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In recent years, many abiotic and biotic factors have negatively impacted the health status of Ulmus glabra trees. Based on the syntaxonomic analysis of vegetation and a set of laboratory diagnostic studies, an attempt was made to isolate the catalysing factors and identify the causative agents of pathogenic processes that lead to the weakening and death of individuals of the U. glabra coenopopulation. The aim of the research was to evaluate the current health condition of trees of the relict coenopopulation of U. glabra, identify the factors of their weakening and dieback, study the pathogenesis and aetiology of the disease and experimentally confirm its causative agent. Classical geobotanical and silvicultural, special microbiological (in particular, bacteriological analysis), mycological, and statistical research methods were used in the work. Based on many years of research in the Pokutsky Carpathians, typical symptoms and signs of bacterial infection of U. glabra individuals resistant to Dutch elm disease were identified and described. It has been found that the current threat to old (100 or more years) U. glabra trees is a systemic vascular parenchymal disease known as bacterial wetwood. It has been studied that the drying of trees develops from the upper part of the crowns, and later, characteristic longitudinal cracks are formed on the trunks. In the active phase of the disease, there is a fountain-like release of exudate, and wet rot with a typical sour smell of fermentation appears. It was investigated and experimentally confirmed that, based on the signs of infection and the set of main characteristics, isolates of bacteria from the wood of diseased trees of U. glabra belong to the causative agent of the disease – the phytopathogenic bacterium – polybiotroph Lelliottia nimipressuralis (Carter 1945) Brady et al. 2013. [ABSTRACT FROM AUTHOR]

Campuses of Nigerian universities, especially the older ones, are home to aged trees that were originally planted for environmental beautification and aesthetics. However, due to the current global climate change and increased vulnerability to abiotic and biotic stressors, the old trees could pose threats to pedestrians, structures, and roads within the university campus environments. Therefore, the objective of this paper is to develop a geodatabase and evaluate the health risk assessment of avenue trees on selected roads in a tertiary institution in Ibadan, Oyo State, Nigeria using appropriate standard methods. Results obtained reported a total of 121 individual avenue trees belonging to 14 species along the study roads. The geospatial distribution analysis revealed that Emotan road had a lower density of avenue trees compared to Benue and Oduduwa roads. Furthermore, the health risk assessment indicated that 17.35% of the individual avenue trees had defects, posing potential hazards and risks of tree failure, and potential damage to pedestrians, vehicles, and neighboring utilities. The developed geodatabase is user-friendly and allows for easy data storage and quick information retrieval on the avenue trees, enhancing their maintenance and risk management. Furthermore, this study shows that systematic replacement, replanting, and management of avenue tree species could be a proactive initiative for the expansion of the geodatabase and to reduce negative health impacts. [ABSTRACT FROM AUTHOR]

The introduction of wood-boring insects to non-native areas can pose a significant threat to global forest ecosystems. Aromia bungii and Massicus raddei, native to Asia including Korea but potentially important in urban forestry worldwide, are severe trunk borers that have recently infested host trees in urban landscapes of Korea. The signs of external injury can help identify cerambycid-infested trees. However, assessing the internal condition of trees without causing damage is challenging, which hinders the management of infested trees that are still alive. This study evaluated the potential use of sonic tomography to assess injury characteristics in the woody parts of trees, such as Prunus × yedoensis and Quercus palustris infested by A. bungii and M. raddei, respectively. Among the 45 investigated trees, the number of holes on external parts was recorded by visual examination. Sonic tomography images revealed decayed areas, allowing for a comparison of internal damage between infested and non-infested trees. The internal status of trees infested by the two cerambycid beetles differed from that of healthy trees. While some healthy trees exhibited minimal internal damage, those that were not infested by beetles showed decayed areas, potentially caused by non-biological factors such as frozen cracks. In conclusion, sonic tomography equipment can potentially be used for non-invasive assessment of internal injuries caused by wood-boring insects in urban trees. [ABSTRACT FROM AUTHOR]

The Rawa Kidang Restoration is an area designated to plant tree species that rhinos like. Food is planted at the Rawa Kidang Restoration to maintain the rhino population. Knowledge of the importance of tree health is necessary because this can be a guide for rejuvenating or breeding trees attacked by disease or pests. To know the quality of rhino food, you need information about the health of rhino food trees. This research aims to investigate the health of rhino food trees in the Rawa Kidang Restoration. This research uses the Cluster Plot Level Index (CLI) formula to observe and examine canopy conditions and tree damage. The canopy condition parameters consist of five parameters: live crown ratio, density, transparency, diameter, and dieback. The parameters for the tree damage condition are the damage's location, the type I feel, and the level of tree damage. The research results show that the tree health value in cluster plot 1 is 2.35; in plot cluster 2, 2.50; in plot cluster 3, 3.70; and in plot cluster 4, 2.92. So, it can be concluded that the average tree health value in the four plot clusters is in the medium category. The severity of canopy conditions and tree damage can be influenced by surrounding conditions such as sunshine, growing conditions, water, and growing space. [ABSTRACT FROM AUTHOR]

Ecological significance of fungi in terrestrial ecosystems is generally acknowledged but the ecological networks mediated by particular fungal species are seldom described. In this note, we draw attention to an undescribed function of a well-known heart-rot fungus, Inonotus obliquus (chaga). This species mostly inhabits live birches (Betula), where it forms sterile conks used in ethnomedicine. Less known is that its short-lived fruit-bodies develop under the bark after the tree death and release the spores by cracking the bark. Based on studies in Estonia, we report that this process is a major mechanism that removes bark from standing dead birches and that the exposed wood becomes a distinct woody substrate. We report nearly 50 species of epixylic lichens and allied fungi on birch snags, most notably calicioid fungi, which include several species of conservation concern. Because forest management suppresses that stage through multiple mechanisms (removal of trees with conks and dead trees; shortened rotations; preference for conifer monocultures), the keystone function can be lost even if I. obliquus persists in the area. Additionally, multi-functional forestry that supports chaga for its conk use should pay attention to that later phase of fruit-body formation to maintain natural functioning of this species. Such microhabitat providing functions may be more widespread among fungi that currently acknowledged.

Urbanization can stimulate economic growth through industrialization; however, urbanization can also lead to dense development and high population densities. Both factors cause stress and negatively impact the quality of life of inhabitants living in cities. In response, a growing body of research has examined the association between urban trees and human health, in general and psychological well-being, in particular. Although this literature has tended to focus on tree canopy broadly, questions remain regarding the effects of specific tree characteristics (e.g., crown dieback, tree with damage, and leaf area). This study examines the association between adult depression and tree structure and condition metrics in ten cities across the United States. Adult depression data were obtained from the Centers for Disease Control and Prevention, and individual tree structure and condition data were calculated using the Urban Forest Inventory and Analysis Program. The linear mixed-effects model showed a positive relationship between depression and tree crown-dieback percentage (p = 0.03). Understanding the interplay between individual tree characteristics and adult depression can inform urban planning, design, and maintenance practices.

