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Biostatic film as a primary treatment against pole failure in soil
1995 - IRG/WP 95-40053
Field liners of low density polyethylene (LDPE) film applied as primary treatment of soil-contact surfaces of creosote-treated poles prevented their detoxification and premature failure by establishing hurdles against microbiological colonisation. These hurdles include low water activity, low oxygen tension and nutrient limitations. Moreover, under conditions of high soil moisture, field trials showed that the hurdle of toxicity provided by creosote is maintained by LDPE films which prevent it from leaching. However, such liners must remain intact to confer sustained protection. Susceptibility of LDPE to termite damage and to possible microbiological damage in the long term led to the development of materials resistant to biodeterioration. A dry film preservative (DFP) was incorporated with masterbatch for use in LDPE manufacture. Laboratory tests showed the masterbatch granules to be biocidal against soil microorganisms, confirming that neither the moulding temperature nor the immobilisation of the DFP in the masterbatch had neutralised the antimicrobial properties of the DFP. The masterbatch was then used to produce LDPE film which, with unpreserved control film, was applied as liners to surfaces of untreated Eucalyptus grandis posts. All posts were placed under flood-irrigation in termite-infested soil in Natal for eight months. Preserved liners remained intact and the wood under these was uncolonised by microorganisms or termites. Some control films, and the wood under them, had been destroyed by termites, and wood surfaces under the other control films which appeared intact were visibly colonised by fungi.
A A W Baecker, M Behr

Field test design for service life prediction of wooden components
2005 - IRG/WP 05-20308
Wood is predominantly degraded by organisms. Thus, compared to other building materials, service life of wooden material is influenced by many more factors, which are divided into direct and indirect factors. Climate, geographical position, and construction criteria count to the indirect decay factors. Besides material inherent properties (natural durability, wood preservatives), wood temperature, wood moisture content, and the presence of certain species of wood degrading organisms are the strongest direct factors influencing service life of wooden building components. On this account an experimental set up was developed to quantify these direct decay factors: Field tests were performed in European Hazard Class 3 (EHC 3) to determine the influence of macro and micro climate on decay progress and decay factors such as temperature and moisture content of wood. Therefore Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) have been positioned in double layer test devices since 2000. Thirty-two sites in Europe and the United States representing preferably different climatic conditions were chosen for exposure of the test devices. For all sites, data on climate were available since they were located next to an official meteorological station. This way all relevant climatic factors (precipitation, air temperature, relative humidity, sunshine duration, wind) are correlated with MC and temperature of the samples to be measured once a minute and logged once a day. Furthermore the samples were evaluated respecting to decay and discolouration every year according to EN 252 (1990). Preliminary results concerning the influence of macro and micro-climate show that this approach will provide a sufficient data base for a better understanding of the most important factors determining decay.
A O Rapp, C Brischke

A non-pressure method of protection based on hurdle theory to control the spectrum of internal environmental factors which affect the decay of poles in soil contact
1993 - IRG/WP 93-20005
A field trial was conducted to establish whether superficial barrier linings on poles in soil contact could function as environmental hurdles against the growth of biological agents and thus provide preventative methodology to preclude premature failure of vineyard poles under flood-irrigation. Assessment after 52 weeks exposure to the prevailing conditions and sub-tropical environment showed that open-ended cylindrical linings of biologically inert heat-shrink polyethylene applied to the vertical soil-contact surfaces of Eucalyptus grandis poles unequivocally prevented termite-induced failure of untreated poles, basidiomycete decay of creosote-treated poles and fungal colonisation of CCA-treated poles. The success of the liners in prevention of incipient decay of these poles was explainable on the basis of hurdle theory and was therefore attributed to the ability of the former to control essential growth factors and create internal conditions inimical to the proliferation of decay agents in the poles. Consequently, sub-optimal conditions of Aw, Eh, and nitrogen content were considered to have arisen to function as environmental hurdles which decay agents could not overcome at wood-soil interfaces.
A A W Baecker

