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Suppression of aerial hypha formation by spent culture filtrate of a non-degradative strain of Postia placenta
1991 - IRG/WP 1498
ME20, a wild-type monokaryotic strain of the brown-rot fungus Postia placenta, does not cause significant weight losses in standard soil-wood block decay tests and fails to form aerial hyphae in liquid and agar culture. This abnormal morphological feature may be caused by the same aberrant physiology that prevents the strain from degrading wood efficiently. ME20 releases elevated levels of the autolytic enzymes laminarinase and protease into culture media. These autolytic enzymes may degrade the cell wall and hyphal sheath, thus preventing aerial hypha formation and limiting wood colonization. If abnormally high levels of autolytic enzymes suppress aerial hypha formation, any strain of Postia placenta grown in their presence should take on the appearance of ME20. MAD698, a standard floccose test strain of Postia placenta, was grown in fresh media containing increasing concentrations of filter-sterilized spent culture filtrate of ME20. Aerial hypha formation was strongly inhibited or prevented when the spent culture filtrate made up 40% or more of the medium. Spent media from MAD698 caused a similar effect but only at higher concentrations (80 and 100%). The suppression does not appear to be caused by extracellular autolytic enzymes since commercial preparations of laminarinase, chitinase, and protease did not reproduce this effect. The suppressive agent appeared in ME20 culture filtrate after only two weeks of growth. It has a molecular weight of less than 10,000 and is resistant to boiling. Additional research is needed to characterize ist nature, thus identifying a potential biorational inhibitor of wood-decay fungi.
J A Micales

Some wood-destroying Basidiomycetes. Volume 1 of a collection of monographs
1981 - IRG/WP 1121
One of the first tasks of the International Research Group on Wood Preservation, when it began its work in 1969, was to compile a series of reports on the common decay fungi which can attack wood. This volume, which contains the first of these reports, has been compiled with the help of mycologists and wood preservation specialists in France, Ghana, the Federal Republic of Germany, the Netherlands, Poland, Sweden and Switzerland, and the United Kingdom. It gives up-to-date information on fifteen common Basidiomycete fungi and indicates the gaps in the world's present knowledge that exist about these.
R Cockcroft

Laboratory experiments on aerial emissions from wood treated with wood stains
1993 - IRG/WP 93-50001-06
Due to the actual environmental interest in wood preservation, a series of experiments was carried out on the emission of biocides from treated wood. The research focussed on the volatilization of 5 biocides from boards treated with wood preservative finishes containing dichlofluanide (DCF) azaconazole (AZA), pentachlorphenol (PCP), iodopropynylbuthylcarbamate (IPCB) and tributhyltinoxide (TBTO). Formulations used were solventborne or waterborne and varried from low build to high build types. Treated samples were exposed in a standard emission column to a conditioned air stream and the emitted gasphase was adsorbed on amberlite xad. The chemical compounds were released in an appropriate solvent and subsequently analysed. A distinct variation was observed between the emission results of the different biocidal compounds. The volatilization values decreased in the following order: TBTO > DCF > IPBC > PCP >> AZA Relating the chemical concentration, obtained under various conditions of test to the inherent toxicity of the preservatives, it can be concluded that azaconazole possesses the lowest aerial toxicity potential. PCP and TBTO are considered to possess a lower aerial safety factor, while dichlofluanide and IPBC take an intermediate position. A significant effect of some of the exposure variables used could be noticed e.g. temperature, application dosis and exposure period. Other variables of importance were type of formulation, pre-curing of coating, moisture content and type of wood. As an overall conclusion, the emission tests gave evidence of no real danger for human inhalation toxicity. In none of the conditions used, for any preservative, the level of emission exceeded the maximal aerial concentration, cited in literature.
G M F Van Eetvelde, M Stevens

Draft of a monographic card for "Pole Fungus A". A paper for dicussion
1974 - IRG/WP 124
L Harmsen

