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The dry rot fungus Serpula lacrymans. Examples of attack and remedial treatment
1988 - IRG/WP 1347
The film deals with several aspects of dry rot attack and eradication in buildings. The detailed biology and morphological charasteristics of the fungus are portrayed. The various forms of mycelial growth, the role of the strands in the nourishment and spread of the fungus, as well as the many types of fruitbody formation are outlined. Environmental and nutritional requirements of the fungus as well as the potential infection danger posed by the basidiospores are discussed. The second part of the film, outlining the main reasons for dry-rot attack and spread in building together with the significant damage caused, shows the full extent of the problem to expert and lay-person alike. The necessity of correct survey and inspection of decayed areas to determine the full range of attack is stressed. Examples of various remedial treatments and the present technological state of eradication techniques, e.g. pressure injection, in Germany are discussed.
G Buchwald, B M Hegarty, W Metzner, R Pospischil, H Siegmund, P Grabow

Successive collections of Basidiospores from wood decay fungi (in vitro) show variation in germination levels on common media
1978 - IRG/WP 191
In the course of various preliminary experiments in which spore germination levels of 6 decay fungi on malt and water agar were recorded as controls, it was noted that one could not reliably obtain an expected level of spore germination for any particular fungus. Inconsistent 'control' spore germination levels of a fungus greatly complicates large scale experiments in which comparisons of data based on germination levels are attempted upon replication of the study over time. This study was done to determine if, in fact, spores collected at different times from specific hymenial areas of wood decay fungi sporulating in vitro differed significantly in germination level on common media under standardized conditions.
E L Schmidt, D W French

Effects of a chitin synthesis inhibitor on spore germination of the decay fungi Gloeophyllum trabeum and Poria tenuis
1986 - IRG/WP 2253
This study sought to determine the effect of a chitin synthesis inhibitor - Polyoxin D, on spore germination and early hyphal development of a brown rot and a white rot fungus in-vitro. Polyoxin D is a competitive, substrate-analogue type of chitin synthtase inhibitor (2). The drawbacks to use of such a compound as a wood preservative tie. cost - $20,000/g, possible leaching or degradation) might be reduced should it be effective in preventing decay initiation by spore germination at very low concentrations.
E L Schmidt

Conditions for basidiospore production in the brown rot fungus Gloeophyllum separium in axenic culture
1984 - IRG/WP 1232
Attempts to control and optimize the production of hymenial structures and basidiospore production in Gloeophyllum sepiarium in axenic culture resulted in the proposal of the following conditions as being suitable. The dikaryotic mycelia originally isolated from basidiocarps could consistently be induced to produce hymenial structures and pure basidiospore collects if illuminated by near ultraviolet light with emission maximum at 355 nm ("black light") at a temperature of 15°C on a chemically defined medium, where the concentration of the carbon and the nitrogen sources were shown to be of critical significance. The necessary conditions for basidiospore production in lignicolous fungi in general are is briefly discussed.
J Bjurman

Basidiosporogenesis by brown-rot basidiomycetes in vitro
1995 - IRG/WP 95-10126
Basidiospores of wood-rotting basidiomycetes are a primary sourse of infection causing wood biodeterioration, especially in wood above ground. Most studies evaluating wood preservatives have used mycelia or basidiospores obtained from wild mushrooms. The objective of this study was to demonstrate in vitro methods that promote carpogenesis and basidiosporogenesis by the brown-rot fungi Antrodia carbonisa, Neolentinus lepideus, and Postia placenta. After preincubation in the dark at 27°C for 3 to 11 days, basidiospores were easily prodused in 1 to 4 months by basidiomata exposed to light at 12°C. Adequate light exposure, aeration, and low temperature treatment after preincubation are essential for fruiting body formation of these brown-rot basidiomycetes. The morphology of the basidiomata differed according to the basidiomycetes and the medium used. These results demonstrate that an enormous quantity of basidiosporee can be easily and continuously prodused in 2 to 4 months in vitro.
S C Croan

