Venche Talgø
Research Scientist
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Katherine Ann Gredvig Nielsen Magne Nordang Skårn Venche Talgø Martin Pettersson Inger Sundheim Fløistad Gunn Strømeng May Bente Brurberg Arne StensvandAbstract
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Iva Franić Eric Allan Simone Prospero Kalev Adamson Fabio Attorre Marie-Anne Auger-Rozenberg Sylvie Augustin Dimitrios Avtzis Wim Baert Marek Barta Kenneth Bauters Amani Bellahirech Piotr Boroń Helena Bragança Tereza Brestovanská May Bente Brurberg Treena Burgess Daiva Burokienė Michelle Cleary Juan Corley David R. Coyle György Csóka Karel Černý Kateryna Davydenko Maarten de Groot Julio Javier Diez H. Tuğba Doğmuş Lehtijärvi Rein Drenkhan Jacqueline Edwards Mohammed Elsafy Csaba Béla Eötvös Roman Falko Jianting Fan Nina Feddern Ágnes Fürjes-Mikó Martin M. Gossner Bartłomiej Grad Martin Hartmann Ludmila Havrdova Miriam Kádasi Horáková Marketa Hrabětová Mathias Just Justesen Magdalena Kacprzyk Marc Kenis Natalia Kirichenko Marta Kovač Volodymyr Kramarets Nikola Lacković Maria Victoria Lantschner Jelena Lazarević Marianna Leskiv Hongmei Li Corrie Lynne Madsen Chris Malumphy Dinka Matošević Iryna Matsiakh Tom W. May Johan Meffert Duccio Migliorini Christo Nikolov Richard O’Hanlon Funda Oskay Trudy Paap Taras Parpan Barbara Piškur Hans Peter Ravn John Richard Anne Ronse Alain Roques Beat Ruffner Alberto Santini Karolis Sivickis Carolina Soliani Venche Talgø Maria Tomoshevich Anne Uimari Michael Ulyshen Anna Maria Vettraino Caterina Villari Yongjun Wang Johanna Witzell Milica Zlatković René EschenAbstract
Non-native pests, climate change, and their interactions are likely to alter relationships between trees and tree-associated organisms with consequences for forest health. To understand and predict such changes, factors structuring tree-associated communities need to be determined. Here, we analysed the data consisting of records of insects and fungi collected from dormant twigs from 155 tree species at 51 botanical gardens or arboreta in 32 countries. Generalized dissimilarity models revealed similar relative importance of studied climatic, host-related and geographic factors on differences in tree-associated communities. Mean annual temperature, phylogenetic distance between hosts and geographic distance between locations were the major drivers of dissimilarities. The increasing importance of high temperatures on differences in studied communities indicate that climate change could affect tree-associated organisms directly and indirectly through host range shifts. Insect and fungal communities were more similar between closely related vs. distant hosts suggesting that host range shifts may facilitate the emergence of new pests. Moreover, dissimilarities among tree-associated communities increased with geographic distance indicating that human-mediated transport may serve as a pathway of the introductions of new pests. The results of this study highlight the need to limit the establishment of tree pests and increase the resilience of forest ecosystems to changes in climate.
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Taavi Riit Michelle Cleary Kalev Adamson Mimmi Blomquist Daiva Burokienė Diana Marčiulynienė Jonàs Oliva Anna Poimala Miguel Angel Redondo Gunn Strømeng Venche Talgø Leho Tedersoo Iben Margrete Thomsen Anne Uimari Johanna Witzell Rein DrenkhanAbstract
This study aimed to determine the differences and drivers of oomycete diversity and community composition in alder- and birch-dominated park and natural forest soils of the Fennoscandian and Baltic countries of Estonia, Finland, Lithuania, Norway, and Sweden. For this, we sequenced libraries of PCR products generated from the DNA of 111 soil samples collected across a climate gradient using oomycete-specific primers on a PacBio high-throughput sequencing platform. We found that oomycete communities are most affected by temperature seasonality, annual mean temperature, and mean temperature of the warmest quarter. Differences in composition were partly explained by the higher diversity of Saprolegniales in Sweden and Norway, as both total oomycete and Saprolegniales richness decreased significantly at higher longitudes, potentially indicating the preference of this group of oomycetes for a more temperate maritime climate. None of the evaluated climatic variables significantly affected the richness of Pythiales or Peronosporales. Interestingly, the relative abundance and richness of Pythiales was higher at urban sites compared to forest sites, whereas the opposite was true for Saprolegniales. Additionally, this is the first report of Phytophthora gallica and P. plurivora in Estonia. Our results indicate that the composition of oomycetes in soils is strongly influenced by climatic factors, and, therefore, changes in climate conditions associated with global warming may have the potential to significantly alter the distribution range of these microbes, which comprise many important pathogens of plants.
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Iva Franić Michelle Cleary Ayse Gülden Aday Kaya Helena Bragança Guro Brodal Thomas L. Cech Anne Chandelier Tuğba Doğmuş-Lehtijärvi René Eschen Asko Lehtijärvi Michael Ormsby Simone Prospero Katharina Schwanda Katarzyna Sikora Hanna Szmidla Venche Talgø Miłosz Tkaczyk Anna Maria Vettraino Ana Pérez-SierraAbstract
Purpose of Review Because tree seeds have been considered a low-risk pathway for the spread of plant pathogenic fungi, their international movement is not subject to strict phytosanitary regulation. However, recent studies have provided scientific evidence that the biosecurity risk of seed trade may not be as negligible as assumed. This review summarises current knowledge about seed trade activity across the world and seed-borne plant pathogenic fungi and highlights knowledge gaps that need to be filled to mitigate the risk of spreading tree pathogens via seeds. Recent Findings Several outbreaks of severe tree diseases in natural forests and plantations worldwide have been linked to fungal pathogens spread by seed trade. Indeed, recent studies based on modern sequencing technologies have shown that tree seeds harbour highly diverse fungal communities, including well-known pathogens and fungal taxa belonging to unknown species. While it has become clear that even apparently healthy seeds can carry potentially pathogenic fungi, the likelihood of seed-borne pathogens being introduced and becoming established, spreading and causing impact in the new environment is still unclear which challenges the assessment of the phytosanitary risk posed by seed trade. Summary Our analyses show that large amounts of tree seeds have been traded among countries and continents. Based on published literature, the risk of spreading pathogenic fungi via tree seed movement is high. However, the role of the taxonomically and functionally diverse fungal communities associated with seeds is still poorly understood. In particular, more research is needed to assess the likelihood of seed-borne fungi being transmitted to the seedlings and spreading and causing impact in the new environment.
