Beech Leaf Research Articles

Effects of the nematode Litylenchus crenatae subsp. mccannii and beech leaf disease on leaf fungal and bacterial communities on Fagus grandifolia (American beech).

Beech leaf disease (BLD) is an emerging threat to American beech (Fagus grandifolia) and has spread quickly throughout the northeastern United States and into southern Canada. This disease leads to disfigurement of leaves and is marked by characteristic dark, interveinal banding, followed by leaf curling and drop in more advanced stages. BLD tends to especially affect understory leaves, which can lead to substantial thinning of the forest understory where F. grandifolia is a dominant tree species. Understanding the cause of BLD is necessary to employ management strategies that protect F. grandifolia and the forests where it is a foundation tree species. Current research has confirmed that the foliar nematode Litylenchus crenatae subsp. mccannii is required for BLD, but whether other organisms are involved is currently unknown. Here, we present a study that investigated leaf-associated fungi and bacteria of F. grandifolia to understand more about how microorganisms may contribute to BLD.

Rapid assessment of beech leaf disease in Fagus sylvatica buds

AbstractThe European beech (Fagus sylvatica) is threatened by the foliar nematode Litylenchus crenatae subsp. mccannii (Lcm), the causal agent of beech leaf disease (BLD). Thus far, the majority of studies regarding BLD have focused on American beech (F. grandifolia). To better determine the impact of Lcm in buds of European beech, a total of 54 buds were collected from naturally symptomatic trees. Here, we characterized for the first time the bud scale morphology of two different cultivars of F. sylvatica infected with Lcm. Detailed observations of asymptomatic and symptomatic bud scales provided insight into the physical changes and arrangements of cells in the bud scale, shedding light on the dynamic processes occurring during Lcm infection. In addition, we evaluated the suitability of using the bud scale morphology for the early detection of BLD and Lcm in naturally infected buds. The distinct cellular arrangement of symptomatic bud scales cells (i.e., asymmetric pattern of enlarged cells) provides a rapid and visual, user‐friendly methodology to prematurely diagnose BLD symptoms within the buds, as well as the detection of associated nematodes.

Diversity and potential sources of introduction of the beech leaf nematode (Litylenchus crenatae mccannii) to Ontario, Canada

Litylenchus crenatae mccannii is a foliar nematode that causes severe damage to beech, known as beech leaf disease (BLD). Previous studies have characterized and identified L. crenataein Japan and a subspecies L. crenatae mccannii in the USA. Litylenchus crenatae mccannii has been found to cause BLD in native and non-native beech hosts in North America. As little is known about the distribution and diversity of the nematode in Ontario, Canada, beech foliage was sampled throughout southcentral Ontario. Incidence and severity maps show that BLD spread from its first detections in 2017, in Elgin and Norfolk counties, to the west and northeast. A gradient in severity and incidence was observed with the highest ratings at the locations where it was originally found. The extent of the nematode’s distribution is much broader than BLD, occurring throughout much of the range of American beech. Sequences of two barcoding loci for the L. crenatae mccannii isolates from 11 locations in Ontario showed 100% similarity within and among these locations. The genotype of L. crenatae mccannii found in Ontario is the same as that identified in the USA. This finding is consistent with the fact that 92% of beech imported into Canada is from the USA and suggests that the USA could be the origin of L. crenatae mccannii nematodes in Ontario or that both countries have imported beech trees from the same source country of BLD. This research provides motivation for further studies to clarify the sources of L. crenatae mccannii.

Exploring Novel Management Methods for Beech Leaf Disease, an Emerging Threat to Forests and Landscapes

Exploring Novel Management Methods for Beech Leaf Disease, an Emerging Threat to Forests and Landscapes

Anatomical and physiological consequences of beech leaf disease in Fagus grandifolia L.