Factors affecting decay rates in a fungus cellar II
1986 - IRG/WP 2259
Tests were initiated to investigate the influence of various factors on the decay rate in a "Fungus Cellar". Birch and pine stakes treated with chromated copper arsenate and didecyldimethyl ammronium chloride, as well as untreated control stakes, were incubated in two soils in a Fungus Cellar test and installed at two field sites for comparative purposes. The visual rating vs actual stake weight loss relationship was also studied. Preliminary results from the initial Fungus Cellar test indicated differences in decay rates between birch and pine and also between soils. The decay rate observed for pine stakes was generally lower than birch in both soils. The decay rate was greatly accelerated in a Michigan soil with birch and pine over that observed in a Florida soil. Soil type had less impact on the primary decay present in the stakes. Soft rot was the primary decay associated with treated wood in both soils, while soft rot, basidiomycete, or combinations of the two were frequently found in untreated wood. The range of weight loss vs visual rating relationship was similar between wood species, treatment, and soil type. Weight losses tended to "overlap" the visual ratings regardless of the decay type.
P A McKaig

An analysis of the effects of some factors on the natural durability of pine (Pinus sylvestris L.) and spruce (Picea abies Karst.)
1986 - IRG/WP 1279
The effects of some factors on the natural resistance of pine and spruce sapwood against fungal decay and against attack of house-longhorn beetle larvae have been studied in laboratory tests and the results are evaluated by analysis of variance and regression analysis. Following conclusions were reached: Wood from summer-felled trees did not have a lower inherent natural durability against fungal decay and house-longhorn beetle than wood from winter-felled trees. Storage of pine logs in water had no significant effect on the weight losses obtained in laboratory tests with Gloeophyllum sepiarium and Fomitopsis pinicola but reduced the weight losses obtained with Phlebiopsis gigantea very significantly. In the case of outdoor use of wood, this result implies that the decreased nutritive value of wood from water-stored logs for certain fungi to some extent compensates for the effect of increased permeability. Wet storage also reduced the growth of house-longhorn beetle larvae. The effects of density on weight loss by fungal decay were different for the three test fungi. The growth rate of the house-longhorn beetle larvae in the inner sapwood was much lower than that in the outer sapwood. In comparison with between-trees variation and with differences between outer and inner sapwood the other observed effects, each on its own account, are of minor practical importance for larval growth.
J B Boutelje, T Nilsson, S Rasmussen

Factors affecting decay rates in a fungus cellar
1985 - IRG/WP 2242
Birch and pine stakes treated with chromated copper arsenate and didecyldimethylammonium chloride were incubated in two soils in a "Fungus Cellar" test. At three month intervals, sets of stakes were inspected and assigned visual ratings or removed from the soil beds for weight loss determination. Preliminary results after nine months exposure have shown differences in the decay rates between birch and pine and also between soils. Overall, the decay rate for pine, treated and untreated, has been considerably lower than birch in both soils. A Michigan soil accelerated the decay rates up to 3 times that observed for a Florida soil. Soil type also influenced the primary decay present in the stakes. Basidiomycete attack was observed in birch stakes treated with subthreshold retentions of both preservatives in the Michigan soil, while the primary decay in the Florida soil was soft rot. Untreated birch controls failed through basidiomycete attack in both soils. Soft rot was the primary decay in treated and untreated pine for both soils. However, more data is needed to determine if this trend will continue. Weight losses as low as 9.3% caused stake failure (visual ratings of 0). Basidiomycete damage caused stake failure at lower weight losses than soft rot. Regardless of the decay type, threshold retentions selected by weight loss or visual ratings were similar.
P A McKaig

Factors affecting the resistance of fibre building boards to fungal attack
1975 - IRG/WP 252
Fungal decay is initiated at lower moisture contents in standard and tempered hardboards (18%) than in pine sapwood (26%). In contrast, in a saturated atmosphere, the equilibrium moisture contents of standard hardboard (14%) and of tempered hardboard (12.5%) are much lower than the moisture content permitting decay initiation whilst the equilibrium moisture content of pine sapwood (25.1%) approaches its decay initiation level. When immersed in water the hardboard, especially when tempered, took much longer to wet to decay initiation moisture contents than the pine sapwood but, on the other hand, the hardboards dried at much the same rate as the solid wood. It is concluded that the physical changes which occur during hardboard manufacture are such that under fluctuating service conditions, even when liquid water is intermittently present, hardboards tend to remain at risk from fungal attack to a much lesser extent than solid wood.
C Grant, J G Savory