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Katherine Ann Gredvig Nielsen Magne Nordang Skårn Venche Talgø Martin Pettersson Inger Sundheim Fløistad Gunn Strømeng May Bente Brurberg Arne StensvandAbstract
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Katherine Ann Gredvig Nielsen Magne Nordang Skårn Venche Talgø Martin Petterson Inger Sundheim Fløistad Gunn Mari Strømeng May Bente Brurberg Arne StensvandAbstract
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Venche Talgø Thomas Jung Ivan Milenković Tamara Corcobado Martin Pettersson May Bente BrurbergAbstract
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Plants with roots and soil clumps transported over long distances in plant trading can harbor plant pathogenic oomycetes, facilitating disease outbreaks that threaten ecosystems, biodiversity, and food security. Tools to detect the presence of such oomycetes with a sufficiently high throughput and broad scope are currently not part of international phytosanitary testing regimes. In this work, DNA metabarcoding targeting the internal transcribed spacer (ITS) region was employed to broadly detect and identify oomycetes present in soil from internationally shipped plants. This method was compared to traditional isolation-based detection and identification after an enrichment step. DNA metabarcoding showed widespread presence of potentially plant pathogenic Phytophthora and Pythium species in internationally transported rhizospheric soil with Pythium being the overall most abundant genus observed. Baiting, a commonly employed enrichment method for Phytophthora species, led to an increase of golden-brown algae in the soil samples, but did not increase the relative or absolute abundance of potentially plant pathogenic oomycetes. Metabarcoding of rhizospheric soil yielded DNA sequences corresponding to oomycete isolates obtained after enrichment and identified them correctly but did not always detect the isolated oomycetes in the same samples. This work provides a proof of concept and outlines necessary improvements for the use of environmental DNA (eDNA) and metabarcoding as a standalone phytosanitary assessment tool for broad detection and identification of plant pathogenic oomycetes.
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Paal Krokene Bjørn Arild Hatteland Christer Magnusson Daniel Flø Iben Margrete Thomsen Johan A. Stenberg May Bente Brurberg Per Hans Micael Wendell Mogens Nicolaisen Simeon Rossmann Venche Talgø Beatrix Alsanius Sandra A.I. Wright Trond RafossAbstract
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Venche Talgø Martin Pettersson Magnhild Sekse Erdal May Bente Brurberg Sigrid Mogan Arne StensvandAbstract
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Hanno Sandvik Olga Hilmo Snorre Henriksen Reidar Elven Per Arvid Åsen Hanne Hegre Oddvar Pedersen Per Anker Pedersen Heidi Solstad Vigdis Vandvik Kristine Bakke Westergaard Frode Ødegaard Sandra Charlotte Helene Åström Hallvard Elven Anders Endrestøl Øivind Gammelmo Bjørn Arild Hatteland Halvor Solheim Björn Nordén Leif Sundheim Venche Talgø Tone Falkenhaug Bjørn Gulliksen Anders Jelmert Eivind Oug Jan Henry Sundet Elisabet Forsgren Anders Gravbrøt Finstad Trygve H. Hesthagen Kjell Harald Nedreaas Rupert Wienerroither Vivian Husa Stein Fredriksen Kjersti Sjøtun Henning Steen Haakon Hansen Inger Sofie Hamnes Egil Karlsbakk Christer Magnusson Bjørnar Ytrehus Hans Christian Pedersen Jon Swenson Per Ole Syvertsen Bård Gunnar Stokke Jan Ove Gjershaug Dag Dolmen Gaute Kjærstad Stein Ivar Johnsen Thomas Correll Jensen Kristian Hassel Lisbeth GederaasAbstract
1. Due to globalisation, trade and transport, the spread of alien species is increasing dramatically. Some alien species become ecologically harmful by threatening native biota. This can lead to irreversible changes in local biodiversity and ecosystem functioning, and, ultimately, to biotic homogenisation. 2. We risk-assessed all alien plants, animals, fungi and algae, within certain delimitations, that are known to reproduce in Norway. Mainland Norway and the Arctic archipelago of Svalbard plus Jan Mayen were treated as separate assessment areas. Assessments followed the Generic Ecological Impact Assessment of Alien Species (GEIAA) protocol, which uses a fully quantitative set of criteria. 3. A total of 1519 species were risk-assessed, of which 1183 were species reproducing in mainland Norway. Among these, 9% were assessed to have a severe impact, 7% high impact, 7% potentially high impact, and 49% low impact, whereas 29% had no known impact. In Svalbard, 16 alien species were reproducing, one of which with a severe impact. 4. The impact assessments also covered 319 so-called door-knockers, i.e. species that are likely to establish in Norway within 50 years, and 12 regionally alien species. Of the door-knockers, 8% and 10% were assessed to have a severe and high impact, respectively. 5. The impact category of most species was driven by negative interactions with native species, transformation of threatened ecosystems, or genetic contamination. The proportion of alien species with high or severe impact varied significantly across the different pathways of introduction, taxonomic groups, time of introduction, and the environments colonised, but not across continents of origin. 6. Given the large number of alien species reproducing in Norway and the preponderance of species with low impact, it is neither realistic nor necessary to eradicate all of them. Our results can guide management authorities in two ways. First, the use of quantitative assessment criteria facilitates the prioritisation of management resources across species. Second, the background information collected for each species, such as introduction pathways, area of occupancy and ecosystems affected, helps designing appropriate management measures.
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Hanno Sandvik Olga Hilmo Snorre Henriksen Reidar Elven Per Arvid Åsen Hanne Hegre Oddvar Pedersen Per Anker Pedersen Heidi Solstad Vigdis Vandvik Kristine Bakke Westergaard Frode Ødegaard Sandra Charlotte Helene Åström Hallvard Elven Anders Endrestøl Øivind Gammelmo Bjørn Arild Hatteland Halvor Solheim Björn Nordén Leif Sundheim Venche Talgø Tone Falkenhaug Bjørn Gulliksen Anders Jelmert Eivind Oug Jan Henry Sundet Elisabet Forsgren Anders Gravbrøt Finstad Trygve H. Hesthagen Kjell Harald Nedreaas Rupert Wienerroither Vivian Husa Stein Fredriksen Kjersti Sjøtun Henning Steen Haakon Hansen Inger Sofie Hamnes Egil Karlsbakk Christer Magnusson Bjørnar Ytrehus Hans Christian Pedersen Jon Swenson Per Ole Syvertsen Bård Gunnar Stokke Jan Ove Gjershaug Dag Dolmen Gaute Kjærstad Stein Ivar Johnsen Thomas Correll Jensen Kristian Hassel Lisbeth GederaasAbstract
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In integrated pest management (IPM), the goal is to keep the impact of damaging agents below a threshold level with reduced pesticide use. The present review is focusing on IPM of fungal diseases and Phytophthora root rot in Norwegian Christmas tree plantations. Healthy transplants are of vital importance to give the production a good establishment. Sanitation of diseased material and weeds is also very important in IPM. Management strategies will vary with the disease-causing agent in question, therefore, correct identification is necessary. The major pathogens are within the kingdom’s Fungi (e.g. Neonectria neomacrospora) and Chromista (e.g. Phytophthora spp.). They depend on relatively high humidity or free moisture to spread and infect. Any factors diminishing the duration of wet conditions will, therefore, reduce the disease pressure. Efficient weed management in Christmas tree fields will increase air circulation and thereby ensure a quicker drying after precipitation. Furthermore, certain weed species are host plants for rust fungi on Christmas trees, and thus, removal of the alternate host is a highly relevant control strategy. In Norway, fungicide use in Christmas trees is limited and only recommended during the short period from bud break to fully elongated shoots, generally the most vulnerable period concerning fungal attacks.
