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A summary of current information on actinomycetes and wood
1978 - IRG/WP 177
B King, R A Eaton, A A W Baecker


Observations on the colonization of freshly-felled timber treated with prophylactic chemicals by mould and sapstain fungi
1989 - IRG/WP 1394
Field tests using freshly felled pine sapwood were set up to determine the effectiveness of a range of antisapstain compounds and to study the problems of colonization by mould and sapstain fungi. Differences were recorded both in the overall performance of the compounds and also their selectivity in controlling specific fungal types. These results were found to be useful in gaining a better understanding of biocide - fungal interactions.
G R Williams, D A Lewis


Contribution to study of the degradation caused in Pinus spp. poles used in field test
1989 - IRG/WP 1417
The study of the degradation produced by soil natural microflora on wood in contact with it in the field, has been going on for several years now. Our contribution to this aim in the present work has dealt with the possible relationship of the microorganisms in the soil. The microscopic visualization of wood colonization by the microorganisms, and the chemical analysis of the degraded wood compared with the undergraded.
M T De Troya, A Garcia, M J Pozuelo, A M Navarrete, A Cabanas


Susceptibility of angiosperm sapwood to white-rot fungal colonization and subsequent degradation: a hypothesis
1997 - IRG/WP 97-10211
It has long been recognized that angiosperm sapwood in nature is relatively easily and preferentially degraded by white-rot fungi. This susceptibility to white-rot fungi is generally believed to be mainly caused by the structure and concentration of angiosperm lignin. However, an explicit explanation as to why lignin structure makes a particular wood vulnerable to white-rot colonisation and subsequent degradation has apparently never been given. We propose that free phenolic groups in wood, such as those present in the lignin or heartwood extractives, can act as free radical scavengers (antioxidants) which disrupt the various white-rot free radical degradative mechanisms. Consequently the presence of a relatively high free phenolic "density", such as that present in gymnosperm sapwood or angiosperm heartwood, may inhibit white-rot degradation. Conversely, white-rot fungi may find wood with a relatively low free phenolic content, such as angiosperm sapwood, easy to colonize. The complex structure of angiosperm wood, in which different cell types have different amounts and types of lignin -- and consequently different levels of free phenolic "densities" -- influences the susceptibility of angiosperm wood to initial white-rot colonisation and, perhaps, also the subsequent decay rate. In addition to the free phenolic ``density" other factors, some as yet unknown, undoubtedly also affect the decay resistance of a particular wood.
T Schultz, D D Nicholas


Étude in vitro de la colonisation et de la dégradation structural du bois de hêtre par Coriolus versicolor (L.) Quélet
1976 - IRG/WP 158
L'attaque du bois de Hêtre par Coriolus versicolor (L.) Quélet, agent de pourriture fibreuse blanche est étudiée après des périodes d'exposition à ce champignon variant de 15 jours à trois mois. L'observation des premiers stades, c'est à dire de la colonisation du bois par les filaments de champignon est faite en microscopie optique, puis au fur et à mesure que le champignon tire profit des éléments du bois aprês des périodes d'exposition plus longues, les observations sont faites à la fois en microscopie optique et électronique à balayage. Une étude comparée de la degradation des parois est faite, à la fin de ce travail, en lumiêre polarisée.
D Dirol


An approach to testing the preventive effectiveness of preservative treatments for wooden joinery
1981 - IRG/WP 2156
The ecological sequence established in field trial samples exposed out of ground contact has shown the need for outdoor exposure in testing potential joinery preservative pretreatments. A system of exposure of L-joint units is proposed. Data obtained by examining samples destructively show promise as the basis for predicting service life after relatively short exposure periods (within 2 years).
J K Carey, A F Bravery, J G Savory


Soil-bed studies
1982 - IRG/WP 2181
This paper discusses factors affecting the design and use of a soil-bed.
P Vinden, J G Savory, D J Dickinson, J F Levy


