Oak Logs Research Articles

Oak Wilt Disease May Reduce the Initial Decay Rate of Dead Quercus serrata Stems by Altering Fungal Communities in the Wood.

Oak wilt causes severe dieback of Quercus serrata, a dominant tree species in the lowlands across Japan. This study evaluated the effects of oak wilt on the wood-inhabiting fungal community and the decay rate of deadwood using a field monitoring experiment. We analysed the fungal metabarcoding community from 1200 wood samples obtained from 120 experimental logs from three forest sites at five different time points during the initial 1.5 years of the experiment. Death due to wilt significantly influenced the fungal community composition and reduced fungal diversity, likely due to the dominance of a limited number of species. The operational taxonomic unit richness, occurrence frequency, and DNA copy number of white rot fungi were also enhanced on the logs killed by wilt, depending on the sites. Structural equation modelling suggested that the wilt-initiated changes in the fungal community reduced the decay rate of oak logs. Temperature and wood moisture also affected the fungal community and log decomposition. These results suggest that, in addition to the direct effect of climate, oak wilt indirectly affects log decomposition by structuring the fungal community. Continuous monitoring is essential to evaluate the longer-term effects of oak wilt on the fungal decomposition of wood.

Arhaeological Research in Okhtyrka — the Arhaeology of War

The article is devoted to the result of archaeological research carried out on the territory of the Okhtyrka fortress of the second half of the 17th–18th centuries. Excavations were conducted in the basement of the Okhtyrka Municipal Local History Museum. The building was severely damaged because of the night bombing in spring 2022. During the reconstruction of the museum, the workers had discovered archaeological artefacts. In the result of archaeological research, there were discovered the remains of a building buried in virgin soil. The most informative were the remains of the cellar walls. In the filling of the building, there were distinguished two layers separated by a sterile one. In the lower layer, the vast majority of fragments of tiles and furnace slag were found, and in the upper layer — numerous fragments of pottery and individual finds. The analysis of the artefacts location and the general stratigraphy allows presuming preliminary conclusions. The dwelling had two levels — the ground living level with the furnace and the underground one, or a cellar. The level had a massive ceiling made of oak logs and a wooden construction made of logs with a diameter of 0.15–0.25 m. The space between the wooden construction and virgin soil was filled with yellow sand. Mostly, in the filling of the dwelling were found light clay pottery fragments and some items covered with green glaze. The tiles were decorated with stylised floral ornament. Among the imports, the most noticeable are a handle of a faience cup produced in the Ottoman Empire and fragments of clay bottles of Riga balsam. In addition, a faience ointment jar, produced in Germany or Austria in the 18th century. Based on the analysis of the finds, the time of construction of the building is dated to the 20s–30s, and the time of destruction — 70s–80s of the 18th century. The first date is indicated by a coin minted in 1731, found in a piece of preserved oak log, and the second one by the lower part of a clay bottle, found on the floor of the cellar. Some of the imported finds are related to medicine, so we can assume using the building as a pharmacy in the last years of its existing.

First Data on the Investigation of Gut Yeasts in Hermit Beetle (Osmoderma barnabita Motschulsky, 1845) Larvae in Lithuania.

In this study, yeasts from the gut of O. barnabita larvae were isolated and molecularly identified. It is worth noting that this research provides the first analysis of the gut yeast community in O. barnabita larvae in Lithuania, which is a significant contribution to the field. Two hermit-like L3-praepupa instars were collected from a decaying oak log in Lithuania. The isolation, morphology, biochemistry, and physiology of the yeast isolates were characterized using standards commonly employed in yeast taxonomy studies. The isolates were identified by sequencing the large subunit (26S) rDNA (D1/D2 domain of the LSU). All gut compartments were colonized by the yeast. A total of 45 yeast strains were obtained from the gut of both O. barnabita larvae, with 23 strains originating from Larva 1, 16 strains from Larva 2, and 6 strains from the galleries. According to our identification results of the 45 yeast strains, most of the species were related to Ascomycota, with most of them belonging to the Saccharomycetales order. Yeasts of the genera Candida, Debaryomyces, Meyerozyma, Priceomyces, Schwanniomyces, Spencermartinsiella, Trichomonascus, and Blastobotrys were present in gut of O. barnabita larvae. Species of the Trichosporonales order represented the Basidiomycota phylum.