Decay factors in termite in-ground monitoring stations
2012 - IRG/WP 12-10775
Subterranean termites are serious pests of wood in service in much of the world. One of the most common techniques for monitoring and controlling termites is the use of in-ground monitoring stations which comprise a wood or other cellulosic material monitor (cellulosic matrix) and/or a termiticide bait held in a open plastic holder so facilitates examination and the termite access. Wood and other cellulosic substrates are subjected not only to termite attack, but also to fungal decay, which may interfere both with usefulness of the monitoring stations and with termite attraction. Decay susceptibility of commercial monitoring stations was assessed over one year in the field. Variables evaluated were: mass loss and moisture content of cellulosic matrix, termite presence, type of cellulosic matrix (cellulose powder, Pinus spp., Populus spp., Pinus pinaster, Hevea brasiliensis, cardboard), monitoring station model (Advance™, FirstLine™, Terminate™, LNEC) and a wood borate-based treatment. A multivariate analysis (RDA) was performed, resulting in 78.8% of mass losses data variability being explained by the decay factors considered in this analysis. Five factors were considered significant (P<0.002): moisture content, cellulose powder and type of monitoring stations (namely FirstLine™, Advance™ and LNEC). Advance™ stations were used with different cellulosic matrices: cellulose + Populus spp. and H. brasiliensis (treated and not treated). Although cellulose powder had very low mass loss and fungi attack, termites were not attracted to this substrate. H. brasiliensis Advance™ stations were attacked by termites. FirstLine™ stations showed no mass loss; however, these traps were attacked by termites and moulds. LNEC baits, using P. pinaster, had low mass losses although termites’ presence was low. The use of wood borate-based treatment was not considered significant for decay resistance in this study; it was noticed that termites did not seem to avoid this fungicide treatments at the levels used. Monitoring stations design must be done carefully for the achievement of good results in termite monitoring and control with in-ground termite baiting systems. The replacement of substrate after wetting and fungal decay may be necessary. Cellulosic matrices’ decay resistance should be considered and evaluated in the field, including the search for adequate fungicides. The type of cellulosic matrix must also be chosen according to termites’ preferences.
S Duarte, A M Taylor, Jae-Woo Kim, J D Lloyd, M Duarte, L Nunes

A survey of factors affecting decay resistance of wood modified with acetic anhydride
2012 - IRG/WP 12-40594
From the range of information published, acetylation appears well suited to provide adequate protection against biological attack for materials derived from typically non-durable wood species. Acetylated wood is now commercially available both in Europe and in the USA. But still there are a lot of unanswered questions related to fungal decay mechanisms in acetylated wood. The paper summarize existing knowledge and highlight future research opportunities related to fungal deterioration of acetic anhydride modified wood. In addition statistical analyses based on previously published data were performed to quantify what factors contribute most to the performance (calculated as test sample/control). The results showed that WPG can explain approximately 50 % of the performance, measured as test sample/control (T/C), for acetic anhydride treated wood. Other of the applied variables, like wood species or type of fungus can reduce the variance in T/C by additional 15 %.
G Alfredsen, P O Flæte, H Militz

A screening of factors that might influence the result of laboratory decay tests
2014 - IRG/WP 14-20548
Laboratory fungal decay tests provide important tools for performance testing of wood materials. But they are also hampered with some uncertainties regarding reproducibility. In addition to variation between fungal species and strains the test conditions are also believed to have some influence. The aim of this study was to screen the effect of a selection of test parameters that might influence the results from a laboratory fungal decay test. The results from this study showed that T. versicolor was more sensitive to the tested factors than P. placenta using P. sylvestris as wood substrate. The data from the agar/malt test showed that the choice of malt was of great importance for the virulence of the test fungus. However, no significant differences in mass loss were detected for two of the fungi; C. puteana and G. trabeum. From these results it can be concluded that it is important to describe the test parameters in detail when presenting results from fungi trials in order to facilitate reproducibility.
E Larnøy, G Alfredsen, A Treu, S Kolstad

