| 1. |
- Polme, S., et al.
(författare)
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FungalTraits: a user-friendly traits database of fungi and fungus-like stramenopiles
- 2020
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Ingår i: Fungal Diversity. - : Springer Science and Business Media LLC. - 1560-2745 .- 1878-9129. ; 105:1, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- The cryptic lifestyle of most fungi necessitates molecular identification of the guild in environmental studies. Over the past decades, rapid development and affordability of molecular tools have tremendously improved insights of the fungal diversity in all ecosystems and habitats. Yet, in spite of the progress of molecular methods, knowledge about functional properties of the fungal taxa is vague and interpretation of environmental studies in an ecologically meaningful manner remains challenging. In order to facilitate functional assignments and ecological interpretation of environmental studies we introduce a user friendly traits and character database FungalTraits operating at genus and species hypothesis levels. Combining the information from previous efforts such as FUNGuild and Fun(Fun) together with involvement of expert knowledge, we reannotated 10,210 and 151 fungal and Stramenopila genera, respectively. This resulted in a stand-alone spreadsheet dataset covering 17 lifestyle related traits of fungal and Stramenopila genera, designed for rapid functional assignments of environmental studies. In order to assign the trait states to fungal species hypotheses, the scientific community of experts manually categorised and assigned available trait information to 697,413 fungal ITS sequences. On the basis of those sequences we were able to summarise trait and host information into 92,623 fungal species hypotheses at 1% dissimilarity threshold.
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| 2. |
- Agostinelli, Marta, et al.
(författare)
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Mycobiome of Fraxinus excelsior With Different Phenotypic Susceptibility to Ash Dieback
- 2021
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Ingår i: Frontiers in Forests and Global Change. - : Frontiers Media S.A.. - 2624-893X. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- For the last two decades, large-scale population decline of European ash (Fraxinus excelsior) has occurred in Europe because of the introduction of the alien fungal pathogen, Hymenoscyphus fraxineus, from East Asia. Since European ash is a keystone species having critical importance for biodiversity, and only a small percentage of the ash population appears to show some tolerance against the pathogen, the loss of ash trees means that other associated organisms, especially those with high or obligate associations to ash, are at risk of further species declines. In this study, we used high throughput DNA sequencing and multivariate analysis to characterize: (i) the mycobiome in aerial tissues (i.e., leaf, bark, and xylem) of ash trees showing different phenotypic response to ash dieback, (ii) the temporal variation in fungal communities across the growing season, and (iii) the similarity in fungal community structure between ash and other common trees species that may serve as an ecological niche substitute for ash microfungi. Results showed that fungal communities differed among the three tissue types, susceptibility classes, in time and between sites. Trophic analysis of functional groups using the FUNGuild tool indicated a higher presence of pathotrophic fungi in leaves than in bark and xylem. The share of pathotrophic fungi increased along a gradient of low to high disease susceptibility in both bark and xylem tissue, while the proportion of symbiotrophic fungi correspondingly decreased in both tissue types. Neighboring, alternative host trees did not share all the fungal species found in ash, however, most microfungi uniquely associated to ash in this study are generalists and not strictly host specific. The progressive disappearance of ash trees on the landscape imposes a high risk for extinction of Red-listed macrofungal species, and breeding for resistance against ash dieback should help sustain important biodiversity associated to ash. Microfungal diversity though may be less prone to such demise since most ash-associated endophytes appear to occur on a broad range of host species.
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| 3. |
- Agostinelli, Marta, et al.
(författare)
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Pedunculate Oaks (Quercus robur L.) Differing in Vitality as Reservoirs for Fungal Biodiversity
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Ecological significance of trees growing in urban and peri-urban settings is likely to increase in future land-use regimes, calling for better understanding of their role as potential reservoirs or stepping stones for associated biodiversity. We studied the diversity of fungal endophytes in woody tissues of asymptomatic even aged pedunculate oak trees, growing as amenity trees in a peri-urban setting. The trees were classified into three groups according to their phenotypic vitality (high, medium, and low). Endophytes were cultured on potato dextrose media from surface sterilized twigs and DNA sequencing was performed to reveal the taxonomic identity of the morphotypes. In xylem tissues, the frequency and diversity of endophytes was highest in oak trees showing reduced vitality. This difference was not found for bark samples, in which the endophyte infections were more frequent and communities more diverse than in xylem. In general, most taxa were shared across the samples with few morphotypes being recovered in unique samples. Leaf phenolic profiles were found to accurately classify the trees according to their phenotypic vitality. Our results confirm that xylem is more selective substrate for endophytes than bark and that endophyte assemblages in xylem are correlated to the degree of host vitality. Thus, high vitality of trees may be associated with reduced habitat quality to wood-associated endophytes.
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| 4. |
- Andersson, Pierre, et al.
(författare)
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Viridin-like steroids from Hymenoscyphus pseudoalbidus
- 2013
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 86, s. 195-200
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Tidskriftsartikel (refereegranskat)abstract
- Three furanosteroids were isolated from the ash dieback causing fungus Hymenoscyphus pseudoalbidus along with the known compounds viridiol and demethoxyviridiol. The compounds were characterized by 1D and 2D NMR spectroscopy, LC-HRMS and polarimetry. (C) 2012 Elsevier Ltd. All rights reserved.
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| 5. |
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| 6. |
- Blomquist, Mimmi, et al.
(författare)
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Size matters but is big always better? Effectiveness of urea and Phlebiopsis gigantea as treatment against Heterobasidion on Picea abies stumps of variable size
- 2020
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 462
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Tidskriftsartikel (refereegranskat)abstract
- Heterobasidion is a severe threat to coniferous forests in the northern hemisphere. Accurate forest management is needed to safeguard the economic values at stake. In this paper we investigate the efficacy of stump treatment with urea and Phlebiopsis gigantea as control treatment in Norway spruce against airborne Heterobasidion infections. The aim of this study was to examine the infection frequency, i.e. frequency of stumps infected by airborne spores, and efficacy of the stump treatments after performing precommercial thinning and final felling, representing highly variable stump diameters. Today treatment after these cuttings are not standard practice across the world.From a total of 27 Norway spruce stands in the southern and mid-regions of Sweden, five precommercial thinning stands and five final felling stands with infection frequencies higher than an economical threshold for treatment, 20%, were selected. In these stands, the efficacy of stump treatment using urea and P. gigantea against Heterobasidion spp. was assessed on stumps of variable diameter. Wooden discs from stumps were analyzed for airborne infections of Heterobasidion spp. 7-8 weeks after treatment. To evaluate the efficacy of treatments, we used the following three different measurements; infection frequency (proportion of infected stumps), relative infected stump area and number of Heterobasidion colonies per square dm, which were tested using three different statistical models each represented by an efficacy value. Overall, untreated stumps were infected to a higher extent than treated stumps, and most infections were found in untreated stumps from final fellings. Treatment with P. gigantea was more efficient for larger sized stumps than small. In precommercial thinnings, urea performed better and had higher mean efficacy values (92-94%) compared to P. gigantea (59%-72%). In final fellings there were no significant differences between the treatments, both had high efficacy values (urea 95.5-99.8% vs P. gigantea 90-98%).Our findings point at the need for accurate stump treatment after precommercial thinning and final felling, when infection rates are likely to be high. Urea seems to be more effective than the biological control agent P. gigantea in controlling Heterobasidion infections in stumps created in precommercial thinnings. We therefore recommend to use urea in precommercial thinnings if possible. In final fellings either urea or P. gigantea can be used.