Biological and chemical observation on the early fungal colonization of TBTO treated Swedish redwood stakes
1984 - IRG/WP 3311
Data on the early fungal colonization of Swedish redwood stakes, impregnated with 1% TBT0 / 0.5% dieldrin solution, both by double vacuum impregnation and immersion processes are presented. Results of chemical analyses of wood samples from the outer 1 mm of separate painted and unpainted stakes, exposed over the same twelve month period, are also discussed.
R Hill, A H Chapman, A Samuel, K Manners, G Morton


Practical testing of wood preservatives to prevent weathering damage and infection by micro-organisms on spruce and pine
1989 - IRG/WP 3530
Brush application, is generally used to prevent wooden window frames from decay caused by influence of weathering and fungi. Accordingly 10 boards of pine (Pinus sylvestris) and spruce (Picea abies) were treated with 10 commercially used wood preservatives. The efficiency of fungicides by using chiptest and blue stain test (EN 152), the effectiveness against weathering as well as the course of colonization of microfungi were measured on boards, that had been hurted by sawing. Results after one year's exposure showed that neither the normally required amount of 250 ml/m² nor the effective depth of penetration of the fungizidal equipment had been realized by using brush application. The smaller the permeability of the coating system, the more likely ideal conditions for the growth of fungi (e.g. basidiomycetes) are provided, answering hurtings of the coating and moisture contents of more than 30%. The variety of fungi (on pine 32 and on spruce 17 species) can be a result of anatomical differences and distinguished compounds of the wood species. After 24, respectively 36 weeks of exposure the frequent occurrance of basidiomycetous yeasts (Cryptococcus albidus, Rhodotorula mucilaginosa), blue stain fungi (Aureobasidium pullulans, Hormonema dematioides), Epicoccum nigrum, Alternaria alternata and Phoma species was noted.
R Gründlinger, O Janotta, H Melzer, K Messner


Fungal colonization of CCA-treated decking
2003 - IRG/WP 03-10491
The identification of fungi isolated from CCA treated decking in Vancouver is reported. About two thousands locations were sampled from over sixty boards recovered from six decks. Wood chips from each location were placed onto four different types of media. Of the large number of isolates obtained, around 15% were obtained from the interior of the boards. The succession of colonization in CCA-treated decking; i.e. bacteria, mould, staining fungi, (soft-rot fungi), and basidiomycetes, was similar to that reported from untreated wood exposed above ground and from CCA treated wood in ground contact. The percent frequency of isolation around checks was higher than that from wood just below the treated surface. In the case of boards where decayed wood was observed during sampling, most decay was associated with checks. In this study, Gloeophyllum sepiarium and Gloeophyllum trabeum (tentatively identified) were the only decay basidiomycetes isolated from the inner wood of decayed decking. Other unidentified basidiomycetes were isolated from the treated surface of the boards, the check surfaces or the cut end of decking from both decayed and non-decayed boards.
S Choi, J N R Ruddick, P I Morris


The colonization of selected naturally durable timbers by marine fungi and borers
1977 - IRG/WP 439
In recent years, concrete and metal have been widely substituted for wood in contact with sea water, but wood products have not lost their usefulness under such conditions. In many cases, wood if sound and durable, may prove to be the most practical and economical of materials used in sea water exposure. Timber when immersed in the sea may be attacked by micro-organisms (bacteria and fungi) and marine borers (members of the molluscan genera: Teredo, Psiloteredo, Lyrodus, Bankia, Pholas, Martesia and others, also members of the crustacean genera: Limnoria, Paralimnoria, Sphaeaeroma and Chelura). Although marine borer damage is the more dramatic, damage by marine micro-organisms can contribute to cause soft rot of wood (Jones and Byrne, 1976), and they are also believed to be implicated in the 'preconditioning' of a wood surface prior to settlement of marine borer larvae (Eltringham, 1971). Ten tropical timbers (Mukulungu = Autranella congolensis, Moabi = Baillonella toxisperme, Angelique = Dicorynia guianensis, Jarrah = Eucalyptus marginata, Congotali = Letestua durissima, Azobe or Ekke = Lophira alata, Bilinga or Opepe = Sarcocephalus diderrichii, Douka = Tieghemella africana, Makore or Baku = Tieghemella heckelii, Wacapou or Acapu = Vouacapoua americana) were choosen to examine their natural durability in sea water in Italy, France, Ghana and Canada.
S E J Furtado, E B G Jones