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Guro Brodal Heidi Røsok Bye Eleonora Høst Martin Pettersson Inger Sundheim Fløistad Øyvind Meland Edvardsen Venche TalgøAbstract
Seedling blight caused by Sirococcus conigenus was recently reported on Norway spruce (Picea abies) from Norwegian forest nurseries. The inoculum source was found to be infected seeds. In a Petri dish assay, the fungicide fludioxonil + difenoconazole was, among other fungicides, found to inhibit mycelial growth of S. conigenus. This fungicide is formulated as a seed treatment and registered for cereals in Norway, and was chosen for an experiment to control S. conigenus on Norway spruce seeds. Samples from two naturally infected seed lots were treated with half, normal and double dose of the recommended rate for cereals. Together with untreated control samples, treated seeds were tested in the laboratory for efficacy against S. conigenus on potato dextrose agar (PDA) in Petri dishes and for germination potential on filter paper. We also recorded seed emergence in soil of one of the seed lots in a growth chamber and in a forest nursery. On agar, the fungus was not detected after seed treatment with fludioxonil + difenoconazole at any of the three dosages, but it was present in the control. Germination on filter paper and emergence in soil was high in both treated and untreated control seeds with no signs of detrimental effects from any of the three fungicide doses.
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Martin Pettersson Venche Talgø Odd Ragnar Johnskås Jan-Ole Skage Torfinn Torp Inger Sundheim FløistadAbstract
Norway spruce (Picea abies) is a widely used Christmas tree species in the Nordic countries. Postharvest needle retention is an important characteristic for Christmas trees and compared to many fir (Abies) species, Norway spruce has poor postharvest needle retention. This trait is one of the most important qualities in choice of natural versus plastic trees. In this study, current year shoots were cut from 30 Norway spruce seedlot sources, including the most widely used Norwegian Christmas tree provenances, and tested to identify genetic variation in postharvest needle retention. Current year shoots were collected from one field in November and December 2018, and from three fields in October, November and December 2019. The current year shoots were displayed indoors under controlled conditions and allowed to dry. Differences in postharvest needle retention were seen between seedlots, harvesting dates and locations. Our study indicates possibilities of selecting for improved postharvest needle retention in Norway spruce seed sources. Furthermore, postharvest needle retention should be considered as one characteristic to add in the ongoing Norway spruce Christmas tree breeding program.
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Carmen Morales-Rodriguez Sten Anslan Marie-Anne Auger-Rozenberg S. Augustin Yuri N. Baranchikov Amani Bellahirech Daiva Burokiene Dovilė Čepukoit Ejup Çota K Davydenko H.T. Doğmuş-Lehtijärvi R. Drenkhan T. Drenkhan Rene Eschen I. Franić M. Glavendekić MB De Groot Magdalena Kacprzyk Marc Kenis Natalia Kirichenko I. Matsiakh DL Musolin Justyna A. Nowakowska Richard O’Hanlon S. Prospero A Roques A Santini Venche Talgø Leho Tedersoo A Uimari A. Vannini J Witzell S Woodward Antonios Zambounis Michelle ClearyAbstract
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Hanno Sandvik Dag Dolmen Reidar Elven Tone Falkenhaug Elisabet Forsgren Haakon Hansen Kristian Hassel Vivian Husa Gaute Kjærstad Frode Ødegaard Hans Christian Pedersen Halvor Solheim Bård Gunnar Stokke Per Arvid Åsen Sandra Åström Tor Erik Brandrud Hallvard Elven Anders Endrestøl Anders Gravbrøt Finstad Stein Fredriksen Øivind Gammelmo Jan Ove Gjershaug Bjørn Gulliksen Inger Hamnes Bjørn Arild Hatteland Hanne Hegre Trygve Hesthagen Anders Jelmert Thomas C Jensen Stein Ivar Johnsen Egil Karlsbakk Christer Magnusson Kjell Nedreaas Björn Nordén Eivind Oug Oddvar Pedersen Per Anker Pedersen Kjersti Sjøtun Jon Kristian Skei Heidi Solstad Leif Sundheim Jon E Swenson Per Ole Syvertsen Venche Talgø Vigdis Vandvik Kristine B Westergaard Rupert Wienerroither Bjørnar Ytrehus Olga Hilmo Snorre Henriksen Lisbeth GederaasAbstract
We present the results of an inventory and status assessment of alien species in Norway. The inventory covered all known multicellular neobiota, 2496 in total, 1039 of which were classified as naturalised. The latter constitute c. 3% of all species known to be stably reproducing in Norway. These figures are higher than expected from Norway’s latitude, which may be due a combination of climatic and historical factors, as well as sampling effort. Most of the naturalised neobiota were plants (71%),followed by animals (21%) and fungi (8%). The main habitat types colonised were open lowlands (79%), urban environments (52%) and woodlands (42%). The main areas of origin were Europe (67%), North America (15%) and Asia (13%). For most taxa, the rate of novel introductions seems to have been increasing during recent decades. Within Norway, the number of alien species recorded per county was negatively correlated with latitude and positively correlated with human population density. In the high-Arctic territories under Norwegian sovereignty, i.e. Svalbard and Jan Mayen, 104 alien species were recorded, of which 5 were naturalised.
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Pablo González-Moreno Lorenzo Lazzaro Montserrat Vilà Cristina Preda Tim Adriaens Sven Bacher Giuseppe Brundu Gordon H. Copp Franz Essl Emili Garcia-Berthou Stelios Katsanevakis Toril Loennechen Moen Frances E. Lucy Wolfgang Nentwig Helen E. Roy Greta Srėbalienė Venche Talgø Sonia Vanderhoeven Ana Andjelković Kęstutis Arbačiauskas Marie-Anne Auger-Rozenberg Mi-Jung Bae Michel Bariche Pieter Boets Mário Boieiro Paulo Alexandre Borges João Canning-Clode Frederico Cardigos Niki Chartosia Elizabeth Joanne Cottier-Cook Fabio Crocetta Bram D'hondt Bruno Foggi Swen Follak Belinda Gallardo Øivind Gammelmo Sylvaine Giakoumi Claudia Giuliani Guillaume Fried Lucija Šerić Jelaska Jonathan M. Jeschke Miquel Jover Alejandro Juárez-Escario Stefanos Kalogirou Aleksandra Kočić Eleni Kytinou Ciaran Laverty Vanessa Lozano Alberto Maceda-Veiga Elizabete Marchante Hélia Marchante Angeliki F. Martinou Sandro Meyer Dan Michin Ana Montero-Castaño Maria Cristina Morais Carmen Morales-Rodriguez Nadia Muhthassim Zoltán Á. Nagy Nikica Ogris Huseyin Onen Jan Pergl Riikka Puntila Wolfgang Rabitsch Triya Tessa Ramburn Carla Rego Fabian Reichenbach Carmen Romeralo Wolf-Christian Saul Gritta Schrader Rory Sheehan Predrag Simonović Marius Skolka António Onofre Soares Leif Sundheim Ali Serhan Tarkan Rumen Tomov Elena Tricarico Konstantinos Tsiamis Ahmet Uludağ Johan van Valkenburg Hugo Verreycken Anna Maria Vettraino Lluís Vilar Øystein Wiig Johanna Witzell Andrea Zanetta Marc KenisAbstract
Standardized tools are needed to identify and prioritize the most harmful non-native species (NNS). A plethora of assessment protocols have been developed to evaluate the current and potential impacts of non-native species, but consistency among them has received limited attention. To estimate the consistency across impact assessment protocols, 89 specialists in biological invasions used 11 protocols to screen 57 NNS (2614 assessments). We tested if the consistency in the impact scoring across assessors, quantified as the coefficient of variation (CV), was dependent on the characteristics of the protocol, the taxonomic group and the expertise of the assessor. Mean CV across assessors was 40%, with a maximum of 223%. CV was lower for protocols with a low number of score levels, which demanded high levels of expertise, and when the assessors had greater expertise on the assessed species. The similarity among protocols with respect to the final scores was higher when the protocols considered the same impact types. We conclude that all protocols led to considerable inconsistency among assessors. In order to improve consistency, we highlight the importance of selecting assessors with high expertise, providing clear guidelines and adequate training but also deriving final decisions collaboratively by consensus.