Campuses of Nigerian universities, especially the older ones, are home to aged trees that were originally planted for environmental beautification and aesthetics. However, due to the current global climate change and increased vulnerability to abiotic and biotic stressors, the old trees could pose threats to pedestrians, structures, and roads within the university campus environments. Therefore, the objective of this paper is to develop a geodatabase and evaluate the health risk assessment of avenue trees on selected roads in a tertiary institution in Ibadan, Oyo State, Nigeria using appropriate standard methods. Results obtained reported a total of 121 individual avenue trees belonging to 14 species along the study roads. The geospatial distribution analysis revealed that Emotan road had a lower density of avenue trees compared to Benue and Oduduwa roads. Furthermore, the health risk assessment indicated that 17.35% of the individual avenue trees had defects, posing potential hazards and risks of tree failure, and potential damage to pedestrians, vehicles, and neighboring utilities. The developed geodatabase is user-friendly and allows for easy data storage and quick information retrieval on the avenue trees, enhancing their maintenance and risk management. Furthermore, this study shows that systematic replacement, replanting, and management of avenue tree species could be a proactive initiative for the expansion of the geodatabase and to reduce negative health impacts.

We present an evaluation of different deep learning and machine learning approaches for tree health classification in the Black Forest, the Harz Mountains, and the Göttinger Forest on a unique, highly accurate tree-level dataset. The multispectral UAV data were collected from eight forest plots with diverse tree species, mostly conifers. As ground truth data (GTD), nearly 1500 tree polygons with related attribute information on the health status of the trees were used. This data were collected during extensive fieldwork using a mobile application and subsequent individual tree segmentation. Extensive preprocessing included normalization, NDVI calculations, data augmentation to deal with the underrepresented classes, and splitting the data into training, validation, and test sets. We conducted several experiments using a classical machine learning approach (random forests), as well as different convolutional neural networks (CNNs)—ResNet50, ResNet101, VGG16, and Inception-v3—on different datasets and classes to evaluate the potential of these algorithms for tree health classification. Our first experiment was a binary classifier of healthy and damaged trees, which did not consider the degree of damage or tree species. The best results of a 0.99 test accuracy and an F1 score of 0.99 were obtained with ResNet50 on four band composites using the red, green, blue, and infrared bands (RGBI images), while VGG16 had the worst performance, with an F1 score of only 0.78. In a second experiment, we also distinguished between coniferous and deciduous trees. The F1 scores ranged from 0.62 to 0.99, with the highest results obtained using ResNet101 on derived vegetation indices using the red edge band of the camera (NDVIre images). Finally, in a third experiment, we aimed at evaluating the degree of damage: healthy, slightly damaged, and medium or heavily damaged trees. Again, ResNet101 had the best performance, this time on RGBI images with a test accuracy of 0.98 and an average F1 score of 0.97. These results highlight the potential of CNNs to handle high-resolution multispectral UAV data for the early detection of damaged trees when good training data are available. [ABSTRACT FROM AUTHOR]

Sustainable urban ecosystems require healthy green spaces that provide ecological services to meet social and environmental needs. This study evaluates the proportion of green areas in the urban campus and assesses the effects of pavement on the health of Samanea saman. The MAPIR Normalised Difference Vegetation Index (NDVI) camera mounted on a drone captured a proportion of green areas of approximately 27.80%, which is roughly a quarter of the total study sites. However, the significance of green areas depends on the health of the trees. Therefore, the pavement effects on the health status of trees in green areas were studied using Visual Tree Assessment (VTA) and aerial image analysis using the MAPIR (NDVI) camera on a drone. Although both methods evaluate health status, the final outputs differed. VTA produced categorical outputs, which assigned trees into health categories based on a visual assessment of factors. In contrast, NDVI produced linear outputs, which provided a numerical value to demonstrate tree health. Both methods indicate that trees in non-paved areas are healthier, particularly for the excellent trees identified by the VTA, which suggests that pavement negatively impacts tree health. However, the effects of paved and non-paved areas on tree health status analysis using the aerial image are not significant (p>0.05), which may be due to the low quality and accuracy of the images. The study provides insights into the importance of green areas and tree health in creating sustainable urban ecosystems. [ABSTRACT FROM AUTHOR]

Greenspaces and urban trees play an important role in moderating and improving urban environments to make them more comfortable and healthy for people. While trees provide important wellbeing benefits to people, urban planning and maintenance practices can create inhospitable and stressful environments where trees are unable to flourish or reach their potential. As the impacts of climate change intensify, the health of urban trees will become increasingly important. To explore how planning and maintenance practices are affecting urban trees, we draw on a case study of 31 street and park trees adjacent to high-use pedestrian areas in Wellington, New Zealand. We analysed these trees using six key factors that influence tree health to identify how planning and maintenance practices could be adjusted to support tree health and ecosystem function. We suggest that the six key factors have planning and maintenance implications for urban trees which are relevant to a variety of urban contexts, but particularly space-constrained urban streets requiring multiple functions and infrastructure. We argue that as climate impacts intensify, using these six key factors can help promote urban tree health and ecosystem function and avoid mal-adaptive planning and maintenance practices.

The widespread tree mortality caused by the European spruce bark beetle (Ips typographus L.) is a significant concern for Norway spruce-dominated (Picea abies H. Karst) forests in Europe and there is evidence of increases in the affected areas due to climate warming. Effective forest monitoring methods are urgently needed for providing timely data on tree health status for conducting forest management operations that aim to prepare and mitigate the damage caused by the beetle. Unoccupied aircraft systems (UASs) in combination with machine learning image analysis have emerged as a powerful tool for the fast-response monitoring of forest health. This research aims to assess the effectiveness of deep neural networks (DNNs) in identifying bark beetle infestations at the individual tree level from UAS images. The study compares the efficacy of RGB, multispectral (MS), and hyperspectral (HS) imaging, and evaluates various neural network structures for each image type. The findings reveal that MS and HS images perform better than RGB images. A 2D-3D-CNN model trained on HS images proves to be the best for detecting infested trees, with an F1-score of 0.759, while for dead and healthy trees, the F1-scores are 0.880 and 0.928, respectively. The study also demonstrates that the tested classifier networks outperform the state-of-the-art You Only Look Once (YOLO) classifier module, and that an effective analyzer can be implemented by integrating YOLO and the DNN classifier model. The current research provides a foundation for the further exploration of MS and HS imaging in detecting bark beetle disturbances in time, which can play a crucial role in forest management efforts to combat large-scale outbreaks. The study highlights the potential of remote sensing and machine learning in monitoring forest health and mitigating the impacts of biotic stresses. It also offers valuable insights into the effectiveness of DNNs in detecting bark beetle infestations using UAS-based remote sensing technology. [ABSTRACT FROM AUTHOR]

