scholarly journals Landscape epidemiology of ash dieback

2019 ◽  
Author(s):  
M. Grosdidier ◽  
T. Scordia ◽  
R. loos ◽  
B. Marçais
Keyword(s):  
Host Density ◽  
Development Stage ◽  
Tree Cover ◽  
Disease Development ◽  
Landscape Epidemiology ◽  
Forest Environment ◽  
Ash Dieback ◽  
Landscape Features ◽  
Hymenoscyphus Fraxineus ◽  
Temporal Models

AbstractAsh dieback caused by Hymenoscyphus fraxineus, an invasive alien pathogen, has been severely damaging European ash populations. Nevertheless, a large range of disease severities was observed at the landscape scale in the field. Several studies suggested that environment, such as climate, site conditions or local tree cover strongly affects ash dieback. We characterized the landscape epidemiology of the disease at two stages of the invasion process with spatio-temporal models using Bayesian models fitted by Integrated Nested Laplace Approximation (INLA). We first analyzed the effect of landscape features on the disease arrival and establishment stage at the scale of a village in NE France in 2012, 2 years after first report of the disease in the area and then, on the disease development stage in 2016-18. Landscape features had little impact on the disease at the establishment stage but strongly determined it further development. The local fragmentation of the tree cover was the most important factor with trees isolated or in hedges in agricultural settings far less affected then trees in forest environment. We showed that they were subjected to different microclimate with higher crown temperatures unfavorable to the pathogen development. Furthermore, host density was important for disease development with ash at low density far less affected by ash dieback. Presence of ashes in the vicinity affected local disease severity up to several hundred meters. These results may help to develop management strategy for the disease.

scholarly journals Expansion of Ash Dieback towards the scattered Fraxinus excelsior range of the Italian peninsula

2022 ◽  
Author(s):  
Duccio Migliorini ◽  
Nicola Luchi ◽  
Emanuele Nigrone ◽  
Francesco Pecori ◽  
Alessia Lucia Pepori ◽  
...  
Keyword(s):  
Western Europe ◽  
Central Italy ◽  
Genetic Material ◽  
Host Density ◽  
Climatic Conditions ◽  
Fraxinus Excelsior ◽  
Disease Spread ◽  
Ash Dieback ◽  
Southern Limit ◽  
Hymenoscyphus Fraxineus

AbstractHymenoscyphus fraxineus, causal agent of Ash Dieback, has posed a threat to Fraxinus excelsior (common ash) in Europe since the 1990s. In south-western Europe, optimal climatic conditions for H. fraxineus become scattered and host density decreases, reducing disease spread rates. To date, the Ash Dieback agent has not been reported from southern and most of central Italy, where native F. excelsior is present as small fragmented populations. This study examines the expansion of Ash Dieback into central Italy, and it considers the consequences of further local spread with regards to the loss of F. excelsior genetic resource. Symptomatic F. excelsior were sampled from sixteen sites in northern and central Italy during 2020. Specimens were analyzed with a culturomics and a quantitative PCR approach. A bibliographic search of F. excelsior floristic reports was conducted for the creation of a detailed range map. The combined use of both techniques confirmed the presence of H. fraxineus in all the sites of central Italy where host plants were symptomatic. These new records represent the southern limit of the current known distribution of this pathogen in Italy, and together with Montenegro, in Europe. The characterization of the F. excelsior scattered range suggests that further spread of Ash Dieback across southern Italy is a realistic scenario. This presents a threat not just to the southern European proveniences of F. excelsior, but to the species as a whole, should Ash Dieback lead to the loss of warm climate adapted genetic material, which may become increasingly valuable under climate change.

scholarly journals Assessing Genotypic and Environmental Effects on Endophyte Communities of Fraxinus (Ash) Using Culture Dependent and Independent DNA Sequencing

2021 ◽  
Vol 7 (7) ◽  
pp. 565
Author(s):  
Anindita Lahiri ◽  
Brian R. Murphy ◽  
Trevor R. Hodkinson
Keyword(s):  
Community Composition ◽  
Environmental Effects ◽  
High Throughput Sequencing ◽  
Fungal Community Composition ◽  
Species Identity ◽  
Ash Dieback ◽  
Hymenoscyphus Fraxineus ◽  
Culture Independent ◽  
The Impact ◽  
Culture Dependent

Fraxinus excelsior populations are in decline due to the ash dieback disease Hymenoscyphus fraxineus. It is important to understand genotypic and environmental effects on its fungal microbiome to develop disease management strategies. To do this, we used culture dependent and culture independent approaches to characterize endophyte material from contrasting ash provenances, environments, and tissues (leaves, roots, seeds). Endophytes were isolated and identified using nrITS, LSU, or tef DNA loci in the culture dependent assessments, which were mostly Ascomycota and assigned to 37 families. Few taxa were shared between roots and leaves. The culture independent approach used high throughput sequencing (HTS) of nrITS amplicons directly from plant DNA and detected 35 families. Large differences were found in OTU diversity and community composition estimated by the contrasting approaches and these data need to be combined for estimations of the core endophyte communities. Species richness and Shannon index values were highest for the leaf material and the French population. Few species were shared between seed and leaf tissue. PCoA and NMDS of the HTS data showed that seed and leaf microbiome communities were highly distinct and that there was a strong influence of Fraxinus species identity on their fungal community composition. The results will facilitate a better understanding of ash fungal ecology and are a step toward identifying microbial biocontrol systems to minimize the impact of the disease.