Susceptibility of CCB treated wood to fungal colonization
2003 - IRG/WP 03-10492
CCB treated wood is generally resistant to all wood decay fungi. However, like CCA impregnated wood, susceptibility of CCB treated wood to copper tolerant fungi have been observed. The ability of various brown rot fungal hyphae to penetrate and overgrow the wood samples was investigated. Samples made of Norway spruce (Picea abies) were impregnated with 5 % CCB solution according to the EN 113 procedure. After conditioning, part of the samples was leached according to the EN 84 method. Small stick of unimpregnated wood (r = 1.5 mm, l = 25 mm) was inserted into a hole, bored in the center of the samples, and after that sealed with epoxy coating. Sterilized, leached and non-leached impregnated and unimpregnated specimens were exposed to two copper-tolerant (Antrodia vaillantii, Leucogyrophana pinastri) and two copper sensitive (Poria monticola, Gloeophyllum trabeum) brown rot fungi for one, two or four weeks. After exposure, the inserted wood pieces were removed from the specimens and put onto nutrient medium in petri dishes. Growth of the hyphae from those wood pieces was then visually determined. Rate of colonization by the fungi were determined by measurement of CO2 production. After that, mass losses of parallel specimens were also determined. The fastest colonization of the unimpregnated specimens was by G. trabeum (one week). On the other hand, no fungal growth could be detected on non-leached CCB impregnated specimens even after four weeks of exposure. However, significantly more intense colonization by the copper tolerant fungi were detected on the leached CCB treated samples.
F Pohleven, U Andoljsek, P Karabegovic, C Tavzes, S A Amartey, M Humar


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


A study of the colonization of wood blocks in a laboratory unsterile soil test
1988 - IRG/WP 2318
CCA treated and untreated beech blocks were exposed to a defined horticultural loam using the method proposed for the collaborative soft rot test in the soft rot sub-group of Working Group Two. At intervals during the incubation wood samples were removed and fungal isolations were made using selective media. Fungi were identified and tested for their cellulolytic ability and their decay capacity in beech in pure culture. Replicate wood samples were examined by microscopy for colonisation and decay.
M T De Troya, S M Gray, D J Dickinson


Feasibility of using biological control agents to arrest and prevent colonization of Douglas fir and southern pine by decay fungi
1988 - IRG/WP 1345
The use of microfungi to control basidiomycetous decay has been evaluated in Europe for many years, where it has produced mixed results against Lentinus lepideus Fries, the fungus presumed to be the major cause of decay in Scots Pine poles. In the United States, remedial decay control has been largely chemical, with little use of alternative decay control strategies. Increasing restrictions on chemical usage have stimulated renewed interest in biological decay control. In our tests, a European biological control, BinabÒ,was evaluated for its ability to prevent or arrest attack of southern pine sapwood or Douglas fir heartwood by 5 Basidiomycetes commonly isolated from poles in service. Lentinus lepideus was included as a comparison. In general, BinabÒ performed well against Lentinus lepideus and the other brown rotters, but was unable to completely eliminate most of the test fungi. In addition, the biological had little effect on white rot fungi, which are an important component of the microflora in decaying poles. The results suggest that biologicals will not be suitable for remedial decay control without supplemental treatments that favor growth and activity of the biocontrol agent.
J J Morrell, C M Sexton


