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IRG Documents 2017
2017 - IRG/WP 17-60427
IRG Secretariat

On the Influence of Wood Destroying Fungi on the Feeding Intensity of Termites
2017 - IRG/WP 17-10893
The baiting and feeding stimulating effect of wood attacked by fungal isolates of the species Coniophora, Lentinus, Poria and Gloeophyllum on termites Reticulitermes santonensis is examined. There are significant relationships between the activity of fungal isolates and the feeding behaviour of termites. The most active isolates can be used for increase the attractiveness of wood to wood-destroying termites.
W Unger, T L Woods

Encapsulated Active Ingredients for Wood Preservation
2017 - IRG/WP 17-30717
Encapsulated organic fungicides and termiticides have been examined for use as wood preservatives in vacuum pressure treatment of wood. Encapsulation of active ingredients was found to improve wood penetration behaviour and reduces leaching as well as biodegradation of the active ingredients compared to industrial standard formulations.
E Oenem-Siakou, R Möller, R Craciun, J Wittenzellner, J Habicht

Radio frequency heating times for sterilization radiata pine solid piles
2017 - IRG/WP 17-40815
In this work was sterilized wood packaging material of radiata pine, stacked as solid piles without stickers, for determining the heating times using radiofrequency treatment. The experiments were performed in a radio frequency semi-industrial equipment. The results showed that the radio frequency heating times increases with wood volume and that radio frequency treatments were faster than conventional vapour heat treatment.
H Esquivel, V Sepúlveda, J Torres, L Salvo, R A Ananías

The IRG48 Scientific Conference on Wood Protection - Poster abstracts
2017 - IRG/WP 17-60414
IRG Secretariat

Annual Report 2016
2017 - IRG/WP 17-60412
IRG Secretariat

Agenda 2017 Plenary Meeting
2017 - IRG/WP 17-60413
IRG Secretariat

Programme. IRG48 Scientific Conference on Wood Protection, 4-8 June 2017
2017 - IRG/WP 17-60415
IRG Secretariat

Budget for 2017 (forecast June 2017)
2017 - IRG/WP 17-60416
IRG Secretariat

Budget for 2018
2017 - IRG/WP 17-60417
IRG Secretariat

Conditions for membership of IRGWP
2017 - IRG/WP 17-60411
IRG Secretariat

Decay of wood in outdoor above ground applications: Preview of results on the effect of climate and species in Spain
2017 - IRG/WP 17-20600
Within the framework of the Project BIA-42434R titled ‘Evaluation of the functional performance of wood in outdoor above ground applications’, seven trials containing seven pieces of sawn wood measuring 750x100x20mm3, belonging to seven different wood species (Scots pine, Radiata pine, Laricio pine, sweet chestnut, eucalyptus, Thermo-treated radiata pine and Spruce), were exposed to unprotected outdoor conditions at seven different locations (Asturias, Palencia, Valencia, Madrid, Cordoba, Huelva and Vitoria). Temperature and moisture content evolution of the wood were monitored every two hours using Scanntronik devices (Thermofox+Gigamodule). Stainless steel screws inserted from the outer face to the centre of the pieces (10 mm) were used as sensors, the first 7mm of which were Teflon covered to avoid measuring the surface moisture. The initial conclusions that can be drawn from the data obtained during 20-24 months with regard to the effect of species on the performance of wood outdoors under different climatic conditions are presented in this work.
J I Fernández-Golfin Seco, M Conde García, M R Diez Barra, M Conde García, L Acuña Rello, E Torres Álvarez, E Perea Alonso, M T Troya

