatment with 40% urea solution and spore suspension of Phlebiopsis gigantea against primary infection by Heterobasidion spp. on hybrid larch (Larix x eurolepis) was tested in two field studies in southern Sweden. In the first study, stumps treated with urea or P. gigantea were sampled by cutting a cross-section disc after 3 months following exposure to natural conditions, and in the second study, stumps treated with only P. gigantea were sampled after 2 months. Spore traps made from hybrid larch, Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) were used to estimate the abundance of ambient spores of Heterobasidion spp. in the second study. Urea significantly reduced infection frequency of Heterobasidion spp. compared to the control. Phlebiopsis gigantea was less effective at reducing infection frequency in the first study than in the second study. Infections were caused by both H. parviporum and H. annosum sensu stricto. The amount of H. annosum infection in proportion to Heterobasidion spp. was significantly lower on the stumps treated with P. gigantea compared to the control; however, the proportion of H. parviporum on the treated stumps was not higher than the control in the first study. Spore traps made of Scots pine had a significantly higher frequency of infection than Norway spruce and hybrid larch. Only the spore traps made of hybrid larch showed significant correlation with the control stumps in terms of relative infected area. Conclusively, it seems prudent to protect hybrid larch stumps from primary infection by Heterobasidion spp., and both urea and P. gigantea can be recommended as stump treatment agents on hybrid larch, even if urea seemed to present more stable results.
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| 15. |
- Arhipova, Natalija, et al.
(författare)
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Armillaria novae-zelandiae and other basidiomycete wood decay fungi in New Zealand Pinus radiata thinning stumps
- 2015
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 45, s. 298-310
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Tidskriftsartikel (refereegranskat)abstract
- Two studies were undertaken in a young New Zealand Pinus radiata stand to find a biological control agent for armillaria root disease caused by Armillaria novae-zelandiae. Fresh thinning stumps were inoculated with saprophytic basidiomycete species as wooden dowel cultures or as homogenized aqueous mycelial suspensions, while all stumps were also inoculated with dowel cultures of A.novae-zelandiae. After a period of between one and twoyears, no differences were found among test fungi in the percentage of Armillaria species isolated from stumps. However, inoculation of Stereum sanguinolentum as homogenate, and of Phlebiopsis gigantea, Sistotrema brinkmannii, Hypholoma acutum and Rigidoporus concrescens as dowel cultures, significantly increased their isolation incidence in comparison with stumps not treated by these species. Phlebiopsisgigantea, Resinicium bicolor and R.concrescens were also isolated with greater frequency nearer to their dowel inoculation points. Results suggest that P.gigantea and S.sanguinolentum should be included in further testing. However, a future trial is likely to be more effective if evaluation is directed towards the portion of the stump below the soil surface, particularly the root system.
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| 16. |
- 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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| 17. |
- Assefa, Addisu, et al.
(författare)
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Characterization of Pyrofomes demidoffii from Ethiopian Afromontane forests
- 2015
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 45, s. 263-273
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Tidskriftsartikel (refereegranskat)abstract
- Pyrofomes demidoffii is a basidiomycetous fungus that causes a white heart rot in living junipers (Juniperus spp.). Morphological characters and genetic variation in species of Pyrofomes were investigated for specimens from Ethiopia, Tanzania, Macedonia, USA and Costa Rica. In addition, the behaviour of isolates from Ethiopia was studied in vitro. The Ethiopian specimens had relatively larger basidiospores than collections from other countries and showed a high sequence similarity in the ITS region of rDNA sequences with most of strains evaluated in this study (95-100%), but only 89-92% with P.demidoffii from the USA. Phylogenetic analysis of ITS-5.8S rDNA sequences resulted in two well-supported (99-100% bootstrap value), separate clades of P.demidoffii. Deeper branches were less well supported (bootstrap<90%), but the two geographically and phylogenetically separated clades within P.demidoffii may still represent sister groups. For Ethiopian strains, the temperature optimum was between 20 and 25 degrees C and the pH optimum was around 5.0. A phylogenetic study with additional genetic markers and with a more representative collection of samples is needed.
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| 18. |
- Axelsson, Karolin, et al.