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Adelges tsugae Annand, the hemlock woolly adelgid, is an invasive insect pest of Tsuga canadensis (L.) Carriere, eastern hemlock, in the eastern United States. An A. tsugae infestation often results in the death of T. canadensis within years and has caused significant changes to hemlock forests. Cycles in T. canadensis health and A. tsugae densities seem to be an important feature in A. tsugae population dynamics in the eastern United States. To investigate mechanisms leading to such cycles, we construct a model composed of systems of ordinary differential equations with time‐dependent parameters to represent seasonality. The model captures the coupled cycles in T. canadensis health and A. tsugae density. We use field data from Virginia to develop the model and to perform parameter estimation. The mechanisms we represent in the model include an A. tsugae density‐dependent T. canadensis growth rate, a T. canadensis health‐dependent A. tsugae mortality rate, and a density‐dependent A. tsugae mortality rate, which produce cycles in T. canadensis health and A. tsugae density commonly seen with the A. tsugae system in the eastern United States. We test sets of initial conditions to determine the scenarios that will likely lead to T. canadensis mortality and explore longer term dynamics of the system. In general, low and high T. canadensis health initial condition values result in likely T. canadensis mortality while T. canadensis with medium health initial condition values are predicted to survive. [ABSTRACT FROM AUTHOR]

The use of canopy density for crop production is a useful tool for evaluating management practices for informed decision-making and predicting crop yields. Traditional methods for analyzing canopy density include expensive equipment that requires advanced software and costly repairs, such as leaf area index analyzers, or equipment that can only be used during optimal weather conditions, such as light meters, that quantify photosynthetically active radiation (PAR), thus making it difficult for researchers to maximize the time needed for field research evaluations and data collection. Digital image analyses using technologically advanced cameras, such as smartphone cameras, have allowed new ways of collecting data without the need to purchase specialized instruments. Using a combination of smartphone cameras and ImageJ software, canopy density can be measured in any weather conditions for a much lower cost than that of traditional equipment. This low-cost, digital image analysis method was compared with traditional PAR measurements for ‘Valencia’ sweet orange [Citrus sinensis (L.) Osb.] trees with varying levels of canopy density. A strong positive correlation between the digital image analysis method and standard canopy density measurement method using PAR measurements (r = 0.79; P

The incident of fallen trees or broken branches is dangerous for tourists visiting Bali Botanical Garden. Tree health monitoring in locations with high human activity and near valuable properties is mandatory to minimize the potency of tree failure. Since the stand stability is influenced by biological and physical factors, multiple variables consisting of species characteristics (stem form), tree dimensions (height, diameter, and slenderness coefficient), and tree health were used as parameters of tree health. The aim of this study is to examine the health condition of trees located in XIV.G vak Bali Botanical Garden and to identify the most significant morphological character related to the result of tomograph measurement. A purposive sampling technique was adopted for locations which highly visited. A total of 80 trees were examined as samples to measure tree health. The evaluation used visual observation and tomograph technology. The result showed the most tree defect found were branches covered with epiphyte and moss. However, tomograph examination found only one tree classified at high risk (Bischofia javanica) and seven trees classified at medium risk (Syzygium polyanthum, Syzygium racemosum, Bischofia javanica, Pittosporum mollucanum, Pittosporum sp. and Dacrycarpus imbricatus (2 trees). This study suggests the use of tree architecture model as the most significant morphological character on tree samples with medium decay. [ABSTRACT FROM AUTHOR]

We present an evaluation of different deep learning and machine learning approaches for tree health classification in the Black Forest, the Harz Mountains, and the Göttinger Forest on a unique, highly accurate tree-level dataset. The multispectral UAV data were collected from eight forest plots with diverse tree species, mostly conifers. As ground truth data (GTD), nearly 1500 tree polygons with related attribute information on the health status of the trees were used. This data were collected during extensive fieldwork using a mobile application and subsequent individual tree segmentation. Extensive preprocessing included normalization, NDVI calculations, data augmentation to deal with the underrepresented classes, and splitting the data into training, validation, and test sets. We conducted several experiments using a classical machine learning approach (random forests), as well as different convolutional neural networks (CNNs)—ResNet50, ResNet101, VGG16, and Inception-v3—on different datasets and classes to evaluate the potential of these algorithms for tree health classification. Our first experiment was a binary classifier of healthy and damaged trees, which did not consider the degree of damage or tree species. The best results of a 0.99 test accuracy and an F1 score of 0.99 were obtained with ResNet50 on four band composites using the red, green, blue, and infrared bands (RGBI images), while VGG16 had the worst performance, with an F1 score of only 0.78. In a second experiment, we also distinguished between coniferous and deciduous trees. The F1 scores ranged from 0.62 to 0.99, with the highest results obtained using ResNet101 on derived vegetation indices using the red edge band of the camera (NDVIre images). Finally, in a third experiment, we aimed at evaluating the degree of damage: healthy, slightly damaged, and medium or heavily damaged trees. Again, ResNet101 had the best performance, this time on RGBI images with a test accuracy of 0.98 and an average F1 score of 0.97. These results highlight the potential of CNNs to handle high-resolution multispectral UAV data for the early detection of damaged trees when good training data are available.

The incident of fallen trees or broken branches is dangerous for tourists visiting Bali Botanical Garden. Tree health monitoring in locations with high human activity and near valuable properties is mandatory to minimize the potency of tree failure. Since the stand stability is influenced by biological and physical factors, multiple variables consisting of species characteristics (stem form), tree dimensions (height, diameter, and slenderness coefficient), and tree health were used as parameters of tree health. The aim of this study is to examine the health condition of trees located in XIV.G Bali Botanical Garden and to identify the most significant morphological character related to the result of tomograph measurement. A purposive sampling technique was adopted for locations which highly visited. A total of 80 trees were examined as samples to measure tree health. The evaluation used visual observation and tomograph technology. The result showed the most tree defect found were branches covered with epiphyte and moss. However, tomograph examination found only one tree classified at high risk (Bischofia javanica) and seven trees classified at medium risk (Syzygium polyanthum, Syzygium racemosum, Bischofia javanica, Pittosporum mollucanum, Pittosporum sp. and Dacrycarpus imbricatus (2 trees)). This study suggests the use of tree architecture model as the most significant morphological character on tree samples with medium decay.