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| 7. |
- Blomquist, Mimmi, et al.
(författare)
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The potential of biological control against Heterobasidion root rot is not realized in practical forestry
- 2023
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 531
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Tidskriftsartikel (refereegranskat)abstract
- For about 25 years, forest managers in Sweden have been treating stumps following harvesting with Phlebiopsis gigantea, retailed as Rotstop (R) S gel, against spore infections of Heterobasidion, which cause root rot in order to minimize losses in timber production. However, not all forest managers trust the efficacy of stump treatment and this fact has hindered widespread adoption of stump treatment using P. gigantea. In this study, we evaluated stump treatment in the field during commercial thinning operations across 15 sites, by assessing the degree of stump coverage and subsequent infection levels in stump discs. In total, 45 % of all stumps were infected with Heterobasidion spp.. Nineteen percent of all stumps were considered to have full (100 %) coverage by Rotstop (R) S but contractors failed to achieve the manufacturers stipulated minimum coverage (85 %) in approximately 1/3 of all stumps. Using PCR, we could only detect the presence of P. gigantea in 73 % of the tested stumps. Large variation occurred between stump coverage and the recovery of P. gigantea in wood chip samples collected from stump discs across sites. In the worst case, we detected P. gigantea in only three out of ten treated stumps at one site. Despite this discrepancy we saw a clear reduction of the size of Heterobasidion infections on stumps where stump treatment coverage was more than 85 % of the stump surface.Our results suggest that forest operators in Sweden repeatedly fail to either apply a spore solution of P. gigantea or cover enough of the stumps to provide the desired protection. The outcome of such sub-standard application, could further undermine the usage of biological control agents in forestry and limit any potential control against Heterobasidion spp..
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| 8. |
- Chaudhary, Rajiv, et al.
(författare)
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Marker-Trait Associations for Tolerance to Ash Dieback in Common Ash (Fraxinus excelsior L.)
- 2020
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Ingår i: Forests. - : MDPI. - 1999-4907. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Common ash (Fraxinus excelsior L.) is a tree species of significant ecological and economic importance that has suffered a devastating decline since the 1990s in Europe. Native ash species are being threatened by the alien invasive fungus Hymenoscyphus fraxineus, which causes ash dieback. The main goal of the study was to develop markers for traits related to tolerance to ash dieback and to investigate whether genotypes selected for tolerance were genetically different from susceptible wild populations. We phenotyped 326 ash trees from Sweden for disease severity and genotyped them using 63 amplicon-derived single-nucleotide polymorphism (SNP) markers derived from genes in 40 scaffolds spanning 8 MB in total, which represents approximately 1% of the ash genome. We used a mixed linear model to test for an association between genotypic variation at these loci and disease severity of ash. In total, two SNPs were found to have significant associations. One non-synonymous SNP associated with the disease severity of ash was found in a gene predicted to encode a subtilisin-related peptidase S8/S53 domain. A second marginally significant marker was associated with an LRR gene. Our results demonstrate an inexpensive time-effective method for generating genomic data that could have potential for use in future tree breeding programs and provide information for marker-assisted selection. Our study also showed a low differentiation between genotypes selected for disease tolerance and the wild population of ash representing a range of susceptibilities to ash dieback, indicating opportunities for further selection without significantly losing genetic diversity in the ash population.
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| 9. |
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| 10. |
- Cleary, Michelle
(författare)
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A glimmer of hope - ash genotypes with increased resistance to ash dieback pathogen show cross-resistance to emerald ash borer
- 2023
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Ingår i: New Phytologist. - 0028-646X .- 1469-8137. ; 240, s. 1219-1232
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Tidskriftsartikel (refereegranskat)abstract
- Plants rely on cross-resistance traits to defend against multiple, phylogenetically distinct enemies. These traits are often the result of long co-evolutionary histories. Biological invasions can force naive plants to cope with novel, coincident pests, and pathogens. For example, European ash (Fraxinus excelsior) is substantially threatened by the emerald ash borer (EAB), Agrilus planipennis, a wood-boring beetle, and the ash dieback (ADB) pathogen, Hymenoscyphus fraxineus. Yet, plant cross-resistance traits against novel enemies are poorly explored and it is unknown whether na_ive ash trees can defend against novel enemy complexes via cross-resistance mechanisms.To gain mechanistic insights, we quantified EAB performance on grafted replicates of ash genotypes varying in ADB resistance and characterized ash phloem chemistry with targeted and untargeted metabolomics.Emerald ash borer performed better on ADB-susceptible than on ADB-resistant genotypes. Moreover, changes in EAB performance aligned with differences in phloem chemical profiles between ADB-susceptible and ADB-resistant genotypes.We show that intraspecific variation in phloem chemistry in European ash can confer increased cross-resistance to invasive antagonists from different taxonomic kingdoms. Our study suggests that promotion of ADB-resistant ash genotypes may simultaneously help to control the ADB disease and reduce EAB-caused ash losses, which may be critical for the long-term stability of this keystone tree species.
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| 11. |
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| 12. |
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| 13. |
- Cleary, Michelle
(författare)
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Citizen science can enhance strategies to detect and manage invasive forest pests and pathogens
- 2023
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 11
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Forskningsöversikt (refereegranskat)abstract
- Incorporating a citizen science approach into biological invasion management strategies can enhance biosecurity. Many citizen science projects exist to strengthen the management of forest pest and pathogen invasions within both pre- and post-border scenarios. Besides the value of citizen science initiatives for early detection and monitoring, they also contribute widely to raising awareness, informing decisions about eradication and containment efforts to minimize pest and pathogen spread, and even finding resistant plant material for restoration of landscapes degraded by disease. Overall, many projects actively engage citizens in the different stages of forest pest and pathogen invasions, but it is unclear how they work together across all stages of the entire biological invasion process to enhance biosecurity. Here we provide examples of citizen science projects for each stage of the biological invasion process, discuss options for developing a citizen science program to enhance biosecurity, and suggest approaches for integrating citizen science into biosecurity measures to help safeguard forest resources in the future.