(författare)
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Chemical defence responses of Norway spruce to two fungal pathogens
- 2020
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Ingår i: Forest Pathology. - : Blackwell Verlag. - 1437-4781 .- 1439-0329. ; 50:6
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Tidskriftsartikel (refereegranskat)abstract
- Constitutive and inducible terpene production is involved in conifer resistance against insects and fungal infestations. To gain knowledge about local defence responses of Norway spruce bark against pathogens and to find potential chemical markers for resistance breeding, we inoculated the stem of 8-year-old Norway spruce (Picea abies) clonal trees with bothEndoconidiophora polonica(Ep, a common fungal pathogen associated with the spruce bark beetleIps typographus) andHeterobasidion parviporum(Hp, a severe pathogen causing root and stem rot disease). Three weeks after inoculation, the fungal-inoculated and intact bark from each tree was sampled. The terpenes in tree bark were extracted with hexane and characterized by gas chromatography-mass spectrometry (GC-MS). The two fungi induced varied terpene responses in the four spruce clones used. Three of the clones showed a 2.3-fold to 5.7-fold stronger terpene response to Hp relative to Ep inoculation, while one clone responded similarly to inoculation with the two fungal pathogens. The amount of the diterpenes thunbergol and geranyllinalool varied between the clones. The level of thunbergol was higher in both intact and fungal-inoculated bark from the less susceptible clones compared with the more susceptible clones. Geranyllinalool was present in higher amounts in the susceptible clones and is thus a possible marker for susceptibility. Our observations show that Norway spruce employs a similar chemical mechanism against the two fungal pathogens. Based on the present and earlier published data, we suggest that certain Norway spruce genotypes have a strong defence reaction against these two pathogens. The diterpenes thunbergol and geranyllinalool might be useful markers of susceptibility in tree-breeding programmes and should be the focus of further detailed investigations.
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| 19. |
- Axelsson, Karolin, et al.
(författare)
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Clone specific chemical defense responses in Norway spruce to infestations by two pathogenic fungi
- 2016
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Ingår i: Forest Pathology. - : Wiley-Blackwell. - 1437-4781 .- 1439-0329.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Heterobasidion parviporum (Hp) were investigated using four clones of Norway spruce (Picea abies) with different susceptibility to Heterobasidion sp. Eight year old trees were inoculated with Ep and Hp to minimize the variation due to environment. After three weeks the bark tissue at the upper border of the inoculation hole were extracted with hexane and analyzed by GC-MS. Both treatment and clonal differences were found based on induced mono-, sesqui- and diterpenes. In addition, the Hp produced toxin, fomanoxin, was identified in lowest amount in the most Hp susceptible clone. The clonal trees seem to use different defense strategies towards the two fungi. One of the clones was able to induce strong chemical defense against both fungi, one clone induced chemical defense only against Ep and the most susceptible clone exhibited the least capacity to produce an effective defense against Ep and Hp. Two diterpenes were found to be distinctly different between clones with different susceptibilities, which can be used as chemical indication of Norway spruce resistance against fungi.
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| 20. |
- Boberg, Johanna
(författare)
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Dothistroma needle blight, weather and possible climatic triggers for the disease's recent emergence
- 2016
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 46, s. 443-452
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Forskningsöversikt (refereegranskat)abstract
- Dothistroma needle blight (DNB), caused by the two fungi Dothistroma septosporum and D. pini, is a major disease of pines with a worldwide distribution. Increases in the incidence and severity of disease in areas where the disease has long been established and notable range expansions have both recently been observed. The aim of this review was to assess the relationship between DNB, weather factors and climate to better understand possible underlying causes of this recent intensification in disease. A substantial body of literature shows that the life cycles of the fungi are closely related to weather factors such as precipitation and temperature. Given the rapid response of DNB to favourable weather conditions, it seems plausible that changes in disease behaviour could be due to changes in climate. The recurrent El Nino-Southern oscillation (ENSO) phenomenon influences patterns of temperature and precipitation in many regions of the world, often resulting in warmer and wetter conditions than normal. We found that since the 1950s, four of the past five strong El Nino events appear to have coincided with reports of increased DNB activity on an intercontinental scale. The lack of long-term standardized data records limits our ability to fully interpret this relationship, but the projected future climatic conditions in the Northern Hemisphere appear to be increasingly favourable for the disease. Still, other areas of the world may become less favourable, and further research is required to be able to accurately predict DNB outbreaks and their impact on pine forests in the future.
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| 21. |
- Capador-Barreto, Hernán Dario, et al.
(författare)
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Development of microsatellite markers for Thekopsora areolata, the causal agent of cherry spruce rust
- 2018
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 48
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Tidskriftsartikel (refereegranskat)abstract
- Cherry spruce rust is a fungal disease of Norway spruce cones caused by Thekopsora areolata and responsible for significant losses in seed production in Sweden and Finland. Here, we report the first set of nine microsatellites, which will allow an effective genetic fingerprinting of T.areolata. The markers were isolated using the FIASCO method and were characterized using DNA from 49 single aecia sampled from spruce cones in three different seed orchards in Sweden. Eight of the nine markers were shown to be polymorphic among the aecia. The markers were unlinked and are therefore suitable for future population genetic studies.