Use of nonnative, invasive tree logs for commercial mushroom production

Abstract Removal and disposal of nonnative trees is expensive and time-consuming. Using these nonnative trees as a substrate to produce edible mushrooms could diversify farming operations and provide additional income to small-scale farmers. This research compared the production of shiitake mushrooms (Lentinula edodes) on nonnative tree logs to shiitake mushroom production on native oak (Quercus L.) logs, which are the traditional substrate. In a 2-yr study, we evaluated nonnative tree species as alternate substrates for growing shiitake mushrooms at farms in northern Florida and southern Georgia. A mix of native Quercus spp. and nonnative trees was targeted for removal on participating farms. Five nonnative tree species were initially tested for their ability to produce edible mushrooms, either shiitake or oyster (Pleurotus ostreatus var. florida). Of the nonnative trees we tested: Chinaberry (Melia azedarach L.), Chinese tallowtree [Triadica sebifera (L.) Small], silktree (Albizia julibrissin Durazz.), earleaf acacia (Acacia auriculiformis A. Cunn. ex Benth.), and paperbark tree [Melaleuca quinquenervia (Cav.) S.F. Blake], only T. sebifera produced shiitake mushrooms, and none produced native Florida oyster mushrooms. In on-farm trials, Quercus spp. logs produced more total mushrooms and more mushrooms per log and had a higher total mushroom yield per log. However, mushrooms produced on T. sebifera logs had higher mean weight per mushroom. Edible mushroom fungi can be used to recycle invasive, nonnative T. sebifera and transform their biomass from waste into an income-producing resource.

Wood Research at the University of Sopron – Physical-mechanical Properties

This study series shows research fields and results in wood science of the University of Sopron, Hungary. In this paper, we review several studies regarding the physical-mechanical properties of wood, including some properties of Turkey oak grown in different stands, showing that it should be planted among other species in same stand to achieve optimal wood quality. Research in the field of the firewood plantations has shown that it is necessary to choose the right species of poplars, in a given area. Paulownia and some invasive species grow rapidly, so they have great potential as raw materials and there are significant differences between paulownia varieties. Based on their densities, box elder, tree of heaven and green ash can be substituted for the noble species. Basswood can be well impregnated with paraffin, making it a good choice for pencils. Low-quality noble oak logs have the potential to be used in structural elements as lamellae, improving the yield and decreasing the loss in the wood industry. Black locust, sessile oak, beech, poplar, larch and spruce were subjected to different mechanical test methods at different moisture contents. Their properties decreased with increasing moisture content between 12% moisture content and FSP for all six wood species, but the ratio of changes varied, depending both on the measurement method and on the species.

Biosurveillance of oak wilt disease in Canadian areas at risk

Biosurveillance of invasive species is critical for protecting native ecosystems and limiting economic losses. Early detection of pathogens through qPCR methods has recently shown great promise and can potentially slow the spread of devastating diseases. For instance, oak wilt, a disease caused by the fungus Bretziella fagacearum, can kill mature trees within weeks of infection. Originally contained in the USA, oak wilt has finally made its way into Canada, where it was recently observed for the first time in June 2023. This study has laid the foundations for a biosurveillance monitoring programme of B. fagacearum in Eastern Canada. From 2019–2021, insect vectors were baited and captured in Lindgren traps in various locations of interest, namely sawmills importing oak logs from the USA, forested areas containing mature oak trees and strategic sites along the border between the two countries. Insect vectors and collection fluids were analysed with our qPCR detection test for the presence of B. fagacearum. As a positive control to validate this method, we included traps in a known centre of oak wilt infection in Michigan (USA). Our analysis showed only one positive site at the border between Ontario (CA) and the USA, even though oak wilt has never been observed there. This result confirms that DNA from B. fagacearum can be detected with this method even before the appearance of symptomatic trees, which could be crucial in the current containment efforts in Ontario (CA).

Pyre wood fuel and food remains in a necropolis of Barcino (Barcelona, NE Iberian Peninsula): The case of Sant Antoni Market site (1st century CE)

Pyre wood fuel and food remains in a necropolis of Barcino (Barcelona, NE Iberian Peninsula): The case of Sant Antoni Market site (1st century CE)

The Accuracy of CT Scanning in the Assessment of the Internal and External Qualitative Features of Wood Logs.