AbstractBeech leaf disease (BLD) is a foliar disease of American Beech (Fagus grandifolia L.) causally linked to the nematode Litylenchus crenatae mccannii and has rapidly spread throughout central and northeastern North America. This study aimed to characterize the anatomical and physiological differences between asymptomatic and symptomatic leaves to provide evidence for a mechanistic link between abnormal leaf development associated with BLD and the long‐term decline of affected trees. We found that leaf mass per area (LMA) and leaf thickness were 45% and 249% higher in symptomatic regions, respectively. The difference in leaf thickness was largely attributable to the spongy mesophyll being 410% thicker in symptomatic as compared with asymptomatic regions of the leaves, but palisade mesophyll and abaxial epidermal tissues were also thicker in symptomatic regions. While major vein density was not significantly different, minor vein density was significantly lower in symptomatic regions, suggesting that the effects on leaf development occur after the formation and initial development of first‐ and second‐order veins. Stomatal density was also lower in symptomatic leaves. Maximum photosynthetic rates were approximately 61% lower in symptomatic leaves and respiration rate increased as the percentage of affected leaf tissue increased. Collectively, our data show reduced photosynthetic capacity, increased respiration rates, and higher leaf construction costs, which will likely have a negative, long‐term impact on the carbon balance of trees affected by BLD.

Mapping the Environmental Risk of Beech Leaf Disease in the Northeastern United States.

The recently emerged beech leaf disease (BLD) is causing the decline and death of American beech in North America. First observed in 2012 in northeast Ohio, U.S.A., BLD had been documented in 10 northeastern states and the Canadian province of Ontario as of July 2022. A foliar nematode has been implicated as the causal agent, along with some bacterial taxa. No effective treatments have been documented in the primary literature. Irrespective of potential treatments, prevention and prompt eradication (rapid responses) remain the most cost-effective approaches to the management of forest tree disease. For these approaches to be feasible, however, it is necessary to understand the factors that contribute to BLD spread and use them in estimation of risk. Here, we conducted an analysis of BLD risk across northern Ohio, western Pennsylvania, western New York, and northern West Virginia, U.S.A. In the absence of symptoms, an area cannot necessarily be deemed free of BLD (i.e., absence of BLD cannot be certain) due to its fast spread and the lag in symptom expression (latency) after infection. Therefore, we employed two widely used presence-only species distribution models (SDMs), one-class support vector machine (OCSVM), and maximum entropy (Maxent) to predict the spatial pattern of BLD risk based on BLD presence records and associated environmental variables. Our results show that both methods work well for BLD environmental risk modeling purposes, but Maxent outperforms OCSVM with respect to both the quantitative receiver operating characteristics (ROC) analysis and the qualitative evaluation of the spatial risk maps. Meanwhile, the Maxent model provides a quantification of variable contribution for different environmental factors, indicating that meteorological (isothermality and temperature seasonality) and land cover type (closed broadleaved deciduous forest) factors are likely key contributors to BLD distribution. Moreover, the future trajectories of BLD risk over our study area in the context of climate change were investigated by comparing the current and future risk maps obtained by Maxent. In addition to offering the ability to predict where the disease may spread next, our work contributes to the epidemiological characterization of BLD, providing new lines of investigation to improve ecological or silvicultural management. Furthermore, this study shows strong potential for extension of environmental risk mapping over the full American beech distribution range so that proactive management measures can be put in place. Similar approaches can be designed for other significant or emerging forest pest problems, contributing to overall management efficiency and efficacy.

Development of Primers Specific for Detection of Litylenchus crenatae, the Causal Agent of Beech Leaf Disease, in Plant Tissue.

Beech leaf disease (BLD), an emerging threat to American beech (Fagus grandifolia) in the northern United States and Canada, was recently confirmed to be caused by the nematode Litylenchus crenatae subsp. mccannii (hereafter L. crenatae). Consequently, there is a need for a rapid, sensitive, and accurate method for detecting L. crenatae for both diagnostic as well as control purposes. This research developed a new set of DNA primers that specifically amplify L. crenatae and allow for accurate detection of the nematode in plant tissue. These primers have also been used in quantitative PCR (qPCR) to determine relative differences in gene copy number between samples. This primer set provides an improved, effective tool for monitoring and detecting L. crenatae in temperate tree leaf tissue which is necessary to understand the spread of this emerging forest pest and to develop management strategies.

Cellular insights of beech leaf disease reveal abnormal ectopic cell division of symptomatic interveinal leaf areas.

