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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

Paper for discussion on monographic cards for Poria vaillantii, Poria vaporaria, and Poria monticola
1973 - IRG/WP 117
J Wazny

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

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

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

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

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

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