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| 14. |
- Cleary, Michelle
(författare)
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Cryptic Risks to Forest Biosecurity Associated with the Global Movement of Commercial Seed
- 2019
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The import and export of tree seed carries with it risks of inadvertent introduction of pests and pathogens to hitherto unaffected regions. Although trade in seed of specified trees is regulated, phytosanitary requirements for most tree species are minimal, even those related to the most important forest tree species in a given region. A better understanding of the microbiome associated with seed intended for commercial production or ornamental use, and their potential risk with the transport from the source origin of distributors, will help regulatory agencies implement measures to safeguard seed health and avoid trade-related spread of potentially harmful pathogens. In this study we used high-throughput sequencing to show that highly diverse fungal communities were associated with seed of 14 different Pinus species obtained from seed banks (seed orchards) and retail sources (online distributors) in North America and Europe. Fungal diversity differed among the 23 seedlots tested. Community composition did not relate to the species of Pinus nor the country of origin. Assigned potential functions based on sequence identity using FUNGuild provided an overall understanding of the likely life strategies of fungal operational taxonomic units (OTUs). Of those sequences classified to a trophic level, 453 were plant pathogens, with the Dothideomycetes having the highest prevalence. The most common plant pathogens included Sydowia polyspora, Lasiodiplodia theobromae, Diplodia intermedia and Diplodia sapinea that were detected from the majority of Pinus species. The evidence presented here illustrates an urgent need for plant protection authorities, practitioners and the general public to recognize the potential risk of introducing harmful pathogens through innocent transport of seed.
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| 15. |
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| 16. |
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| 17. |
- Cleary, Michelle, et al.
(författare)
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Diversity, migration routes, and worldwide population genetic structure of Lecanosticta acicola, the causal agent of brown spot needle blight
- 2022
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Ingår i: Molecular Plant Pathology. - : Wiley. - 1464-6722 .- 1364-3703.
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Tidskriftsartikel (refereegranskat)abstract
- Lecanosticta acicola is a pine needle pathogen causing brown spot needle blight that results in premature needle shedding with considerable damage described in North America, Europe, and Asia. Microsatellite and mating type markers were used to study the population genetics, migration history, and reproduction mode of the pathogen, based on a collection of 650 isolates from 27 countries and 26 hosts across the range of L. acicola. The presence of L. acicola in Georgia was confirmed in this study. Migration analyses indicate there have been several introduction events from North America into Europe. However, some of the source populations still appear to remain unknown. The populations in Croatia and western Asia appear to originate from genetically similar populations in North America. Intercontinental movement of the pathogen was reflected in an identical haplotype occurring on two continents, in North America (Canada) and Europe (Germany). Several shared haplotypes between European populations further suggests more local pathogen movement between countries. Moreover, migration analyses indicate that the populations in northern Europe originate from more established populations in central Europe. Overall, the highest genetic diversity was observed in south-eastern USA. In Europe, the highest diversity was observed in France, where the presence of both known pathogen lineages was recorded. Less than half of the observed populations contained mating types in equal proportions. Although there is evidence of some sexual reproduction taking place, the pathogen spreads predominantly asexually and through anthropogenic activity.
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| 18. |
- Cleary, Michelle
(författare)
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Effects of Host Variability on the Spread of Invasive Forest Diseases
- 2017
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 8
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Forskningsöversikt (refereegranskat)abstract
- Biological invasions, resulting from deliberate and unintentional species transfers of insects, fungal and oomycete organisms, are a major consequence of globalization and pose a significant threat to biodiversity. Limiting damage by non-indigenous forest pathogens requires an understanding of their current and potential distributions, factors affecting disease spread, and development of appropriate management measures. In this review, we synthesize innate characteristics of invading organisms (notably mating system, reproduction type, and dispersal mechanisms) and key factors of the host population (namely host diversity, host connectivity, and host susceptibility) that govern spread and impact of invasive forest pathogens at various scales post-introduction and establishment. We examine spread dynamics for well-known invasive forest pathogens, Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz, Hosoya, comb. nov., causing ash dieback in Europe, and Cryphonectria parasitica, (Murr.) Barr, causing chestnut blight in both North America and Europe, illustrating the importance of host variability (diversity, connectivity, susceptibility) in their invasion success. While alien pathogen entry has proven difficult to control, and new biological introductions are indeed inevitable, elucidating the key processes underlying host variability is crucial for scientists and managers aimed at developing effective strategies to prevent future movement of organisms and preserve intact ecosystems.
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| 19. |
- 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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| 20. |
- Cleary, Michelle, et al.
(författare)
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First Report of Phytophthora gonapodyides Causing Stem Canker on European Beech (Fagus sylvatica) in Southern Sweden
- 2016
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Ingår i: Plant Disease. - 0191-2917 .- 1943-7692. ; 100, s. 2174-2175
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Tidskriftsartikel (refereegranskat)abstract
- Since 2010, extensive crown transparency of European beech (Fagus sylvatica) has been recorded in southern Sweden, with Phytophthora cambivora, P. plurivora, and P. cactorum as well as associated climatic triggers believed to be the major factors involved. In 2015, a different Phytophthora sp. was isolated from three F. sylvatica trees showing characteristic bleeding canker symptoms in Pildammsparken in Malmö, Sweden. Small sections of inner phloem were dissected at the interface between necrotic and healthy tissue, directly plated onto PAR(PH)-V8 selective medium containing 0.250 g/liter sodium ampicillin, 0.01 g/liter benomyl, 0.05 g/liter hymexazol, 0.1 g/liter PCNB, 0.05 g/liter pimaricin, and 0.01 g/liter rifamycin, and incubated at 20°C in darkness. Growing hyphae were later transferred to PDA and incubated at 20°C in the dark. The colony pattern was stellate. The average radial growth rate at 20°C was 0.6 cm/day. These morphological features are similar to that previously described for P. gonapodyides (Corcobado et al. 2010; Erwin and Ribeiro 1996; Jung et al. 1996). The isolates grown on PDA formed irregularly branched hyphae. Nonpapillate, elongated-ovoid to obpyriform sporangia (∼50 × 40 µm) were produced after 7 days by incubating on V8 agar culture (nonsterile soil water). DNA was extracted from mycelia and the identity of P. gonapodyides was confirmed by sequencing the internal transcribed (ITS) spacer region of the rDNA with the primers ITS4/ITS6 (GenBank accession nos. KX055998, KX055999, and KX056000). BLAST search showed 99 to 100% identity with reference sequences of P. gonapodyides deposited in GenBank. Pathogenicity on F. sylvatica was confirmed in a greenhouse experiment using two different isolates of P. gonapodyides. Mycelial plugs of 3-week-old cultures of each isolate grown on PDA were inoculated on the stems of 1-year-old seedlings at two locations, separated by 20 cm, by aseptically excising a small 5-mm flap of bark, inserting the mycelial plug along the cambium, and adding a droplet of Milliq H2O before sealing the wound with Parafilm. Ten seedlings were inoculated for each isolate. Controls consisted of stem-wound inoculation with a sterile plug of PDA, and no wounding at all. After 7 weeks, lesion length was measured. All seedlings inoculated with P. gonapodyides showed distinct necrotic lesions, whereas control treatments did not show any symptoms of disease. The average cumulative lesion length on seedlings inoculated with P. gonapodyides was significantly higher than on the wounded control treatment (25.4 mm ± 1.66 vs. 0.4 mm ± 0.01; P < 0.0001 for isolate 1 and 28.9 mm ± 1.42 vs. 0.4 mm ± 0.01; P < 0.001 for isolate 2). Koch's postulates were fulfilled by successfully reisolating the pathogen from infected seedlings. To our knowledge, this is the first report of P. gonapodyides causing disease on trees in Sweden. P. gonapodyides has been noted previously in Denmark (Erwin and Ribeiro 1996), and has been traditionally regarded as a weak parasite with saprophytic abilities, usually associated with aquatic environments such as rivers, riparian areas, and wetlands (Brasier et al. 2003). We cannot exclude that recent climatic triggers such as high summer precipitation coupled with mild winter temperatures have favored conditions to multicyclic spread of P. gonapodyides via zoospores, or that increased average age of beech stands has contributed to their higher susceptibility to weaker pathogens. Damage caused by P. gonapodyides however might be underestimated as it also can inhibit seed germination and is known to cause root rot and stem lesions in Quercus robur and Q. ilex (Corcobado et al. 2010; Jung et al. 1996). The newly reported damage caused by P. gonapodyides on F. sylvatica trees in southern Sweden is alarming particularly since beech is a dominant and ecologically important hardwood species that is widely used in forestry and as a planted ornamental in urban and landscape settings. Furthermore, other hosts such as Alnus glutinosa, Q. petraea, Q. robur (Jung et al. 1996), Picea abies, Betula spp., Acer spp., Tilia spp. (Jung et al. 2009), and Salix spp. (Brasier et al. 2003), also common in southern Sweden, may face an increased risk of damages caused by P. gonapodyides in the future.
