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Annual Report 2019
2020 - IRG/WP 20-60469
IRG Secretariat

Agenda 2020 Plenary meeting (online)
2020 - IRG/WP 20-60470
IRG Secretariat

Programme. The IRG51 webinar on Wood Protection
2020 - IRG/WP 20-60471
IRG Secretariat

Budget for 2020 (forecast May 2020)
2020 - IRG/WP 20-60472
IRG Secretariat

Budget for 2021
2020 - IRG/WP 20-60473
IRG Secretariat

IRG Documents 2020
2020 - IRG/WP 20-60483
IRG Secretariat

IRG51 Webinar recordings - Day 1
2020 - IRG/WP 20-recordings-1
IRG Secretariat

IRG51 Webinar recordings - Day 2
2020 - IRG/WP 20-recordings-2
IRG Secretariat

All IRG documents 2020 (zip file)
2020 - IRG/WP 20-zip
Collection of following documents: 20-10957, 20-10958, 20-10959, 20-10960, 20-10961, 20-10962, 20-10963, 20-10964, 20-10965, 20-10966, 20-10967, 20-10968, 20-10969, 20-10970, 20-10971, 20-10972, 20-20665, 20-20666, 20-20667, 20-20668, 20-20669, 20-20670, 20-20671, 20-20672, 20-20673, 20-20674, 20-20675, 20-20676, 20-30752, 20-30753, 20-30754, 20-30755, 20-30756, 20-40888, 20-40889, 20-40890, 20-40891, 20-40892, 20-40893, 20-40894, 20-40895, 20-40896, 20-40897, 20-40898, 20-40899, 20-40900, 20-40901, 20-40902, 20-40903, 20-40904, 20-40905, 20-40906, 20-40907, 20-40908, 20-40909, 20-50363, 20-50364, 20-60469, 20-60470, 20-60471, 20-60472, 20-60473, 20-60483.
IRG Secretariat

Pigment production by the spalting fungus Scytalidium ganodermophthorum and its industry potential
2020 - IRG/WP 20-10957
Scytalidium ganodermophthorum is best known as a pathogen of cultivated mushrooms, with infected cultures turning yellow in color. The fungus is also used in the art form known as ‘spalting’ to produce yellow, green, and purple colors in wood for decorative purposes. Wood colored by fungus in this manner has been traditionally used in the creation of fine art and woodworking since the 16th century in Europe. However, most fungal species known to spalt wood only produce a single color of pigment, making S. ganodermophthorum unique. Other pigments isolated from fungi in the family Helotiales have shown unique physical characteristics including UV-stability, bioactivity, and semiconduction. This has stimulated research into their use across a range of fields including organic photovoltaics and environmentally friendly dyes. In order to identify the pigments produced by S. ganodermophthorum and allow for research into their physical properties, the growth conditions needed to stimulate production of different pigments by the fungus must be identified. This study characterizes the differential coloration of S. ganodermophthorum cultures, including variation over time and across a range of pHs. Pigment production was found to change with colony age, with initial yellow extractions transitioning through a series of green colors to a purple/red color with time. In addition, growth across multiple pHs was tested for potential changes in pigmentation, and pigment response to pH change was tested to identify if changes in color were due to only one or multiple pigments. Growth was found to vary across pH range, and the presence of multiple pigments was indicated. With the innovative potential of pigments from other spalting fungi established, identification of new fungal pigments from S. ganodermophthorum could lead to development of new forest-based green technologies including textile coloration, optoelectronics, and wood protection
R C Van Court, P Vega Gutierrez, S C Robinson

Different levels of acetylation lead to groupwise upregulation of non-enzymatic wood degradation genes of Rhodonia placenta during initial brown-rot decay
2020 - IRG/WP 20-10958
Rhodonia placenta, often used as a model fungus to represent brown rot fungi, uses a two-stepped degradation mechanism to degrade wood. Regarding the overcoming of wood protection systems the initial degradation phase seems to be the crucial point. A new laboratory test enables the separation of the non-enzymatic oxidative and the enzymatic degradation phases, which has previously been proven challenging. In this study this new method was used to investigate gene expression of ten genes, presumably involved in non-enzymatic oxidative degradation. Therefore, R. placenta was grown on untreated and to three different levels acetylated Scots pine (Pinus sylvestris L.) samples. Gene expression was analyzed via qPCR. Results showed a groupwise upregulation of genes involved in the non-enzymatic oxidative degradation phase, according to increasing weight percentage gain (WPG). However, not all genes thought to be involved in initial brown-rot decay showed an upregulation.
M Kölle, R Ringman, A Pilgård