Germination of basidiospores on preservative treated wood after leaching or natural weathering
1981 - IRG/WP 2150
In tests of residual toxic efficacy after leaching or natural weathering, spore germination with Gloeophyllum trabeum has proved to be a less reliable criterion of attack than when used with unaged preservative treatments. Since spores sometimes prove more tolerant than their parent mycelium, their use should be continued.
J K Carey

In vitro sporulation of selected wood decay fungi
1978 - IRG/WP 190
Basidiospores produced axenically without laborious attention in the laboratory are useful in studies of wood decay initiation. Such spores presumably approach those collected from natural sporophores in size and germinability (Morton, 1964). Production of spores in vitro by inversion of cultures grown on 2% malt extract agar in deep glass dishes (100x80 mm²) has been the preferred method (Morton and French, 1966; Toole, 1971). However, for many decay fungi desired as test organisms, spore production is capricious at best, and variation in onset and duration of sporulation frustrates carefully planned experiments. In an effort to improve reliability of this fast: and simple method of spore production, two approaches to minimize the change in nuclear and/or cytoplasmic factors presumed responsible for loss of sporulation were tried. First, freeze-drying of cultures and success of subculturing was investigated. Secondly, a direct subculture method from sporulating 'donor' cultures was used which attempted to transfer enough diversity within mycelial types to increase the number of replicates sporulating.
E L Schmidt, D W French

Effect of fumigant residue in aerated wood blocks on the spore germination of decay fungi
1991 - IRG/WP 2382
Fumigants are increasingly used in several countries for remedial treatments of transmission poles to increase the service life. The present study was initiated primarily to test the remaining toxic effects of spruce (Picea rubra) wood, fumigated with chloropicrin (trichloronitro methane) or MIT (Methyl isothiocyanate) after long period of aeration, on the spore germination of decay fungi. This study indicates that spore germination of decay fungi is more sensitive than mycelia for these fumigants. An assay involving spores could therefore complement the earlier proposed open and closed tube bioassays for assessment of remaining ability to prevent reestablishment of decay fungi in fumigated wood. This assay is sensitive both to bound wood residues contributed by the fumigants as well as to fumigant vapor.
J Bjurman, B Goodell

A technique for fructification and basidiospore production by Serpula lacrymans (Schum. ex fr.) SF Gray in artificial culture
1986 - IRG/WP 2255
A method for fructification and basidiospore production by Serpula lacrymans is outlined. A wheat flour/malt extract medium or an oat grain medium, enriched with alanine, tri-potassium phosphate and thiamine supported good fructification of the fungus at a temperature of 12°C. The influence on fructification of temperature, light and inoculum is discussed. To date, 22 stains from a total of 38 tested, fructify in culture.
S Cymorek, B M Hegarty

Basisiospore production by Lentinus lepideus in vitro
1987 - IRG/WP 2276
Evaluation of fungicides active against the lower fungi by spore based bioassays is very common. Possibilities of using similar assays to evaluate preservatives against brown rot and white rot fungi, especially for use in above ground constructions, are limited by the lack of methods for production of basidiospores. Tested media containing glucose 10-30 g/l and ammonium tartrate concentrations 2-20 g/l supported fairly good spore production. Media buffered with the organic buffer 2 (N-morpholino) ethane sulfonate (MES) with phosphate concentrations of 12.5-50 mM supported good spore production.
J Bjurman

Antagonistic effect of Trichoderma spp. against basidiospores
1993 - IRG/WP 93-10027
All screening of potential biocontrol agents of wood decay fungi have previously been used against basidiomycete mycelium. Similarly, experiments designed to evaluate the mechanisms involved in antagonism (soluble metabolites and volatile antibiotics) between biological control agents and target fungi have always been carried out on mycelial inoculum. Basidiospores are a primary source of infection leading to decay of wood exposed above ground and are the pathogenic form of the target fungus contact with a biocontrol antagonist. This paper examines the antagonistic responses of Trichoderma spp. against wood decay basidiospores. The paper also examines the influence of nutrient composition of growth media on the antagonistic responses by Trichoderma isolates. Assessment of individual modes of antagonism were carried out on two media types, a 3% malt extract agar and a nutritionally poorer minimal medium. The outcome of antagonism between Trichoderma isolates and wood decay basidiospores was often found to be dependent on the media type. Further studies were also carried out to evaluate the extent of inhibition of the basidiospores by concentrated soluble metabolites of Trichoderma isolates in vitro and in vivo i.e., in wood. The significance of using mycelial or spore inoculum with respect to antagonism for screening of biological control agents for wood protection is discussed.
U Srinivasan, T L Highley, S C Croan, A Bruce