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Invasive alien species and new plant pests are introduced into new regions at an accelerating rate, due to increasing international trade with soil, plants and plant products. Exotic, plant pathogenic oomycetes in soil from the root zone of imported plants pose a great threat to endemic ecosystems and horticultural production. Detecting them via baiting and isolation, with subsequent identification of the isolated cultures by Sanger sequencing, is labour intensive and may introduce bias due to the selective baiting process. We used metabarcoding to detect and identify oomycetes present in soil samples from imported plants from six different countries. We compared metabarcoding directly from soil both before and after baiting to a traditional approach using Sanger-based barcoding of cultures after baiting. For this, we developed a standardized analysis workflow for Illumina paired-end oomycete ITS metabarcodes that is applicable to future surveillance efforts. In total, 73 soil samples from the rhizosphere of woody plants from 33 genera, in addition to three samples from transport debris, were analysed by metabarcoding the ITS1 region with primers optimized for oomycetes. We detected various Phytophthora and Pythium species, with Pythium spp. being highly abundant in all samples. We also found that the baiting procedure, which included submerging the soil samples in water, resulted in the enrichment of organisms other than oomycetes, compared to non-baited soil samples.
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Carmen Morales-Rodríguez Sten Anslan Marie-Anne Auger-Rozenberg Sylvie Augustin Yuri Baranchikov Amani Bellahirech Daiva Burokienė Dovilė Čepukoit Ejup Çota Kateryna Davydenko H. Tuğba Doğmuş Lehtijärvi Rein Drenkhan Tiia Drenkhan René Eschen Iva Franić Milka Glavendekić Maarten de Groot Magdalena Kacprzyk Marc Kenis Natalia Kirichenko Iryna Matsiakh Dmitry L. Musolin Justyna A. Nowakowska Richard O’Hanlon Simone Prospero Alain Roques Alberto Santini Venche Talgø Leho Tedersoo Anne Uimari Andrea Vannini Johanna Witzell Steve Woodward Antonios Zambounis Michelle ClearyAbstract
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 naïve 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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S. 48 i https://www.iufro.org/fileadmin/material/publications/proceedings-archive/20209-ctre-proceedings-19.pdf
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S. 47 i . https://www.iufro.org/fileadmin/material/publications/proceedings-archive/20209-ctre-proceedings-19.pdf
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Venche TalgøAbstract
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S. 26 i https://www.iufro.org/fileadmin/material/publications/proceedings-archive/20209-ctre-proceedings-19.pdf
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Venche TalgøAbstract
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S. 33 i . https://www.iufro.org/fileadmin/material/publications/proceedings-archive/20209-ctre-proceedings-19.pdf
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A. Pérez-Sierra V. Rafiei C. Olivares H. Rees S. van der Linde N. Keča K. Schwanda Venche Talgø B. B. LandaAbstract
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Venche TalgøAbstract
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Marie-Laure Desprez-Loustau Marie Massot Maude Toïgo Tania Fort Ayse Gülden Aday Kaya Johanna Boberg Uwe Braun Xavier Capdevielle Thomas Cech Anne Chandelier Petya Christova Tamara Corcobado Tugba Dogmus Cyril Dutech Olivier Fabreguettes Julie Faivre d'Arcier Andrin Gross Marilia Horta Jung Eugenia Iturritxa Thomas Jung Corina Junker Levente Kiss Kaloyan Kostov Asko Lehtijarvi Aneta Lyubenova Benoit Marçais Jonas Oliva Funda Oskay Martin Pastirčák Katarína Pastircakova Dominique Piou Gilles Saint-Jean Arnaud Sallafranque Slavtcho Slavov Jan Stenlid Venche Talgø Susumu Takamatsu Ayco JM. TackAbstract
The spatial distribution and niche differentiation of three closely related species (Erysiphe alphitoides, Erysiphe quercicola and Erysiphe hypophylla) causing oak powdery mildew was studied at scales ranging from the European continent, where they are invasive, to a single leaf. While E. alphitoides was dominant at all scales, E. quercicola and E. hypophylla had restricted geographic, stand and leaf distributions. The large-scale distributions were likely explained by climatic factors and species environmental tolerances, with E. quercicola being more frequent in warmer climates and E. hypophylla in colder climates. The extensive sampling and molecular analyses revealed the cryptic invasion of E. quercicola in nine countries from which it had not previously been recorded. The presence of the three species was also strongly affected by host factors, such as oak species and developmental stage. Segregation patterns between Erysiphe species were observed at the leaf scale, between and within leaf surfaces, suggesting competitive effects.
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Guro Brodal Heidi Røsok Bye May Bente Brurberg Inger Sundheim Fløistad Øyvind Meland Edvardsen Venche TalgøAbstract
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Total forfattarliste: Franić, I., Prospero, S., Adamson, K., Allan, A., Auger-Rozenberg, A-M, Augustin, S., Avtzis, D., Barta, M., Boroń, P., Bragança, H., Brestovanská, T., Brurberg, M. B., Burgess, B., Burokienė, D., Černý, K., Cleary, M., Corley, J., Coyle, D. R., Csóka, G., Davydenko, K., Elsafy, M. A. O., Eötvös, C., de Groot, M., Diez, J. J., Lehtijärvi, H. T. D., Drenkhan, R., Fan, J., Grabowski, M., Grad, B., Havrdova, L., Hrabetova, M., Iede, E. T., Kacprzyk, M., Kenis, M., Kirichenko25,45, N., Lacković26,N., Lazarević, J., Leskiv, M., Li, H., Madsen, C.L., Matošević, D., Matsiakh, I., Meffert, J., Migliorini, D., Mikó, Á., Nikolov, C., O'Hanlon, R., Oskay, F., Paap, T., Parpan, T., Petrakis, P.V., Piškur, B., Ravn, H.P., Ronse, A., Roques, A., Schühli, G.S., Sivickis, K., Talgø, V., Tomoshevich, M., Uimari, A., Ulyshen, M., Vettraino, A.M., Villari, C., Wang, Y., Witzell, J., Zlatković, M., Eschen, R.