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| 22. |
- Cleary, Michelle
(författare)
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First report of Lecanosticta acicola on non-native Pinus mugo in southern Sweden
- 2019
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 49
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Tidskriftsartikel (refereegranskat)abstract
- In 2017, severe symptoms of brown spot needle blight, similar to those caused by Lecanosticta acicola, were observed on needles of non-native Pinus mugo var. Hesse planted in an arboretum in southern Sweden. Microscopic characterization and molecular diagnostics of isolates obtained from diseased needles confirmed the identity of L. acicola. This is the first report of the quarantine pathogen L. acicola in Sweden. Subsequent surveys are urgently needed to assess the presence and extent of the L. acicola invasion in Scots pine (Pinus sylvestris) stands in Sweden and other Scandinavian countries.
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| 23. |
- Cleary, Michelle, et al.
(författare)
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Natural infection of Fraxinus excelsior seeds by Chalara fraxinea
- 2013
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 43, s. 83-85
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of Chalara fraxinea, the fungus responsible for dieback of European ash (Fraxinus excelsior), was investigated in the current and previous seed years collected from symptomatic trees in Latvia and Sweden using molecular techniques (DNA extraction, ITS-PCR, Sanger sequencing). Molecular analysis of seeds revealed the presence of 30 different fungal taxa. Chalara fraxinea was detected in 8.3% of seeds tested from the current year originating from Latvia. The presence of C.fraxinea in seeds of F.excelsior is of great concern to phytosanitary protection authorities in countries outside the current zone of infestation.
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| 24. |
- Cleary, Michelle, et al.
(författare)
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Oomycetes in rhizosphere soil of ornamental plants from retail nurseries in Southern Sweden
- 2021
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Ingår i: Forest Pathology. - : John Wiley & Sons. - 1437-4781 .- 1439-0329. ; 51:2
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Tidskriftsartikel (refereegranskat)abstract
- Trade of herbaceous and woody ornamental plants is recognized as a principal pathway for the introduction of alien plant pathogens, such as soil-borne Phytophthora and Pythium species (oomycetes). The rhizosphere soil of container-grown plants obtained from 13 nurseries and garden centres in southern Sweden were sampled and the presence of Phytophthora and Pythium species determined using traditional baiting and isolation. DNA sequencing of isolates revealed five Phytophthora taxa including P. cinnamomi, P. citricola s.l., P. plurivora, P. undulata and a non-identified Phytophthora sp., as well as Phytopythium cf. citrinum and several species of Pythium. Phytophthora cinnamomi was detected on two different ornamental plants at the same nursery and is a first record of P. cinnamomi in Sweden. The survey revealed that a diversity of potentially pathogenic oomycetes is associated with ornamental plants available for sale in Sweden and emphasizes the need to recognize potential risks if these organisms get introduced in nature.
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| 25. |
- Cleary, Michelle, et al.
(författare)
-
Susceptibility of common tree species in Sweden to Phytophthora cactorum, P. cambivora and P. plurivora
- 2017
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 47
-
Tidskriftsartikel (refereegranskat)abstract
- In Sweden, invasive Phytophthora pathogens have been recognized as a growing threat to urban and production forests, calling for an urgent update of regeneration strategies for infested areas. Stem inoculation tests were performed to test the relative susceptibility of common conifer and broadleaved tree species Pinus sylvestris, Picea abies, Larix x eurolepis, Betula pendula, Quercus robur, Fagus sylvatica, Populus trichocarpa and Tilia cordata to the root pathogens Phytophthora cactorum, P. cambivora and P. plurivora commonly isolated from Swedish soils. Results indicate that all the species tested were susceptible and formed lesions following stem inoculation with all three Phytophthora species, but to varying degrees. Of particular interest are the high levels of susceptibility in P. trichocarpa to all three Phytophthora species compared to other tested tree species.