Analysis of degradation observed on ancient wooden objects buried underground
2001 - IRG/WP 01-10403
Ancient wooden objects were sometimes excavated from the moat of mounded tombs in Japan. Such wooden objects were in the shape of a sunshade, bird, shield, pole, yugi(a bag that holds arrows) among others. Archaeologists discussed the usage of such shaped objects, but no one could clearly explain their use. Some objects were observed using an ordinary microscope. Deterioration by bacteria was found in all parts of the objects. This showed that all the objects had been in water or in heavily water-logged earth. Heavy degradation by soft rot fungi was found at the bottom of the shield and pole shaped objects. It is thought that at one time these objects were erected and partly buried in the ground. A lot of hyphae were found at the bottom of another shield and yugi shaped objects. A small amount of hyphae were additionally found at the top of these objects. These are thought to have been placed on top of the ground. From these results, it is supposed that at the first stage, objects had been placed somewhere on the mound, at the following stage they had fallen into the moat and became buried under the water-logged ground, and at the last stage they came to be excavated.
H Sakai

Health hazards and environmental aspects when using Cu-HDO-containing wood preservatives in vacuum pressure plants
1993 - IRG/WP 93-50001-11
Apart from the biological efficacy of wood preservatives, the health and environmental aspects concerning the utilisation of wood preservatives, the use of treated timber and the disposal of impregnated wood are of high significance today. Therefore, information on a possible aerial concentration of wood preservatives, on the mobility of active substances in soil leached from treated timber in service and on the composition and toxicity of thermal decomposition gases releasing on combustion of impregnated wood, are of absolutely fundamental interest. Measuring procedures relevant for the practical application will be presented, and the results concerning the utilisation of Cu-HDO-containing wood preservatives will be described. With the proper use of Cu-HDO-containing wood preservatives, the aerial concentration at workplace falls distinctly below the maximum permissible limit. If vacuum pressure treated timber is used properly, no active substances will seep into the ground water as a result of the leaching process of impregnated wood in service. The composition measured and the acute toxicity of the thermal decomposition gases released on combustion of impregnated wood may axtually be compared to those of untreated timber.
W Hettler, S Breyne, M Maier

An electron spin resonance study of manganese changes in wood decayed by the brown-rot fungus, Postia placenta
1988 - IRG/WP 1359
Electron spin resonance (ESR) spectrometry was used to examine wood decay by the brown-rot fungus, Postia placenta. Wood slivers of Douglas-fir, white fir, redwood, sweetgum and yellow poplar were incubated for 4 weeks in custom-made quartz ESR tubes with or without Postia placenta. In all wood species without fungus, a weak partially resolved signal (about g=2, presumably due to manganese) was detected. No manganese-like signal was found in aerial hyphae of the fungus. Wood slivers with fungus had a smooth, well-resolved manganese signal with a larger amplitude than wood without fungus, indicating a larger amount of paramagnetic manganese. The ratio of amplitudes for slivers with and without fungus increased with incubation time, reflecting an accumulation of paramagnetic manganese during decay. Due to the nature of this closed system without culture media, the accumulation of paramagnetic manganese is most likely due to the change of wood manganese by the fungus.
B Illman, D C Meinholtz, T L Highley

Étude in vitro de la colonisation et de la dégradation structurale du bois d'aubier de Pin sylvestre par la Mérule: Serpula lacrymans Schum. ex Fr. S. F. Gray
1979 - IRG/WP 198
The degradation of Scots pine sapwood cell walls by Serpula lacrymans, a brown rot fungus, is observed after various periods of exposure from two weeks to twelve weeks. The observation by microscopy shows that the hyphae of Serpula rapidly invade the wood tissues as cell wall degradation starts. That deterioration is not gradual, it is observed to be very irregular as well within the whole of the tissues as within one single tracheid considered alone. The enzymatic action occurs at a distance from the secreting hyphae, causing an irregular desintegration of the various layers of the wall. The degradation of the wall is observed and analysed by scanning electron microscopy.
D Dirol

Occupant re-entry times following insecticidal remedial treatments of timber in dwellings
1995 - IRG/WP 95-50055
This work was carried out principally to obtain quantitative data on the aerial concentrations of permethrin and white spirit likely to arise following the remedial treatment of timber in buildings, using insecticidal formulations. Such data are needed to allow assessments to be made of the length of time buildings should remain unoccupied following such treatments prior to re-occupation, and the likely levels of exposure of the occupants to the treatment products concerned. Two large, free-standing, wood-lined chambers were treated (in separate experiments) with a dilute oil-in-water emulsion and a micro-emulsion, both containing 0.2% m/m permethrin. The atmospheres in the chambers were sampled at intervals and analysed for their permethrin content. In addition, the aerial concentrations of white spirit were determined following treatment with the dilute oil-in-water emulsion. Results indicated that the aerial concentrations of permethrin following treatment never exceeded 20 µg/m³. Comparison of the measured levels with the threshold limit value (TLV) for permethrin (modified to a TLV/40 to represent the value associated with 24 hours-a-day continuous occupancy) indicated that such levels of permethrin constituted no significant risk to occupants. Aerial concentrations of white spirit in the test chambers from the dilute oil-in-water emulsion product indicated by calculation that the TLV/40 of this solvent would be attained approximately 10 hours after treatment in a model domestic situation having the relatively low air exchange rates of the test chambers. This work has shown the importance of further studies needed to identify the rate determining step in the evaporation of deposited constituents from the surface of timber and to quantify the effect of different air exchange rates in treated premises on the aerial levels of formulation constituents.
R J Orsler, G E Holland, G M F Van Eetvelde