The colonisation pattern of anaerobic fungi in wood
1989 - IRG/WP 1403
Timber foundations may be degraded in service in anaerobic conditions. The present work was conducted to investigate whether anaerobic fungi could colonise wood, using rumen fungi as test microorganisms. Strictly anaerobic fungi were isolated and purified from cow dung and goat and sheep rumen fluids respectively. Colonisation of Eucalyptus grandis and Pinus patula by these fungi and Neocallimastix LM 1, was examined by scanning electron microscopy. All isolates colonised each timber within 6-12 days, even when wood was the only available carbohydrate source. Rays of both Eucalyptus grandis and Pinus patula were extensively colonised. Colonisation was observed to a greater extent in Eucalyptus grandis vessels than in fibres. Zoospores encysted and germinated on wood. The wood was penetrated passively via pits in both timbers and actively by degradation of Eucalyptus grandis pit membranes. Aerial hyphae emerged from wood surfaces and the production of sporangia suggested that substrate rhizoids had derived energy from wood nutrients. These results show for the first time that anaerobic fungi may colonise and degrade wood elements.
A H Wiederhold, M Morrison, A A W Baecker


Identification of brown rot fungi on wood in above ground conditions by PCR, T-RFLP and sequencing
2004 - IRG/WP 04-10512
Fungi selected in test fields in Germany and Estonia and fungi (Coniophora puteana) cultivated on medium have been identified by the molecular methods PCR (Polymerase Chain Reaction), T-RFLP (Terminal Restricted Fragment Length Polymorphism) and sequenced to species level. The samples from the German field test showed that the fruit body sample was a different fungus than from the mycelium sample. The fruit body is identified as Gloeophyllum sepiarium, the mycelium is still unidentified but has different T-RFLP pattern. It means that the fruit body may not always be responsible for all, or parts of the degradation of wood. The fungi samples from Estonian all showed to be Serpula lacrymans when comparing the T-RFLP patterns with sequences from NCBI (National Center for Biotechnology Information) gene bank. Before the analysis it was suggested that it could be either of the S. lacrymans or S. himantioides. The S. lacrymans from Sweden do not have the same T-RFLP pattern as the Estonian S. lacrymans. The Coniophora species cultivated in lab have been sequenced and have the same or a very close agreement in sequence. They all matched C. puteana when the sequences were compared to other sequences in the NCBI gene bank.
U Råberg, N Högberg, C J Land


The use of selective media for studying the colonization of wood in ground contact by microorganisms
1978 - IRG/WP 186
In October1976 a field trial was set up in order to monitor the progressive colonisation of wood in ground contact using orientated small stakes of Scots pine (Pinus sylvestris) and birch (Betula sp.) (30 x 45 x 250 mm³). Half the number of each species were treated with a 1% solution of CCA by a vacuum impregnation process. All the stakes were coated on three sides with an epoxy-resin sealant to enable the ingress of organisms from the single uncoated face (the outer 30 x 250 mm² tangential longitudinal face) to be monitored, in depth. The stakes were then set up at the Imperial College Field Station at Silwood Park in an adjacent plot to the one that now contains a complete set of replicates for the IRG Field Trial.
C P Clubbe


Effects of air-seasoning on fungal colonization and wood strength of Douglas fir poles
1987 - IRG/WP 1315
Air seasoning economically reduces the moisture content of Douglas fir poles before pressure treatment with preservatives. Advanced decay in poles in service has resulted when decay fungi (Basidiomycetes) colonized poles during air-seasoning and survived the treatment process. These problems have led to recommendations to severely limit this practice. To determine the role of these fungi in peeled and unpeeled Douglas fir poles during air-seasoning in the Pacific Northwest, we identified many of the fungi involved, measured their effect on wood strength, and studied methods for limiting fungal colonization. Over 90 percent of peeled poles air-dried for more than 1 year contained decay fungi, suggesting that air-seasoning in the Pacific Northwest might pose some hazard; however, no significant strength losses were noted in poles dried 1 to 2 years. Poles seasoned for 3 years began to show significant strength losses, but these strength values fell within suggested design parameters for Douglas fir poles. Although Douglas fir poles are colonized by decay fungi as they dry, our results indicate that these fungi do not cause serious damage for at least 2 years. On the basic of these results, we recommend that poles be air dried no longer than 3 years in the Pacific Northwest. We also emphasize the importance of heating air-seasoned wood adequately during the treatment process to kill any fungi present.
J J Morrell, M E Corden, R D Graham, B L Kropp, P Przybylowicz, S M Smith, C A Sexton