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| 21. |
- Cleary, Michelle, et al.
(författare)
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First report of Pleuroceras pseudoplatani on Acer rubrum, A. griseum, A. saccharinurn, A. negundo, A. circinatum and A. macrophyllum in Scotland
- 2018
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Ingår i: Forestry Chronicle. - : Canadian Institute of Forestry. - 0015-7546 .- 1499-9315. ; 94, s. 147-150
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Tidskriftsartikel (refereegranskat)abstract
- In September 2016, large necrotic lesions were observed on the foliage of several maples in Aberdeenshire, Scotland. Symptoms resembled giant leaf blotch disease caused by Pleuroceras pseudoplatani (formerly Gnomonia pseudoplatani; Ophiognomia pseudoplatani) on sycamore maple (Acer pseudoplatanus), a common disease in Europe. Other than A. pseudoplatanus, no other Acer species have previously been reported as hosts for this pathogen. Symptomatic leaves were collected from Acer rubrum, A. rubrum var. Somerset, A. griseum, A. saccharinum, A. negundo, A. macrophyllum, and A. circinatum, and the known host of P pseudoplatani, A. pseudoplatanus. Next generation sequencing was used to determine presence of the suspected P. pseudoplatani and other associated fungi in symptomatic leaves. P pseudoplatani was predominant in all symptomatic samples with 99-100% identity with reference ITS sequences of P pseudoplatani deposited in GenBank (NCBI). This is the first report of P. pseudoplatani associated with leaf blotch on Acer species other than A. pseudoplatanus. The newly reported damage on North American Acer species may be of particular concern because of the economic importance of maples for timber products, syrup production and as ornamental trees in urban landscapes. Precautions should be taken to limit trade of plants from infested areas in Europe.
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| 22. |
- Cleary, Michelle
(författare)
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FORMATION OF TRAUMATIC RESIN DUCTS IN THE PHLOEM OF WESTERN REDCEDAR (THUJA PLICATA) ROOTS FOLLOWING ABIOTIC INJURY AND PATHOGENIC INVASION BY ARMILLARIA OSTOYAE
- 2011
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Ingår i: IAWA Journal. - : Brill. - 0928-1541 .- 2294-1932. ; 32, s. 351-359
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Tidskriftsartikel (refereegranskat)abstract
- Anatomical changes involved in traumatic phloem resin duct (TPRD) formation in western redcedar (Thuja plicata) roots were examined following abiotic wounding and fungal invasion by Armillaria ostoyae. Following necrophylactic periderm formation, hyperplasia and expansion of a band of phloem parenchyma cells occurred in close proximity to the vascular cambium and schizogenous and lysigenous separation of its derivatives resulted in a series of longitudinal resin ducts in the inner to mid-phloem region. Fungal invasion appeared to amplify traumatic resin duct formation in the phloem. While traumatic cavities in the phloem have been reported for other Cupressaceae, this is the first report documenting TPRD formation in western redcedar.
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| 23. |
- Cleary, Michelle, et al.
(författare)
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Friend or foe? Biological and ecological traits of the European ash dieback pathogen Hymenoscyphus fraxineus in its native environment
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Hymenoscyphus fraxineus, an introduced ascomycete fungus and primary causal agent of European ash dieback, was investigated on Fraxinus mandshurica trees in its native range in Primorye region of Far East Russia. This evidence is the first report of H. fraxineus on healthy, asymptomatic F. mandshurica trees. High-throughput sequencing revealed 49 distinct fungal taxa associated with leaves of F. mandshurica, 12 of which were identified to species level. Phyllosphere fungal assemblages were similar among sites despite being largely geographically distant. Many organisms comprising the foliar fungal community on F. mandshurica in Far East Russia have similarity to those reported inhabiting F. excelsior in Europe based on previous studies. However, Mycosphaerella sp., the most dominant species in this study and detected in nearly all samples, was associated only with F. mandshurica. Genetic diversity of H. fraxineus was significantly higher in the Far East Russian population than in Europe. In contrast to its aggressive behaviour on Fraxinus excelsior in Europe, H. fraxineus appears to be a benign associate of indigenous F. mandshurica that initially induces quiescent and asymptomatic infections in healthy trees prior to active host colonization normally associated with modification of host tissue during senescence.
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| 24. |
- Cleary, Michelle, et al.
(författare)
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Genotypes of Fraxinus excelsior with different susceptibility to the ash dieback pathogen Hymenoscyphus pseudoalbidus and their response to the phytotoxin viridiol - A metabolomic and microscopic study
- 2014
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 102, s. 115-125
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Tidskriftsartikel (refereegranskat)abstract
- Eight European ash (Fraxinus excelsior) genotypes with different known susceptibility to Hymenoscyphus pseudoalbidus were tested against the phytotoxin viridiol and their response described at the microscopic and metabolomic level. All ash genotypes were sensitive to the toxin and necrosis was detectable after 24 h. Among the three viridiol concentrations used in the experiment, the lowest concentration (14.7 mu M) yielded markedly lower mean damage scores compared to those resulting from seedlings tested at higher dosages. The highest damage scores were associated with the susceptible ash clones S-101, S-106 and S-125, but also with resistant clone R-104. Three resistant clones (R-131, R-121, and R-118) had lower mean damage scores compared to susceptible clones. Wilting of leaves was more common 48 h after treatment and more pronounced on seedlings with high damage scores. The resulting lesions generally lacked browning of tissue and displayed only surface disruption of cells in direct contact with the toxin. A delay in symptom development was evident on all five resistant clones tested with the two higher concentrations of viridiol. LC-HRMS and MS/MS analyses of ash seedling extracts suggest several secoiridoid compounds as well as compounds related to abscisic acid (ABA) to be produced in response to viridiol. ABA-cysteine and xanthoxin were found at significantly higher concentrations in susceptible clones compared to resistant clones after treatment with viridiol, suggesting a primary role of ABA in response to stress. The results observed in this study suggest that genetic resistance to H. pseudoalbidus among ash genotypes may be explained, in part, by the varied response to phytotoxins produced by the fungus. (C) 2014 Elsevier Ltd. All rights reserved.