Armillaria species show considerable variation in ecological roles and virulence, from mycorrhizae and saprophytes to important root pathogens of trees and horticultural crops. We studied two Armillaria species that can be found in coniferous forests of northwestern USA and southwestern Canada. Armillaria altimontana not only is considered as a weak, opportunistic pathogen of coniferous trees, but it also appears to exhibit in situ biological control against A. solidipes, formerly North American A. ostoyae, which is considered a virulent pathogen of coniferous trees. Here, we describe their genome assemblies and present a functional annotation of the predicted genes and proteins for the two Armillaria species that exhibit contrasting ecological roles. In addition, the soil microbial communities were examined in association with the two Armillaria species within a 45-year-old plantation of western white pine (Pinus monticola) in northern Idaho, USA, where A. altimontana was associated with improved tree growth and survival, while A. solidipes was associated with reduced growth and survival. The results from this study reveal a high similarity between the genomes of the beneficial/non-pathogenic A. altimontana and pathogenic A. solidipes; however, many relatively small differences in gene content were identified that could contribute to differences in ecological lifestyles and interactions with woody hosts and soil microbial communities. [ABSTRACT FROM AUTHOR]

Background: In Singapore, determining the level of infestation by lebbek borer (Xystrocera globosa)(Olivier, 1795)[Coleoptera: Cerambycidae] is the crucial first step in control of this pestra in rain tree (Albizia saman [Jacq.] Merr.)[Fabales: Fabaceae]. Current assessment methods rely on symptoms such as canopy colour, defoliation, dieback, and actual estimation of borer population via counting of larvae or exit holes created by adults. Currently, there is a lack of systematic approach to integrate different tree health indicators and symptoms to quantify infestation level. This gap poses challenges in assessment of treatment efficacy as managers could not quantitatively determine whether infestation level has changed following treatment. Thus, this study aimed to develop a visual assessment method that can integrate all mentioned symptoms to quantify infestation level. Methods: We surveyed a total of 388 rain trees and used principal component analysis (PCA) to investigate the correlation between X. globosa infestation and different borer infestation symptoms. Borer Infestation Score (BIS) formula was developed based on the linear combinations of the statistically significant principal component. Results: Infestation level was strongly associated with bark peeling, exit holes, and proximity of bark peeling and/or exit holes to trunk base and weakly associated with defoliation, dieback, and canopy colour. Developed BIS formula generated numerical values that distinguished between noninfested and infested trees, reflected infestation level in surveyed areas and temporal progression of infestation. Conclusions: Described integrated visual assessment method can be executed quickly on field. BIS formula generates quantitative scores easy to be interpreted, tracked, and compared. [ABSTRACT FROM AUTHOR]

The use of canopy density for crop production is a useful tool for evaluating management practices for informed decision-making and predicting crop yields. Traditional methods for analyzing canopy density include expensive equipment that requires advanced software and costly repairs, such as leaf area index analyzers, or equipment that can only be used during optimal weather conditions, such as light meters, that quantify photosynthetically active radiation (PAR), thus making it difficult for researchers to maximize the time needed for field research evaluations and data collection. Digital image analyses using technologically advanced cameras, such as smartphone cameras, have allowed new ways of collecting data without the need to purchase specialized instruments. Using a combination of smartphone cameras and ImageJ software, canopy density can be measured in any weather conditions for a much lower cost than that of traditional equipment. This low-cost, digital image analysis method was compared with traditional PAR measurements for ‘Valencia’ sweet orange [Citrus sinensis (L.) Osb.] trees with varying levels of canopy density. A strong positive correlation between the digital image analysis method and standard canopy density measurement method using PAR measurements (r 5 0.79; P<0.0001) was found, indicating that this method can be used as an alternative to the PAR method. The digital image analysis method was also consistent when used during different weather conditions, whereas the PAR method was highly variable when quantifying the canopy when clouds were present in comparison with clear sky conditions. This novel method provides researchers and growers with an easy, flexible, consistent, and low-cost option for analyzing canopy density. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate fungal communities associated with leaves and roots of healthy-looking and declining U. glabra trees. The study was expected to demonstrate whether and how the diversity and composition of fungal communities change in these functional tissues following the infection by Dutch elm disease-causing fungi. The study sites included six U. glabra sites in Lithuania, where leaves and roots were sampled. DNA was isolated from individual samples, amplified using ITS2 rRNA as a marker, and subjected to high-throughput sequencing. The sequence analysis showed the presence of 32,699 high-quality reads, which following clustering, were found to represent 520 non-singleton fungal taxa. In leaves, the fungal species richness was significantly higher in healthy-looking trees than in diseased ones (p < 0.05). In roots, a similar comparison showed that the difference was insignificant (p > 0.05). The most common fungi in all samples of roots were Trichocladium griseum (32.9%), Penicillium restrictum (21.2%), and Unidentified sp. 5238_7 (12.6%). The most common fungi in all samples of leaves were Trichomerium sp. 5238_8 (12.30%), Aureobasidium pullulans (12.03%), Cladosporium sp. 5238_5 (11.73%), and Vishniacozyma carnescens (9.86%). The results showed that the detected richness of fungal taxa was higher in samples collected from healthy-looking trees than from diseased ones, thereby highlighting the negative impact of the Dutch elm disease on the overall fungal diversity. [ABSTRACT FROM AUTHOR]

Climate change, which leads to higher temperatures, droughts, and storms, is expected to have a strong effect on both health of forest trees and associated biodiversity. The aim of this study was to investigate the diversity and composition of fungal communities associated with the functional tissues and rhizosphere soil of healthy-looking Picea abies to better understand these fungal communities and their potential effect on tree health in the process of climate change. The study sites included 30 P. abies stands, where needles, shoots, roots, and the rhizosphere soil was sampled. DNA was isolated from individual samples, amplified using ITS2 rRNA as a marker and subjected to high-throughput sequencing. The sequence analysis showed the presence of 232,547 high-quality reads, which following clustering were found to represent 2701 non-singleton fungal OTUs. The highest absolute richness of fungal OTUs was in the soil (1895), then in the needles (1049) and shoots (1002), and the lowest was in the roots (641). The overall fungal community was composed of Ascomycota (58.3%), Basidiomycota (37.2%), Zygomycota (2.5%), Chytridiomycota (1.6%), and Glomeromycota (0.4%). The most common fungi based on sequence read abundance were Aspergillus pseudoglaucus (7.9%), Archaeorhizomyces sp. (3.6%), and Rhinocladiella sp. (2.0%). Pathogens were relatively rare, among which the most common were Phacidium lacerum (1.7%), Cyphellophora sessilis (1.4%), and Rhizosphaera kalkhoffii (1.4%). The results showed that the detected diversity of fungal OTUs was generally high, but their relative abundance varied greatly among different study sites, thereby highlighting the complexity of interactions among the host trees, fungi, and local environmental conditions. [ABSTRACT FROM AUTHOR]

Policy makers are challenged to find ways of influencing and supporting land manager behaviours and actions to deal with the impacts of increasing pressure from tree pests and diseases. This paper investigates attitudes and behaviours of farmers towards managing trees on farmland for pests and diseases. Data collection with farmers included deliberative workshops and semi-structured interviews. Data were thematically analyzed using the COM-B (Capacity/Opportunity/Motivation-Behaviour) model to understand the drivers of farmer behaviour for tree health. Results suggested farmers had some knowledge, experience and skills managing trees, but they did not recognize this capacity. Social norms and networks impacted the context of opportunity to act for tree health, along with access to trusted advice and labour, and the costs associated with management action. Motivational factors such as self-efficacy, perceived benefits of acting, personal interest and sense of agency were impacted by farmers' self-identity as food producers. The COM-B model also provides a framework for identifying intervention design through a Behaviour Change Wheel. This suggests that enhancing self-efficacy supported by the right kind of advice and guidance, framed and communicated in farmers' terms and brokered by appropriate knowledge intermediaries, seems critical to building action amongst different farmer types and attitudinal groups. [ABSTRACT FROM AUTHOR]