10 year Report on COST E37 Round Robin Tests – Comparison of results from laboratory and field tests
2017 - IRG/WP 17-30718
A round robin involving 15 European participants was set up in 2006. The round robin consisted of both a field test according to the double layer test method and a laboratory test with two different preconditioning methods. The laboratory test results were reported in an earlier IRG paper (IRG/WP13-20535) but are included also in this paper in order to facilitate the comparison with the field test results. As expected, the decay generally developed more rapidly at the southern European compared to the northern European field sites. However, the rank order of the different test groups concerning average decay ratings were the same for most field sites – Untreated pine sapwood controls had the highest decay ratings followed by TMT-UC2 (Thermally Modified Timber treated for use class 2 application), TMT-UC3, metal-free organic preservative in low retention, metal-free organic preservative in high retention, CCA in medium retention, and finally CCA in high retention that had very low decay ratings. The best compliance between field performance and laboratory test results is obtained when comparing the average results from the field tests with results from EN 113 tests with Postia placenta after natural preconditioning according to CEN/TS 15397. When evaluating the test methods it was clear that CEN/TS 15397 before the EN 113 test in laboratory seems to give far more relevant results than EN 113 after preconditioning according to EN 84 (water leaching for 2 weeks). The double layer field test does not function the way it was meant after failure ratings were reached for one or more stakes within a test group leading to collapse of the deck. This has occurred not only at the Southern European field sites but also in some cases for mid-European and Nordic test sites. After this type of collapse has been reached it is doubtful whether there is any point with continuing the test and therefore the test has now been terminated in some fields.
M Westin, E Conti, J Creemers, P-O Flæte, A Gellerich, I Irbe, M Klamer, E Melcher, R Moeller, L Nunes, S Palanti, L Reinprecht, E Suttie, H Viitanen

Prevention of fungal damage of oil and date palm wood by organic acids
2017 - IRG/WP 17-10877
Felled palm trunks are susceptible to fungi as long as their moisture content is above fibre saturation. During this period, palm wood has to be protected against mould and rot fungi. Environmental-friendly organic acids are suitable. Small samples of oil palm (Elaeis guineensis) and date palm (Phoenix dactylifera) wood were treated with 1 to 10% solutions of acetic acid and propionic acid, respectively, and subsequently infected by moulds, blue-stain and wood-decay fungi. Short dipping of the samples in 2% solutions of both acids protected all samples for two months from colonization and discolouration by Aspergillus niger, Penicillium commune, Mucor sp., and a natural infection. A blue-stain fungus was inhibited by 5% solutions. Decay tests with the white-rot fungus Pleurotus ostreatus, the brown-rot species Coniophora puteana and the soft-rot fungus Chaetomium globosum showed that 5 and 10% solutions of both acids reduced degradation.
M Bahmani, O Schmidt

Effects of wollastonite nanofibers on biological resistance of historical paper against Aspergillus niger
2017 - IRG/WP 17-10878
Effect of wollastonite nanofibers on biological resistance of historical paper against Aspergillus niger was studied. Specimens from A4 papers were also prepared for comparison purposes. Paper specimens were dipped in aqueous nanowollastonite (NW) with 10, 20, 30, and 40% concentrations and compared with control specimens. In order the nanofibers be fixed on paper specimens, 5% of polyvinyl acetate (PVA) resin was added to all nanosuspensions. Moreover, in order to find out the effect of PVA on fungal growth, a separate set of specimens was prepared dipped in a 5% resin solution, without nanowollastonite content. Results clearly demonstrated the preventing effect of wollastonite nanofibers on the growth of A. niger, resulting in significant decrease in weight loss as NW-content increased. It was concluded that as to the mineral, non-toxic, and non-acidic nature of wollastonite, it can effectively be used for paper preservation and conservation purposes. In this regard, NW-content of 20% is recommended to the industry to both achieve a high level of protection against A. niger, and keep the preservation costs to the minimum level.
H R Taghiyari, A Kalantari, A Ershad-Langroudi, A Kalantari

Durability Testing of a Cattail (Typha spp.) based Insulation Material against Termite Attack
2017 - IRG/WP 17-10879
The use of insulating materials is particularly important in the construction industries, especially with regard to the use of wood and naturally occurring substances. The use and durability of natural materials as insulating materials is of keen interest to many construction experts, and continues to be a topic of intense investigation. It is generally agreed that the use of natural substances as insulation is possible if certain harmful influences are prevented or controlled. We investigated plant material of the cattail plant (Typha spp.) which consists of long, tear-resistant fibers and a compressible sponge-like tissue. The test material has a low specific density of 0.65 kg/m³. Test specimens consisted of sections of insulating panels which would typically be used in walls and roofing areas, as well as inside living areas. It is especially desirable that cattail-based insulating material is suitable for use in tropical environments where the insect and decay hazard is more severe than in temperate climates. In our research, we examined the resistance of a cattail-based insulation material against destruction by termites. Objectives were to determine resistance against termites and to assign a durability class to the test material. The experiments are in accordance with the European standard EN 117 and EN 118. The termite species Reticulitermes santonensis de Feytaud is the test organism. The test specimens have dimensions of 50 x 25 x 15 mm, and the test duration is 56 days. The test arrangement includes three different variations: the Force Test is a test with only one specimen in a vessel; the Choice Test includes two specimens; and the Control Test demonstrates the behavior of termites under optimal conditions. The test results are discussed with emphasis on the possible use of cattail-based insulation material in tropical countries where termite resistance is of particular importance.
M Dass, W Unger, T L Woods