The qualitative evaluation of harvested raw logs and sawlogs is mainly based on the quantitative and qualitative evaluation of the visible macroscopic features of the wood. Modern methods allow for the analysis of whole logs by means of computed tomography. These devices can analyze the internal qualitative features of wood that are not visible on the external structures of the logs. The aim of this work was to evaluate the detection accuracy of a CT-scanning device intended for scanning logs on the internal qualitative features of wood using model trunks. Two logs of beech and oak with a length of 4 m were selected for the analysis, based on availability. Qualitative features were identified through computed tomography scanning, visually identified on cut sections, and then manually measured in accordance with applicable legislation. Relatively good agreement was demonstrated for the detected features in terms of identifying their location (dimension in millimeters from the end of the log). For this parameter, the average differences were 0.90% on the beech log and only 1.21% on the oak log. Relatively high accuracy was shown via CT detection of qualitative features in the beech section (with average differences in dimensions of only 3.5%). In the case of the oak log, the dimensions of the quality features were significantly overestimated. These results indicate that CT scanning technology may have a problem with some hardwood species. It was primarily developed for coniferous tree species, and software algorithms are, therefore, not yet fully adapted to the precise detection of the dimensions of individual quality features. Despite the detected differences, it was confirmed that the CT technology of scanning harvested wood can have a fundamental impact on optimization procedures in the recovery and processing of wood. Renting a scanning line for a certain capacity of wood volume appears to be a deployment option for forestry operations and smaller wood processing operations. Thus, this technology can become an important factor in improving the economic evaluation of the final production of wood.

Water concentration and rate of decrease in shiitake cultivation log during fruiting body development, as measured by MRI

Large shiitake mushrooms (Lentinula edodes, pileus > 8 cm in diameter) are difficult to cultivate and account for only 3-5% of the total harvest. This study focused on the water absorption process within a log during the growth of fruiting bodies in order to increase the yield of large shiitake mushrooms. Konara oak logs (Quercus serrata, 85-95 mm in diameter, 290 mm in length) were inoculated with shiitake mycelium plugs and nine months later, young fruiting bodies developed, at which point the log was analyzed using magnetic resonance imaging (MRI) over a period of two weeks. The signal intensity andT1andT2relaxation time constants were determined from the acquired images, along with the distribution of water concentration within the entire log. The axial distributions of water concentrations in the log were higher in the 80 mm region around the fruiting body. The rate of decrease in water concentration indicated that water was supplied to the fruiting body from 80 mm axially in the upper half of the sapwood in the log. On the other hand, the water concentration in the heartwood did not decrease and the heartwood did not contribute to the water supply to the fruiting bodies.

Oak Wilt Fungus (Bretziella fagacearum) Survival in Logs Following Fumigation with Ethanedinitrile

Abstract The phaseout of methyl bromide (MB) fumigation creates an urgent need for an alternative phytosanitary treatment to limit the risk of international spread of the oak wilt fungus, Bretziella fagacearum. Fumigation with ethanedinitrile (EDN) is considered a potential alternative to MB fumigation to eradicate wood-inhabiting pests and pathogens. We evaluated the efficacy of EDN fumigation by comparing the rate of B. fagacearum isolation before and after fumigation of red oak (Quercus rubra or Quercus ellipsoidalis) log sections from oak wilt–affected trees. Logs (range 15.2 to 98.0 cm long; diameter 9.1 to 46.1 cm) were obtained from red oak trees that were naturally infected (NI) or artificially inoculated (AI) with B. fagacearum. The logs were fumigated for 24, 48, and/or 72 hours with 120 g/m3 EDN. Frequencies of pathogen isolation from the sapwood before treatment were higher for AI logs than for NI logs. EDN treatments greatly reduced the frequency of viable pathogen recovery, but eradication occurred only in experiments using the smallest log diameters (9 to 14 cm). Our results suggest that EDN may have limited penetration in oak logs with intact bark, similar to fumigants currently used on wood products, such as MB and sulfuryl fluoride. Results of future work may help in the understanding of the limitations for consistent and full efficacy of EDN against B. fagacearum in logs harvested from diseased trees.

International supply chain handling practices and the quality of heat-treated, white oak veneer logs

The most promising alternative to the methyl bromide fumigation of exported logs is steam-heating the log in a vacuum. Research has confirmed that steam heating to 56 °C for 30 minutes kills all viable propagules of oak wilt pathogen (Bretziella fagacearum) in the sapwood of oak logs. The purpose of this study was to determine whether this heat-treatment method has any effect on the quality or value of white oak veneer logs shipped between the US and EU. Seventeen steam- and vacuum-treated and seventeen untreated control logs were shipped from Baltimore, Maryland to the Czech Republic, for processing into veneer, between December 2021 and February 2022. The treated and untreated logs were sawn into flitches, soaked in hot water vats, sliced, dried, and the veneer from each log was graded for quality. Each log was assigned a value based on the veneer quality and yield. The average value of treated log was 1,547 €/m³, and the average value of the untreated logs was 1,539 €/m³. The null hypothesis was statistically confirmed. Therefore, it is concluded that the 56 °C/30 min, sapwood heat treatment using vacuum and saturated steam had no adverse impact on the value of the white oak veneer logs.