The colonisation and succession of fungi in wood
1980 - IRG/WP 1107
A study of the microbial ecology of small stakes of Pinus sylvestris and Betula pendula, both untreated, and treated with a 1% solution of CCA is in progress. Results are presented for the early stages, up to 18 months.Two new techniques were developed linked by the philosophy of objective assessment. Isolations were made from the wood in a pre-determined pattern and transferred to four selective media. Fungi were assigned to the most appropriate 'Ecological Group" and analysed in terms of frequency of isolation and related to space, time and substrate. Secondly, sections were cut and "microquadrats" scored for various colonisation/decay features in a regime compatable with that of the isolation. These were then analysed using a computer. Results from the two techniques were pooled to reveal what the main colonists were at any.·time and their possible functional significance - whether passive inhabitant or active decomposer. In this way a succession of organisms was revealed, which varied in nature and rates of colonisation and·decay dependant upon the substrate. In both untreated woods Rasteria, Primary Moulds and Stainers were the initial colonists being followed by Soft Rots and then Basidiomycetes and the cellulolytic Secondary Moulds. Decay was principally caused by Basidiomycetes and reached significant levels in untreated birch by 12 months, but not until 18 months in pine. Soft rot attack remained at low levels throughout. In both treated woods a similar succession was evident except that Basidiomycetes were excluded, Soft Rots representing the climax organisms. Significant soft rot attack was evident in trated birch by 12 months, but the treated pine remained sound, although soft rot organisms were present in large numbers, posing the question of their food source.
C P Clubbe


Effect of wood species on colonization by an unknown wood boring organisms in marine waters
1995 - IRG/WP 95-10108
The effect of wood species on the initial settlement by surface fouling organisms in marine environments was investigated by exposing heartwood panels of Douglas-fir ((Mirb.) Franco), western redcedar (Donn.), and Oregon white oak (Dougl. ex. Hooke) in an estuary located on the coast of Oregon. The oak and western redcedar panels were sparsely colonized over the first 39 days of exposure, while the Douglas-fir panels were rapidly colonized by an unknown wood burrowing organism which had characteristics typical of a Bryozoan. While Bryzoans have been reported previously from wood exposed in marine environments, they are have usually been associated with decayed wood and are typically not considered to be capable of wood damage. The implications for the presence of these organisms on subsequent colonization by Teredinids and Limnorans are considered.
K S Rao, P F Schnieder, J J Morrell


Colonization of treated and untreated ponderosa pine exposed in Hilo, Hawaii
1995 - IRG/WP 95-20068
The rate of decay in above ground exposures is largely controlled by rainfall and temperature, factors which can be used to construct a climate index of decay hazard in above ground exposures. Developers of new biocide formulations have utilized this knowledge by establishing test sites in sub-tropical regions such as the Gulf Coast of the United States. More recently, field sites have been located in regions with even higher climate indices with more severe risks of decay. One such site is Hilo, Hawaii which receives nearly 4000 mm of rainfall per year and has near optimal temperatures for microbial growth. Previous field trials have shown that untreated control L-joints fail in as little as one year at such sites, but the organisms associated with these failures and their interactions in the deterioration process remain poorly understood. It has been suggested that results from such tests may be poor indicators of chemical performance under less severe exposures. To address this issue, the fungal flora colonizing wood was assessed in L-joints and deck boards exposed above ground in Hilo, Hawaii. The samples were either untreated or treated with 0.5% triazole 1, 0.5% tributyltinoxide, 0.5% 3-iodo-2-propynyl butylcarbamate, or 0.25% triazole 2 in mineral spirits or water. Selected samples were removed periodically and cultured for the presence of decay fungi. While basidiomycetes were not prevalent among the initial colonizers, they became increasingly abundant after 18 months of exposure. Among the fungi isolated were Trametes versicolor, Fomitopsis meliae, Schizophyllum commune, and Antrodia sinuosa. These fungi are also found under more temperate exposures suggesting that data from tropical sites represents a similar, albeit more accelerated, progression of decay organisms. Further studies on the decay capabilities of selected isolates are underway.
C M Freitag, J J Morrell, K J Archer