The beech leaf disease nematode, Litylenchus crenatae subsp. mccannii, is recognized as a newly emergent nematode species that causes beech leaf disease (BLD) in beech trees (Fagus spp.) in North America. Changes of leaf morphology before emergence from the bud induced by BLD can provoke dramatic effects on the leaf architecture and consequently to tree performance and development. The initial symptoms of BLD appear as dark green, interveinal banding patterns of the leaf. Despite the fast progression of this disease, the cellular mechanisms leading to the formation of such aberrant leaf phenotype remains totally unknown. To understand the cellular basis of BLD, we employed several types of microscopy to provide an exhaustive characterization of nematode-infected buds and leaves. Histological sections revealed a dramatic cell change composition of these nematode-infected tissues. Diseased bud scale cells were typically hypertrophied and showed a high variability of size. Moreover, while altered cell division had no influence on leaf organogenesis, induction of cell proliferation on young leaf primordia led to a dramatic change in cell layer architecture. Hyperplasia and hypertrophy of the different leaf cell layers, coupled with an abnormal proliferation of chloroplasts especially in the mesophyll cell layers, resulted in the typical interveinal leaf banding. These discrepancies in leaf cell structure were depicted by an abnormal rate of cellular division of the leaf interveinal areas infected by the nematode, promoting significant increase of cell size and leaf thickness. The formation of symptomatic BLD leaves is therefore orchestrated by distinct cellular processes, to enhance the value of these feeding sites and to improve their nutrition status for the nematode. Our findings thus uncover relevant cellular events and provide a structural framework to understand this important disease.

First report of the beech leaf disease nematode Litylenchus crenatae mccannii (Nematoda: Anguinidae) in Michigan.

The North American beech leaf disease (BLD) nematode, Litylenchus crenatae mccannii Handoo, Li, Kantor, Bauchan, McCann, Gabriel, Yu, Reed, Koch, Martin and Burke, 2020, is recognized as a newly emergent nematode species that causes BLD in beech trees (Fagus spp.) in North America (Carta et al. 2020; Kantor et al. 2022a). Since the first report of BLD on American beech (Fagus grandifolia Ehrh) within the Lake County, located at the north-eastern corner of the state of Ohio in 2012 (Carta et al. 2020), the disease has rapidly spread to other US states and a province in Canada (Erwing et al. 2018; Carta et al 2020; Marra and LaMondia 2020; Reed et al 2020; Kantor et al. 2022b). Currently, besides Ohio, this nematode has been reported in Pennsylvania, New York, Connecticut, Massachusetts, Maine, Rhode Island, New Jersey, West Virginia, and Virginia, as well as Ontario, Canada. Different life stages of L. crenatae mccannii were isolated from symptomatic American beech leaves from an isolated natural maple-beech stand in rural Saint Clair Cty., Michigan, US; presenting typical symptoms of beech leaf disease, i.e., swelling and darkening of interveinal leaf tissues. Samples were taken to the Forest Pathology Laboratory at Michigan State University where L. crenatae mccannii presence was confirmed in the leaves after which samples were sent to the Mycology and Nematology Genetic Diversity and Biology Laboratory (USDA-ARS) in Beltsville, Maryland for official confirmation. Nematodes were identified based on morphology and sequence analysis of the internal transcribed spacer (ITS), and the D2D3 region of the 28S large subunit ribosomal DNA. To validate the morphological identification two different ribosomal DNA loci were amplified, sequenced and the phylogenetic relationships were generated. The amplification yielded fragments of 784 and 741 bp flanked by the ITS (GenBank accession no. OP689654) and D2D3 (GenBank accession no. OP689710) primers, respectively. The sequences obtained for the specimens collected in Michigan revealed 100% similarity to L. crenatae mccannii sequences obtained from specimens collected from other geographical areas in the US, and therefore validating the morphological analyses as well. The ITS sequence shared a 99.75% similarity with the subspecies L. crenatae (GenBank accession no. LC383724.1), and 90.53% similarity to L. coprosma Zhao, Davies, Alexander and Riley, 2011 (GU727548.1). While the D2D3 sequences of both L. crenatae subspecies revealed a 100% similarity (versus LC383725.1), they revealed 95.35% similarity to L. coprosma (KY679564.1). Since the first confirmed detection of BLD in June 2022 in St. Clair Cty, BLD has been reported in Oakland and Wayne Ctys (7 reports total across the three counties), suggesting BLD spread in the SE of Michigan. BLD confirmation was based on either physical symptoms (leaf banding), and/or the presence of the beech leaf nematode by morphological or molecular confirmation. The presence of the beech leaf nematode in symptomatic leaves follow the results obtained by Carta et al. (2020) after inoculation of beech seedlings with L. crenatae mccannii. Based on both morphological and molecular analyses the specimens collected in the state of Michigan were identified as L. crenatae mccannii. To our knowledge, this is the first report of this species in conjunction with symptomatic F. grandifolia leaves in this state.