Factors Affecting Performance of Preserved Wood Decking Against Decay Fungi
2015 - IRG/WP 15-30663
Decking is the largest market for residential preserved wood in the United States. Preserved decking must be resistant to colonization by decay fungi initiating from spores, and occasionally from mycelia due to elevated soil levels or adjacent untreated wood. The most vulnerable parts of a preserved wood deck are untreated, or under-treated, wood that becomes exposed by field cuts and checking. Field cuts can be protected by applying field-cut preservatives. Checks can be protected by mobile preservatives present in the treated wood. Copper ions from chromated copper arsenate and particulate copper preservatives can protect untreated checks; however, copper-ethanolamine leached from copper-amine systems has lower efficacy against basidiospore germination. DDAC and tebuconazole have limited abilities to protect checks. The potential contribution of borates has not been adequately studied. Protection against mycelial attack depends largely on the toxic thresholds of the actives and their distribution within the wood. Toxic thresholds determined by soil block decay testing are higher than currently standardized retentions for the major systems currently used to treat decking in the United States. Improved data are needed to determine toxic thresholds from tests on shell-treated material exposed to realistic above-ground conditions. Further research on a number of fronts is needed to understand and optimize the decay resistance of preserved wood decking.
R Stirling, P I Morris

Confocal laser scanning microscopy of a novel decay in preservative treated radiata pine in wet acidic soils
1997 - IRG/WP 97-10215
Light microscopy of radiata pine (Pinus radiata D. Don) field test stakes (20x20x500mm3) exposed in wet acidic (pH 3-4) soil for 12 - 24 months showed predominance of an unusual type of decay characte-rised by tunnelling attack of wood cell walls. After two years decay was moderate to severe in wood treated to ground contact CCA specifications and also equivalent retentions of creosote, and a number of new generation preservatives. Relative to other New Zealand temperate test sites and also an Australian tropical site, the New Zealand acidic soil test site was very aggressive. Correlative scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to elucidate the micromorphology of this attack. Tunnels of diameter 0.2-5 µm were present throughout all layers of the cell wall, and their orientation was not related to cellulose microfibril orientation. They also showed no preference for particular cell wall layers, indicating a lignin degrading capability. CLSM images showed that living, connecting fungal hyphae were present in the cell lumina and tunnels. This type of attack was predominant in wood that was highly saturated with water whereas wood that was less moist was predominantly attacked by classical white rot. Ongoing isolation and incubation studies in conjunction with further microscopy should enable identification of the fungal species involved.
R N Wakeling, Ying Xiao, A P Singh

Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton&apos;s reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi

Field trial with poles of Scots pine treated with six different creosotes
1996 - IRG/WP 96-30115
In the middle of the 50&apos;s field trials with creosote-treated poles were started in France, Germany and Sweden. The trials were initiated by WEI (Western-European Institute for Wood Preservation). Six different creosotes were used and 40 poles per creosote were installed at each test field. Results after 39 years of exposure in Simlangsdalen, Sweden are reported. Poles treated with a heavy creosote were less decayed than poles treated with medium-heavy creosotes. Poles treated with a light creosote were most decayed.
Ö Bergman

Questionnaire - Fungal decay types
1985 - IRG/WP 1265
T Nilsson

JWPA method for testing effectiveness of surface coatings with preservatives against decay fungi
1981 - IRG/WP 2164
In 1979 JWPA established a new method for testing effectiveness of surface coatings in accordance with practical use of preservative-treated lumber. Comparing the new testing method with JIS A 9302, a few new trials - size of wood specimen, weathering procedure, and decay-test procedure - are incorporated.
K Tsunoda

Utilization of curcumin for detection of presence of boron in wood
1982 - IRG/WP 3191
It has been shown that curcumin is not a reliable reagent for detecting boron in wood that has been attacked by fungi
M-L Edlund

Co-operative studies on determining toxic values against wood-destroying Basidiomycetes: Progress report to May 1989
1989 - IRG/WP 2339
This document reports progress on the co-operative study between nine laboratories set up following the proposals contained in Document IRG/WP/2316. Results have been received from two laboratories. Toxic values data have been established successfully using the test fungus Coniophora puteana but problems have been encountered with the other test fungi.
A F Bravery, J K Carey

Monographic cards for wood-destroying fungi. [Fiches monographiques pour les champignons lignivores]
1970 - IRG/WP I 5B
C Jacquiot

On Donkioporia expansa (Desm.) Kotl. & Pouzar
1986 - IRG/WP 1285
Donkioporia expansa is found more often in houses than realised until now. Virulence tests according to EN 113 show not only an attack of oak, but also of other hardwoods and even soft-woods.
G Buchwald