Colonisation of painted wood by Aureobasidium pullulans - Analysis of features and consequences for failure in service
1996 - IRG/WP 96-10144
Wooden blocks of spruce were painted with different paint formulations. Water- and solvent-borne model and commercial paints were used. The painted wooden blocks were inoculated with a spore suspension of Aureobasidium pullulans (de Bary) Berkg. and placed in an environment of high humidity for 14 months. Different colonisation and growth patterns were observed on the different paint surfaces. The susceptibility to staining and/or degradation of tested painted wood blocks are discussed. The commercial paints with and without a fungicide became heavily stained. Model paints were not as susceptible to blue stain as the commercial paints tested. Estimation of degree of staining was done with digital image analysis. Further observations were done with a stereo microscope and scanning electron microscopy.
S L Bardage


Development and Implementation of a DNA – RFLP Database for Wood Decay and Wood Associated Fungi
2004 - IRG/WP 04-10527
We are developing Restriction Fragment Length Polymorphism (RFLP) and Internal Transcribed Spacer (ITS) sequence databases for wood decay basidiomycetes and other fungi associated with wood. These databases currently house information for 39 fungal species consisting of 9 brown-rot basidiomycetes, 12 white rot basidiomycetes, 1 soft rot, 1 stain fungi, and 16 molds or other ascomycetes or imperfect fungi. We plan to add 6 brown rot, 14 white rot and 8 other species that we have in culture by summer 2004. Using the RFLP database, we were able to identify wood decay basidiomycetes that were isolated from a local forest and that could not be distinguished based on morphology. In addition, RFLP data confirmed identifications of several other wood associated fungi. One of our ultimate goals is to establish a web-based database of wood basidiomycetes and wood-associated fungi emphasizing ITS sequence and RFLP pattern data plus morphological characteristics in one searchable system. These databases will be able to provide sensitive and reliable identifications of the wood decay community and important wood decay fungal species.
S V Diehl, T C McElroy, M L Prewitt


Hydrolysis of bordered pits during colonization of conifers by brown-rot fungi
1995 - IRG/WP 95-10103
Brown-rot decay results in rapid reduction in degree of polymerization (DP) of holocellulose with concomitant strength loss (MOR) without removing lignin. Development of new methods of wood protection will require focusing on early events in the sequence of depolymerization. Bordered pit membranes (sapwood) represent a readily available source of non-lignified carbohydrate, ie. pectin and cellulose. Commercial pectinases (Pectinol) and Trichoderma sp. have been shown to degrade pit membranes and increase penetration of preservatives. Brown-rot fungi have previouely been shown to produce oxalic acid (OA) during the decay process. Plant pathogens have been shown to degrade pectin by the synergistic action of OA and polygalacturonase (PG). The OA solubilizes the pectin by chelating the Ca++ and the PG hydrolyses the a-1,4 linkages. We have demonstrated the ability of Postia placenta, Gloeophyllum trabeum and Serpula incrassata to use pectin as a sole carbon sourse and to produce OA and PG on both liquid media and wood. Aspergillus niger and Trichoderma sp. also produce PG on wood but no OA or weight loss. The optimal pH of brown-rot polygalacturonase activity is circa 4.0. As the pH of the wood drope below pH 4, due to acid production during decay, there is a progressive decrease in PG activity and the possibility of acid catalyzed hydrolysis of pit membranes is suggested by increased permeability. We hypothesize that pectin utilization is an essential step during incipient brown-rot decay which helps to initiate fungal metabolism and promote the spread of fungal hyphae between tracheids.
F Green III, J L Tschernitz, T A Kuster, T L Highley


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