Beech Leaf Disease Severity Affects Ectomycorrhizal Colonization and Fungal Taxa Composition.

Beech leaf disease (BLD) is an emerging forest infestation affecting beech trees (Fagus spp.) in the midwestern and northeastern United States and southeastern Canada. BLD is attributed to the newly recognized nematode Litylenchus crenatae subsp. mccannii. First described in Lake County, Ohio, BLD leads to the disfigurement of leaves, canopy loss, and eventual tree mortality. Canopy loss limits photosynthetic capacity, likely impacting tree allocation to belowground carbon storage. Ectomycorrhizal fungi are root symbionts, which rely on the photosynthesis of autotrophs for nutrition and growth. Because BLD limits tree photosynthetic capacity, ECM fungi may receive less carbohydrates when associating with severely affected trees compared with trees without BLD symptoms. We sampled root fragments from cultivated F. grandifolia sourced from two provenances (Michigan and Maine) at two timepoints (fall 2020 and spring 2021) to test whether BLD symptom severity alters colonization by ectomycorrhizal fungi and fungal community composition. The studied trees are part of a long-term beech bark disease resistance plantation at the Holden Arboretum. We sampled from replicates across three levels of BLD symptom severity and compared fungal colonization via visual scoring of ectomycorrhizal root tip abundance. Effects of BLD on fungal communities were determined through high-throughput sequencing. We found that ectomycorrhizal root tip abundance was significantly reduced on the roots of individuals of the poor canopy condition resulting from BLD, but only in the fall 2020 collection. We found significantly more ectomycorrhizal root tips from root fragments collected in fall 2020 than in spring 2021, suggesting a seasonal effect. Community composition of ectomycorrhizal fungi was not impacted by tree condition but did vary between provenances. We found significant species level responses of ectomycorrhizal fungi between levels of both provenance and tree condition. Of the taxa analyzed, two zOTUs had significantly lower abundance in high-symptomatology trees compared with low-symptomatology trees. These results provide the first indication of a belowground effect of BLD on ectomycorrhizal fungi and contribute further evidence to the role of these root symbionts in studies of tree disease and forest pathology.

Physiological impacts of beech leaf disease across a gradient of symptom severity among understory American beech

Beech leaf disease (BLD) damage is associated with the parasitic nematode Litylenchus crenatae ssp. mccannii. Foliar symptoms manifest as darkened or chlorotic galls in the interveinal portions in the leaf, which become leathery and crinkled under high severity of infection. Though nearly a decade has passed since the discovery of this disease, little is known regarding the impact of BLD on leaf function and physiology. This study assesses the variation in leaf gas exchange and physiological leaf traits among asymptomatic and BLD-infected leaves across a gradient of symptom severity within a natural forested stand in central Connecticut, USA. Leaves with BLD symptoms are found to have significantly reduced carbon assimilation and instantaneous water use efficiency, with increased levels of stomatal conductance as symptom severity progresses. Leaf response to light manipulation is also affected, with an increase in dark respiration and the light compensation point among banded and crinkled leaves. Additionally, BLD symptoms are found to have a significant influence on leaf water content, specific leaf area, and leaf nitrogen content. Relationships between gas exchange and these leaf traits yield linear correlations that are used to infer functional relationships impacted by the disease.