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| 26. |
- Cleary, Michelle
(författare)
-
Symptom development and mortality rates caused by Armillaria ostoyae in juvenile mixed conifer stands in British Columbia's southern interior region
- 2021
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 51
-
Tidskriftsartikel (refereegranskat)abstract
- Plots were established in 20 juvenile mixed conifer stands in the Interior Cedar Hemlock biogeoclimatic zone of British Columbia's southern interior region in western Canada to assess mortality and host response to infection in the form of basal lesions caused by Armillaria ostoyae. Western redcedar showed significantly lower mortality and a higher proportion of callused lesions at the root collar than Douglas-fir and western hemlock. Mortality decreased with increasing tree diameter for all species; however, the rate of decrease was markedly greater for western redcedar than Douglas-fir or western hemlock. Results from logistic regression analysis showed that the probability of Douglas-fir being killed is 14.6 times greater than western redcedar in these juvenile stands. Because western redcedar displayed significant resistance to A. ostoyae at both the root and stand level, this species represents an excellent choice as a significant stand component with more susceptible conifers. Should susceptible conifers succumb to Armillaria root disease, western redcedar will likely fill in the stand.
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| 27. |
- Davydenko, Kateryna, et al.
(författare)
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Fraxinus excelsior seed is not a probable introduction pathway for Hymenoscyphus fraxineus
- 2018
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 48
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the transmission of Hymenoscyphus fraxineus from infested seed to germinating seedlings of common ash (Fraxinus excelsior) in order to determine the potential risk associated with intra- and intercontinental movement of seed. Neither fungal isolations from necrotic or healthy embryos nor PCR testing with H.fraxineus-specific primers detected the pathogen. Similarly, H.fraxineus was not detected in axenically grown seedlings generated from infested seed lots. The results help clear up prior confusion of the pathogen being seed-borne. Any remaining surface contamination by pathogen spores could be washed off seeds as a quarantine measure.
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| 28. |
- Davydenko, Kateryna, et al.
(författare)
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Fungi in foliage and shoots of Fraxinus excelsior in eastern Ukraine: a first report on Hymenoscyphus pseudoalbidus
- 2013
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 43, s. 462-467
-
Tidskriftsartikel (refereegranskat)abstract
- In eastern Ukraine, the first symptoms of dieback on common ash (Fraxinus excelsior) were observed in 2010, as sparse flushing of leaves, bark necrosis and wood discoloration of shoots. The aim of this study was to assess possible causal agents of the damage by studying fungal communities in both symptomatic and healthy-looking shoots, and leaf petioles. Field sampling was carried out in 2010 in Kharkiv and Sumy regions in eastern Ukraine and included 68 segments of symptomatic shoots, 68 segments of healthy-looking shoots and 240 segments of petioles. DNA isolation from individual segments and direct sequencing of fungal ITS rRNA resulted in 430 fungal sequences representing 29 distinct taxa. Results showed that Hymenoscyphus pseudoalbidus - the primary causal agent of ash dieback in Europe - was present at low proportion (5.6%) in symptomatic shoots. Other more frequently detected fungi were Epicoccum nigrum, Venturia fraxini, Colletotrichum truncatum, Aureobasidium pullulans, Alternaria alternata, Alternaria sp. and Lophiostoma corticola. In conclusion, the study reports on the first incidence of ash decline in the Ukraine and other possible causal agents of damage which may help to evaluate and forecast the future situation with F.excelsior stands in the region.
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| 29. |
- Gomez-Gallego, Mireia
(författare)
-
Impact of weather variables and season on sporulation of Phytophthora pluvialis and Phytophthora kernoviae
- 2020
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 50
-
Tidskriftsartikel (refereegranskat)abstract
- Phytophthora pluvialis and Phytophthora kernoviae are the causal agents of important needle diseases on Pinus radiata in New Zealand. Little is known about the epidemiology of the diseases, making the development of control strategies challenging. To investigate the seasonality and climatic drivers of sporulation, inoculum traps, consisting of pine fascicles floating on water in plastic containers, were exchanged fortnightly at five sites in P. radiata plantations between February 2012 and December 2014. Sections of needle baits were plated onto selective media and growth of Phytophthora pluvialis and P. kernoviae recorded. To explore the generalizability of these data, they were compared to detection data for both pathogens from the New Zealand Forest Health Database (NZFHDB). Further, equivalent analyses on infection of Rhododendron ponticum by P. kernoviae in Cornwall, UK allowed the comparison of the epidemiology of P. kernoviae across different host systems and environments. In New Zealand, inoculum of P. pluvialis and P. kernoviae was detected between January-December and March-November, respectively. Inoculum of both species peaked in abundance in late winter. The probability of detecting P. pluvialis and P. kernoviae was greater at lower temperatures, while the probability of detecting P. pluvialis also increased during periods of wet weather. Similar patterns were observed in NZFHDB data. However, the seasonal pattern of infection by P. kernoviae in the UK was the opposite of that seen for sporulation in New Zealand. Phytophthora kernoviae was likely limited by warmer and drier summers in New Zealand, but by colder winter weather in the UK. These results emphasize the importance of considering both environmental drivers and thresholds in improving our understanding of pathogen epidemiology.