FTIR analysis of wood blocks decayed by brown-rot fungi
2020 - IRG/WP 20-10959
Calibration curves of the relative lignin contents in Cryptomeria japonica decayed by brown-rot fungi were developed with Infrared Spectroscopy and Klason technique. First, wood decay test was conducted using brown-rot fungi (Fomitopsis palusris, F. pinicola, Wolfiporia cocos, Gloeophyllum trabeum, and Neolentinus suffrutescens) and white-rot fungus (Trametes versicolor) was used as a comparison. Then, Fourier Transform Infrared analysis was carried out to monitor chemical changes of wood components. After extraction procedure, FTIR analysis was conducted again to obtain the spectra of extractives-free wood samples. IR spectra of mycelia were also recorded to identify bands other than wood components and avoid using them for calibration curves. The peak intensities of some lignin bands were correlated to lignin contents (Klason lignin plus acid-soluble lignin). This method is expected to be generally available for estimating lignin contents for brown-rotted woods decayed to different degrees.
R Kondo, Y Horikawa, R Kose, M Yoshida

Update on the Distribution of Termites and other Wood-boring Insects in Europe
2020 - IRG/WP 20-10960
In Europe, most of the timber used in construction is made from softwood species that are poorly or not durable against wood-boring organisms (beetles, termites, decay fungi). Timber with a moisture content of less than 20% can be attacked and degraded by different species of insect whose larvae consume wood and significantly reduce its mechanical strength. The risk of attack by wood-boring insects exists irrespective of the wood end-use, although the frequency and importance of the insect occurrence depends on the geographical region considered. The identification of insect species harmful to wood and derived materials is essential in order to monitor the movement of populations over long periods and anticipate the risk of invasions from new territories. Therefore, we established an inventory of the main insect species causing damage to wood used inside and/or outside buildings in Europe, based on existing publications, maps and questionnaires sent to a group of European experts on the problems due to insects in the construction sector. At least 83 insect species have been identified, evidence of whose attacks can be found in buildings. A new distribution map, based on the gathered information, is proposed for the two main pests, the subterranean and drywood termites. A map of distribution was also drawn for two representatives of dry wood boring insects, the furniture beetle Anobium punctatum and the house longhorn beetle Hylotrupes bajulus, two other species known to cause significant damage to wood used for building purpose in Europe.
M Kutnik, I Paulmer, D Ansard, M Montibus, C Lucas

Analysis of larval development and feeding of an Anobiid beetle using X-ray computed tomography
2020 - IRG/WP 20-10961
Priobium sp., an anobiid beetle, can attack wood used for historic constructions in Japan. Its life history and feeding biology, especially larval development and behavior, are poorly understood because the beetles are hidden inside wood most of the time. We used X-ray computed tomography (CT) to regularly scan wood blocks infested with the larvae of the Priobium sp. and observed the process of their movement and development inside. The wood blocks were scanned at intervals of approximately 10 days from July 2019, and the analysis was based on the CT data until February 2020. The CT images clearly captured the silhouettes of the larvae, as well as parts of wood and frass. By registering the CT volume data obtained on different scanning dates, the movement of individual larvae could be traced. The larvae, in most cases, seemed to move about within the frass packed inside the wood blocks, instead of newly tunneling into undamaged parts of the blocks. By measuring the position coordinates of the larvae, their displacement in the scanning intervals was quantified. The larvae became inactive when the temperature dropped to around 10 °C. The body length of the larvae kept fluctuating, but no apparent growth was observed throughout the experiment.
H Watanabe, R Kigawa, Y Fujiwara, Y Fujii