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| 25. |
- Cleary, Michelle, et al.
(författare)
-
Global Geographic Distribution and Host Range of Fusarium circinatum, the Causal Agent of Pine Pitch Canker
- 2020
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 11
-
Forskningsöversikt (refereegranskat)abstract
- Fusarium circinatum, the causal agent of pine pitch canker (PPC), is currently one of the most important threats ofPinusspp. globally. This pathogen is known in many pine-growing regions, including natural and planted forests, and can affect all life stages of trees, from emerging seedlings to mature trees. Despite the importance of PPC, the global distribution ofF. circinatumis poorly documented, and this problem is also true of the hosts within countries that are affected. The aim of this study was to review the global distribution ofF. circinatum, with a particular focus on Europe. We considered (1) the current and historical pathogen records, both positive and negative, based on confirmed reports from Europe and globally; (2) the genetic diversity and population structure of the pathogen; (3) the current distribution of PPC in Europe, comparing published models of predicted disease distribution; and (4) host susceptibility by reviewing literature and generating a comprehensive list of known hosts for the fungus. These data were collated from 41 countries and used to compile a specially constructed geo-database. A review of 6297 observation records showed thatF. circinatumand the symptoms it causes on conifers occurred in 14 countries, including four in Europe, and is absent in 28 countries. Field observations and experimental data from 138 host species revealed 106 susceptible host species including 85Pinusspecies, 6 non-pine tree species and 15 grass and herb species. Our data confirm that susceptibility toF. circinatumvaries between different host species, tree ages and environmental characteristics. Knowledge on the geographic distribution, host range and the relative susceptibility of different hosts is essential for disease management, mitigation and containment strategies. The findings reported in this review will support countries that are currently free ofF. circinatumin implementing effective procedures and restrictions and prevent further spread of the pathogen.
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| 26. |
- Cleary, Michelle
(författare)
-
High-throughput identification and diagnostics of pathogens and pests: Overview and practical recommendations
- 2019
-
Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-098X .- 1755-0998. ; 19, s. 47-76
-
Forskningsöversikt (refereegranskat)abstract
- High-throughput identification technologies provide efficient tools for understanding the ecology and functioning of microorganisms. Yet, these methods have been only rarely used for monitoring and testing ecological hypotheses in plant pathogens and pests in spite of their immense importance in agriculture, forestry and plant community dynamics. The main objectives of this manuscript are the following: (a) to provide a comprehensive overview about the state-of-the-art high-throughput quantification and molecular identification methods used to address population dynamics, community ecology and host associations of microorganisms, with a specific focus on antagonists such as pathogens, viruses and pests; (b) to compile available information and provide recommendations about specific protocols and workable primers for bacteria, fungi, oomycetes and insect pests; and (c) to provide examples of novel methods used in other microbiological disciplines that are of great potential use for testing specific biological hypotheses related to pathology. Finally, we evaluate the overall perspectives of the state-of-the-art and still evolving methods for diagnostics and population- and community-level ecological research of pathogens and pests.
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| 27. |
- Cleary, Michelle, et al.
(författare)
-
Increasing understanding of alien species through citizen science (Alien-CSI)
- 2018
-
Ingår i: Research Ideas and Outcomes. - : Pensoft Publishers. - 2367-7163. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- There is no sign of saturation in accumulation of alien species (AS) introductions worldwide, additionally the rate of spread for some species has also been shown to be increasing. However, the challenges of gathering information on AS are recognized. Recent developments in citizen science (CS) provide an opportunity to improve data flow and knowledge on AS while ensuring effective and high quality societal engagement with the issue of IAS (Invasive Alien Species). Advances in technology, particularly on-line recording and smartphone apps, along with the development of social media, have revolutionized CS and increased connectivity while new and innovative analysis techniques are emerging to ensure appropriate management, visualization, interpretation and use and sharing of the data. In early July 2018 we launched a European CO-operation in Science and Technology (COST) Action to address multidisciplinary research questions in relation to developing and implementing CS, advancing scientific understanding of AS dynamics while informing decision-making specifically implementation of technical requirements of relevant legislation such as the EU Regulation 1143/2014 on IAS. It will also support the EU biodiversity goals and embedding science within society. The Action will explore and document approaches to establishing a European-wide CS AS network. It will embrace relevant innovations for data gathering and reporting to support the implementation of monitoring and surveillance measures, while ensuring benefits for society and citizens, through an AS CS European network. The Action will, therefore, increase levels of participation and quality of engagement with current CS initiatives, ensuring and evaluating educational value, and improve the value outcomes for potential users including citizens, scientists, alien species managers, policy-makers, local authorities, industry and other stakeholders.
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| 28. |
- Cleary, Michelle
(författare)
-
Insights into the phylogeny of Northern Hemisphere Armillaria: Neighbor-net and Bayesian analyses of translation elongation factor 1-alpha gene sequences
- 2017
-
Ingår i: Mycologia. - : Informa UK Limited. - 0027-5514 .- 1557-2536. ; 109, s. 75-91
-
Tidskriftsartikel (refereegranskat)abstract
- Armillaria possesses several intriguing characteristics that have inspired wide interest in understanding phylogenetic relationships within and among species of this genus. Nuclear ribosomal DNA sequence based analyses of Armillaria provide only limited information for phylogenetic studies among widely divergent taxa. More recent studies have shown that translation elongation factor 1-alpha (tefl) sequences are highly informative for phylogenetic analysis of Armillaria species within diverse global regions. This study used Neighbor-net and coalescence-based Bayesian analyses to examine phylogenetic relationships of newly determined and existing tefl sequences derived from diverse Armillaria species from across the Northern Hemisphere, with Southern Hemisphere Armillaria species included for reference. Based on the Bayesian analysis of tefl sequences, Armillaria species from the Northern Hemisphere are generally contained within the following four superclades, which are named according to the specific epithet of the most frequently cited species within the superclade: (i) Socialis/Tabescens (exannulate) superclade including Eurasian A. ectypa, North American A. socialis (A. tabescens), and Eurasian A. socialis (A. tabescens) clades; (ii) Mellea superclade including undescribed annulate North American Armillaria sp. (Mexico) and four separate clades of A. mellea (Europe and Iran, eastern Asia, and two groups from North America); (iii) Gallica superclade including Armillaria Nag E (Japan), multiple clades of A. gallica (Asia and Europe), A. calvescens (eastern North America), A. cepistipes (North America), A. altimontana (western USA), A. nabsnona (North America and Japan), and at least two A. gallica clades (North America); and (iv) Solidipes/Ostoyae superclade including two A. solidipes/ostoyae clades (North America), A. gemina (eastern USA), A. solidipes/ostoyae (Eurasia), A. cepistipes (Europe and Japan), A. sinapina (North America and Japan), and A. borealis (Eurasia) Glade 2. Of note is that A. borealis (Eurasia) Glade 1 appears basal to the Solidipes/Ostoyae and Gallica superclades. The Neighbor-net analysis showed similar phylogenetic relationships. This study further demonstrates the utility of tefl for global phylogenetic studies of Armillaria species and provides critical insights into multiple taxonomic issues that warrant further study.