Inhibitory effects of leachates from Scots pine wood on germination of some wood rotting fungi
1986 - IRG/WP 1282
Leachates from sapwood of Pinus sylvestris inhibited or reduced the germination of basidiospores of the wood decay fungi tested. The fungi were selected among those preferentially colonizing hardwood or softwood, representatives for brown rot and white rot fungi, early basidiomycete colonizers and late basidiomycete colonizers in above-ground parts of pine as well as fungi found in high frequencies in window frames. In contrast, leachates from the heartwood were less inhibitory to germination of the majority of the tested fungi. Wood materials for the tests were selected to reveal differences in inhibitory effect of pine heartwood and sapwood according to: 1. Trees cut in the summer or in the winter 2. Latitude at which the trees had grown 3. Method of drying kiln-dried or air-seasoned wood No differences in inhibitory effect against the test fungi in relation to these different wood materials were revealed.
J Bjurman

Basidiospore structure and germination of Serpula lacrymans and Coniophora puteana
1988 - IRG/WP 1340
Using a nuclear staining technique and fluorescence microscopy, the basidiospores of Serpula lacrymans were shown to be uninucleate whereas those of Coniophora puteana were binucleate. The germination rate of the Serpula lacrymans spores, which was considerably lower than that of Coniophora puteana, decreased further after storage or heat treatment. Transmission electron micrographs indicate that the majority of Serpula lacrymans spores have a disorganised internal cellular structure and are filled mainly with lipidic material; these spores lack a nucleus. Germination of viable Serpula lacrymans spores occurs through the spore apiculus or through the spore apex. In contrast, Coniophora puteana spores can produce two germ tubes and germinate simultaneously through the apiculus and the apex.
B M Hegarty, U Schmitt

The effect of storage and subculturing on in vitro fruit body formation and spore production in Gloeophyllum sepiarium and Oligoporus placentus
2001 - IRG/WP 01-20232
Spores are widely assumed to be the main mode of infection of wood in conditions conducive to decay above ground. In order to supply spores on demand as an experimental material, fruiting body and basidiospore production in vitro by Gloeophyllum sepiarium and Oligoporus placentus have been examined. The optimum medium, time to spore production, and duration of fruiting as well as fruiting body shape varied among strains of both species. Even when the same strain was used as the inoculum source, there were differences in duration of fruiting and time to spore production in different experimental sets. This suggests that the method of mycelium storage and repeated subculturing could affect fungal capacity for fruiting and basidiospore production. Among the tested methods of mycelium storage, mycelia stored on wood blocks showed the most stable response in both fruiting and spore production.
S Choi, J N R Ruddick, P I Morris

Basidiospore germination threshold against borate in-vitro may vary between liquid and agar media
1992 - IRG/WP 92-2405
The concentration of disodium octaborate (BAE) which prevented mycelial growth of a common brown rot and 3 white rot fungi was compared to that required to prevent basidiospore germination on malt extract agar. Spore germination sensitivity was lower (50%) for only one of the white rot fungi. However, when spore germination thresholds were tested in malt extract-borate solutions in well slides (no agar), much lower thresholds were noted for 3 of 4 fungi. Neither set of threshold data predicted that noted in limited tests on aspen (Populus tremuloides).
E L Schmidt, Ya-Lih Lin