Morphophysiological Acclimation of Developed and Senescing Beech Leaves to Different Light Conditions

Common beech is a shade-tolerant tree species that can adapt to varying light intensities at the level of whole plants, crown fragments, and individual leaves. The acclimation abilities of the morphological, physiological, and biochemical characteristics of beech leaves were experimentally determined in tree crowns for different levels of light availability. About 24% higher length, width, and area and about 35% higher thickness were recorded in the sun leaves compared with shade leaves. Lower and earlier maximum leaf pigment levels, a faster degradation of leaf pigments during senescence, and a higher chlorophyll a/b ratio were observed in fully sun-grown leaves compared with leaves growing deeper in the canopy. Changes in the intensity of oxidative stress and the differential ability of developing and senescing leaves to defend against this effect under different light conditions were determined. This resulted in a higher redox imbalance and faster senescence in the outer parts of the tree crowns. Due to higher ascorbic acid and glutathione content and slower activity loss of antioxidative enzymes involved in superoxide anion and hydrogen peroxide decomposition, better control over the redox balance, oxidative stress, and senescence induction was noted in the sun leaves.

A combined approach for early in-field detection of beech leaf disease using near-infrared spectroscopy and machine learning

The ability to detect diseased trees before symptoms emerge is key in forest health management because it allows for more timely and targeted intervention. The objective of this study was to develop an in-field approach for early and rapid detection of beech leaf disease (BLD), an emerging disease of American beech trees, based on supervised classification models of leaf near-infrared (NIR) spectral profiles. To validate the effectiveness of the method we also utilized a qPCR-based protocol for the quantification of the newly identified foliar nematode identified as the putative causal agent of BLD, Litylenchus crenatae ssp. mccannii (LCM). NIR spectra were collected in May, July, and September of 2021 and analyzed using support vector machine and random forest algorithms. For the May and July datasets, the models accurately predicted pre-symptomatic leaves (highest testing accuracy = 100%), but also accurately discriminated the spectra based on geographic location (highest testing accuracy = 90%). Therefore, we could not conclude that spectral differences were due to pathogen presence alone. However, the September dataset removed location as a factor and the models accurately discriminated pre-symptomatic from naïve samples (highest testing accuracy = 95.9%). Five spectral bands (2,220, 2,400, 2,346, 1,750, and 1,424 nm), selected using variable selection models, were shared across all models, indicating consistency with respect to phytochemical induction by LCM infection of pre-symptomatic leaves. Our results demonstrate that this technique holds high promise as an in-field diagnostic tool for BLD.

Suitability of Turkey Oak, European Beech, and Hornbeam to Gypsy Moth Feeding

Pest resistance of trees should be taken into account in future forest strategy planning and predicting risks of defoliation. The gypsy moth (GM) (Lymantria dispar L.) is a serious forest pest with outbreaking population dynamics. To estimate defoliation risk of the most widely distributed tree species in Balkan Peninsula and Europe (Turkey oak Quercus cerris L., European beech Fagus sylvatica L. and hornbeam Carpinus betulus L.), we carried out laboratory feeding trials and investigated their acceptability and suitability for GM development. We determined morphological and chemical attributes of these hosts as well as larval host preference, growth and nutritional indices. Preference, growth, and efficiency of food conversion into biomass were ranked in the order: Turkey oak ˃ European beech ˃ hornbeam. Hornbeam was the most avoided and showed the lowest conversion efficiency although, comparing to optimal oak host, its leaves were less tough, contained more water and exhibited similar values of nitrogen (index of protein content) and C/N ratio (index of investment into carbon based plant defense). We suggest that hornbeam and beech leaf chemical profiles should be further studied to reveal specific compounds that impose high metabolic cost to GM larvae. Moreover, additional research are needed to understand how intermediate hosts in natural populations affect GM outbreaks.

A Pilot Study of Transplanting Methods for Wilding American Beech (Fagus grandifolia)

American beech is facing pressure from a number of emergent health issues including beech bark disease, beech leaf disease, beech leaf mining weevil, and climate and habitat change. Interest has increased in the propagation of American beech in response to the demand for more disease-resistant American beech for use in restoration. This study describes the first steps towards publishing methods for transplanting beech in order to supplement commercially available beech seedlings in an area with multiple agencies depleting the existing stock of slow growing species. American beech seedlings were purchased from a nursery in northern Michigan and were excavated from natural stands in the Hiawatha National Forest. Survival rates for these cohorts were compared after a growing season and by the relative amounts of fine roots present on the trees. Generally, the wildling seedlings had a higher survivability than the purchased bare root seedlings. Future work is proposed that could clarify the conditions leading to the higher survival in these wildling seedlings, including the potential for handling the time or age of the seedlings to influence survival.

First Report of Beech Leaf Disease, Caused by Litylenchus crenatae mccannii, on American Beech (Fagus grandifolia) in Virginia.