The double-spined bark beetle Ips duplicatus (Coleoptera: Curculionidae, Scolytinae) is an invasive forest pest having a broad range of coniferous hosts within Europe. We found this species to be also developing in the Serbian spruce Picea omorika. Ips duplicatus infested 14 (52%) of 27 P. omorika mature trees in an arboretum garden in northern Slovakia in Central Europe during the summer of 2019. Logs from the upper part of stems of P. omorika trees placed in eclectors in the laboratory, yielded a total of 179 individuals of three scolytine species, with prevalence of I. duplicatus. Our results show that I. duplicatus also colonized less likely host such as the Serbian spruce, causing threat to this ornamental tree and contributing to its mortality in urban habitats during hot and dry summer weather.

The weakening and decline of European ash Fraxinus excelsior L. and other ash species have been recorded at different locations in the suburbs of Saint Petersburg, Russia. During the summer of 2019 and spring of 2020, samples from leaves, petioles, and shoots were collected from the weakened and declining ash trees in three parks in Pushkin and Gatchina and maintained in humid chambers to induce the fructification of fungi. In total, 30 taxa of micromycetes belonging to 23 genera were identified using methods of light microscopy. Hymenoscyphus fraxineus, a putative agent of ash dieback, was not recorded in the samples collected in the crowns of trees, but only on the petioles of the fallen leaves in spring. Out of all the micromycetes recorded, only coelomycetes from the genus Diplodia Fr. (in particular, D. mutila) can damage the branches of ash trees and, thus, be considered pathogenic. It is likely that H. fraxineus opens “the entry of infection” and Diplodia spp. cause the major weakening and decline of branches. The data obtained can significantly change our understanding of the causes of ash dieback and possible methods of ash stand preservation. The reason for the low pathogenicity and activity of H. fraxineus, as well as the possible role of ascomycetes Diplodia spp. in the dieback of ash stands requires further research.

Abstract The early detection of plant pests and diseases is vital to the success of any eradication or control programme, but the resources for surveillance are often limited. Plant health authorities can however make use of observations from individuals and stakeholder groups who are monitoring for signs of ill health. Volunteered data is most often discussed in relation to citizen science groups, however these groups are only part of a wider network of professional agents, land-users and owners who can all contribute to significantly increase surveillance efforts through “passive surveillance”. These ad-hoc reports represent chance observations by individuals who may not necessarily be looking for signs of pests and diseases when they are discovered. Passive surveillance contributes vital observations in support of national and international surveillance programs, detecting potentially unknown issues in the wider landscape, beyond points of entry and the plant trade. This review sets out to describe various forms of passive surveillance, identify analytical methods that can be applied to these “messy” unstructured data, and indicate how new programs can be established and maintained. Case studies discuss two tree health projects from Great Britain (TreeAlert and Observatree) to illustrate the challenges and successes of existing passive surveillance programmes. When analysing passive surveillance reports it is important to understand the observers’ probability to detect and report each plant health issue, which will vary depending on how distinctive the symptoms are and the experience of the observer. It is also vital to assess how representative the reports are and whether they occur more frequently in certain locations. Methods are increasingly available to predict species distributions from large datasets, but more work is needed to understand how these apply to rare events such as new introductions. One solution for general surveillance is to develop and maintain a network of tree health volunteers, but this requires a large investment in training, feedback and engagement to maintain motivation. There are already many working examples of passive surveillance programmes and the suite of options to interpret the resulting datasets is growing rapidly.

Huanglongbing (HLB), or citrus greening disease, affects practically all fruit-bearing trees in commercial citrus orchards in Florida with no cure identified yet. High-density plantings and enhanced nutritional programs such as application of controlled-release fertilizer (CRF) with higher micronutrient levels can mitigate disease symptoms and extend the tree life span of sweet oranges (Citrus sinensis). The objective of this study was to evaluate the effects of tree planting density and application of CRF blends differing in N to K ratio and micronutrient content on grapefruit (Citrus paradisi) plant health, canopy volume, fruit yield, and fruit quality in an HLB-affected orchard. A study was conducted in Florida for two growing seasons (2017–18 and 2018–19) to evaluate the response of ‘Ray Ruby’ grapefruit on Kuharske citrange (Citrus sinensis × Poncirus trifoliata) to three planting densities (300, 440, and 975 trees per ha) and two CRF blends [12 nitrogen (N)–1.31 phosphorus (P)–7.47 potassium (K) and 16N–1.31P–16.6K] with different nutrient sources and composition. According to quantitative real-time polymerase chain reaction testing, all sampled trees tested positive for Candidatus Liberibacter asiaticus, the pathogen associated with HLB. Trees planted at 975 trees per ha had 33% lower canopy volume per tree but 160% greater fruit yield per hectare and 190% higher yield of solids compared with 300 trees per ha. Fruit produced in high-density planting (975 trees per ha) was 18% more acidic with higher soluble solid compared with low-density planting (300 trees per ha). The use of a CRF blend with higher amounts of micronutrients along with lower K increased canopy volume in both seasons and resulted in 24% and 29% reduction in fruit yield per hectare and yield of solids, respectively, in 2017–18. Our results indicate that high-density plantings increase fruit yield per area, and regardless of the N to K ratio, the use of CRF blends supplemented with micronutrients may not increase fruit yield in HLB-affected grapefruit.

Trees and woody plants can be attacked by many pests and pathogens either individually or as polymicrobial infections. In particular, infections caused by tree‐specific bacterial pathogens have become more common during the last decade, causing serious concern for important tree and woody plant species in horticulture, urban environments, and forests. For example, Xylella and Pseudomonas bacteria are causing significant economic and ecological devastation throughout Europe in olive, cherry, and other stone fruits, mainly because of lack of efficient control methods and the emergence of bacterial resistance to traditional antimicrobial compounds such as copper and antibiotics. Hence, there is an urgent need for innovative approaches to tackle bacterial plant diseases. One way to achieve this could be through the application of biological control, which offers a more environmentally friendly and targeted approach for pathogen management. This review will explore recent advances in use of pathogen‐specific viruses, bacteriophages (or phages), for the biocontrol of bacterial tree diseases. Phages are an important component of plant microbiomes and are increasingly studied in plant pathogen control due to their highly specific host ranges and ability to selectively kill only the target pathogenic bacteria. However, their use still poses several challenges and limitations, especially in terms of managing the bacterial diseases of long‐lived trees. A particular insight will be given into phage research focusing on controlling Pseudomonas syringae pathovars, Erwinia amylovora, Xanthomonas species, Ralstonia solanacearum, and Agrobacterium tumefaciens. Recent milestones, current challenges, and future avenues for phage therapy in the management of tree diseases are discussed. [ABSTRACT FROM AUTHOR]