Effect of long-term immersion in fresh and salt water on mould growth on Scots pine (Pinus Sylvestris L.) wood
2020 - IRG/WP 20-10962
Wood exposed outdoors will eventually be degraded by fungi, depending on exposure and material characteristics. Numerous wooden constructions in the Røros municipality have existed since the 17th century, but wood used in recent repairs have decayed faster than expected. Before 1970 timber was mainly transported by log driving or rafting, and the logs were immersed in water for longer or shorter periods. The effect from immersion on growth of mould fungi is studied, using small samples from wood immersed in fresh or salt water or stored on land. Heartwood was less susceptible to mould than most sapwood. Sapwood from sunken logs, immersed for almost 60 years, performed similarly to heartwood. Immersion for five months in fresh or salt water had no effect, but sapwood immersed in fresh water for two years showed similar performance to sapwood from sunken logs.
M Sand Austigard, J Mattsson

Performance of naturally durable decks after 15 years of field exposure
2020 - IRG/WP 20-10963
A decking test of Canadian species considered to be naturally durable was inspected after 15 years of exposure at test sites in Ontario and British Columbia. Based on the materials used in this experiment, Douglas-fir and yellow cypress had the greatest decay resistance, followed by eastern white cedar and western redcedar, and then by western larch and tamarack. All materials tested were more durable than the ponderosa pine sapwood control which had completed failed. Whether the wood came from old growth stands or second growth stands had little effect on decay resistance. Only old-growth Douglas-fir had significantly less decay than second-growth. The presence of sapwood reduced the decay resistance of yellow cypress, eastern white cedar and western redcedar, but did not impact the overall decay resistance of the less-durable western larch or tamarack. An initial coating of deck stain was associated with no change or slightly improved decay resistance.
R Stirling, D Wong

Durability of tropical species from Peru according to European Standards
2020 - IRG/WP 20-10964
Natural durability is defined as the intrinsic resistance of wood against the attack of destructive organisms. There are standardized methods to estimate a durability value. In Europe, the standard EN-350 is responsible for establishing the basic guidelines, as well as the necessary tests to determine this value, which is essential to know the degree of protection needed for the tested wood to extend its service life. This standard applies to commercial wood, both native and imported, and helps to improve and obtain better construction applications depending on the final use of the wood. However, there are many species, including tropical ones, for which there is no or little information available. In this work, the natural durability of four timber-bearing Amazonian species from Peru - Calycophyllum spruceanum Benth, Schizolobium excelsum Vogel, Matisia cordata Humb, et Bonpl, and Cedrelinga cateniformis Ducke - have been studied against the attack of xylophagous fungi and termites compliant with the current European regulations. The results show that these species are durable, a fact that opens up a potential market in South America to export this timber to Europe. The data obtained will be incorporated into the European standard EN-350, given that there is no information on these species in it, with the exception of C. catenaeformis
J Valdivia, P Gómez, M T Troya, L Robertson, J A Martín, A Loayza

Durability of Eucalyptus globulus floating structures mussels trough in marine environment against marine borers in the Atlantic coast of Spain
2020 - IRG/WP 20-10965
In Spain, since forever damages caused by marine borers are frequent in wood elements and wood structures located in sea water conditions. Galicia is a region located in the North West of Spanish, above Portugal, characterized by their typical estuaries, where since ancient times, the natural production of mussels from floating structures mussels trough. Since ever, wood species selected to build the wood structures mussels trough is Eucalyptus globulus. Currently there are more than 3,300 platforms in the sea water of Galicia. The choice of wood species with medium-high natural durability is an appropriate step of protection in the case of marine environment in sea water timber structures such as floating structures mussels trough. Eucalyptus globulus heartwood is characterized by its durability against wood destroying fungi and moderately durability against marine borers, so using only heartwood it does not require preventive preservative treatment for using in a structure mussels trough, where is exposure in Use Class 3 and Use Class 5, to achieve a good performance and the expected service life. This paper shows the suitability of eucalyptus wood for its characteristics, since it combines strength and flexibility to withstand the elements and a durability of about 25 years to achieve the profitability of the installation. For its elaboration, only eucalyptus wood serves, the only one flexible and resistant enough to withstand the effects of the tides without breaking, without using preservatives and considering very well the design details and the maintenance of wood elements of floating structures mussels as key items to ensure a good performance during the estimated service life.
D Lorenzo, M Touza, J Fernández-Golfin, A Lozano, J Benito