Beech leaf disease (BLD) was first reported in 2012 in Lake County, Ohio on American beech trees (Fagus grandifolia Ehrh.). Since then, it spread across the Northeastern United States and has been reported from Ohio, Pennsylvania, New York, New Jersey, Connecticut, Rhode Island, Maine, West Virginia, and Ontario, Canada (Carta et al. 2020; Mara and LaMondia 2020, Reid et al. 2020). The symptoms of BLD are characterized by dark interveinal banding of leaves appearing soon after spring flush that become chlorotic and necrotic through autumn, resulting in canopy thinning in advanced stages, followed in some young trees by death. Litylenchus crenatae mccannii has similar morphological characteristics with Litylenchus crenatae (Kanzaki et al. 2019) reported on Fagus crenata from Japan. However that beech species has not shown BLD symptoms or yielded any L. crenatae mccannii in North America. There are several morphological differences between the two. The North American subspecies have shorter post-uterine sac, narrower body width in mature females, shorter tail in immature females, longer tail in mature females, and longer stylet in males when compared to the Japanese subspecies (Carta et al. 2020). BLD symptoms were found on American beech trees in Prince William Forest Park, Prince William County, Virginia in June, 2021. The affected leaves contained females, males, and juveniles with morphometrics consistent with L. crenatae mccannii (Carta et al. 2020). The crude genomic DNA from a live single Litylenchus was prepared with freeze-thaw lysis (Carta and Li, 2019). The ITS PCR were performed by using the procedures and primer set, ITS-CL-F2 and 28S-CL-R described in the previous study (Carta and Li, 2020). The visualization, the cleanup and the direct DNA sequencing of the PCR products were performed by using the procedures described in the previous studies (Carta and Li, 2018 and 2019). Sequences were submitted to GenBank as accessions MZ611855 and MZ611856. This represents the first report of BLD in Virginia. It is also approximately 300 miles south of the 2020 detection of BLD from New Cumberland, WV, and represents the southernmost detection of the disease and nematode in North America. The author(s) declare no conflict of interest. References Carta, L.K., Li, S. 2018. Improved 18S small subunit rDNA primers for problematic nematode amplification. Journal of Nematology. 50, 533-542. Carta, L.K., Li, S. 2019. PCR amplification of a long rDNA segment with one primer pair in agriculturally important nematodes. Journal of Nematology. 51, e2019-26. Carta, L.K., Li, S. 2020. Improvement of long segment ribosomal PCR amplification for the molecular taxonomic identification of Litylenchus crenatae mccannii in beech trees with beech leaf disease. Journal of Nematology. 52, e2020-016. Kanzaki, N., Ichihara, Y., Aikawa, T., Ekino, T., Masuya, H. 2019. Litylenchus crenatae n. sp. (Tylenchomorpha: Anguinidae), a leaf gall nematode parasitising Fagus crenata Blume Nematology 21 (1), 5-22. http://www.brill.com/nematology doi: 10.1163/15685411-00003190 Marra, R.E., LaMondia, J. 2020. First report of beech leaf disease, caused by the foliar nematode, Litylenchus crenatae mccannii, on American beech (Fagus grandifolia) in Connecticut. Plant Disease (early view). https://doi.org/10.1094/PDIS-02-20-0442-PDN Reed, S. E., Greifenhagen, S., Yu, Q., Hoke A., Burke D. J., Carta L. K., Handoo Z.A., Kantor, M.R., Koch, J. 2020. Foliar nematode, Litylenchus crenatae ssp. mccannii, population dynamics in leaves and buds of beech leaf disease-affected trees in Canada and the US. Forest Pathology 50 (3), e12599.