Effect of microfibril orientation of bamboo cell wall on soft rot penetration hyphae
1994 - IRG/WP 94-10087
The effect of microfibrillar orientation of bamboo (Phyllostachys virideglaucescence) cell wall on the development of soft rot (Chaetomium globosum) penetration hyphae was investigated. It was found that the soft rot penetration hyphae normally followed the microfibril angle of the cell wall. Bamboo cell walls have alternating broad and narrow lamellae with different microfibrillar angles. The microfibrillar angle of the broad lamellae is mostly oriented vertically, whilst the narrow lamellae are mostly oriented horizontally. Soft rot penetration hyphae normally follow these microfibrillar angles.
O Sulaiman, R J Murphy

Effect of test site, preservative and wood species on decay type Glenbervie pastoral and radiata pine forest sites
2000 - IRG/WP 00-30248
Pinus radiata stakes were treated with 0.8, 1.2, 1.8, 2.7 and 4.1 kg/m3 of CCA and Fagus sylvatica with 2.7, 4.1 and 6.1 kg/m3 of CCA. Both wood species were also treated with equivalent retentions of a copper plus triazole preservative (CT) (0.89, 1.3, 2 and 3 kg/m3 of copper for pine & 2.5 and 4 for beech) and chlorothalonil plus chlorpyriphos in oil (CC) (1.4, 2.1, 3.2 and 4.8 kg/m3 of chlorothalonil for pine and 3.2 and 7.2 for beech). Furthermore, P. radiata was treated with ammoniacal copper plus a quaternary ammmonium compound (ACQ) (0.8, 1.1, 1.7 and 2.6 kg/m3 copper) and a 60/40 mixture of high temperature creosote plus oil (C) (18, 27, 41 and 61 kg/m3). Treated and untreated stakes were exposed in the ground at 13 sites in New Zealand and Australia for between 4 and 6 years. This paper reports the significance of site, timber species, preservative and its concentration and time of exposure, on extent and type of decay, at two sites in Northland, New Zealand. The two sites were adjacent (200 metres), appeared to have essentially similar clay loam soil and climate but one was pastoral and the other was situated within a radiata pine forest. Most types of decay reported in the literature, were observed in this study but other undescribed or only partially characterised types were also found. The decay types found differed between test sites, preservative and timber species. The significance of tunnelling hyphae, which often caused severe decay of wood treated with the higher retentions of various preservatives, appears much greater than the prior literature would suggest. For pine the highest retentions of CC, CT and ACQ gave at least equivalent performance to the reference standards creosote and CCA, after approximately 5 years, at both test sites. For beech CC and CT both gave superior protection to CCA, at both sites. All the preservatives tested exhibited some weaknesses in terms of resistance to the various decay types observed.
R N Wakeling

Secretion of ligninolytic enzymes by hyphal autolysis of the white rot fungus Phanerochaete chrysosporium
1991 - IRG/WP 1480
The secretion of ligninases by Phanerochaete chrysosporium was investigated with polyclonal antibodies, followed by immmunogold-silver staining and light microscopy. After growing fungal mycelium on nitrocellulose, extracellular ligninases were detected around old, plasmaless hyphae, but not at arthrospores, chlamydospores, or blastoconidia. Labeling of fungal hyphae on coverslip cultures was observe only when the cell wall was highly porous and translocation of cell material occurred. These experiments suggested that ther is a correlation between hyphal lysis and the release of extracellular ligninases from hyphae.
R Lackner, E Srebotnik, K Messner