Moisture and temperature conditions in an old, highly moisture-loaded timber building in the Røros municipality, Norway
2020 - IRG/WP 20-10966
A 150 years old log building near Røros, Norway, has been in active use as a cowshed since its erection. The animals are kept inside the cowshed all winter and this causes a situation of a high moisture load on the wooden floor, wooden walls and ceiling. Logging of temperature and humidity over one year shows that there are favourable levels of moisture in the wood and air for development of mould and wood-decaying fungi. Despite this fact, there are no signs of mould growth or fungal decay in the exposed constructions. It is of interest to clarify the physical conditions that ensures the long service life of the wood despite critical humid conditions. This could give valuable insights into protection of wooden materials in other, similar moisture exposures in both historic and new buildings. Various possible explanations for the unexpected long service life of the wooden materials in the cowshed are discussed.
M Sand Austigard, J Mattsson

Observed and projected changes in the climate based decay hazard of timber in the United Kingdom
2020 - IRG/WP 20-20665
The risk of microbiological attack on wood is determined by both material and climatic factors and indeed the hazard for a component is based on its intrinsic durability and the conditions in which it is used. The use of wood and organic materials in construction is increasing but ultimately all these materials will be susceptible to microbiological attack. The Scheffer Climate index applies climatic variables such as temperature and wetting time to assess hazard zones within geographical areas. A changing and variable climate e.g. an increase in heavy but short duration rain events, may have an effect on the incidence or severity of microbiological attack and with the increase in the use of timber this could have significant impact on buildings and construction. This paper shows a significant increase in the Scheffer climate indices for various locations of the UK from 1990 to 2019. The highest index values are seen in the Northern and western areas of the United Kingdom, but increases are seen across the country. The paper also uses representative concentration pathway (RCP) scenarios to project future climate decay indices for the United Kingdom until the end of the 21st century. The projections show a significant increase in the climate decay index even in the lowest RCP scenario, with all regions of the UK moving to index values indicating a very high hazard based on climatic conditions
S F Curling, G A Ormondroyd

Performance of bio-based building materials – durability and moisture dynamics
2020 - IRG/WP 20-20666
When exposed to conditions favourable for decay, bio-based building materials can be susceptible to degradation. Their ability to withstand deterioration over time (performance) depends on the intrinsic or enhanced durability of the material as well as its wetting and drying behaviour. The effect of fungicidal components in wood is known since long. Other material characteristics, such as the material’s moisture dynamics and structure, are crucial as well in prolonging a material’s service life in outdoor exposure conditions. The importance of these other material characteristics should not be underestimated, as there are many opportunities to alter a material’s moisture dynamics and to optimize the structural design of engineered wood products and bio-based insulation products. In order to do so, it is necessary to understand how different material characteristics influence the performance. In this paper, we assess the moisture dynamics of oriented strand board (OSB), porous bituminized wood fibre board (PBF), radiata pine plywood (PL), thermally modified spruce (TMT) and two wood fibre insulation boards (WF-A and WF-B). With the ‘paste test’, we assess whether these materials contain fungicidal components affecting decay. Additionally, we assess how they perform in an adapted mini-block test. We are able to show that fungicidal components are not always of major importance for the durability of a bio-based building material. Some of the assessed materials have a remarkable moisture performance. We need to work towards specific moisture performance criteria and consider including them in performance classification.
L De Ligne, J Caes, S Omar, J Van den Bulcke, J M Baetens, B De Baets, J Van Acker

Profiling fungal degradation of Scots pine sapwood by short wave infrared hyperspectral image analysis
2020 - IRG/WP 20-20667
Hyperspectral image analysis of Scots pine sapwood wood affected by decay fungi has been carried out as part of a Ph.D. thesis within the project Remote Inspection of Wooden Utility Poles (RIWUP). In a lab experiment, Petri-dishes with Scots pine sapwood samples on malt agar medium were infected with two types of decay fungi, a brown rot and a white rot. The wood samples were scanned with a HySpex SWIR-384 hyperspectral camera at different stages of decay progression to create a time series of short wave infrared hyperspectral measurements. The time series captures the wood-decay effect for a period of sixteen weeks. The primary variables in this experiment are mass loss and the recorded wood spectra. The correlation of the wood mass loss with the wood infrared spectra was performed with Partial Least Squares (PLS) regression. The preliminary analysis show that the change in the wood infrared spectra can largely be modelled by a single component for both the brown rot and the white rot decay processes.
A Jochemsen, G Alfredsen, I Burud