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Total forfattarliste: Franić, I., Prospero, S., Adamson, K., Allan, A., Auger-Rozenberg, A-M, Augustin, S., Avtzis, D., Barta, M., Boroń, P., Bragança, H., Brestovanská, T., Brurberg, M. B., Burgess, B., Burokienė, D., Černý, K., Cleary, M., Corley, J., Coyle, D. R., Csóka, G., Davydenko, K., Elsafy, M. A. O., Eötvös, C., de Groot, M., Diez, J. J., Lehtijärvi, H. T. D., Drenkhan, R., Fan, J., Grabowski, M., Grad, B., Havrdova, L., Hrabetova, M., Iede, E. T., Kacprzyk, M., Kenis, M., Kirichenko25,45, N., Lacković26,N., Lazarević, J., Leskiv, M., Li, H., Madsen, C.L., Matošević, D., Matsiakh, I., Meffert, J., Migliorini, D., Mikó, Á., Nikolov, C., O'Hanlon, R., Oskay, F., Paap, T., Parpan, T., Petrakis, P.V., Piškur, B., Ravn, H.P., Ronse, A., Roques, A., Schühli, G.S., Sivickis, K., Talgø, V., Tomoshevich, M., Uimari, A., Ulyshen, M., Vettraino, A.M., Villari, C., Wang, Y., Witzell, J., Zlatković, M., Eschen, R.
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Venche TalgøAbstract
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NIBIO BOOK 4(4):33-34
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NIBIO BOOK 4(4):30-32
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NIBIO BOOK 4(4):24-26
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The fungus Neonectria fuckeliana has become an increasing problem on Norway spruce (Picea abies) in the Nordic countries during recent years. Canker wounds caused by the pathogen reduce timber quality and top-dieback is a problem for the Christmas tree industry. In this study, four inoculation trials were conducted to examine the ability of N. fuckeliana to cause disease on young Norway spruce plants and determine how different wound types would affect the occurrence and severity of the disease. Symptom development after 8–11 months was mainly mild and lesion lengths under bark were generally minor. However, N. fuckeliana could still be reisolated and/or molecularly detected. Slow disease development is in line with older studies describing N. fuckeliana as a weak pathogen. However, the results do not explain the serious increased damage by N. fuckeliana registered in Nordic forests and Christmas tree plantations. Potential management implications, such as shearing Christmas trees during periods of low inoculum pressure, cleaning secateurs between trees, and removal and burning of diseased branches and trees to avoid inoculum transfer and to keep disease pressure low, are based on experiments presented here and experiences with related pathogens.
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Phytophthora cryptogea, P. gonapodyides, P. lacustris, P. megasperma, P. plurivora, P. taxon paludosa and an unknown Phytophthora species were isolated from waterways and soil samples in Christmas tree fields in southern Sweden. In addition, P. megasperma was isolated from a diseased Norway spruce (Picea abies) plant from one of the fields in Svalöv. Inoculation tests were sequentially carried out with one isolate from each of the three species P. cryptogea, P. megasperma, and P. plurivora, all known pathogens on conifers. The same three isolates were used to study a few morphological features to confirm the identification, and temperature-growth relationships were carried out to see how well the organisms fit into Swedish climatic conditions. Seedlings of Norway spruce and Nordmann fir (Abies nordmanniana) were inoculated in the roots and the stems. None of the isolates caused extensive root rot under the experimental conditions, but all three species could be re-isolated from both Norway spruce and Nordmann fir. Phytophthora root rot is currently of minor concern for Christmas tree growers in Sweden. However, the Phytophthora isolations from soil and water indicate the presence of this damaging agent, which may lead to future problems.
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Introduction and purpose: The ability of apple rootstocks to become infected by Neonectria ditissima, the cause of European canker, was studied over two years. Materials and methods: Rootstocks B9 and M9 with a size suitable for grafting (6-10 mm stem diameter, termed rootstocks), and smaller sized rootstocks (<5 mm stem diameter, termed transplants) of B9, M9, M26, MM106 and Antonovka were inoculated with N. ditissima at different times, either with contaminated map pins or with spore suspensions. In addition, the rootstocks were either defeathered (side shoots removed), topped (top shoot headed) or both, to create wounds that would normally occur during propagation, while wounds on transplants were made by removing leaves. Results and discussion: One month after inoculation, slightly sunken canker lesions had developed around the inoculation points of the map pins or wounds. No lesions developed on the non-inoculated controls. Map pin inoculation resulted in 30% to 89% infection and spore suspension sprayed on wounds from 5% to 45% infection. When the cankered areas were split open, brown lesions with necrotic tissue due to infection by N. ditissima appeared. The transplants of M9, M26 and MM106 inoculated with contaminated map pins in 2014 developed necrosis on 40% to 67% of the plants, but there were no differences in the incidence or severity among the different types. On the transplants of B9, Antonovka and M9 inoculated in 2015, there was more necrosis on B9 (42%) than on Antonovka (11%) and more sporulating lesions on B9 (29%) than on M9 (9%) or on Antonovka (4%). Conclusion: It can be concluded that rootstocks used for apple trees may become infected by N. ditissima, and wounds should thus be protected during propagation.
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Field trials of Abies lasiocarpa were undertaken with the aim of assessing the potential for Christmas tree production in Denmark. Twenty-six provenances originating from Alaska to New Mexico were tested. Damage by the insect Adelges piceae and the fungus Neonectria neomacrospora was recorded for the first time 8 and 12 years after the initial planting. Damage from N. neomacrospora increased rapidly in the period 12–15 years after planting. Trees from the northern provenances and humid climates exhibited less damage than those from southern ones. Previous attack by A. piceae had a minor effect on N. neomacrospora infection. Greenhouse tests showed that detached shoots from healthy Abies lasiocarpa can be used to rank provenances for resistance to N. neomacrospora, but results varied according to host subspecies.