Monitoring foliar symptom expression in beech leaf disease through time

AbstractWhen studying a forest disease, understanding the phenological relationship of the host tree and its pathogens is essential for identifying optimal management strategies to help prevent future spread of the disease. Since beech leaf disease (BLD) is a recently discovered disease, information about the general epidemiology and symptom phenology is largely unavailable. This study sought to answer questions related to symptom progression by conducting two observational studies on 10 trees from Cleveland Metroparks during the 2019 and 2020 growing seasons. BLD symptoms are characterized by two distinct leaf symptom types: dark green interveinal banding pattern or completely dark green and thickened leaf. Since there is evidence that the exotic nematode Litylenchus crenatae ssp. mccannii is associated with symptom development after direct inoculation into the buds, we hypothesized that symptoms would be apparent on the leaves at bud break. In our study, we visually confirmed the presence of both BLD leaf symptom types at bud break in naturally infected trees. Along with visual confirmation, a generalized linear mixed model (GLMM) showed that symptoms do not change throughout the growing season as time was not a significant variable when comparing symptoms across a growing season. Using both a Fisher's exact test and GLMM, we also determined that BLD leaf symptoms from a single leaf–bud pair do not progress in a specific or predictable pattern through subsequent growing seasons. These results formally validate the timing of BLD symptom expression and patterns of severity between years which will assist in furthering our understanding of the BLD pathosystem.

The distribution of beech leaf disease and the causal agents of beech bark disease (Cryptoccocus fagisuga, Neonectria faginata, N. ditissima) in forests surrounding Lake Erie and future implications

Over the past century, beech bark disease has dramatically altered the composition and structure of stands containing American beech (Fagus grandifolia). Management of beech bark disease has focused on reducing beech thickets and identifying resistant trees in aftermath forests. Beech leaf disease is a recently detected invasive disease, now also affecting beech forests. In 2019, a plot network was established in central North America to examine the extent of beech leaf disease spread and the severity of effects on trees and forests. Here, data from this plot network was used to determine the extent to which American beech is exposed to beech leaf disease, beech scale (Cryptococcus fagisuga), and beech bark disease (C. fagisuga and Neonectria spp. complex) in forests surrounding the Great Lakes in southwestern Ontario, northeastern Ohio, western Pennsylvania, and western New York. Beech leaf disease and scale were found to be well established, not only among sites but also in the different canopy layers. Beech bark disease was present, but occurrence was low. Pest accumulation differed between overstory and sapling layers. Beech leaf disease was the primary pest of saplings while both beech leaf disease and beech scale dominated in the overstory. Forest composition was similar throughout the study range; American beech, sugar maple, red maple, and white ash were abundant and common in the sapling and seedling layer. Few invasive plants were evident among saplings and seedlings. Sugar maple and red maple will likely fill small canopy gaps following beech decline or mortality. Intervention should be considered in stands with potential for increasing tree diversity or promoting beech leaf disease-resistant American beech trees to the overstory. New strategies are needed for beech conservation along with research to determine the extent of beech leaf disease resistance in American beech.

UHPLC-HRMS Analysis of Fagus sylvatica (Fagaceae) Leaves: A Renewable Source of Antioxidant Polyphenols.

European beech (Fagus sylvatica L.) is a deciduous tree, widely distributed in Europe and largely appreciated for its wood and nutritive nuts. Beech leaf also enjoys food use as salad, but an understanding of its nutraceutical value is still far from being achieved. Indeed, and also taking into account beech leaf as a consistent biomass residue available beechwood production and use, it needs to be explored as a valuable renewable specialized source of bioactive molecules. In this context, an untargeted ultra-high-performance liquid chromatography hyphenated with high resolution mass spectrometry (UHPLC-HRMS) approach was favorably applied to a beech leaf alcoholic extract, which also was evaluated for its antiradical capability (by means of assays based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and [2,2’-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid)] (ABTS) radical cation) and its ferric ion reducing power. Redox mitochondrial activity towards Caco-2 cells paved the way to explore the extract’s capability to inhibit intracellular Reactive Oxygen Species (ROS) using 2’,7’dichlorofluorescin diacetate (DCFH-DA) assay. Hydroxycinnamoyl derivatives, mainly belonging to the chlorogenic acid class, and flavonoids were the main constituents. Uncommon flavanone C-glycosides were also found, together with a plentiful flavonol diversity. Cell-free and cell-based assays highlight its dose-dependent antioxidant efficacy, providing a foundation for further investigation of beech leaf constituents and its valorization and use as a reservoir of bioactive natural products with potential nutraceutical applications.

Use of Modified Nano Particles of Beech Leaves for Nitrate Removal from Aqueous Solutions in the Column System

Use of Modified Nano Particles of Beech Leaves for Nitrate Removal from Aqueous Solutions in the Column System