Evaluating the role of Actinobacteria in the gut of wood-feeding termites (Reticulitermes spp.)
2017 - IRG/WP 17-10880
Nitrogen has been shown to be a limiting nutrient across a range of xylophagous insects. These insects often rely on symbiotic microorganisms in the gut for nitrogen acquisition, via fixation of atmospheric nitrogen or break down of other available nitrogenous substances. In phylogenetically lower, wood-feeding termites, the role of nitrogen fixing bacteria has been well studied. However, there is also evidence that uric acid can be metabolized into ammonia and serve as an additional nitrogen source. In this study, 36 Actinobacterial isolates (Streptomyces spp.) from the guts of Reticulitermes flavipes (Kollar) and Reticulitermes tibialis Banks, were screened for uric acid breakdown using culture-based methods. Results showed 92% of isolates are capable of degrading uric acid, with 35% classified as having “very strong” uricase activity in vitro. Enzyme assays of four representative Actinobacterial isolates confirmed that uric acid was broken down and ammonia was produced. Soil materials manipulated by termites also showed increased uricase activity compared to soil alone. However, this increase was not accompanied by an increase in overall abundance of Actinobacteria. It is still possible, however, that only those Actinobacteria with uricase activity increase while others remain the same or decrease, which would not change overall abundance values. Results from this study support the hypothesis that Actinobacteria associated with the gut of wood-feeding termites have the potential to contribute to nitrogen acquisition via uricolysis. Future work will be aimed at better understanding this complex relationship between wood-feeding subterranean termites and gut-associated Actinobacteria.
Evaluating the role of Actinobacteria in the gut of wood-feeding termites (Reticulitermes spp.)

Comparative studies on the durability of English oak (Quercus robur L.) under in-service, field and laboratory conditions
2017 - IRG/WP 17-10881
The durability of many wood species varies due to differences in extractive content, anatomical features, growth conditions, and not at least in dependence of the respective exposure conditions either under test or in real life applications. And so does the durability of English oak (Quercus robur L.), which has recently been considered in the revised European standard EN 350 (2016) and is now classified as ‘durable to less durable’ (Durability class DC 2 – 4) in ground contact (Use class UC 4), but in case of standard lab tests using basidiomycetes as ‘very durable to durable’ (DC 1 2). To increase the knowledge about reasons of durability variation within one wood species, this study aimed on comparative evaluation of results from different laboratory, field and in-service tests with English oak. This paper considers the final results from three different projects with in-ground field tests after five, seven, and twelve years respectively. The three English oak assortments showed generally higher durability in decay resistance tests with monocultures of different basidiomycetes compared to tests using terrestrial microcosms (TMC). The results from the TMC tests, which can be seen as semi-field tests, were confirmed by the in-ground field test results at three different locations in Germany. Obviously, the degradation patterns under laboratory conditions in the TMC are similar enough to those in the field that they might serve as predictors for outdoor performance of wood. Finally, full-size double-split fence posts were exposed at the test field in Trenthorst in parallel with smaller EN 252 (2015) standard specimens. Standard specimens of all three Oak assortments decayed severely during five years of exposure in ground. In contrast, the heartwood portions of the full size fence posts was on average decayed less than 12 %, which might suggest a positive effect of bigger dimensions on wood durability in ground.
C Brischke, L Meyer-Veltrup, A Soetbeer, M Höpken, E Melcher, J Trautner

Analysis of hindgut bacterial phyla frequency and diversity in subterranean termites exposed to chitosan-treated wood
2017 - IRG/WP 17-10882
The termite hindgut contains a microbial community that symbiotically aids in digestion of lignocellulosic materials. For better understanding of the dynamics of the bacteria-termite relationship, a species survey of bacterial hindgut microbes in subterranean termites (Reticulitermes flavipes: Kollar) collected from Louisville, Mississippi was performed after exposure to chitosan-treated and control (water-treated) wood samples. Total genomic DNA was isolated from termite hindguts, amplified and 16S ribosomal RNA (rRNA) gene fragments were analyzed using next-generation sequencing techniques. Twenty-seven bacteria phyla were identified in both treatment groups, with six bacteria phyla showing significantly differences in abundance between the chitosan-treated and control groups. These results suggest that there was a treatment driven effect on the hindgut bacteria diversity.
O Raji, J D Tang, T Telmadarrehei, D Jeremic