Various biotic and abiotic stresses are causing decline in forest health globally. Presently, one of the major biotic stress agents in Europe is the European spruce bark beetle (Ips typographus L.) which is increasingly causing widespread tree mortality in northern latitudes as a consequence of the warming climate. Remote sensing using unoccupied aerial systems (UAS) together with evolving machine learning techniques provide a powerful tool for fast-response monitoring of forest health. The aim of this study was to investigate the performance of a deep one-stage object detection neural network in the detection of damage by I. typographus in Norway spruce trees using UAS RGB images. A Scaled-YOLOv4 (You Only Look Once) network was implemented and trained for tree health analysis. Datasets for model training were collected during 2013–2020 from three different areas, using four different RGB cameras, and under varying weather conditions. Different model training options were evaluated, including two different symptom rules, different partitions of the dataset, fine-tuning, and hyperparameter optimization. Our study showed that the network was able to detect and classify spruce trees that had visually separable crown symptoms, but it failed to separate spruce trees with stem symptoms and a green crown from healthy spruce trees. For the best model, the overall F-score was 89%, and the F-scores for the healthy, infested, and dead trees were 90%, 79%, and 98%, respectively. The method adapted well to the diverse dataset, and the processing results with different options were consistent. The results indicated that the proposed method could enable implementation of low-cost tools for management of I. typographus outbreaks.

The aim of this study was to investigate fungal communities associated with leaves and roots of healthy-looking and declining U. glabra trees. The study was expected to demonstrate whether and how the diversity and composition of fungal communities change in these functional tissues following the infection by Dutch elm disease-causing fungi. The study sites included six U. glabra sites in Lithuania, where leaves and roots were sampled. DNA was isolated from individual samples, amplified using ITS2 rRNA as a marker, and subjected to high-throughput sequencing. The sequence analysis showed the presence of 32,699 high-quality reads, which following clustering, were found to represent 520 non-singleton fungal taxa. In leaves, the fungal species richness was significantly higher in healthy-looking trees than in diseased ones (p < 0.05). In roots, a similar comparison showed that the difference was insignificant (p > 0.05). The most common fungi in all samples of roots were Trichocladium griseum (32.9%), Penicillium restrictum (21.2%), and Unidentified sp. 5238_7 (12.6%). The most common fungi in all samples of leaves were Trichomerium sp. 5238_8 (12.30%), Aureobasidium pullulans (12.03%), Cladosporium sp. 5238_5 (11.73%), and Vishniacozyma carnescens (9.86%). The results showed that the detected richness of fungal taxa was higher in samples collected from healthy-looking trees than from diseased ones, thereby highlighting the negative impact of the Dutch elm disease on the overall fungal diversity.

The double-spined bark beetle Ips duplicatus (Coleoptera: Curculionidae, Scolytinae) is an invasive forest pest having a broad range of coniferous hosts within Europe. We found this species to be also developing in the Serbian spruce Picea omorika. Ips duplicatus infested 14 (52%) of 27 P. omorika mature trees in an arboretum garden in northern Slovakia in Central Europe during the summer of 2019. Logs from the upper part of stems of P. omorika trees placed in eclectors in the laboratory, yielded a total of 179 individuals of three scolytine species, with prevalence of I. duplicatus. Our results show that I. duplicatus also colonized less likely host such as the Serbian spruce, causing threat to this ornamental tree and contributing to its mortality in urban habitats during hot and dry summer weather. [ABSTRACT FROM AUTHOR]

This research evaluated the effect of pruning, fertilization and pesticide injection on crown dieback in urban trees in Colombia and analyzed the factors involved. Systemic insecticides and/or fungicides were applied through injections in the trunk of 15 tree species affected by the progressive deterioration of the crown in the urban forests of the Metropolitan Area of the Aburrá Valley. The presence of progressive deterioration was evaluated qualitatively on a scale from zero to three in an average sample of 12 individuals for each species. Two treatments were used: i) application of insecticide + fungicide, and ii) application of insecticide, both treatments were applied three times, plus a general treatment of pruning and fertilization. Also, two controls were evaluated: healthy trees and diseased trees without treatment. The probability of individual progressive deterioration (PD) during the study period according to the species, treatment applied, and the initial state of affectation was estimated using a generalized linear mixed model. The analysis of factors involved also included planting site, traffic flow of the site, the wood density of the species, and time. The results suggest that the deterioration is a dynamic phenomenon associated with environmental stresses caused mainly by the climatic variability. From the evaluated variables, the species seems to be the most determinant factor for the affectation, since intrinsic variables of the species, like wood density, can favor its appearance. On the contrary, the treatments evaluated did not affect the recovery of the species. The action of insects and pathogens seems to be opportunistic once trees are affected.

Homegarden–dry field is one of land management form that maintains biodiversity while at the same time synergize the production and conservation. Changes in market conditions pose a threat for monoculturalism on homegarden and dry field. On the basis of this consideration, it is necessary to do a research on trees health in homegarden and dry field. This study aimed to determine the constituent species in the agroforestry system of Kulon Progo, tree health typology in Kulon Progo, and the type of damages to homegarden and dry field tree species in agroforestry. This research method used inventory of species in the agroforestry system and identification of damage to trees using Forest Health Monitoring (FHM). The result showed that there were three typologies of trees’ health. Those were classified into typology 1, 2 and 3 in Kulon Progo. The types of damage that present at homegarden and dry field in Kulon Progo are the open wound, galls rust, broken branch, leaf spot, excessive branching, gummosis and termite attack.

The weakening and decline of European ash Fraxinus excelsior L. and other ash species have been recorded at different locations in the suburbs of Saint Petersburg, Russia. During the summer of 2019 and spring of 2020, samples from leaves, petioles, and shoots were collected from the weakened and declining ash trees in three parks in Pushkin and Gatchina and maintained in humid chambers to induce the fructification of fungi. In total, 30 taxa of micromycetes belonging to 23 genera were identified using methods of light microscopy. Hymenoscyphus fraxineus, a putative agent of ash dieback, was not recorded in the samples collected in the crowns of trees, but only on the petioles of the fallen leaves in spring. Out of all the micromycetes recorded, only coelomycetes from the genus Diplodia Fr. (in particular, D. mutila) can damage the branches of ash trees and, thus, be considered pathogenic. It is likely that H. fraxineus opens "the entry of infection" and Diplodia spp. cause the major weakening and decline of branches. The data obtained can significantly change our understanding of the causes of ash dieback and possible methods of ash stand preservation. The reason for the low pathogenicity and activity of H. fraxineus, as well as the possible role of ascomycetes Diplodia spp. in the dieback of ash stands requires further research. [ABSTRACT FROM AUTHOR]