Semiempirical modeling of a traditional wood-fired pizza oven in quasi-steady-state operating conditions.

Wood-fired ovens are mandatorily used to bake the Neapolitan pizza. Unfortunately, they are still empirically operated. In this work, a pilot-scale wood-fired oven was kept operating in quasi-steady-state conditions. Once the combustion reaction of oak logs had been modeled, the composition of flue gas measured, and the external oven wall and floor temperatures thermographically scanned, it was possible to check for the material and energy balances and, thus, assess that the heat loss rates through flue gas and insulated oven chamber were, respectively, equal to 46% and 26% of the energy supplied by burning firewood. The enthalpy accumulation rate in the internal fire brick oven chamber amounted to about 3.4kW, this being adequate to keep not only the temperatures of the oven vault and floor practically constant but also to bake one or two pizzas at the same time. Such a rate was predicted by contemplating the simultaneous heat transfer mechanisms of radiation and convection between the oven vault and floor surface areas. The efficacy of the semiempirical modeling developed here was further tested by reconstructing quite accurately the time course of water heating in aluminum trays with a diameter near to that of a typical Neapolitan pizza. The heat flow from the oven vault to the water-containing tray was of the radiative and convective types for about 73% and 15%, whereas the residual 12% was of the conductive type from the oven floor. PRACTICAL APPLICATION: Despite wood-fired ovens are largely used in the restaurant and food service industry, their operation is highly dependent on the operator's ability. This study shows how the heat loss rates through flue gas and insulated oven chamber can be assessed, and how the enthalpy accumulation rate in the internal fire brick oven chamber can be predicted by accounting for the simultaneous heat transfer mechanisms of radiation and convection between the oven vault and floor surface areas. The efficacy of this semi-empirical modelling was further checked for via some water heating tests.

Modeling knot features using branch scars from Mongolian oak (Quercus mongolica).

Wood quality is an important indicator for modern sawmills. Internal wood characteristics can be derived from their correlations with external appearances. In this study, we developed linear regression models to predict knot size from surface features of Mongolian oak (Quercus mongolica) using data collected from 53 trees. For this, manual measurements and X-ray computed tomography scanning technology was respectively used to obtain internal and external features of 1,297 knots. Our results showed that Mongolian oak knots were generally concentrated in the middle part of oak stems, with fewer knots observed at the top and base. The parameters of knot and scar showed significant correlations (P<0.01), where length and diameter of the corresponding external scar increase with increasing the length and diameter of a knot. The corresponding external scar can be used as an effective indicator to predict the internal value of oak logs. The accuracy of our constructed model is more than 95% when assessed against independent test samples. These models thus can be applied to improve the practical production of oak timber and reduce commercial loss caused by knots. These additional data can improve the estimation of the influence of knots on wood quality and provide a theoretical foundation for investigating the characteristics of hardwood knots.

Proteomic characterization of Shiitake (Lentinula edodes) post-harvest fruit bodies grown on hardwood logs and isolation of an antibacterial serine protease inhibitor

Lentinula edodes (Shiitake) is one of the most heavily cultivated mushrooms in the world with proven antioxidant and antibacterial properties, among others. Evidence indicates that the choice of mushroom cultivation technique strongly influences the production of bioactive compounds, but to date the nature of many of these compounds has not been fully established. This work focuses on the proteomic characterization of L.edodes to highlight the main active processes two days after harvest and elucidates the proteins involved in the known antioxidant and antibacterial proprieties of Shiitake fruit bodies cultivated on oak logs. A label-free approach allowed us to identify a total of 2702 proteins which were mainly involved in carbohydrate and protein metabolism, cell growth and replication, indicating that several developmental processes remain active in fruit bodies post-harvest. Proteins with antioxidant activities were identified, indicating the contribution of proteins to the antioxidant properties of L.edodes extracts. Antibacterial assays also reveal the activity of a serine protease inhibitor that strongly accumulates in the post-harvest fruit body grown on oak logs. Overall, this study contributes to the understanding of the impact of the log cultivation method on the production of Shiitake mushrooms richest in high-value bioactive compounds.