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Johanna Witzell Iryna Matsiakh Leopold Poljakovic-Pajnik Marc Kenis Venche Talgø Hans Peter Ravn Marek Barta Michelle ClearyAbstract
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Iryna Matsiakh Dimitrios N. Avtzis Kalev Adamson Sylvie Augustin Refika Ceyda Beram Thomas Cech Rein Drenkhan Natalia Kirichenko Giorgio Maresi Carmen Morales-Rodriguez Leopold Poljakovic-Pajnik Alain Roques Venche Talgø Anna Maria Vettraino Johanna WitzellAbstract
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Natalia Kirichenko Sylvie Augustin Ellie Barham Thomas Cech Rein Drenkhan Carmen Morales-Rodriguez Iryna Matsiakh Alain Roques Venche Talgø Anna Maria Vettraino Johanna WitzellAbstract
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Iryna Matsiakh Johanna Witzell Leopold Poljakovic-Pajnik Marc Kenis Venche Talgø Traian Manole Irina Ionescu-Malancus Marek BartaAbstract
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Magdalena Kacprzyk Iryna Matsiakh Dmitry L. Musolin Andrey V. Selikhovkin Yuri N. Baranchikov Daiva Burokiene Thomas Cech Venche Talgø Anna Maria Vettraino Andrea Vannini Simone ProsperoAbstract
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Iryna Matsiakh Magdalena Kacprzyk Dmitry L. Musolin Andrey V. Selikhovkin Yuri N. Baranchikov Andrea Vannini Venche Talgø Simone ProsperoAbstract
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The impact of Delphinella shoot blight (Delphinella abietis) and Grovesiella canker (Grovesiella abieticola) on subalpine (Abies lasiocarpa) and corkbark fir (A. lasiocarpa var. arizonica) in a provenance trial in Idaho (ID) was evaluated in 2013. Both pathogens were previously reported from North America on fir species. D. abietis had been found on subalpine fir in USA, but not in ID, and G. abieticola on grand fir (Abies grandis) in ID, but not on subalpine or corkbark fir. D. abietis kills current-year needles and in severe cases buds and shoots, and G. abieticola results in dead shoots and branches and can eventually kill whole trees. Significant differences between provenances in susceptibility to D. abietis and G. abieticola were observed in the provenance trial in ID. In general, subalpine fir was more susceptible to both diseases than corkbark fir. In 2013, D. abietis was also found on subalpine fir in the Puget Sound area of Washington State and G. abieticola was seen on white fir (Abies concolor), but neither disease was detected in native stands of subalpine fir in Washington State. Morphological features of both fungi were described from samples collected in the provenance trial in ID in May 2016.
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Fire blight, caused by Erwinia amylovora, was detected for the first time in Norway in 1986. It was a limited outbreak on the south-western coast, only on ornamentals, and particularly on Cotoneaster spp. An action group handling the eradication and containment of the disease was quickly established. Comprehensive statutory powers and resources were given by the government to do surveys and eradicate diseased or symptomless but highly susceptible plant species from contaminated areas. These activities have likely restricted fire blight to the western and southern coastal areas. Eastern and northern parts of Norway are considered free from fire blight. The disease has not been observed in important fruit-growing areas. Uncontrolled movement of beehives from areas with fire blight to areas free from the disease has contributed to its introduction to new areas. From 1969 to 2016 import of most host plants of E. amylovora from countries with fire blight was prohibited. A yearly program for annual surveys in parts of the country with commercial fruit-growing and nurseries, using digital maps on internet connected tablets with GPS and software for in situ registrations, proved to be an efficient method for discovering new outbreaks at an early stage, and to start eradication and thus limit further spread.
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Production of inoculum of Colletotrichum acutatum from both previously infected and overwintered tissue, as well as newly developed plant tissue of sour cherry (Prunus cerasus), was studied in southern Norway. Plant parts were sampled from commercial, private, or research orchards, and incubated for 2 to 14 days (time depended on tissue type) in saturated air at 20°C. In early spring, abundant sporulation was found on scales of overwintered buds and shoots. A mean of 35% infected buds in four cultivars was observed, with a maximum of 72% of the buds infected in one of the samples. Over 3 years, the seasonal production of overwintered fruit and peduncles of cv. Fanal infected the previous year was investigated. In all three years, the infected plant material was placed in the trees throughout the winter and the following growing season; in two of the years, fruit and peduncles were also placed on the ground in the autumn or the following spring. Old fruit and peduncles formed conidia throughout the season, with a peak in May and June. Spore numbers declined over the season, but the decline was more rapid for plant material on the ground than in the trees. On average over 2 years, 68.7, 24.0, or 7.3% of the inoculum came from fruit placed in the trees, placed on the ground in spring, or placed on the ground the preceding autumn, respectively. The number of fruit and peduncles attached to the trees in a planting of cv. Hardangerkirsebær was followed from February to July one year, and although there was a decline over time, fruit and/or their peduncles were still attached in substantial numbers in July, thus illustrating their potential as sources of inoculum. In observations over 2 years in a heavily infected orchard of cv. Stevnsbær, 75 and 47% of flowers and newly emerged fruit, respectively, were infected. Artificially inoculated flowers and fruit produced conidia until harvest, with a peak in mid-July. It may be concluded that previously infected and overwintered, as well as newly emerged tissue of sour cherry, may serve as sources of inoculum of C. acutatum throughout the growing season.
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On September 6th – 11th in 2015, the Norwegian Institute of Bioeconomy Research (NIBIO) organized The 12th International Christmas Tree Research and Extension Conference (CTREC) at Honne, Norway. Around 40 participants from Australia, Austria, Canada, Denmark, France, Greece, Hungary, Iceland, Norway, UK, and USA gathered to share skills and recent research related to Christmas tree production and marketing. Nearly 50 presentations (oral and poster) were given during the conference covering the following topics; Breeding & genetic, Insects, Tree health, Physiology, Growth conditions & integrated pest management, Postharvest, and Market & economy. Abstracts, extended abstracts or papers from all presentations are available in this proceedings.
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The fungus Neonectria neomacrospora has recently caused an epidemic outbreak in conifer species within the genus Abies in Denmark and Norway. Christmas tree producers in Europe and North America rely, to a large extent, on Abies species. The damage caused by N. neomacrospora, including dead shoot tips, red flagging of branches and potentially dead trees, have therefore caused concern about reduced quality and loss of trees, and thereby of revenue. Field observations of natural infection of 39 taxa, from 32 species, within the genus Abies in the Hørsholm Arboretum, Denmark, were evaluated; significant differences were seen between taxa, that is, species, and between some species and their subspecies. The Greek fir, Abies cephalonica, was the only species without damage. An inoculation experiment on detached twigs with mycelium plugs from a N. neomacrospora culture showed that all species could be infected. The damage observed in the inoculation experiment could explain 30% of the variation in the field observations based on species mean values. The epidemic outbreak and the high number of species susceptible to this fungus indicate that N. neomacrospora requires attention in the cultivation and conservation of Abies species.
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Fire blight was detected for the first time in Norway in 1986. It was a limited outbreak on the West Coast, only on ornamentals, particularly on Cotoneaster. An organization for the eradication and containment of fire blight was quickly established, and given comprehensive statutory powers and government resources to do surveys and eradicate diseased plants and highly susceptible plants from contaminated areas. The work has managed to restrict fire blight to the West Coast. Eastern and Northern parts of the country are considered pest free areas. The disease has not moved into important fruit-growing areas. Spread of fire blight to new areas has mainly been due to uncontrolled movement of beehives. From 1969 to 2016 import of all host plants from countries with fire blight has been prohibited. Systematic yearly surveys by foot and car in all parts of the country, using digital maps, internet connected tablets with GPS, and software for registrations made in the field have proved to be an efficient tool to spot new outbreaks at an early stage and start eradication, thus limiting further spread.