The trees and forests of Europe are increasingly under threat from new pests and diseases that have originated in other parts of the world. Early detection of alien species when they first appear in European countries allows rapid response and offers the best chance to mitigate against their establishment and spread. Citizen science initiatives such as LIFE ARTEMIS in Slovenia, and Observatree in the UK, provide members of the public with the necessary training and educational resource to identify these tree pests and diseases and report them to the appropriate authorities, thereby increasing the level of surveillance and the capacity of the early warning system. This paper summarises some of the outcomes of these two projects and how they have both become integral parts of the official forest and tree health monitoring systems within their respective countries of Slovenia and the United Kingdom. [ABSTRACT FROM AUTHOR]

Huanglongbing (HLB), or citrus greening disease, affects practically all fruitbearing trees in commercial citrus orchards in Florida with no cure identified yet. Highdensity plantings and enhanced nutritional programs such as application of controlledrelease fertilizer (CRF) with higher micronutrient levels can mitigate disease symptoms and extend the tree life span of sweet oranges (Citrus sinensis). The objective of this study was to evaluate the effects of tree planting density and application of CRF blends differing in N to K ratio and micronutrient content on grapefruit (Citrus paradisi) plant health, canopy volume, fruit yield, and fruit quality in an HLB-affected orchard. A study was conducted in Florida for two growing seasons (2017-18 and 2018-19) to evaluate the response of 'Ray Ruby' grapefruit on Kuharske citrange (Citrus sinensis 3 Poncirus trifoliata) to three planting densities (300, 440, and 975 trees per ha) and two CRF blends [12 nitrogen (N)-1.31 phosphorus (P)-7.47 potassium (K) and 16N-1.31P-16.6K] with different nutrient sources and composition. According to quantitative real-time polymerase chain reaction testing, all sampled trees tested positive for Candidatus Liberibacter asiaticus, the pathogen associated with HLB. Trees planted at 975 trees per ha had 33% lower canopy volume per tree but 160% greater fruit yield per hectare and 190% higher yield of solids compared with 300 trees per ha. Fruit produced in high-density planting (975 trees per ha) was 18% more acidic with higher soluble solid compared with low-density planting (300 trees per ha). The use of a CRF blend with higher amounts of micronutrients along with lower Kincreased canopy volume in both seasons and resulted in 24% and 29% reduction in fruit yield per hectare and yield of solids, respectively, in 2017-18. Our results indicate that high-density plantings increase fruit yield per area, and regardless of the N to K ratio, the use of CRF blends supplemented with micronutrients may not increase fruit yield in HLB-affected grapefruit. [ABSTRACT FROM AUTHOR]

Despite being well adapted to the long seasonal droughts of the Mediterranean Basin, the holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.) has undergone a gradual decline during the last decades. The reasons of this decline are not fully understood, but evidence suggests that the quality and quantity of the interactions of holm oaks with the soil microbiota are playing a central role in the resilience of this species. With the aim to test the previous statement as our hypothesis, 9 oak savannah sites (called dehesas from here on) were sampled, in which asymptomatic (healthy) and symptomatic (early stage of decline) trees were interspersed. Using high throughput amplicon sequencing, soil bacterial and fungal biota (called soil microbiota from here on) were sequenced. Our results showed that soil fungal community composition differed between healthy and declining trees whereas bacterial communities did not show significant differences. Specifically, the degree of holm-oak defoliation was negatively correlated to the relative abundance of ectomycorrhizal (ECM) fungi and fungal endophytes, suggesting a relation between trees' health and soil fungal symbionts. Although our observational study cannot give a final answer to the directionality of the relationships observed, our results support the idea that small changes in symbiont abundance might be causing holm oaks to lose their ability to withstand the strong environmental pressures. • Microbial soil diversity correlates with tree health status. • Fungal diversity is more related to tree health than bacterial diversity. • The abundance of ectomycorrhiza (ECM) and fungal endophytes is related to tree resilience. • Small spatial variability in plant-fungal symbiotic relations influences tree health. [ABSTRACT FROM AUTHOR]

• Suspended pavement practices can increase opportunities to manage urban stormwater. • Performance of two bioretention suspended pavement systems studied over 27 months. • Exfiltration, evapotranspiration were major hydrologic pathways from both systems. • Limited surface ponding, drainage-treatment area ratio led to high volume reduction. • Bioretention suspended pavement systems effectively reduced influent runoff volumes. Trees supply numerous ecosystem services to the urban environment, including mitigating the urban heat island, improving air quality, and providing habitat for wildlife. However, due to the structural stability requirements of infrastructure such as sidewalks, roadways, and parking areas, urban soils are commonly characterized by high compaction levels, low porosity, and nutrient deficiency, often to the detriment of urban tree health. By transmitting surface loads to a compacted subbase, suspended pavement systems create a matrix of uncompacted soil that promotes tree health through increased root access to oxygen, water, and nutrients. Recently, interest has grown in making suspended pavement systems multi-functional by designing them to act as subsurface bioretention practices in ultra-urban areas where space may be limited due to concentrated development and high land costs. Despite this interest, only one study has tested suspended pavement systems in this application. Further, the study utilized lined installations to allow a controlled water quality assessment; however, this negated the ability to fully quantify runoff reduction. Two unlined suspended pavement systems designed to function as subsurface bioretention practices were installed in Knoxville, Tennessee, USA, in 2015 and monitored over 27-months. During that period, over 99% of runoff volumes were reduced by the free-drained north system, which completely captured runoff from 79% of storms. The underdrained south system reduced influent runoff by over 88% and captured all runoff from 83% of events during the study. Influent TSS concentrations were significantly reduced by the south suspended pavement system, though no other significant differences between influent and effluent pollutant concentrations were observed, presumably due to low influent concentrations. This study demonstrates the viability of field-scale suspended pavement systems in a stormwater management application and illustrates the hydrologic and pollutant removal capabilities of these systems to manage urban stormwater runoff. [ABSTRACT FROM AUTHOR]

This research evaluated the effect of pruning, fertilization and pesticide injection on crown dieback in urban trees in Colombia and analyzed the factors involved. Systemic insecticides and/or fungicides were applied through injections in the trunk of 15 tree species affected by the progressive deterioration of the crown in the urban forests of the Metropolitan Area of the Aburrá Valley. The presence of progressive deterioration was evaluated qualitatively on a scale from zero to three in an average sample of 12 individuals for each species. Two treatments were used: i) application of insecticide + fungicide, and ii) application of insecticide, both treatments were applied three times, plus a general treatment of pruning and fertilization. Also, two controls were evaluated: healthy trees and diseased trees without treatment. The probability of individual progressive deterioration (PD) during the study period according to the species, treatment applied, and the initial state of affectation was estimated using a generalized linear mixed model. The analysis of factors involved also included planting site, traffic flow of the site, the wood density of the species, and time. The results suggest that the deterioration is a dynamic phenomenon associated with environmental stresses caused mainly by the climatic variability. From the evaluated variables, the species seems to be the most determinant factor for the affectation, since intrinsic variables of the species, like wood density, can favor its appearance. On the contrary, the treatments evaluated did not affect the recovery of the species. The action of insects and pathogens seems to be opportunistic once trees are affected. [ABSTRACT FROM AUTHOR]