Computed Tomography as a Tool for Quantification and Classification of Roundwood—Case Study

The first goal of this paper is to verify the accuracy of four calculation methods of log volume. The tool to achieve this goal is to compare the results of the calculation of the log volume with the real log volume obtained from the three-dimensional reconstruction obtained by computed tomography. The second goal of this paper is to determine the effectiveness of displaying the qualitative features of wood in three-dimensional models of selected pieces of logs of oak, beech, and spruce, which were obtained using computed tomography. It is possible to state that each of the tested calculation methods of wood log volume are applicable in practice. The tested methods achieve excellent accuracy in determining the volume of spruce logs with a small variance of values, and conversely, in the case of beech wood, the tested methods are the most inaccurate with the largest variance of values. When determining the volume of wood logs, we recommend using the calculation method STN 48 0009, because it achieves the best results. Qualitative analysis based on CT scans of internal features can be described as a completely new level of approach to the evaluation of log quality. The performed analysis showed great potential for automatic detection of internal qualitative features in the tested spruce log. In this wood, wood defects are distinguishable by computed tomography. In the case of deciduous oak and beech, the situation is more complicated. The internal structure of these trees overlaps the internal qualitative features of the wood. To accurately detect internal errors in these trees, it will be necessary to perform many comparative tests to achieve optimal results.

Bog oak: Characteristics and characterization of a log from the Venetian Plain (Italy)

• Bog oak forms after a long persistence of oak wood in conditions of humidity and anoxia. • Density and mechanical strength increase. • Degradation phenomena are present in the apparently intact wood. • The different time of stay in the ground does not seem to influence physical parameters. The bog oak is a particular archeobotanical oak wood, which is formed after hundreds of years in anoxia and wet conditions. Following the persistence of oak wood for long periods in conditions of humidity and anoxia, its colour turns to dark brown/black, and its density and mechanical strength, in particular its hardness, increase. Wet and anoxic environments are, for example, the peat bogs of Northern Europe, and the muddy beds of rivers. In Italy, old oak trunks with a characteristic charred appearance emerge periodically during the cleaning of riverbeds. This paper presents the characterization of a bog oak log found in Zero river in the Veneto countryside. The trunk has been dated back to around 400 CE, using radiocarbon dating technique. The log is bark-free, and the black and cracked external surface has a charred appearance. On the inside, underneath the more weathered layer, the wood appears intact, without signs of apparent degradation, carbon black in colour. Towards the internal parts of the trunk, the colour of the intact wood goes from black to light brown. The physical characterization (basic density, shrinkage and maximum water content) indicates that degradation phenomena are also present in the apparently intact wood. Indeed, the bog oak linear shrinkage is more than double that of recent oak wood. Microscopic analysis clearly highlighted bacterial degradation. From the analysis of the ash content, it seems that the density increase of the apparently intact areas is due to the presence of inorganic material.

Price Determinant Factors of Oak Logs in the Precious Timber Market

Price Determinant Factors of Oak Logs in the Precious Timber Market

Sampled Letters of Elisabeth Koren in Translation

Sampled Letters of Elisabeth Koren in Translation Øyvind T. Gulliksen (bio) and Orm Øverland Letter 35 “I have to boil the pigs’ heads for my pickled pork out in the yard.” The Vicarage, Little Iowa18 December 5, 1856 Dear Mother,19 This letter should be in the Manor House by Christmas.20 At least this was my plan, but in spite of my best intentions I have been unable to write as soon as I wished. The entire house was busy with the slaughter of our pigs and plastering our walls and then cleaning up afterwards. Now this has all been done and as I sit here, I am glad to feel how much warmer the house now is. Today, with a strong wind blowing from the Northwest, this is quite noticeable. This time Vilhelm was at home during the plastering, something he has always been able to avoid, and he insisted that this should be the last time we would have such [End Page 114] reparations. I sincerely hope that this is true and that we by next winter will be able to have at least our entire living room properly rough-cast or—and this is said to cost no more—have all walls covered with canvas and then painted or papered. Having plaster between the logs is such a mess. You can hardly believe what it all looks like and this must be repeated every fall. What has made the house warmer than it has ever been is that we have had the walls whitewashed. This is a significant improvement, and it fills in all cracks and holes. I liked it better the way it was before with the darkened and gray-striped oak logs, but I don’t really care as long as this is warmer. The whitewash is also said to be a good protection against bedbugs, and this should also be taken into account. Moreover, we have also done repairs on the cement floor making it much warmer. All in all, it is much better than last year so I hope that we will not suffer even if the winter is just as harsh. Well, I am quite happy that we are done with repairs of our house as well as with the slaughter of our pigs. The one interfered with the other, which is quite a problem in quarters as close as ours. But we cannot ask the laborers to come later; we must simply accept them gratefully when it is convenient for them. The amount of pork that we salt also gives us a lot of work, especially when I have such good help from Henriette.21 Pork sausage is the best hot lunch I can serve Vilhelm, so I have made a large store of these.22 I wish I had some sort of cooking shed so I could cook indoors! I must boil the pigs’ heads for my head cheese in the yard, and this is not so convenient in winter.23 I had a couple of pigs’ feet smoked, but when Vilhelm pronounced them a great improvement, it didn’t matter much at all. Soap and whatever else needs a large pot must be boiled in the yard. Yesterday my new cow had a calf so today Henriette has enjoyed kalvedans.24 She also had great fun coming into the cow barn to see Anne give drink to the calf. It is a bull calf. We will let it live and see what happens to the other cow that is expecting a calf in a few days. I have been unlucky with my chickens recently. I lost about twenty and—sadly—one was among the different breed of chickens that I had been given. But most were young males from last summer that I had planned to make use of this winter. The culprit is a little animal that digs under the ground and sucks the blood from them and lets them lie dead. He gets at the chickens because they sit on the ground instead [End Page 115] of standing up. One night he killed eight but now he has not been here for a while so...