Nondestructive Evaluation of Oriented Strand Board Exposed to Decay Fungi
2002 - IRG/WP 02-20243
Stress wave nondestructive evaluation (NDE) technologies are being used in our laboratory to evaluate the performance properties of engineered wood. These techniques have proven useful in the inspection of timber structures to locate internal voids and decayed or deteriorated areas in large timbers. But no information exists concerning NDE and important properties of wood composites exposed to decay fungi. For our pilot study on several types of wood composites, we examined the relationship between nondestructive stress wave transmission, decay rate and the bending properties of OSB exposed to the brown-rot fungus, Gloeophyllum trabeum (MAD-617). The following measurements were taken: stress wave transmission time (pulse echo test method), static bending test (ASTM D3043-95), and decay (expressed as percent weight). Stress wave measurements correlated with strength loss and with increasing rate of fungal decay. Stress wave NDE has great potential as a method for inspection of wood composite load-bearing (in-service) structures, detection of decay in laboratory tests, assessment of chemical additives to improve wood composite durability, and prediction of long term composite performance.
B Illman, V W Yang, R J Ross, W J Nelson

Moisture content levels and decay of hemlock
1986 - IRG/WP 1287
As a model of decay conditions of wooden members in wooden houses, a decay test was set up in which samples of western hemlock (Tsuga heterophylla) under 4 moisture levels were examined. Each week the samples were weighed and if the weights indicated that their moisture contents were lower than the expected levels, distilled water was added. Every 8 weeks 3 samples from each condition were oven dried at 60°C for 48 hours, up to 48 weeks. After 48 weeks, 3 samples from each condition were oven dried every 16 weeks. The results obtained were as follows: After examining the samples for 96 weeks at 27°C, the mean weight loss of the hemlock samples kept at about 50-100% moisture content level was larger than those of the other levels. If the samples were dried every 8 weeks, the amount of decay in them was not significant. Decay was also not significant in the samples kept at approximately 20-30% moisture content level.
K Suzuki

Dimensional stability and decay resistance of hot-melt self-bonded particleboard by surface benzylated pine chips
1991 - IRG/WP 3652
Akamatsu (Pinus densiflora Sieb. et Zucc: Japanese red pine) particles were pretreated with 40% NaOH solution and benzylated with benzyl chloride, and the surface of particle was converted into meltable materials. Hot-melt self bonded particleboard having smooth and high glossiness surface was prepared by hot pressing at 150°C and 1.96 MPa without using any conventional adhesives. Dimensional stability and decay resistance of the benzylated particleboard were evaluated. Particleboards made of benzylated particles having more than 38% of weight percent gain (WPG) showed that dimensional stability and decay resistance were superior to the conventional particleboard made by using phenolformaldehyde resin as a binder, because hydroxyl groups of wood were substituted by hydrophobic benzyl groups with benzylation. Though bending strength of the board was a little lower than control board due to the damage of benzylated particles during benzylation, its internal bonding strength was very high, because the hot-melting strengthened the inter-particle bonding.
M Kiguchi, K Yamamoto

How to Document the Performance of Super-Critical Treated Wood in above Ground Situations?
2005 - IRG/WP 05-20316
The paper presents practical experiences from the preparation of a new preservative treated wood product for introduction to the market. The product in question is Superwood™, which is treated with organic biocides using CO2 in a supercritical state as a solvent. The question is how to evaluate the performance of a new product such as Superwood™ in order to get an acceptance on the market and fulfil the formal requirements. In the European Union countries, the EN 599-1 is the standard that needs to be complied when approving a new product for the market, but it only focuses on the toxic limit against representative decay fungi according to EN 113. However, decay test, above ground and other forms of field tests are optional, this is not in line with the traditional test philosophy in the Scandinavian countries. The open question is to which extent treatment to the level of the toxic threshold value also ensures a long service life and expected performance of the treated commodity. Superwood™ is evaluated using a strategy, in which basic laboratory tests are done to get the toxic value (according to EN 599-1) and in addition a number of field tests are done including accelerated testing in the tropics. These tests are focussed on the evaluation of the performance criteria such as durability and service life and maintenance requirements. These questions must be answered by the producer without having a full record of performance test for their new products. A short status on the test performed on super-critical treated wood (Superwood™) is presented. Based on a comparison between field test in Scandinavia and in the tropical Malaysia a service life of more than 25 years for a specific supercritical treated product is estimated. It is stated that the existing European standardisation system is insufficient when it comes to service life prediction. A number of important questions need to be addressed by the European standardisation system as soon as possible because the market and the public opinion change quickly due to environmental concern.
N Morsing, A H H Wong, F Imsgard, O Henriksen

Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley

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