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| 30. |
- Kusumoto, Norihisa, et al.
(författare)
-
Antifungal properties of terpenoids in Picea abies against Heterobasidion parviporum
- 2014
-
Ingår i: Forest Pathology. - : Blackwell Wissenschafts-Verlag. - 1437-4781 .- 1439-0329. ; 44, s. 353-361
-
Tidskriftsartikel (refereegranskat)abstract
- The antifungal properties of 14 major oleoresin‐constitutive terpenoids of Norway spruce (Picea abies) against Heterobasidion parviporum were evaluated in vitro at three gradient concentrations, 0.1, 0.2 and 0.4 μ mol/cm2, on potato dextrose agar medium. Eight monoterpene hydrocarbons (+)‐ and (−)‐α‐pinene, (−)‐β‐pinene, (+)‐3‐carene, myrcene, (+)‐ and (−)‐limonene, terpinolene; four oxygenated monoterpenes α‐terpineol, terpinen‐4‐ol, 1,8‐cineole, bornyl acetate; and two resin acids abietic acid and dehydroabietic acid were selected. Abietic and dehydroabietic acids showed the highest antifungal activities at all concentrations. Among oxygenated monoterpenes, bornyl acetate and α‐terpineol showed antifungal activity at the highest concentration. Among monoterpene hydrocarbons, (+)‐α‐pinene showed similar activity to terpinen‐4‐ol and 1,8‐cineole at the highest concentration; however, it was lower than α‐terpineol and bornyl acetate. Other monoterpene hydrocarbons inhibited mycelial growth by <10%. Re‐extraction of medium surfaces after the test period revealed that most α‐terpineol and terpinen‐4‐ol remained unchanged on the surface but monoterpene hydrocarbons completely disappeared. However, notable fungal transformed products were observed on surfaces applied with 1,8‐cineole and bornyl acetate. Thus, mycelial growth inhibition of monoterpenoids might be caused by complex functions such as biodegradation and/or detoxification by interaction between mycelium and compound. These results provide a basis for future studies considering the role of chemodiversity in the comprehensive chemical defence of P. abies .
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| 31. |
- Madigan, Andrew, et al.
(författare)
-
Can Hymenoscyphus fraxineus infect hardy members of the Oleaceae other than ash species?
- 2015
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 45, s. 426-429
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction between the ash dieback fungus, Hymenoscyphus fraxineus, and two commonly grown members of the Oleaceae (Forsythiaxintermedia Lynwood' and Ligustrum vulgare) was investigated. Shoots were inoculated with three isolates of H.fraxineus and harvested after 2 and 10weeks. DNA was extracted from tissue collected at the point of inoculation, as well as 15mm below and above (distal), and analysed using fungal-specific ITS primers and specific primers for H.fraxineus. The fungus was frequently detected in tissue at the point of inoculation, but rarely in distal samples. There was no evidence that H.fraxineus was pathogenic on either of the two oleaceous species over the duration of the experiment.
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| 32. |
- Matsiakh, Iryna, et al.
(författare)
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Occurrence and diversity of Phytophthora species in declining broadleaf forests in western Ukraine
- 2021
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 51
-
Tidskriftsartikel (refereegranskat)abstract
- In western Ukraine, forest decline and dieback of several broadleaved tree species have become increasingly evident during recent years, and surveys in some areas have shown symptoms indicative of Phytophthora infections. In this study, we aimed to determine the occurrence and diversity of Phytophthora species associated with several broadleaved tree species (Alnus glutinosa, Betula pendula, Castanea sativa, Fagus sylvatica and Quercus robur) from forest stands where dieback has been observed. Rhizosphere soil samples were collected from 14 forest stands during 2017 and 2018 and tested for the presence of Phytophthora species using morphological and molecular methods. Seven Phytophthora species (P. bilorbang, P. cactorum, P. gallica, P. gonapodyides, P. lacustris, P. plurivora and P. polonica), and two other clade six taxa were detected from the various forest types, several of which are probable agents responsible for decline. Four of the Phytophthora species (P. bilorbang, P. gallica, P. plurivora and P. polonica) have previously never been reported from broadleaf forests in Ukraine.
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| 33. |
- Menkis, Audrius, et al.