Hymenoscyphus fraxineus (ash dieback).

2021 ◽  
Author(s):  
Jessica Needham ◽  
Joan Webber
Keyword(s):  
North Africa ◽  
Fungal Pathogen ◽  
The Other ◽  
New Disease ◽  
Ash Dieback ◽  
South West ◽  
Hymenoscyphus Fraxineus ◽  
Natural Range

Abstract H. fraxineus is an anamorphic fungal pathogen that causes ash dieback. Due to the severity of ash dieback H. pseudoalbidus has been on the EPPO Alert list since 2007. It is not known what caused the emergence of this 'new' disease (NAPPO, 2009). Its spread in Europe is thought to be mainly by ascospores, but infected nursery saplings may carry the fungus to new areas. The entire natural range of known hosts, including North Africa, Russia and south-west Asia (USDA-ARS, 2009), is currently threatened by ash dieback, with large areas already affected (Pautasso et al., 2013). Little is known about the susceptibility of the other species of ash in temperate zones.

scholarly journals Rising out of the ashes: additive genetic variation for susceptibility to Hymenoscyphus fraxineus in Fraxinus excelsior

2015 ◽  
Author(s):  
F. Muñoz ◽  
B. Marçais ◽  
J. Dufour ◽  
A. Dowkiw
Keyword(s):  
Genetic Variation ◽  
Fraxinus Excelsior ◽  
Narrow Sense ◽  
Narrow Sense Heritability ◽  
Ash Dieback ◽  
Family Effects ◽  
Hymenoscyphus Fraxineus ◽  
Natural Range ◽  
Spatio Temporal ◽  
Crown Dieback

AbstractSince the early 1990s, ash dieback due to the invasive ascomycete Hymenoscyphus fraxineus is threatening Fraxinus excelsior in most of its natural range. Previous studies reported significant levels of genetic variability for susceptibility in F. excelsior either in field or inoculation experiments. The present study was based on a field experiment planted in 1995, fifteen years before onset of the disease. Crown and collar status were monitored on 788 trees from 23 open-pollinated progenies originating from 3 French provenances. Susceptibility was modeled using a Bayesian approach where spatio-temporal effects were explicitly taken into account. Moderate narrow-sense heritability was found for Crown Dieback (CD, h2=0.42). This study is first to show that Collar Lesions are also heritable (h2=0.49 for prevalence and h2=0.42 for severity) and that there is significant genetic correlation (r=0.40) between the severities of both symptoms. There was no evidence for differences between Provenances. Family effects were detected, but computing Individual Breeding Values (IBV) showed that most of the genetic variation lies within families. In agreement with previous reports, early flushing correlates with better crown status. Consequences of these results in terms of management and breeding are discussed.

scholarly journals First report of Hymenoscyphus fraxineus causing ash dieback in Spain

2021 ◽  
Vol 44 (2) ◽  
Author(s):  
S. Stroheker ◽  
V. Queloz ◽  
M. Nemesio‐Gorriz
Keyword(s):  
Ash Dieback ◽  
First Report ◽  
Hymenoscyphus Fraxineus

scholarly journals Detection of a Conspecific Mycovirus in Two Closely Related Native and Introduced Fungal Hosts and Evidence for Interspecific Virus Transmission

2018 ◽  
Author(s):  
Corine N. Schoebel ◽  
Simone Prospero ◽  
Andrin Gross ◽  
Daniel Rigling
Keyword(s):  
Nucleotide Diversity ◽  
Virus Transmission ◽  
Virus Evolution ◽  
Close Relative ◽  
Pairwise Identity ◽  
Ash Dieback ◽  
Virus Diversity ◽  
Hymenoscyphus Fraxineus

Hymenoscyphus albidus is a native fungus in Europe where it behaves as a harmless decomposer of leaves of common ash. Its close relative Hymenoscyphus fraxineus was introduced into Europe from Asia and currently threatens ash (Fraxinus sp.) stands all across the continent causing ash dieback. H. fraxineus isolates from Europe were previously shown to harbor a mycovirus named Hymenoscyphus fraxineus Mitovirus 1 (HfMV1). In the present study, we describe a conspecific mycovirus that we detected in H. albidus. HfMV1 was consistently identified in H. albidus isolates (mean prevalence: 49.3%) which were collected in the sampling areas before the arrival of ash dieback. HfMV1 strains in both fungal hosts contain a single ORF of identical length (717 AA) for which a mean pairwise identity of 94.5% was revealed. The occurrence of a conspecific mitovirus in H. albidus and H. fraxineus is most likely the result of parallel virus evolution in the two fungal hosts. HfMV1 sequences from H. albidus showed a higher nucleotide diversity and a higher number of mutations compared to those from H. fraxineus, probably due to a bottleneck caused by the introduction of H. fraxineus in Europe. Our data also points to multiple interspecific virus transfers from H. albidus to H. fraxineus, which could have contributed to the intraspecific virus diversity found in H. fraxineus.

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