Evidence for actinomycete degradation of wood cell walls
1990 - IRG/WP 1444
Several unique patterns of degradation occurring in wood cell walls have been observed in wooden stakes inserted in unsterile soil in the laboratory. Some of the patterns have also been observed in coniferous wood taken from forest floors. All the observed attack types occur within wood cell walls, mainly within the S2 layer. Attack is characterised by channels of varying diameter or small fusiform cavities arranged in the form of a rosette. Some channels are narrow, 0.5-1.0 µm, and form a highly branched network. Other channels are wider, up to approx. 2-3 µm and less branched. All channels are produced by hyphae growing within the wood cell walls. Attack has been observed to arise from the branching of thin hyphae growing longitudinally in the fibre lumina. The small diameter of the hyphae and the fact that these decay patterns have not been described for wood degrading fungi indicate that actinomycetes may be responsible.
T Nilsson, G F Daniel, S L Bardage

Assessing health risks to occupants following remedial insecticidal treatment of timber in dwellings
1998 - IRG/WP 98-50101-27
Experiments have been carried out to assess (i) the aerial concentrations of volatile wood preservative constituents, and (ii) the potential for contamination from treated surfaces, following in situ insecticidal treatment of timbers in dwellings. Using white spirit as a model for volatile constituents in the treatment of free-standing, wood-lined chambers indicated that temperature and air exchange rate significantly affect the rate of decrease of aerial concentration, but that the rate of diffusion through the treated wood surface may be the ultimate rate-determining step. A simple mathematical model has been proposed to assist in calculating minimum re-entry times after treatment associated with different wood preservative constituents. Using lindane as a model compound in different solvent formulations, comparison between measurements of the concentration at the surface of the treated wood and pick-up by direct contact has demonstrated the need for an agreed methodology for assessing risk through contamination from treated surfaces. Both methods demonstrated that the amount of lindane close to or at the surface of the treated wood decreased with time, thus reducing potential for pick-up.
R J Orsler, E D Suttie, V Rijckaert

Evaluation of white-rot fungal growth on Southern Yellow pine wood chips pretreated with blue-stain fungi
2000 - IRG/WP 00-10349
White-rotting basidiomycetes do not colonize on southern yellow pine. This study seeks to reduce the resinous extractive content of southern yellow pine by treating it with blue stain fungi. The mycelial growth of wood-inhabiting ligninolytic white-rot fungi can be achieved on pretreated southern yellow pine wood. Aureobasidium, Ceratocystis, and Ophiostoma spp. removed 70% to 100% of the extractives from the southern yellow pine wood within a period of 3 to 6 days. Griofora fondosa, Hericium erinaceus, and Pleurotus ostreatus colonized readily after the treatment. As a result, ligninolytic white-rot fungi can be easily colonized on southern yellow pines pretreated with blue stain fungi.
S C Croan

The development of soft rot decay in bamboo fibres
1992 - IRG/WP 92-1572
The development of decay by soft rot fungus Chaetomium globosum was investigated in young and mature culms of bamboo Phyllostachys virideglaucescens. Soft rot decay was influenced both quantitatively and qualitatively by the differing levels of lignification in the material. Weight loss was significantly greater in the younger culm compared with the older, more heavily lignified culm. The distribution of soft rot decay cavities was also highly variable in the young culm, cavities being much more frequent in the lower lignin fibres of the inner layers of the culm wall. In the mature culm a more homogeneous pattern of lignification resulted in a more evenly distributed decay. Studies with light and electron microscopy showed that soft rot cavity morphology was greatly influenced by the degree of cell wall lignification and stratification. Cavities were usually initiated at the boundary between two layers and, in heavily stratified walls, their form was typically restricted being crescent shaped in transverse section. Variable lignification of the wall layers also had a direct influence, with high lignin levels reducing cavity formation. It is considered that the characteristic pattern of lignification which is influence by age and location in the bamboo culm makes this a particularly useful substrate in which to study aspect of soft rot development.
O Sulaiman, R J Murphy