Assessment of the quality and lifetime of wooden pile foundations
2017 - IRG/WP 17-10883
The development of wooden pile foundations started centuries ago and enable man to build and live in strategic and fertile areas. Although the building methods, the building materials and the building regulations chanced especially over the last decades, worldwide wooden pile foundations still fulfil their function to support above ground constructions of which many belong to our cultural heritage. In the Netherlands wooden foundations are a national bench mark and Amsterdam is often regarded as the City on wooden piles. The pile population in service is estimated on 25 million and as they are carrying many ordinary family houses and water building constructions their importance is far above building history. The behaviour of wood in the soil and the special threats for pile foundations asked for an adapted method in order to assess the actual and future status of these underground constructions. This paper describes a method quantifying the actual and future stability taking in to account the special behaviour of wood in constructions in the ground. This method was developed in the last decades in the Netherlands by a multidisciplinary group of researchers.
R W W M Klaassen, A Jorissen, H Keijer

Effects of climatic factors and material properties on mould growth on untreated wooden claddings
2017 - IRG/WP 17-10884
Mould growth is an important contributor to colour change of untreated wood exposed outdoors. Predicting the development of mould growth is therefore important to ensure successful use of untreated wood as a façade material. More knowledge about the factors affecting mould growth on outdoor exposed wood is required to give better predictions. In this study, climatic factors and material properties affecting mould growth have been investigated by exposing selected wooden specimens (aspen, pine sapwood, pine heartwood, spruce sapwood and spruce heartwood) to 8 different climates for 91 days. The climates were defined in a factorial design with two levels of relative humidity (65 and 85 %), wetting period (2 and 4 hours per day) and temperature (10 and 25 °C), respectively. The degree of mould growth was visually evaluated once a week during the exposure period. Aspen and pine sapwood were the substrates most susceptible to mould growth. There were no significant differences in susceptibility between pine heartwood and spruce heartwood, but the difference between heartwood and sapwood was significant for both pine and spruce. The effect of density on mould growth was tested for the spruce heartwood material, but was not found to reduce the residual variance significantly. However, all the tested climatic factors affected mould growth significantly; relative humidity was most important, while there was a somewhat smaller effect of wetting period and a minor effect of temperature. Overall, increased RH, longer wetting period and increased temperature had a positive effect on the mould growth. It was found a significant interaction between temperature and relative humidity, indicating that the temperature had larger effect on the mould growth at lower relative humidity, and that the relative humidity had larger effect at lower temperature. There was a tendency that the relative performance of the substrates was dependent on climate, but this interaction effect was not significant for any of the climatic factors.
S Karlsen Lie, G I Vestøl, O Høibø, L Ross Gobakken

The First Description of Soft-rot Cavity in Waterlogged Archaeological Woods by a Japanese Wood Anatomist Prof. F. Onaka in 1935
2017 - IRG/WP 17-10885
The term soft rot, which was caused by Ascomycetes and Deuteromycetes, was first used by J G Savory in 1954. Soft rot decay can be characterized by cavities within secondary cell walls align along the cellulose microfibrils. Our recent literature search revealed, however, that Prof. F. Onaka in Kyoto University described the soft rot cavities in the waterlogged archaeological woods in detail from the year of 1935 on, almost 20 years earlier than Savory. Although Dr. Onaka did not use the term of cavity, however, “micro boreholes” matched precisely with the definition of Savory’s soft-rot cavity. He described that the boreholes (= cavities) were developed along the microfibril in the latewood of waterlogged archaeological larch, yew and umbrella pine. Dissemination of his novelty would limited due to the language unfamiliar to Western hemisphere.
Yoon Soo Kim, K Yamamoto