Impact of Storage Conditions on Shear Strength of Beech (Fagus sylvatica L.) and Sessile Oak (Quercus petraea (Matt.) Liebl.)

The structure of a bark as a component of a living tree is completely different from wood. Different structures significantly influence the physical and mechanical properties of the bark. In the processing of logs, it is in most cases necessary to separate the bark from the wood. Problems can arise mainly in the pulp and paper industry. The research focused on the impact of storage conditions on shear strength, showing that the value of shear strength decreased remarkably due to the storage. A decrease in strength can mainly be explained by the changes in the moisture content of bark, remarkably affected by the surrounding environment (climate). The research showed that three months of storage seemed to be the most appropriate and effective period for removing the bark in the case of beech logs and that a storage time of up to five months was the best in the case of oak logs.

Raffaelea quercina sp. nov. Associated with Cork Oak (Quercus suber L.) Decline in Portugal

Research Highlights: Raffaelea quercina sp. nov. is an ophiostomatoid fungus isolated from the ambrosia beetle Platypus cylindrus. The species occurs in symptomatic Portuguese cork oak trees, (Quercus suber L.), exhibiting vegetative decline. Background and Objectives: Quercus suber L. is a species restricted to the Mediterranean basin, of special economic importance as it constitutes the crucial raw material for the cork production industry, in particular for Portugal, the world’s leading producer. Over the last three decades a progressive and alarming decline of cork oak trees has been observed across its distribution area, including Portugal. The ambrosia beetle Platypus cylindrus, commonly known as the oak pinhole borer, establishes symbiotic relationships with fungi from which it depends for survival and for oak colonization. Some of these fungi are ophiostomatoid species of the Raffaelea genus, known as ambrosia fungi associated with ambrosia beetles. Some Raffaelea species exhibit phytopathogenic activity causing wilting and/or death of trees. The objective of the present study is to identify the association between P. cylindrus and Raffaelea species in Portuguese cork oak stands showing symptoms of disease and decline. Materials and Methods: A total of 300 adult insects were collected as they emerged from cork oak logs, sampled from symptomatic trees. Axenic isolates of Raffaelea species were obtained from the beetles and their galleries in the trunks and identified based on morphological features and molecular analysis of the SSU and LSU rDNA regions. Results: Two Raffaelea species were identified, i.e., R. montetyi and a novel Raffaelea species closely related to R. canadensis. The novel species is morphologically and genetically characterized in this study, and erected as Raffaelea quercina M.L. Inácio, E. Sousa &amp; F. Nóbrega, sp. nov. Raffaelea quercina constitutes a new phytopathogenic fungal species associated with P. cylindrus and cork oak trees exhibiting symptoms of vegetative decline. Conclusions: Raffaelea species appear to have a significant role in cork oak decline. Future research on the association between P. cylindrus and Raffaelea species, encompassing the trans-European and North African wide-range of cork oak stands, would further clarify the relationships between ambrosia beetles, associated fungi and cork oak decline, contributing to a better understanding of the phenomena and for strategies aiming to halt the continuous decline of the unique cork oak stands enclosed in the Mediterranean basin.