New methods for estimating the volume of shipworm tunnels supported by image analysis
2020 - IRG/WP 20-20668
In marine environment, the main threat for wood is the bioerosion by woodborers, both peracarid crustaceans (such as gribbles Limnoria and pincher scuds Chelura) and bivalve molluscs (shipworms, Teredinidae). The damage caused by gribbles on wood structure is surficial and easy identifiable, whereas the damage caused by shipworms is internal, therefore not evident, inducing unexpected crashes with consequence for navigation safety. To give an estimation of the volume eroded by shipworms from conventional X-ray pictures, a model was elaborated from shell size measured on radiographs. A simple method to compare wood poles of different shapes and dimensions is also presented based on image analysis. The methods here presented can be used to study shipworm attack and give new tools for implementing the current standard EN275, avoiding subjective visual assessments and to speed-up the analysis.
I Guarneri, M Sigovini, E Keppel, D Tagliapietra

Resistance against marine borers: About the revision of EN 275 and the attempt for a new laboratory standard for Limnoria
2020 - IRG/WP 20-20669
Wood protection technology in the marine environment has changed over the last decades and will continue to do so. New active ingredients, newer formulations, and novel wood-based materials including physically- and chemically-modified wood, together with increasing concerns over environmental impacts of wood preservatives, urgently demand a major revision of EN 275 “Wood preservatives – Determination of the Protective Effectiveness against Marine Borers”, dated from 1992. This IRG document reports on the technical work in CEN TC 38 regarding the revision of this standard. A Task Group within WG 24 of CEN TC 38 was formed consisting of experts from different field of competence (e.g. wood preservatives industry, wood scientists, marine biologists, archaeologists and cultural heritage conservators). Starting by e-mail correspondence in 2014, and continuing with four physical meetings (Berlin 2x, Florence, Venice) with experts from Germany, Italy, Sweden, and UK were held so far. Significant items for revision in EN 275 were identified as: number of replicates, duration of the test, dimension of specimens, number of test sites, number of reference species, reference material including reference preservative, re-immersion of specimens after non-destructive periodical evaluation for longer periods of time vs higher number of replicates for successive destructive examinations without re-immersion, utilization of X- ray apparatus and specific software to ease evaluation, etc. Furthermore, the task group is working on a standardized lab test for time-saving evaluation of different wood qualities for their potential to resist attack by limnorids. The suitability of this lab test will be determined by round robin tests as soon as safe face-to-face collaboration permits. The outcome will be published as a CEN TR (Technical Report) document, with a view to eventual adoption within the revised standard.
S Palanti, S Cragg, R Plarre

Chemical composition and performances of slow pyrolysis by-product from sugarcane bagasse for wood protection
2020 - IRG/WP 20-30752
Pyrolysis distillate or bio-oil, a by-product of biomasses’ slow pyrolysis in the char-making process, has been traditionally used as bio-pesticides by Asian farmers. Due to its large composition of bio-active chemicals, bio-oil obtained from various biomass has become of interest in many applications, including wood protectants. This study aims to characterize the chemical composition of bio-oil obtained from the slow pyrolysis of sugarcane bagasse at the temperatures of 400 °C and 500 °C, along with the efficacy test against two Basidiomycete fungi (Coniophora puteana, a cubic rot, and Trametes versicolor, a fibrous rot) and subterranean termites (Reticulitermes flavipes). The test on wood was also conducted by impregnating the bio-oil to the beech wood samples. Treated samples were dried at various temperatures (ambient, 40°C, 60°C, 80°C and 103°C), and leached before being exposed to termites R. flavipes. Gas Chromatography-Mass Spectrometry (GC/MS) analysis revealed that bio-oil is composed mainly of oxygenated compounds such as carboxylic acids, alcohols, aldehydes, ketones, furans, and anhydrosugars. In contrast, about 40% of the bio-oil consisted of water. At the concentration of 0.25% (v/v), bio-oil were observed to be able to inhibit the growth of both Basidiomycete fungi, when performing inhibition growth tests in Petri dishes. Further, no termites survived when exposed to a filter paper with a 10% concentration of bio-oil. All the wood samples have been shown durable against R. flavipes. However, bio-oil remains leachable from the wood, which indicates that future studies should be conducted in order to find out how to decrease its leachability.
F D Boer, M-F Thévenon, J-M Commandre, M Fournier

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