Challenges in forest protection research: Looking backwards and forwards from a forest entomology and forest pathology perspective

Die Waldschutzforschung hat ihre Anfänge im 19. Jahrhundert und ist im Vergleich zur langen und facettenreichen Geschichte der Waldnutzung eine recht junge Disziplin, die bereits eine umfangreiche Entwicklung vollzogen hat. Der verfasste Übersichtsartikel möchte die Entwicklung der Waldschutzforschung ausgehend von den Anfängen, über die Entwicklung von Regulierungsmaßnahmen bis hin zu den großen Herausforderungen im Klima­wandel und der Globalisierung darstellen, ohne hierbei Anspruch auf Vollständigkeit zu erheben. Der Fokus liegt dabei auf der Forstentomologie und der Forstpathologie. Ergänzend erfolgt eine systematische Auswertung von Beiträgen zur Waldschutzforschung im Journal für Kulturpflanzen sowie ein kurzer Ausblick über die zukünftigen Möglichkeiten der Waldschutzforschung.Research with regard to forest protection started in the 19th century and is a relatively young field when compared to the long and diverse history of the human use of forests. However, since then there has been significant progress and development in the field of forest protection research. This article provides an overview on this deve­lopment in Germany, starting from the mainly descriptive research in the beginning, followed by the subsequent development of control measures up to the large challenges of climate change and globalisation. The article does not claim to be complete and focuses on forest entomology and forest pathology. The overview is accom­panied by a systematic analysis of publications on forest protection research in the Journal für Kultur­pflanzen. Moreover, a short outlook on the future of forest protection research is provided

Advanced spectroscopy-based phenotyping offers a potential solution to the ash dieback epidemic

Natural and urban forests worldwide are increasingly threatened by global change resulting from human-mediated factors, including invasions by lethal exotic pathogens. Ash dieback (ADB), incited by the alien invasive fungus Hymenoscyphus fraxineus, has caused large-scale population decline of European ash (Fraxinus excelsior) across Europe, and is threatening to functionally extirpate this tree species. Genetically controlled host resistance is a key element to ensure European ash survival and to restore this keystone species where it has been decimated. We know that a low proportion of the natural population of European ash expresses heritable, quantitative resistance that is stable across environments. To exploit this resource for breeding and restoration efforts, tools that allow for effective and efficient, rapid identification and deployment of superior genotypes are now sorely needed. Here we show that Fourier-transform infrared (FT-IR) spectroscopy of phenolic extracts from uninfected bark tissue, coupled with a model based on soft independent modelling of class analogy (SIMCA), can robustly discriminate between ADB-resistant and susceptible European ash. The model was validated with populations of European ash grown across six European countries. Our work demonstrates that this approach can efficiently advance the effort to save such fundamental forest resource in Europe and elsewhere

Diversity, migration routes, and worldwide population genetic structure of Lecanosticta acicola, the causal agent of brown spot needle blight

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

Global Geographic Distribution and Host Range of Fusarium circinatum, the Causal Agent of Pine Pitch Canker

Funding: This study was financially supported by COST Action FP1406 (PINESTRENGTH), the Estonian Science Foundation grant PSG136, the Forestry Commission, United Kingdom, the Phytophthora Research Centre Reg. No. CZ.02.1.01/0.0/0.0/15_003/0000453, a project co-financed by the European Regional Development Fund. ANSES is supported by a grant managed by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” programme (ANR-11-LABX-0002-01, Laboratory of ExcellenceARBRE). SW was partly supported by BBSRC Grant reference BB/L012251/1 “Promoting resilience of UK tree species to novel pests & pathogens: ecological & evolutionary solutions (PROTREE)” jointly funded by BBSRC, Defra, ESRC, the Forestry Commission, NERC and the Scottish Government, under the Tree Health and Plant Biosecurity Initiative. Annual surveys in Switzerland were financially supported by the Swiss Federal Office for the Environment FOEN. Acknowledgments: Andrea Kunova and Cristina Pizzatti are acknowledged for the assistance in the sampling. Thanks are due to Dina Ribeiro and Helena Marques from ICNF-Portuguese Forest Authority for providing location coordinates. We thank three anonymous reviwers for valuable corrections and suggestions.Peer reviewedPublisher PD

Susceptibility of autochthonous German Fraxinus excelsior clones to Hymenoscyphus pseudoalbidus is genetically determined

International audienceAbstractContextIt might be possible to establish a new generation of Fraxinus excelsior which is insusceptible towards ash dieback (agent: Hymenoscyphus pseudoalbidus) by efficient breeding. However, a considerable number of highly tolerant individuals which have the ability to pass on this trait to their progeny are needed.AimsThe aim of this study was to identify the potential of provenances from southwestern Germany as a source of future selection for resistance or resistance breeding.MethodsIn July 2012 and 2013, ash dieback severity was scored by assessing the crown defoliation and the portion of epicormic shoots in the crowns in clonal seed orchards with a total of 1,726 ash trees in southwestern Germany.ResultsAsh dieback severity differed strongly between the orchards and the clones. Broad-sense heritability ranged from 0.18 to 0.55 for crown defoliation and from 0.48 to 0.58 for the portion of epicormic shoots between the orchards. Clones from nearby populations did not show differences in general levels of susceptibility.ConclusionThe study highlights that there is high genetic variation in susceptibility and considerable genetic potential for resistance breeding in provenances from southwestern Germany

Ash Dieback on Sample Points of the National Forest Inventory in South-Western Germany

The alien invasive pathogen Hymenoscyphus fraxineus causes large-scale decline of European ash (Fraxinus excelsior). We assessed ash dieback in Germany and identified factors that were associated with this disease. Our assessment was based on a 2015 sampling of national forest inventory plots that represent a supra-regional area. In the time from 2012 to 2015, the number of regrown ash trees corresponded to only 42% of the number of trees that had been harvested or died. Severe defoliation was recorded for almost 40% of the living trees in 2015, and more than half of the crowns mainly consisted of epicormic shoots. Necroses were present in 24% of root collars. A total of 14% of the trees were in sound condition, which sum up to only 7% of the timber volume. On average, trees of a higher social status or with a larger diameter at breast height were healthier. Collar necroses were less prevalent at sites with a higher inclination of terrain, but there was no evidence for an influence of climatic variables on collar necroses. The disease was less severe at sites with smaller proportions of the basal area of ash compared to the total basal area of all trees and in the north-eastern part of the area of investigation. The regeneration of ash decreased drastically

First report of Cryptostroma corticale on Aesculus hippocastanum causing sooty bark disease in Germany

Cryptostroma corticale is the causal agent of sooty bark disease, which was first described in the middle of the last century and has developed in recent years to a relevant threat for Acer spp. trees in Central Europe. Triggered by extreme heat and drought, this tree disease is becoming more and more important in the course of climate change. Acer pseudoplatanus is a particularly affected tree species, but the disease has also been observed on other Acer spp., and there is some indication that there are suitable hosts outside the Acer genus. In literature, Aesculus hippocastanum was mentioned twice to be a host, however, without any proof or details. With this study, we verify the assumption that A. hippocastanum is a host of C. corticale by morphological and phylogenetic analyses based on a case in Germany. Furthermore, we provide microscope pictures of microtome sections of the specimens, showing the spore production of C. corticale on A. hippocastanum

Diversity, migration routes, and worldwide population genetic structure of Lecanosticta acicola, the causal agent of brown spot needle blight

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