A model for attack at a distance from the hyphae based on studies with the brown rot Coniophora puteana
1995 - IRG/WP 95-10104
In timber infested by brown rot fungi, a rapid loss in strength is attributed to production of hydroxyl radicals (HO·) at a distance from the hyphae. The immediate precursor is Fenton's reagent (Fe(II)/H2O2), but the pathways leading to Fe(II) and H2O2 have remained unclear. Cellobiose dehydrogenase, purified from cultures of Coniophora puteana, will couple oxidation of cellodextrins to reduction of Fe(III). Two characteristics of brown rot are release of oxalic acid and lowering of the local pH, often to about pH 2. Modelling of Fe(II) speciation in the presence of oxalate has revealed that Fe(II) oxalate complexes are important at pH 4-5, but at pH 2 almost all Fe(II) is uncomplexed. The uncomplexed Fe(II) reacts very slowly with dioxygen. Diffusion of Fe(II) away from the hyphae will promote conversion to Fe(II)-oxalate and autoxidation with H2O2 as product. Thus the critical Fe(II)/H2O2 combination is formed at a distance.
S M Hyde, P M Wood

Production of fungal protoplasts from selected wood-degrading fungi
1991 - IRG/WP 1500
Studies of hyphal morphology and the effects of various chemicals on growth are often difficult to perform on filamentous fungi because of the difficulty of observing the protoplasm through the rigid hyphae wall and because most activity occurs in a limited region near the hyphal tip. As an alternative, hyphae can be reacted with certain cell wall degrading enzymes to remove the cell wall to produce protoplasts. Procedures for producing fungal protoplasts have been developed for a number of fungi, including Lentinulus edodes, but there have been few efforts to develop similar protocals for producing protoplasts from common wood decay fungi. This paper describes methodology for producing protoplasts from hyphae of Phanerochaete chrysosporium, Postia placenta, Gloeophyllum trabeum, and Trametes versicolor using commercially prepared cell wall degrading enzymes (Novozyme 234). The effect of culture age, osmotic stabilizers, pH, and exposure time are explored in relation to the number of protoplasts produced and the number of protoplasts which can be regenerated. Protoplasts can be used for a number of studies including chemical sensitivity and enzyme production.
C Rui, J J Morrell

Preservation of basidiomycete hyphae in ancient waterlogged wood materials
1992 - IRG/WP 92-1536
Studies on waterlogged archaeological wood show that basidiomycete hyphae may persist as long as 800 years. In two pine wood samples with Phellinus pini heartrot, one from the foremast of the ship Vasa and the other from a bulwark constructed in the first part of the 12th century, numerous resin covered hyphae were observed. Hyphae with clamp connections that were associated with brown and white rot decay were observed in other samples from the bulwark.
T Nilsson, G F Daniel

Wood decay fungi from New Zealand leaky buildings – PCR identification (Part 2) and aerial spore trapping
2008 - IRG/WP 08-10649
Prior to this study, it was not know which species of decay fungi caused decay in New Zealand leaky buildings. Use of molecular biology methodology, polymerase chain reaction (PCR), and subsequent DNA sequencing, as well as classical mycological techniques based on morphology, has enabled identification of decay fungi and has provided insight into their relative importance based on isolation frequency. Fungi colonising Pinus radiata D. Don framing timber of leaky New Zealand buildings were isolated to produce pure cultures. Mycelia from these cultures on agar media were collected to extract DNA. To identify the fungi to the species level, PCR with primer pairs NSI1 + NLB4 and ITS1-F + ITS4 were performed followed by sequencing of the internal transcribed spacer (ITS) region. Identification was by BLAST (Basic Local Alignment Search Tool) search on sequences in GenBank. In total, 421 samples from leaky buildings were processed, mainly decayed timber, but also fibre cement boards and building paper. Sixty-eight fungal identifications were achieved of which 4 species are very common as follows: • Gloeophyllum sepiarium (Wulf.: Fr.) Karst. 13x • Oligoporus placenta (Fries 1865) Gilb. In Ryv.1985 11x • Antrodia sinuosa (Fr.) Karst. 8x • Gloeophyllum trabeum (Fr.) Murr 4x An aerial spore study of internal air, wall cavity air and exterior air of leaky buildings was carried out using a Merck MAS-100 instrument which collects spores directly onto various selective media plates. Also, decayed wood samples from the same leaky buildings enabled identification of G. sepiarium and A. sinuosa at the same test site. Viable fungal aerial spores were detected at every sampling location, with a highest mean of 3714 colony-forming units (CFU) per square meter found in water-damaged walls. The use of Carboxymethylcellulose medium further demonstrated the presence of cellulose degrading fungi within and around the location. Overall, the combination of these two approaches proved useful for detection of fungal species variation at a multi-unit building complex and it was possible to identify the brown rot decay fungal genus Antrodia with both methods.
D Stahlhut, R L Farrell, R Wakeling, M Hedley