Assessing the natural durability for different tropical timber species using the mini-block test
2017 - IRG/WP 17-10886
The Xylarium in the Royal Museum for Central Africa (RMCA, Tervuren, Belgium) contains over 60,000 wood-samples, comprising over 12,000 species. These samples are of great historical and scientific value yet have a random format, which complicates standard testing. The wood-durability against Coniophora puteana and Trametes versicolor was tested for 36 species. Due to the random sample sizes the standardised test for testing durability related to basidiomycetes CEN/TS 15083-1 (2005) was not applicable as such. Instead, the mini-block test, as proposed by Bravery (1978) was used. The similarity between the standard test and the mini-block test will be assessed for 13 reference species. Virulence check for both test fungi was performed using beech, Fagus sylvatica L. For both Coniophora puteana and Trametes versicolor a standard durability only allowed standard classification according to durability class DC 2 when referring to the criteria set in EN 350 (2016), showing that the fungal growth was not optimal. There appears to be no direct link between the mass loss of the tested species using the criteria and the durability class listed in EN 350 (2016). Prior to fungal testing the same samples were also chemically analysed, by DART TOFMS to check potential correlation between ion-intensity and mass loss. Several ions which are linked to certain compounds or metabolites, appear to play an important role in explaining the variability in mass loss between samples.
V Deklerck, I De Windt, N Defoirdt, J Van den Bulcke, H Beeckman, E Espinoza, J Van Acker

Natural durability of Sextonia rubra, an Amazonian tree species: description and origin
2017 - IRG/WP 17-10887
Sextonia rubra is a tropical tree species belonging to Lauraceae family. In French Guiana, its long lasting heartwood is largely exploited for different purposes including house construction, and furniture making. Decay tests have confirmed S. rubra natural durability, and led us to discover some variability. Rubrynolide and rubrenolide, which are two majors metabolites isolated from the heartwood of S. rubra, exhibit potent antifungal and termiticidal activities that result in the exceptional natural durability of this species heartwood. Interestingly, we have also described and isolated acylated precursors of these two secondary metabolites from the sapwood. Although the constitutions and total synthesis of rubrynolide and rubrenolide have been comprehensively described in literature, little is known about their origin and fate in the context of the heartwood formation process. HPLC was thus used to investigate the repartition of rubrenolide and rubrynolide as well as the acylated precursors in sapwood and heartwood of S. rubra, leading to propose that the biotransformation of the precursors into rubrenolide and rubrynolide occurs at the transition zone between sapwood and heartwood. Finally, 13 trees were sampled from natural populations characterized by different growth dynamics evaluated through dendrometric parameters, tree architecture description and bark desquamation. Our aim was to study the influence of life-history traits on S. rubra heartwood formation from a chemical quantitative and qualitative (LC-MS analysis) point of view. We observed significant variations concerning sapwood and heartwood extraction yields depending on the trees, as well as a noticeable variability of the heartwood chemical signature.
E Houël, A Rodrigues, E Nicolini, O Ngwete, C Duplais, D Stien, N Amusant

Untreated and copper-treated wood soaked in sodium oxalate: Effects of decay by copper-tolerant and copper-sensitive fungi
2017 - IRG/WP 17-10888
Copper is widely used as the primary component in wood protectants because it demonstrates a broad range of biocidal properties. However, a key concern with using copper in wood preservative formulations is the possibility for brown-rot basidiomycetes to resist the toxic effect. Many brown-rot basidiomycetes have evolved mechanisms, like the production and accumulation of oxalate, which helps these fungi to tolerate copper-treated wood by detoxifying copper. The purpose of this study was to determine if untreated wood and copper-treated wood soaked in sodium oxalate influenced the rate of decay by brown-rot basidiomycete fungi. Both untreated and 1.2 % ammoniacal copper citrate-treated test blocks were subjected to an additional sodium oxalate treatment via two soaking methods (ten minute and two hour). Test blocks were exposed to two Fibroporia radiculosa isolates (FP-90848-T and L-9414-SP) and one isolate of Gloeophyllum trabeum isolate (MAD 617) and evaluated for weight loss at four and eight weeks. Decay was between 40-43% weight loss at week eight for F. radiculosa L-9414-SP when untreated blocks were soaked with sodium oxalate. F. radiculosa L-9414-SP demonstrated decay of 38% at week eight when copper citrate-treated blocks were soaked with sodium oxalate. F. radiculosa FP-90848-T decay was much lower for untreated blocks soaked with sodium oxalate (12-13%) and only slightly higher on copper-treated blocks soaked with sodium oxalate (19%) by week eight. G. trabeum MAD 617 decay was between 40-46% when untreated blocks were soaked with sodium oxalate. G. trabeum was unable to successfully decay the copper citrate-treated blocks soaked with sodium oxalate (0.5%) by week eight. The copper-tolerant and copper-intolerant test fungi used in this study demonstrated no major increase in decay when untreated and copper-treated wood was amended with oxalate.
K M Ohno, G T Kirker, A B Bishell, C A Clausen

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