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| 29. |
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| 30. |
- Cleary, Michelle, et al.
(författare)
-
Natural infection of Fraxinus excelsior seeds by Chalara fraxinea
- 2013
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 43, s. 83-85
-
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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| 31. |
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| 32. |
- Cleary, Michelle
(författare)
-
Novel Pathogen-Plant Host Interaction: Colletotrichum jiangxiense and Fraxinus americana L. (White Ash) in a Sentinel Garden in China
- 2023
-
Ingår i: Plants. - 2223-7747. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Fraxinus americana L. (white ash), a native North American tree commonly cultivated for its ornamental qualities, displayed symptoms of leaf spot disease in a sentinel garden located in Nanjing, Jiangsu, China, in 2022. This disease led to premature leaf shedding, adversely affecting the plant's growth and substantially diminishing its ornamental value. Potential fungal pathogens were isolated from the diseased leaves and the subsequent application of Koch's postulates confirmed the pathogenicity of the fungal isolates (BL-1, BL-2). Through a combination of multi-locus phylogenetic analysis, including ITS, ACT, ApMat, CAL, CHS-1, GAPDH, and TUB2, alongside morphological assessments, the fungus was conclusively identified as Colletotrichum jiangxiense. This represents the first record of C. jiangxiense affecting white ash, highlighting the important role of sentinel gardens in uncovering novel pathogen-plant host interactions.
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| 33. |
- Cleary, Michelle, et al.
(författare)
-
Oomycetes in rhizosphere soil of ornamental plants from retail nurseries in Southern Sweden
- 2021
-
Ingår i: Forest Pathology. - : John Wiley & Sons. - 1437-4781 .- 1439-0329. ; 51:2
-
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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| 34. |
- Cleary, Michelle
(författare)
-
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
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 42, s. 481-491
-
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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| 35. |
- Cleary, Michelle, et al.
(författare)
-
Pine Pitch Canker and Insects: Regional Risks, Environmental Regulation, and Practical Management Options
- 2019
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 10
-
Forskningsöversikt (refereegranskat)abstract
- Pine pitch canker (PPC), caused by the pathogenic fungus Fusarium circinatum (Nirenberg and O' Donnell), is a serious threat to pine forests globally. The recent introduction of the pathogen to Southern Europe and its spread in Mediterranean region is alarming considering the immense ecological and economic importance of pines in the region. Pines in forests and nurseries can be infected, resulting in severe growth losses and mortality. The pathogen is known to spread in plants for planting and in seeds, and results from recent studies have indicated that F. circinatum may also spread through phoretic associations with certain insects. With this review, we aim to expand the current understanding of the risk of insect-mediated spread of PPC in different parts of Europe. Through the joint action of a multinational researcher team, we collate the existing information about the insect species spectrum in different biogeographic conditions and scrutinize the potential of these insects to transmit F. circinatum spores in forests and nurseries. We also discuss the impact of environmental factors and forest management in this context. We present evidence for the existence of a high diversity of insects with potential to weaken pines and disseminate PPC in Europe, including several common beetle species. In many parts of Europe, temperatures are projected to rise, which may promote the activity of several insect species, supporting multivoltinism and thus, further amplifying the risk of insect-mediated dissemination of PPC. Integrated pest management (IPM) solutions that comply with forest management practices need to be developed to reduce this risk. We recommend careful monitoring of insect populations as the basis for successful IPM. Improved understanding of environmental control of the interaction between insects, the pathogen, and host trees is needed in order to support development of bio-rational strategies to safeguard European pine trees and forests against F. circinatum in future.
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| 36. |
- Cleary, Michelle, et al.
(författare)
-
Potential Interactions between Invasive Fusarium circinatum and Other Pine Pathogens in Europe
- 2020
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 11
-
Forskningsöversikt (refereegranskat)abstract
- Pines are major components of native forests and plantations in Europe, where they have both economic significance and an important ecological role. Diseases of pines are mainly caused by fungal and oomycete pathogens, and can significantly reduce the survival, vigor, and yield of both individual trees and entire stands or plantations. Pine pitch canker (PPC), caused by Fusarium circinatum (Nirenberg and O'Donnell), is among the most devastating pine diseases in the world, and is an example of an emergent invasive disease in Europe. The effects of microbial interactions on plant health, as well as the possible roles plant microbiomes may have in disease expression, have been the focus of several recent studies. Here, we describe the possible effects of co-infection with pathogenic fungi and oomycetes with F. circinatum on the health of pine seedlings and mature plants, in an attempt to expand our understanding of the role that biotic interactions may play in the future of PPC disease in European nurseries and forests. The available information on pine pathogens that are able to co-occur with F. circinatum in Europe is here reviewed and interpreted to theoretically predict the effects of such co-occurrences on pine survival, growth, and yield. Beside the awareness that F. circinatum may co-occurr on pines with other pathogens, an additional outcome from this review is an updating of the literature, including the so-called grey literature, to document the geographical distribution of the relevant pathogens and to facilitate differential diagnoses, particularly in nurseries, where some of them may cause symptoms similar to those induced by F. circinatum. An early and accurate diagnosis of F. circinatum, a pathogen that has been recently introduced and that is currently regulated in Europe, is essential to prevent its introduction and spread in plantings and forests.
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| 37. |
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| 38. |
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| 39. |
- Cleary, Michelle, et al.
(författare)
-
Sampling and Detection Strategies for the Pine Pitch Canker (PPC) Disease Pathogen Fusarium circinatum in Europe
- 2019
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 10
-
Forskningsöversikt (refereegranskat)abstract
- Fusarium circinatum Nirenberg & O'Donnel is listed among the species recommended for regulation as quarantine pests in Europe. Over 60 Pinus species are susceptible to the pathogen and it also causes disease on Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and species in genera such as Picea and Larix. The European Food Safety Authority considers the probability of new introductions-via contaminated seeds, wood material, soil and growing substrates, natural means and human activities-into the EU very likely. Due to early detection, constant surveillance and control measures, F. circinatum outbreaks have officially been eradicated in Italy and France. However, the global spread of F. circinatum suggests that the pathogen will continue to be encountered in new environments in the future. Therefore, continuous surveillance of reproductive material, nurseries and plantations, prompt control measures and realistic contingency plans will be important in Europe and elsewhere to limit disease spread and the "bridgehead effect", where new introductions of a tree pathogen become increasingly likely as new environments are invaded, must be considered. Therefore, survey programs already implemented to limit the spread in Europe and that could be helpful for other EU countries are summarized in this review. These surveys include not only countries where pitch canker is present, such as Portugal and Spain, but also several other EU countries where F. circinatum is not present. Sampling protocols for seeds, seedlings, twigs, branches, shoots, soil samples, spore traps and insects from different studies are collated and compiled in this review. Likewise, methodology for morphological and molecular identification is herein presented. These include conventional PCR with a target-specific region located in the intergenic spacer region, as well as several real-time PCR protocols, with different levels of specificity and sensitivity. Finally, the global situation and future perspectives are addressed.