Homegarden-dry field is one of land management form that maintains biodiversity while at the same time synergize the production and conservation. Changes in market conditions pose a threat for monoculturalism on homegarden and dry field. On the basis of this consideration, it is necessary to do a research on trees health in homegarden and dry field. This study aimed to determine the constituent species in the agroforestry system of Kulon Progo, tree health typology in Kulon Progo, and the type of damages to homegarden and dry field tree species in agroforestry. This research method used inventory of species in the agroforestry system and identification of damage to trees using Forest Health Monitoring (FHM). The result showed that there were three typologies of trees' health. Those were classified into typology 1, 2 and 3 in Kulon Progo. The types of damage that present at homegarden and dry field in Kulon Progo are the open wound, galls rust, broken branch, leaf spot, excessive branching, gummosis and termite attack. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Damage to ash trees by ash dieback caused by the emerging fungal pathogen Hymenoscyphus fraxineus is impacting people across Europe. This poses challenges to: public safety; productivity of commercial forestry; green spaces and human wellbeing; and ecosystem services and carbon sequestration. Here, we seek to quantify the impact of ash dieback on tree mortality by analyzing surveys counting the proportion of trees that have died in sites across Europe. However, more and better data are needed to inform policy makers, foresters, conservationists, and other stakeholders as they plan for a long‐term future with ash dieback. Summary: The ash dieback epidemic, caused by the fungus Hymenoscyphus fraxineus, has been present in Europe for over 20 years and caused widespread damage and mortality in ash tree (Fraxinus excelsior) populations. Ash is a major natural capital asset and plays an important role in nature's contribution to people in Europe.Here, we present a meta‐analysis of surveys of ash mortality due to ash dieback, and a time‐dependent model to estimate longer term mortality. In plantations established previous to the arrival of the epidemic, we analyze 12 surveys, finding a maximum recorded mortality of ~85%. In woodlands with exposure to ash dieback of between 4 and 20 years, we analyze 36 surveys, finding a maximum recorded mortality (which may have missed some dead trees) of ~70%. We also analyze 10 surveys of naturally regenerated saplings, finding maximum recorded mortality of ~82%. We apply logistic models to these data sets to seek longer term predictions.More data are needed before our models can be relied upon for policy decisions. If survival found so far in woodlands is due in part to heritable resistance, natural selection or a breeding program may allow future recovery of ash populations in Europe. We review surveys of ash tree death due to ash dieback in Europe and find a maximum mortality so far of 70% of trees in woodlands and 85% of trees in plantations established before the epidemic. It is still hard to predict what the long‐term outcomes will be, and more data are needed. [ABSTRACT FROM AUTHOR]

The incidence of tree disease has been increasing in the UK in recent years as a result of a range of alien tree pests and pathogens new to the country. In the early 2010s government staff resources to monitor, identify and eradicate these pathogens were limited, so we tested the efficacy of “citizen scientists” to support these needs. The Open Air Laboratories (OPAL) is a successful citizen science programme launched in 2007, which at that time of launch involved over 650 thousand people in a range of environmental surveys. In 2012–2013, the Food and Environment Research Agency (Fera) and Forest Research staff worked with OPAL and its partners to launch a citizen science tree health survey in Great Britain and this was extended to cover Northern Ireland until it closed in 2019. Over 2800 surveys were completed including records on more than 4500 trees, the majority from urban areas. This paper discusses the results of the survey and their value for the assessment of tree health. It also considers the implications of engagement with the general public for the future of tree health surveillance. Recommendations are made for further development of the OPAL “model” and more generally for the role of citizen science in this important area.

Abstract Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Coniferiporia sulphurascens and Coniferiporia weirii, two well‐defined and distinguishable fungal species of the family Hymenochaetaceae. The pathogens are regulated in Council Directive 2000/29/EC (Annex IAI, under the previous name Inonotus weirii for both species) as a harmful organism whose introduction into the EU is banned. The two pathogens are native to North America, where C. sulphurascens causes laminated root rot primarily in Douglas fir (Pseudotsuga menziesii) and grand fir (Abies grandis), while C. weirii causes cedar laminated root and butt rot mainly in cedars (Thuja plicata and Cupressus nootkatensis). C. weirii has been reported from Japan and China, and C. sulphurascens from China, Russia and Turkey. Neither species has been reported from the EU. C. sulphurascens may infect all conifers, while C. weirii is reported to mainly cause disease in tree species of Thuja spp. and Cupressus spp. The two pathogens could enter the EU mainly via wood with bark, isolated bark and plants for planting (including artificially dwarfed plants) of Pinaceae and Cupressaceae. Both fungi could establish in the EU, as hosts are present and climatic conditions are favourable. The two pathogens would be able to spread following establishment by the pathways mentioned for entry and also by dissemination of basidiospores and root contact with infected root/wood. Should the pathogen be introduced in the EU, impacts can be expected on coniferous woodlands, plantations and ornamental trees, thus leading to reduced tree growth and ecosystem service provision. The key uncertainties concern (i) the distribution of the two pathogens in Asia, (ii) the level of susceptibility of conifers native to Europe and (iii) the role of plants for planting as a pathway of entry and spread. For both pathogens, the criteria assessed by the Panel for consideration as a potential quarantine pest are met. As the two pests are not present in the EU, not all the criteria for consideration as regulated non‐quarantine pests are met.

Changing climate is increasing the amount and intensity of forest stress agents, such as drought, pest insects, and pathogens. Leaf water content, measured here in terms of equivalent water thickness (EWT), is an early indicator of tree stress that provides timely information about the health status of forests. Multispectral terrestrial laser scanning (MS-TLS) measures target geometry and reflectance simultaneously, providing spatially explicit reflectance information at several wavelengths. EWT and leaf internal structure affect leaf reflectance in the shortwave infrared region that can be used to predict EWT with MS-TLS. A second wavelength that is sensitive to leaf internal structure but not affected by EWT can be used to normalize leaf internal effects on the shortwave infrared region and improve the prediction of EWT. Here we investigated the relationship between EWT and laser intensity features using multisensor MS-TLS at 690, 905, and 1,550 nm wavelengths with both drought-treated and Endoconidiophora polonica inoculated Norway spruce seedlings to better understand how MS-TLS measurements can explain variation in EWT. In our study, a normalized ratio of two wavelengths at 905 and 1,550 nm and length of seedling explained 91% of the variation (R2) in EWT as the respective prediction accuracy for EWT was 0.003 g/cm2 in greenhouse conditions. The relation between EWT and the normalized ratio of 905 and 1,550 nm wavelengths did not seem sensitive to a decreased point density of the MS-TLS data. Based on our results, different EWTs in Norway spruce seedlings show different spectral responses when measured using MS-TLS. These results can be further used when developing EWT monitoring for improving forest health assessments.