(författare)
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Identifying Fraxinus excelsior tolerant to ash dieback: Visual field monitoring versus a molecular marker
- 2020
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 50
-
Tidskriftsartikel (refereegranskat)abstract
- Ash dieback (ADB) caused by the pathogen Hymenoscyphus fraxineus is the cause of massive mortality of Fraxinus spp. in Europe. The aim of this work was to check for the presence of the molecular marker for ADB tolerance in mapped healthy-looking F. excelsior trees, and to compare its occurrence in trees exhibiting severe ADB symptoms. Monitoring of 135 healthy-looking F. excelsior on the island of Gotland, Sweden, showed that after 3-4 years 99.3% of these trees had 0%-10% crown damage, thus remaining in a similar health condition as when first mapped. After 5-6 years, 94.7% of these trees had 0%-10% crown damage. Molecular analysis of leaf tissues from 40 of those showed the presence of the molecular marker in 34 (85.0%) trees, while it was absent in 6 (15.0%) trees. Analysis of leaf tissues from 40 severely ADB-diseased trees showed the presence of the molecular marker in 17 (42.5%) trees, but its absence in 23 (57.5%) trees (p < .0001). The results demonstrated that monitoring of healthy-looking F. excelsior is a simple and straightforward approach for the selection of presumably ADB-tolerant ash for future breeding. The cDNA-based molecular marker revealed moderate capacity on its own to discriminate between presumably ADB-tolerant and susceptible F. excelsior genotypes.
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| 34. |
- Millberg, Hanna, et al.
(författare)
-
Disease development of Dothistroma needle blight in seedlings of Pinus sylvestris and Pinus contorta under Nordic conditions
- 2016
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 46, s. 515-521
-
Tidskriftsartikel (refereegranskat)abstract
- Dothistroma needle blight (DNB), caused by Dothistroma septosporum, was observed for the first time in the Nordic countries during the 21st century, and the dynamics of the disease under Nordic conditions are still poorly explored. In this study, we followed the development of DNB on seedlings of Pinus sylvestris and Pinus contorta, planted at two forest sites in central Sweden. PCR with species-specific primers was used to detect infections of D. septosporum in needle samples collected over a two-year period. The seedlings were also examined for typical red bands and fruit bodies (conidiomata). One-year-old needles that were present on the seedlings at the time of planting became infected during the first summer. The first conidiomata appeared on P. sylvestris in autumn the same year and on P. contorta in spring the following year. The first infections of the current-year needles of both host species occurred in summer, as they were starting to elongate, and the following spring the first conidiomata appeared. On one of the sites, many seedlings carried latent infections without any symptom development. At some time points, infections of D. septosporum were detected in more than 50% of the seedlings, but red bands and conidiomata were only observed on a small number of the seedlings throughout the study period. No clear difference was observed in the susceptibility of infection between the two host species; nonetheless, at the same site, the mortality of P. sylvestris was higher than that of P. contorta, and this is likely primarily due to other stresses and the presence of another needle pathogen, Lophodermium seditiosum.
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| 35. |
- Millberg, Hanna, et al.
(författare)
-
Global geographic distribution and host range of Dothistroma species: a comprehensive review
- 2016
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 46, s. 408-442
-
Forskningsöversikt (refereegranskat)abstract
- Dothistroma needle blight (DNB) is one of the most important diseases of pine. Although its notoriety stems from Southern Hemisphere epidemics in Pinus radiata plantations, the disease has increased in prevalence and severity in areas of the Northern Hemisphere, including Europe, during the last two decades. This increase has largely been attributed to expanded planting of susceptible hosts, anthropogenic dispersal of the causative pathogens and changes in climate conducive to disease development. The last comprehensive review of DNB was published in 2004, with updates on geographic distribution and host species in 2009. Importantly, the recognition that two species, Dothistroma septosporum and D. pini, cause DNB emerged only relatively recently in 2004. These two species are morphologically very similar, and DNA-based techniques are needed to distinguish between them. Consequently, many records of host species affected or geographic location of DNB prior to 2004 are inconclusive or even misleading. The objectives of this review were (i) to provide a new database in which detailed records of DNB from 62 countries are collated; (ii) to chart the current global distribution of D. septosporum and D. pini; (iii) to list all known host species and to consider their susceptibility globally; (iv) to collate the published results of provenance trials; and (v) to consider the effects of site factors on disease incidence and severity. The review shows that DNB occurs in 76 countries, with D. septosporum confirmed to occur in 44 and D. pini in 13. There are now 109 documented Pinaceae host taxa for Dothistroma species, spanning six genera (Abies, Cedrus, Larix, Picea, Pinus and Pseudotsuga), with Pinus being the dominant host genus, accounting for 95 host taxa. The relative susceptibilities of these hosts to Dothistroma species are reported, providing a resource to inform species choice in forest planting. Country records show that most DNB outbreaks in Europe occur on Pinus nigra and its subspecies. It is anticipated that the collaborative work described in this review will both underpin a broader global research strategy to manage DNB in the future and provide a model for the study of other forest pathogens.