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| 40. |
- Cleary, Michelle
(författare)
-
Seed quantity affects the fungal community composition detected using metabarcoding
- 2022
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Pest introductions via trade in tree seed may result from a lack of adequate survey and validation protocols. Developing better diagnostic protocols to identify potentially harmful pests and pathogens in forest tree seed is of critical importance. High-throughput sequencing-based barcoding and metabarcoding provide effective tools for screening potentially harmful organisms in various plant materials, including seeds. However, the sample size needed to detect the total microorganism diversity of a community is a major challenge in microbiome studies. In this work, we examined how increasing sample size (ranging between 100 and 1000 seeds) influences diversity of fungal communities detected by high throughput sequencing in Pinus sylvestris seeds. Our results showed that as sample size increased, fungal alpha diversity also increased. Beta-diversity estimators detected significant differences between the mycobiota from different samples. However, taxonomic and functional diversity were not correlated with sample size. In addition, we found that increasing the number of PCR replicates resulted in a higher abundance of plant pathogens. We concluded that for the purpose of screening for potentially harmful pathogens using HTS, greater efforts should be made to increase the sample size and replicates when testing tree seed.
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| 41. |
- Cleary, Michelle, et al.
(författare)
-
Stump removal to control root disease in Canada and Scandinavia: A synthesis of results from long-term trials
- 2013
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 290, s. 5-14
-
Tidskriftsartikel (refereegranskat)abstract
- Heterobasidion annosum sensu lato (s.l.), Armillaria ostoyae, and Phellinus sulphurascens are economically important fungal pathogens in temperate forests of the northern hemisphere that cause decay, growth reduction and tree mortality of coniferous hosts. Fungal inoculum residing in roots and stumps after final felling can remain viable for decades and place stands at an increased risk of mortality in subsequent rotations. Stump removal is one strategy that can be used to reduce the impact of root rot fungi in regenerating stands. This paper presents results from five long-term stump removal trials in Canada, Denmark, and Sweden. In all studies, stumps were extracted and larger roots removed. After a period of time ranging between 21 and 50 years, tree mortality, infection or both caused by A. ostoyae, P. sulphurascens and H. annosum s.l. was compared between stumped and non-stumped areas. In all but one trial, efficacy of stump removal to reduce disease occurrence over the long-term was 80-100% for A. ostoyae, 85-100% for P. sulphurascens, and 20-72% for H. annosum s.l. Stump removal for H. annosum s.l. was more effective in the Swedish trial than in the Danish trial, but in both locations the frequency of root disease increased with tree age. Results from trials indicate that stump removal is effective in reducing disease incidence and likely improves site productivity in subsequent rotations. Forest managers should consider stump removal as a routine operation when harvesting, especially on sites that have high hazard for A. ostoyae, P. sulphurascens, or both. Even though stump removal can provide adequate control against H. annosum, use of the biocontrol agent Phlebiopsis gigantea on freshly cut stump surfaces after harvest and following thinnings is perhaps a more cost effective control measure to reduce the frequency of H. annosum rot in next rotation forests. New initiatives involving harvesting of stumps for bioenergy may offer the additional benefit of minimizing disease impacts in next rotation forests. (C) 2012 Crown Copyright and Elsevier B.V. All rights reserved.
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| 42. |
- 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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| 43. |
- 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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| 44. |
- Cleary, Michelle, et al.
(författare)
-
The increasing threat to European forests from the invasive foliar pine pathogen, Lecanosticta acicola
- 2023
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 536
-
Tidskriftsartikel (refereegranskat)abstract
- European forests are threatened by increasing numbers of invasive pests and pathogens. Over the past century, Lecanosticta acicola, a foliar pathogen predominantly of Pinus spp., has expanded its range globally, and is increasing in impact. Lecanosticta acicola causes brown spot needle blight, resulting in premature defoliation, reduced growth, and mortality in some hosts. Originating from southern regions of North American, it devastated forests in the USA's southern states in the early twentieth century, and in 1942 was discovered in Spain.Derived from Euphresco project 'Brownspotrisk,' this study aimed to establish the current distribution of Lecanosticta species, and assess the risks of L. acicola to European forests. Pathogen reports from the literature, and new/ unpublished survey data were combined into an open-access geo-database (http://www.portaloff orestpathology.com), and used to visualise the pathogen's range, infer its climatic tolerance, and update its host range. Lecanosticta species have now been recorded in 44 countries, mostly in the northern hemisphere. The type species, L. acicola, has increased its range in recent years, and is present in 24 out of the 26 European countries where data were available. Other species of Lecanosticta are largely restricted to Mexico and Central America, and recently Colombia.The geo-database records demonstrate that L. acicola tolerates a wide range of climates across the northern hemisphere, and indicate its potential to colonise Pinus spp. forests across large swathes of the Europe. Pre-liminary analyses suggest L. acicola could affect 62% of global Pinus species area by the end of this century, under climate change predictions.Although its host range appears slightly narrower than the similar Dothistroma species, Lecanosticta species were recorded on 70 host taxa, mostly Pinus spp., but including, Cedrus and Picea spp. Twenty-three, including species of critical ecological, environmental and economic significance in Europe, are highly susceptible to L. acicola, suffering heavy defoliation and sometimes mortality. Variation in apparent susceptibility between reports could reflect variation between regions in the hosts' genetic make-up, but could also reflect the signif-icant variation in L. acicola populations and lineages found across Europe. This study served to highlight sig-nificant gaps in our understanding of the pathogen's behaviour.Lecanosticta acicola has recently been downgraded from an A1 quarantine pest to a regulated non quarantine pathogen, and is now widely distributed across Europe. With a need to consider disease management, this study also explored global BSNB strategies, and used Case Studies to summarise the tactics employed to date in Europe.
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| 45. |
- Cleary, Michelle
(författare)
-
Tree species selection revisited for plantations in the Interior Cedar Hemlock zone of southern British Columbia
- 2013
-
Ingår i: Forestry Chronicle. - : Canadian Institute of Forestry. - 0015-7546 .- 1499-9315. ; 89, s. 382-391
-
Tidskriftsartikel (refereegranskat)abstract
- We provide results from two trials comparing performance of species of known provenance planted on logged sites in the southern Interior Cedar Hemlock biogeoclimatic zone of southern British Columbia 20 and 26 years after establishment. The commonly used plantation species, lodgepole pine (Pinus contorta var. latifolia), interior spruce (a naturally occurring hybrid between Picea glauca and P. engelmannii) and Douglas-fir (Pseudotsuga menziesii var. glauca), survived as well as, but grew more slowly than, western larch (Larix occidentalis), western white pine (Pinus monticola) and ponderosa pine (Pinus ponderosa), and faster than western redcedar (Thuja plicata). Site index values were generally higher than published values for similar sites. Numerous pests affected all species in the trials. Mountain pine beetle (Dendroctonus ponderosae) caused heavy mortality in lodgepole pine in part of one trial, and Armillaria root disease caused widespread damage to western larch and Douglas-fir in the other trial. Western white pine from local seed sources were severely damaged by white pine blister rust (Cronartium ribicola) in both trials but a rust-resistant seed source used in one trial survived better. Frost damage reduced survival and growth of Douglas-fir in one trial and may have affected western white pine. Survival of two planted broadleaves (Betula papyrifera) and a hybrid of black cottonwood (Populus trichocarpa) and black poplar (Populus nigra) was severely reduced by drought. The results support ongoing efforts to broaden the number of species used in British Columbia reforestation programs.