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Lecture – Christmas tree and bough production – what are the most challenging diseases?
Venche Talgø
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Venche TalgøAbstract
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Venche TalgøAbstract
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Venche Talgø Jan-Ole Skage Arne Steffenrem Corina Junker Håvard Eikemo May Bente Brurberg Odd Ragnar JohnskåsAbstract
Delphinella shoot blight (Delphinella abietis) attacks true firs (Abies spp.) in Europe and North America. Especially subalpine fir (A. lasiocarpa), one of the main Christmas tree species in Norway, is prone to the disease. The fungus kills current year needles, and in severe cases entire shoots. Dead needles become covered with black fruiting bodies, both pycnidia and pseudothecia. Delphinella shoot blight has mainly been a problem in humid, coastal regions in the northwestern part of Southern Norway, but, probably due to higher precipitation in inland regions during recent years, heavy attacks were found in 2011 in a field trial with 76 provenances of subalpine fir in Southeastern Norway. However, the amount of precipitation seemed less important once the disease had established in the field. Significant differences in susceptibility between provenances were observed. In general, the more bluish the foliage was, the healthier the trees appeared. The analysis of provenance means indicated that, at least for the southern range, the disease ratings were correlated with foliage color. This study also includes isolation, identification, a pathogenicity test, a seed test and electron microscopy of the wax layer on the needles. The fungus was identified based on the morphology of spores and by sequencing the Internal Transcribed Spacer (ITS) regions of the ribosomal DNA. Koch’s postulates were fulfilled. The fungus was found present on newly harvested seeds and may therefore spread via international seed trade. When comparing the wax layers on green and blue needles, those of the latter were significantly thicker, a factor that may be involved in disease resistance.
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Venche TalgøAbstract
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T. Jung L. Orlikowski B. Henricot P. Abad-Campos A.G. Aday O. Aguín Casal J. Bakonyi S.O. Cacciola T. Cech D. Chavarriaga T. Corcobado A. Cravador T. Decourcelle G. Denton S. Diamandis H.T. Doğmuş-Lehtijärvi A. Franceschini B. Ginetti M. Glavendekić J. Hantula G. Hartmann Maria Herrero D. Ivic M. Horta Jung A. Lilja N. Keca V. Kramarets A. Lyubenova H. Machado G. Magnano di San Lio P.J. Mansilla Vázquez B. Marçais I. Matsiakh I. Milenkovic S. Moricca Z.Á. Nagy J. Nechwatal C. Olsson T. Oszako A. Pane E.J. Paplomatas C. Pintos Varela S. Prospero C. Rial Martínez D. Rigling C. Robin A. Rytkönen M.E. Sánchez B. Scanu A. Schlenzig J. Schumacher S. Slavov A. Solla E. Sousa J. Stenlid Venche Talgø Z. Tomic P. Tsopelas A. Vannini A. M. Vettraino M. Wenneker S. Woodward A. Perez-SierraAbstract
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Venche TalgøAbstract
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Gunn Strømeng May Bente Brurberg Maria Herrero W. Couanon Arne Stensvand Isabella Børja Venche TalgøAbstract
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Gunn Strømeng May Bente Brurberg Maria Herrero W. Couanon Arne Stensvand Isabella Børja Venche Talgø Kari ØrstadAbstract
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Venche TalgøAbstract
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Venche TalgøAbstract
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Venche TalgøAbstract
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Venche TalgøAbstract
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Gunn Strømeng May Bente Brurberg Maria Herrero Willy Couanon Arne Stensvand Isabella Børja Venche TalgøAbstract
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Venche TalgøAbstract
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Venche Talgø Maria Herrero May Bente Brurberg Louisa Kitchingman Kari H. Telfer Gunn StrømengAbstract
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Venche TalgøAbstract
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Venche TalgøAbstract
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In 2008, an epidemic caused by a new Neonectria sp. was discovered on white fir (Abies concolor) in several counties in southern Norway [1]. Later the pathogen was also found on other fir species in Norway and Denmark [2]. Typical symptoms and signs were dead shoots, flagging (dead branches), canker wounds, heavy resin flow, and occasionally red fruiting bodies (perithecia). Pathogenicity tests on several Abies spp. proved the fungus to be very aggressive, which corresponds well with observations of mortality of white fir and subalpine fir (A. lasiocarpa) from different age classes under field conditions. Sequencing of the internal transcribed regions (ITS) of the ribosomal DNA showed that this Neonectria sp. was most similar to N. ditissima (only 5 bp different from isolates in the GenBank), a common pathogen worldwide on broad leaf trees. The ITS sequences were very different (> 20 bp) from N. fuckeliana, a well-known fungus on Norway spruce in Scandinavia and other parts of the world, especially in the northern hemisphere. In 2011, the new Neonectria species was found on diseased trees in a Danish nordmann fir (Abies nordmanniana) seed orchard. Resin flow was seen from mature cones, and tests revealed that the seeds were infected by the Neonectria sp.
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Winter damage caused by frost is frequently observed on common ash (Fraxinus excelsior) in Norway. In spring 2007, extensive winter damage most likely camouflaged ash dieback caused by Chalara fraxinea. In 2008, ash dieback caused by C. fraxinea had spread to large areas in the southern part of Norway. The disease was widespread in forests and nurseries, but also on roadside trees, and in gardens and parks. In 2009, the disease had spread to new areas; about 30 km into Rogaland county in southwestern Norway and also further into some valleys in southeastern Norway.
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Venche TalgøAbstract
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Venche TalgøAbstract
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Venche TalgøAbstract
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Sydowia polyspora is a pathogenic, seed borne fungus on conifers [1]. It is especially troublesome in the Christmas tree industry, where it causes current season needle necrosis (CSNN) on fir (Abies spp.). Needles get chlorotic spots or bands and in severe cases the entire needles turn necrotic and shed. The fungus also commonly kills current year shoots (Sclerophoma shoot dieback) on both fir and spruce (Picea spp.). The latter we proved on subalpine fir (A. lasiocarpa) inoculated by S. polyspora from noble fir (Abies procera) seeds. Two conifer seed lots known from previous tests to contain a high percentage of S. polyspora were selected for a treatment experiment; alpine pine (Pinus mugo var. rotundata) and Noble fir. Both seed lots received the following five treatments; surface sterilized (10 sec. in 70 % ethanol plus 90 sec. in 0,5 % NaOCl), dipped in 15 % acidic acid, mixed with 0,36 gram Signum (boskalid and pyraklostrobin) per 100 gram seeds, mixed with 0,8 gram Mycostop (Streptomyces griseovirides) per 100 gram seeds, dipped in different concentrations of thyme oil (extracted from Thymus vulgaris), and control (no treatment). Based on the results we recommend Signum for conifer seed treatment. This fungicide controlled S. polyspora well and did not influence on the germination ability. Agricultural
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Venche Talgø Leif Sundheim Halvor B. Gjærum Maria Herrero Aruppillai Suthaparan Brita Toppe Arne StensvandAbstract
This paper presents powdery mildew species recorded on woody ornamentals, with special emphasis on the latest arrivals; Erysiphe flexuosa on horse chestnut (Aesculus hippocastanum), Erysiphe syringae-japonicae on lilac (Syringa vulgaris) and Podosphaera spireae on white spirea (Spiraea betulifolia). The two former were found in 2006, while the latter was first detected in 2008. Chasmothecia (formerly named cleistothecia) were not found on white spirea until 2010. Several locations seemed to have optimal conditions for development of powdery mildew diseases in 2006. That year the long established Sawadaea bicornis on sycamore maple (Acer pseudoplatanus), was found for the first time on tatarian maple (Acer tataricum ssp. ginnala) and one cultivar from hedge maple (Acer campestre "Red Shine"). Also several species and cultivars of Rhododendron had massive attacks of powdery mildew in 2006. In 2010, chasmothecia of E. azaleae were found on severely affected R. "Magnifica" in western Norway. Most powdery mildew species are host specific, but especially Phyllactinia guttata has a wider host range, e.g. hazel (Corylus spp.) and common ash (Fraxinus excelsior).