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| 36. |
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| 37. |
- Olsson, Christer, et al.
(författare)
-
Widespread Phytophthora infestations in European nurseries put forest, semi-natural and horticultural ecosystems at high risk of Phytophthora diseases
- 2016
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 46, s. 134-163
-
Tidskriftsartikel (refereegranskat)abstract
- An analysis of incidence of Phytophthora spp. in 732 European nurseries producing forest transplants, larger specimen trees, landscape plants and ornamentals, plus 2525 areas in which trees and shrubs were planted, is presented based on work conducted by 38 research groups in 23 European countries between 1972 and 2013. Forty-nine Phytophthora taxa were recorded in 670 nurseries (91.5%); within these nurseries, 1614 of 1992 nursery stands (81.0%) were infested, although most affected plants appeared healthy. In forest and landscape plantings, 56 Phytophthora taxa were recovered from 1667 of 2525 tested sites (66.0%). Affected plants frequently showed symptoms such as crown thinning, chlorosis and dieback caused by extensive fine root losses and/or collar rot. Many well-known highly damaging host-Phytophthora combinations were frequently detected but 297 and 407 new Phytophthora-host associations were also observed in nurseries and plantings, respectively. On average, 1.3 Phytophthora species/taxa per infested nursery stand and planting site were isolated. At least 47 of the 68 Phytophthora species/taxa detected in nurseries and plantings were exotic species several of which are considered well established in both nurseries and plantings in Europe. Seven known Phytophthora species/taxa were found for the first time in Europe, while 10 taxa had not been previously recorded from nurseries or plantings; in addition, 5 taxa were first detections on woody plant species. Seven Phytophthora taxa were previously unknown to science. The reasons for these failures of plant biosecurity in Europe, implications for forest and semi-natural ecosystems and possible ways to improve biosecurity are discussed.
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| 38. |
- Rönnberg, Jonas, et al.
(författare)
-
Mortality and basal area growth following precommercial thinning in stands affected by Armillaria, Laminated and Tomentosus root diseases in southern British Columbia
- 2022
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 52
-
Tidskriftsartikel (refereegranskat)abstract
- Precommercial thinning aims to reduce the density of immature stands to stimulate growth of well-spaced crop trees of preferred species and free from defects and disease. The chronic persistence of Armillaria, Laminated and Tomentosus root diseases in coniferous forests of British Columbia, Canada may offset potential gains in timber yield of commercially important tree species by creating stumps that the fungi utilize as an energy source to infect neighbouring trees. In juvenile plantations and naturally regenerated stands in six biogeoclimatic (BEC) zones with evidence of root disease caused by Armillaria ostoyae (8 sites), Coniferiporia sulphurascens (2 sites) or Onnia tomentosa (1 site), five of ten 20 m square plots per site were randomly selected for thinning to British Columbia Ministry of Forests specifications. Crop tree diameter at breast height and mortality from all causes were recorded at establishment and periodically thereafter up to 19 years post-thinning. Logistic regression analysis of mortality rates showed significant differences among root disease pathogens, between planted and natural stands, and among ecological zones. Yet over all sites, differences between thinned and control plots were not significant. At the final assessment, crop tree basal area was higher in thinned than in control plots at 10 of 11 sites. Root disease, including infected and dead trees and other lethal biotic and abiotic agents, reduced potential yield in both treatments (thinned and control). At several Armillaria sites, mortality was slightly to substantially higher in thinned than in control plots, suggesting that thinning can increase the amount and potential of inoculum which may continue to adversely impact productivity of those stands. Recommendations for silvicultural management of the three root diseases are discussed.