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| 46. |
- Davydenko, Kateryna, et al.
(författare)
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Forewarned is forearmed: harmonized approaches for early detection of potentially invasive pests and pathogens in sentinel plantings
- 2019
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Ingår i: NeoBiota. - : Pensoft Publishers. - 1619-0033 .- 1314-2488. ; , s. 95-123
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Tidskriftsartikel (refereegranskat)abstract
- The number of invasive alien pest and pathogen species affecting ecosystem functioning, human health and economies has increased dramatically over the last decades. Discoveries of invasive pests and pathogens previously unknown to science or with unknown host associations yet damaging on novel hosts highlights the necessity of developing novel tools to predict their appearance in hitherto naive environments. The use of sentinel plant systems is a promising tool to improve the detection of pests and pathogens before introduction and to provide valuable information for the development of preventative measures to minimize economic or environmental impacts. Though sentinel plantings have been established and studied during the last decade, there still remains a great need for guidance on which tools and protocols to put into practice in order to make assessments accurate and reliable. The sampling and diagnostic protocols chosen should enable as much information as possible about potential damaging agents and species identification. Consistency and comparison of results are based on the adoption of common procedures for sampling design and sample processing. In this paper, we suggest harmonized procedures that should be used in sentinel planting surveys for effective sampling and identification of potential pests and pathogens. We also review the benefits and limitations of various diagnostic methods for early detection in sentinel systems, and the feasibility of the results obtained supporting National Plant Protection Organizations in pest and commodity risk analysis.
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| 47. |
- Davydenko, Kateryna, et al.
(författare)
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Fraxinus excelsior seed is not a probable introduction pathway for Hymenoscyphus fraxineus
- 2018
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 48
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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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| 48. |
- Elfstrand, Malin, et al.
(författare)
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Comparative analyses of the Hymenoscyphus fraxineus and Hymenoscyphus albidus genomes reveals potentially adaptive differences in secondary metabolite and transposable element repertoires
- 2021
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Background The dieback epidemic decimating common ash (Fraxinus excelsior) in Europe is caused by the invasive fungus Hymenoscyphus fraxineus. In this study we analyzed the genomes of H. fraxineus and H. albidus, its native but, now essentially displaced, non-pathogenic sister species, and compared them with several other members of Helotiales. The focus of the analyses was to identify signals in the genome that may explain the rapid establishment of H. fraxineus and displacement of H. albidus. Results The genomes of H. fraxineus and H. albidus showed a high level of synteny and identity. The assembly of H. fraxineus is 13 Mb longer than that of H. albidus', most of this difference can be attributed to higher dispersed repeat content (i.e. transposable elements [TEs]) in H. fraxineus. In general, TE families in H. fraxineus showed more signals of repeat-induced point mutations (RIP) than in H. albidus, especially in Long-terminal repeat (LTR)/Copia and LTR/Gypsy elements. Comparing gene family expansions and 1:1 orthologs, relatively few genes show signs of positive selection between species. However, several of those did appeared to be associated with secondary metabolite genes families, including gene families containing two of the genes in the H. fraxineus-specific, hymenosetin biosynthetic gene cluster (BGC). Conclusion The genomes of H. fraxineus and H. albidus show a high degree of synteny, and are rich in both TEs and BGCs, but the genomic signatures also indicated that H. albidus may be less well equipped to adapt and maintain its ecological niche in a rapidly changing environment.
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| 49. |
- Felton, Adam, et al.
(författare)
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Forest biodiversity and ecosystem services from spruce-birch mixtures : The potential importance of tree spatial arrangement
- 2022
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Ingår i: Environmental Challenges. - : Elsevier BV. - 2667-0100. ; 6
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Forskningsöversikt (refereegranskat)abstract
- There is increasing empirical support for the biodiversity and ecosystem service (ES) benefits of mixed-species production forests. However, few studies control for the spatial arrangement of the trees within mixtures to determine the influence that clustering the tree species (patch scale mixtures), versus evenly dispersing them (intimate scale mixtures), may have for biodiversity and ES outcomes. To highlight the potential implications of altering tree spatial arrangement in mixtures, and the need to fill related knowledge gaps, here we provide a qualitative multi-disciplinary overview of ecological and socio-economic drivers with the potential to alter biodiversity, ecosystem services, and management-related outcomes from patch versus intimate scale mixtures. We focused our overview on even-aged mixtures of Norway spruce (Picea abies) and birch (Betula pendula or B. pubescens) in Sweden, which enabled us to contrast findings within a biogeographical and silvicultural setting. Specifically, we targeted implications for biodiversity (understory vascular plants, epiphytic lichens, saproxylic beetles, birds), biomass production, harvesting costs, management ease, recreation and aesthetics, cervid game, as well as abiotic and biotic risks (wind, fire, pathogens, pests, browsing damage). In the absence of direct empirical evidence, we primarily relied on expert inference from theory and relevant empirical studies sourced from the Fennoscandian region, and further afield if needed. Collectively these efforts allowed us to develop a number of informed hypotheses indicating that for spruce-birch mixtures in this region, patch scale mixtures may have the potential to favour the diversity of several forest dependant taxonomic groups, cervid game and reduce harvesting costs, whereas intimate mixtures may have the potential to reduce pathogen and pest damage, and likewise, potentially benefit production outcomes. Current knowledge was too limited, inconsistent or context dependant to even tentatively infer outcomes for fire risk, wind damage, browsing damage, management ease, recreational and aesthetic outcomes. We emphasize that our hypotheses require testing, but are sufficient to (1) highlight the likely importance of spatial-scale to biodiversity and ecosystem services outcomes in mixed-species production forests, (2) caution against generalization from mixture studies that lack scale considerations, and (3) motivate the targeted consideration of spatial grain in future mixture studies.
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| 50. |
- Felton, Adam, et al.
(författare)
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The tree species matters : Biodiversity and ecosystem service implications of replacing Scots pine production stands with Norway spruce.
- 2020
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Ingår i: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 49:5, s. 1035-1049
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Forskningsöversikt (refereegranskat)abstract
- The choice of tree species used in production forests matters for biodiversity and ecosystem services. In Sweden, damage to young production forests by large browsing herbivores is helping to drive a development where sites traditionally regenerated with Scots pine (Pinus sylvestris) are instead being regenerated with Norway spruce (Picea abies). We provide a condensed synthesis of the available evidence regarding the likely resultant implications for forest biodiversity and ecosystem services from this change in tree species. Apart from some benefits (e.g. reduced stand-level browsing damage), we identified a range of negative outcomes for biodiversity, production, esthetic and recreational values, as well as increased stand vulnerability to storm, frost, and drought damage, and potentially higher risks of pest and pathogen outbreak. Our results are directly relevant to forest owners and policy-makers seeking information regarding the uncertainties, risks, and trade-offs likely to result from changing the tree species in production forests.
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