The influence of timber species and preservative treatment on spore germination of some wood-destroying Basidiomycetes
1988 - IRG/WP 2300
Basidiospores from six wood decay fungi exhibited varying germination rates on untreated softwood and hardwood blocks. Germination inhibition of all test fungi was recorded on pine sapwood. No preference for a certain timber species by a particular fungus was evident. Whereas almost complete inhibition of germination occurred on wood treated with a quarternary-ammonium based wood preservative, most fungi germinated successfully on wood treated with a boron based preservative. Further work is necessary to determine whether a reliable preservative screening using spore germination tests as criteria can be developed.
B M Hegarty, G Buchwald

Partial characterization of inhibitors extracted from pine (Pinus sylvestris) sapwood active against germination of wood rotting fungi
1988 - IRG/WP 1351
Germination inhibitors in pine sapwood could be extracted and separated with the aid of solvent partitioning and chromatography on silicic acid. The inhibitory action was tested by three different bioassays. Active fractions have been characterized by TLC and HPLC. Inhibitory activity could be correlated with phenolic compounds. The minimum active concentration of inhibitors have been determined.
J Bjurman

Sensitivity to Copper of Basidiospores from Copper Tolerant Fungi: Fomitopsis palustris and Oligoporus placentus
2010 - IRG/WP 10-10707
Copper continues to be an important fungicide in wood preservation. It is the primary component of the preservatives that have replaced chromated copper arsenate for treated wood in residential construction in North America. However, a co-biocide is normally needed to protect against copper tolerant organisms. Previous work has shown that the spores of at least one copper tolerant fungus, Oligoporus placentus, were not very tolerant of copper. This explained the unexpectedly good performance of copper-only preservatives when just exposed to spores and not exposed to mycelium of such fungi. This work was designed to determine if the same was true of another copper-tolerant fungus that produces basidiospores in agar culture. An agar medium bio-assay was used to assess inhibition of basidiospore germination and mycelial growth of Fomitopsis palustris (Berk. et Curt) with O. placentus (Fr.) Gilb. & Ryvarden, as a known reference. The spores of F. palustris and O. placentus had the same copper sensitivity. The basidiospores were sensitive to copper concentrations between 20 and 50 times lower than their corresponding mycelium. These data confirm that spores of copper tolerant fungi are not very tolerant of copper.
C S Woo, P I Morris

Inhibition of Basidiospore Germination by Copper from MCQ, ACQ and CCA Leachates
2012 - IRG/WP 12-10778
The long-term decay resistance of refractory wood shell-treated with chromated copper arsenate (CCA) in above-ground exposures has been attributed to mobile copper that migrates into checks and inhibits the germination of basidiospores. Copper from micronized copper quat (MCQ) has also been shown to migrate into checks suggesting similar performance as a shell treatment, but questions have been raised about the form of this mobile copper. The concern was that if the copper is present as small particles rather than ions, it might not provide protection against basidiospore germination. The present work examined checks on MCQ-treated boards exposed above-ground in Vancouver for one year using Environmental Scanning Electron Microscopy (ESEM) with energy dispersive X-ray spectroscopic mapping. The copper detected on checks from MCQ-treated wood was not present as micro- or macro-particles. ESEM and EDS data were consistent with the vast majority of detected copper being soluble copper adsorbed to the wood, but did not preclude the presence of some copper-containing nano-particles below 9 nm. In addition, a laboratory test evaluated the efficacy of leachates from treated wood on spore germination. Untreated spruce disks were attached to wood treated with ACQ, MCQ or CCA for up to 36 days under conditions of periodic water spray and high humidity. These disks were used for either copper analysis or spore germination testing against Gleophyllum sepiarium and Oligoporus placentus. After eight weeks of incubation, spores had germinated on most of the untreated controls and on most of the disks previously attached to ACQ-treated wood. Disks previously stored adjacent to MCQ- and CCA-treated wood were largely free of spore germination. These data suggest that the mobile copper from MCQ is effective against basidiospore germination, and that the mobile copper from ACQ may be less effective under the test conditions in this study.
R Stirling, J Drummond, P I Morris

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