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| 39. |
- Stenlid, Jan
(författare)
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Characterization of Corynelia uberata Fr., a putative fungal pathogen of Podocarpus falcatus in Ethiopian forests
- 2014
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 44, s. 45-55
-
Tidskriftsartikel (refereegranskat)abstract
- Corynelia spp. are ascomycetes belonging to the order Coryneliales and are thought to be obligate parasites of trees in the Podocarpaceae. The aims of this study were to determine the disease intensity of Corynelia infection on Podocarpus falcatus in Ethiopian forests and verify the identity of Corynelia spp. from Ethiopia and other countries using morphological and molecular methods. Disease surveys were conducted in P.falcatus forest areas at Adaba-Dodola, Bushoftu, Menagesha, Shashamane and Wondo Genet in Ethiopia between 2009 and 2011, and samples were collected for morphological and molecular studies. Additional dried specimens morphologically collected as C.uberata, C.portoricensis and C.tropica from Podocarpus species in Kenya, South Africa, Puerto Rico and New Zealand were also characterized. Morphologically, the South African specimen (F-006479) of C.uberata had significantly larger ascospores when compared with the other specimens. There was a high sequence similarity (99-100%) in the internal transcribed spacer and 5.8S (ITS-5.8S) region among the studied C.uberata sequences. Cloning and amplification of the insert spanning partial small ribosomal unit (SSU) and ITS-5.8S regions of ribosomal DNA validated the unidentified ITS-5.8S region as the sequence of C.uberata by inferring the reference sequence of SSU rDNA of C.uberata in GenBank. Both neighbour-joining and/or maximum parsimony methods placed ITS-5.8S and SSU rDNA sequences of Corynelia spp. at the basal position of the clade Eurotiomycetidae. C.uberata was found to be a potential pathogen on leaves, fruits and young stems of P.falcatus in Ethiopia.
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| 40. |
- Strid, Ylva, et al.
(författare)
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The primer fITS9 prevents chimera formation during fungal DNA amplification in a bark beetle DNA background
- 2015
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 45, s. 9-13
-
Tidskriftsartikel (refereegranskat)abstract
- Insects are frequently associated with fungi in natural habitats. Molecular detection of fungal species using the primer pair ITS1F and ITS4 to amplify the ribosomal ITS region has become standard for studies of fungal ecology. When addressing insect and fungal DNA together, sequencing of the ITS region often results in chimeras due to ITS4 binding to both insect and fungal DNA. Using the newly developed primer fITS9, placed in the 5.8S region in the middle of the ITS region, we show that chimeras (insect-fungal, fungal-fungal, fungal-plants or fungal-mammals) can be avoided and a shorter and less variable DNA sequence product can be obtained. This method allows a more targeted amplification of fungal DNA from mixed samples and decreases the necessity for a nested PCR approach.
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| 41. |
- Tolio, Beatrice, et al.
(författare)
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Monitoring of long-term tolerance of European ash to Hymenoscyphus fraxineus in clonal seed orchards in Sweden
- 2022
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 52
-
Tidskriftsartikel (refereegranskat)abstract
- The invasive alien pathogenic fungus Hymenoscyphus fraxineus causing ash dieback (ADB) has devastated European ash (Fraxinus excelsior) populations across Europe. Breeding for resistance is the most feasible measure to reduce future losses of ash, and the presence of resistance, albeit at low level, has been demonstrated in numerous genetic trials around Europe. This study is a continuation of the inventories tracking the vitality status of different clones, which started in 2006 at two ash seed orchards in southern Sweden. A new inventory conducted in the summer of 2021 revealed that the ten clones previously identified as the most tolerant to ADB based on periodic surveys from 2006 and onwards still remain the most tolerant, while susceptible clones continued to decline and are completely disappearing from the orchards. Browsing caused mortality in some of the most tolerant clones in one of the orchards during the last assessment period. Despite the animal damage, the stable resistance observed in tolerant clones over a 15 years period forms a solid basis for the continuation of the breeding programme where good candidates are selected for further study.
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| 42. |
- Zhang, Ke, et al.
(författare)
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Detection and quantification of Cronartium pini from Scots pine bark and wood with Cronartium spp.-specific quantitative PCR
- 2023
-
Ingår i: Forest Pathology. - 1437-4781 .- 1439-0329. ; 53
-
Tidskriftsartikel (refereegranskat)abstract
- The forest disease, Scots pine blister rust, is caused by the rust fungus Cronartium pini. This pathogen was previously known as the host-alternating type C. flaccidum and non-host-alternating type Peridermium pini. Recent epidemics of this disease in Northern European forests, especially young Scots pine forests in Sweden, caused significant economic and ecological losses. Cronartium pini can be identified based on the typical orange blister-like aecia in Scots pine in summer, but any molecular identification and quantification method has not been available for Cronartium spp. This study developed qPCR primers that are specific to Cronartium spp. and evaluated DNA extraction protocols from pine bark and wood to enable robust qPCR assays. As little as three Cronartium ITS copies can be detected with the protocol. Since only C. pini is known to infect Scots pine in Northern Europe, the protocols were applied to detect C. pini from Scots pine samples without typical symptoms and investigate the C. pini colonization in Scots pine branches from the forest. These results will aid the detection and quantification of C. pini in asymptomatic or symptomatic samples and monitoring Scots pine blister rust in the forest in northern Europe.
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