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In Norway, Nordmann fir (Abies nordmanniana) and subalpine fir (A. lasiocarpa) are the dominant Christmas tree species, and noble fir (A. procera) the dominant bough plant species. To determine if fungi found to cause diseases on fir in Norway might be seed borne, samples from twelve seed lots, including Nordmann fir from Austria, Georgia and Russia, subalpine fir from Canada and Norway and noble fir from Norway were tested using agar plate methods (PDA and WA). The most important finding was that Sydowia polyspora was present on seed from all firs from all countries (nine samples infected, 0.5 - 85 % infected seeds). Recently, it has been demonstrated in Norway that this fungus is the cause of current season needle necrosis (CSNN), which is considered a major disease in the Christmas tree and bough production both in Europe and USA. Sirococcus coniguenus was found in a Norwegian A. procera seed lot (31% infected seeds), which to our knowledge is the first report of this pathogen on fir seeds. Caloscypha fulgens was detected on subalpine fir seed from Canada. In addition the following fungal genera were detected: Acremoniella, Acremonium, Alternaria, Aspergillus, Botrytis, Chaetomium, Cladosporium, Diaphorte, Dictyopolyschema, Epicoccum, Fusarium, Genicularia, Mucor, Neonectria, Penicillium, Phoma, Rhizopus, Sordaria, Trichoderma, Trichothecium, and an unidentified fungus.
Authors
Venche Talgø G. Chastagner I. M. Thomsen T. Cech K. Riley K. Lange Sonja Klemsdal Arne StensvandAbstract
Current season needle necrosis (CSNN) has been a serious foliage disorder on true fir Christmas trees and bough material in Europe and North America for more than 25 y. Approximately 2-4 weeks after bud break, needles develop chlorotic spots or bands that later turn necrotic. The symptoms have been observed on noble fir (Abies procera), Nordmann fir (A. nordmanniana) and grand fir (A. grandis) on both continents. CSNN was reported as a physiological disorder with unknown aetiology from USA, Denmark, and Ireland, but was associated with the fungus Kabatina abietis in Germany, Austria and Norway. In 2007, a fungus that morphologically resembled K. abietis was isolated from symptomatic needle samples from Nordmann fir from Austria, Denmark, Germany, Norway, and USA. Sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA of these cultures, plus a K. abietis reference culture from Germany (CBS 248.93), resulted in Hormonema dematioides, the imperfect stage of Sydowia polyspora, and thus the taxonomy is further discussed. Inoculation tests on Nordmann fir seedlings and transplants with isolates of S. polyspora from all five countries resulted in the development of CSNN symptoms. In 2009, S. polyspora was also isolated from symptomatic needles from Nordmann fir collected in Slovakia. (c) 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
Abstract
European ash (Fraxinus excelsior), also known as common ash, occurs naturally inland in lower areas of southeastern Norway and along the southern coast of the country. It is important both as a forest and ornamental tree. During the last decade, dieback has become a disastrous disease on F. excelsior in many European countries. The anamorphic fungus Chalara fraxinea T. Kowalski (1), described for the first time from dying ash trees in Poland, is now considered the cause of ash dieback (2). In May of 2008, C. fraxinea was isolated from 1.5 m high diseased F. excelsior in a nursery in Østfold County in southeastern Norway. Symptoms included wilting, necrotic lesions around leaf scars and side branches, and discoloration of the wood. From symptomatic branches, small pieces (approximately 1 cm3) were excised in the transition area between healthy and discolored wood. After surface sterilization (10 s in 70% ethanol + 90 s in NaOCl), the pieces were air dried for 1 min in a safety cabinet, cut into smaller pieces, and placed on media. The fungus was isolated on potato dextrose agar (PDA) and water agar (WA). On PDA, the cultures were tomentose, light orange, and grew slowly (21 mm mean colony diameter after 2 weeks at room temperature). Typical morphological features of C. fraxinea developed in culture. Brownish phialides (14.8 to 30.0 [19.5] × 2.5 to 5.0 [4.1] μm, n = 50) first appeared in the center of the colonies on the agar plugs that had been transferred. The agar plugs were 21 days old when phialides were observed. Abundant sporulation occurred 3 days later. Conidia (phialospores) extruded apically from the phialides and formed droplets. Conidia measured 2.1 to 4.0 (3.0) × 1.4 to 1.9 (1.7) μm (n = 50). The first-formed conidia from each phialide were different in size and shape from the rest by being longer (6 μm, n = 10) and more narrow in the end that first appeared at the opening of the phialide. Internal transcribed spacer sequencing confirmed that the morphological identification was correct (Accession No. EU848544 in GenBank). A pathogenicity test was carried out in June of 2008 by carefully removing one leaf per plant on 10 to 25 cm high F. excelsior trees (18 trees) and placing agar plugs from a 31-day-old C. fraxinea culture (isolate number 10636) on the leaf scars and covering with Parafilm. After 46 days, isolations were carried out as described above from discolored wood that had developed underneath necrotic lesions in the bark and subsequently caused wilting of leaves. All the inoculated plants showed symptoms, and C. fraxinea was successfully reisolated. No symptoms were seen on uninoculated control plants (eight trees) that had received the same treatment except that sterile PDA agar plugs had been used.
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Division of Food Production and Society
Risk management of imported plants and seeds: possibilities for improved pest detection to prevent the introduction and spread of new pests
Plant pathogens and invertebrates harmful to plants continue to threatenfood security and natural habitats. In Norway, the responsibility of performingplant health inspections on imported plants has gradually shifted to importersof plants who are currently responsible for internal pest control and mustbe registered with the Norwegian Food Safety Authority.
Division of Biotechnology and Plant Health
Plant Pest Prevention through technology-guided monitoring and site-specific control (PurPest)
The main objective of PurPest is to control serious plant pests during import and to manage them in the field by developing a unique concept enabling pest detection in a timely and non-invasive manner.