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In vitro studies on the effect of chitosan on mycelial growth and spore germination of decay fungi, moulds and staining fungi
2004 - IRG/WP 04-10507
The effect of solubilised, low molecular weight chitosan on established mycelial growth of a range of decay fungi, moulds and staining fungi was investigated using nutrient medium amended with different concentrations of chitosan that ranged from 0.1 to 0.4% weight per volume (%w/v). Also, spore germination of Trichoderma harzianum and Leptographium procerum was examined on chitosan amended nutrient medium using visual and microscopic assessment. The results showed that chitosan affected mycelial growth of a wide range of test fungi which generally showed lower growth rates as the chitosan concentration increased. However, the degree of inhibition exhibited by chitosan varied with fungal species. Under the present test conditions, chitosan was fungistatic, but not fungitoxic, against established mycelium of the staining fungi tested and also two moulds, Botrytis cinera and Cladosporium herbarum, but not against any of the decay fungi tested. Spores of T. harzianum germinated on chitosan amended nutrient medium at all chitosan concentrations tested, except for the highest level (0.2%w/v) used, while L. procerum failed to germinate on 0.15 and 0.2%. Also, T. harzianum and L. procerum spores incubated on 0.15% and 0.2% chitosan failed to germinate when placed onto fresh malt extract agar suggesting fungitoxic activity of chitosan at these higher concentration levels.
C Chittenden, B Kreber, N McDowell, T Singh

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

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

Antagonistic effects of Dacrymyces stillatus against growth of other fungi
1991 - IRG/WP 2363
The antagonistic effects in dual cultures on malt extract agar of 5 wood decay fungi and the antagonistic effects of Dacrymyces stillatus against 1 mould fungus and 1 blue stain fungus were determined. Dacrymyces stillatus was the only fungus which exhibited clear antagonistic effects. The effects of Dacrymyces stillatus against the different test fungi varied however to a great extent. Dacrymyces stillatus exhibited clear antagonism against brown rot fungi and a weaker effect against a mould fungus and a blue stain fungus. The antagonistic effect against a white rot fungus was weaker in dual culture. Spore germination of the responding white rot fungus Pycnoporus cinnabarinus was completely inhibited on an agar overlay over a culture of Dacrymyces stillatus on malt extract agar. Inhibitory activity was present in extracts.
J Bjurman

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

Inhibition of wood-inhabiting fungi by actinomycetes
1981 - IRG/WP 1137
Actinomycetes of the genera Streptomyces, Micromonospora, Microtetraspora, Nocardia and Rhodococcus, isolated from wood, were laboratory tested for their inhibitory effects against the Basidiomycete fungi Polystictus sanguineus and Sistrotrema brinkmannii. One-third of the representatives of the genus Streptomyces which were tested produced significant inhibitory zones whereas actinomycetes belonging to the other genera did not.
M S Cavalcante, R A Eaton

Synergistic effect of boron on Streptomyces rimosus metabolites in preventing conidial germination of sapstain and mold fungi
1992 - IRG/WP 92-1565
We evaluated the synergistic effect of boron (4% BAE solution of Tim-Bor or 4% boric acid) on Streptomyces rimosus metabolites in preventing spore germination of sapstain and mold fungi using plate bioassay, Southern yellow pine and sweetgum block tests, and green pine log sections: sapstain -- Ceratocystis coerulescens, Ceratocystis minor, and Aureobasidum pullulans; mold fungi -- Aspergillus niger, Penicillium spp, and Trichoderma spp. Inhibition of spore germination in plate bioassay by metabolites with boron was more effective than without added boron. Treatment of wood samples with the mixture of boron and unconcentrated metabolites also resulted in the synergistic effect and completely inhibited spore germination of sapstain and mold fungi.
S C Croan, T L Highley

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

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

Use of vermiculite as substrate in assays on phytotoxicity of treated wood
1989 - IRG/WP 3547
It is considered the possibility of using vermiculite instead of soil as substrate in assays on phytotoxicity of wood treated with preservatives for agricultural use. Three organic preservatives were used. It had been tested the behaviour of both, vermiculite and soil in case of preservative leaking due to a leach. So that, assays of germination with cucurbitaceous were carried out, mixing a dose of preservatives with both substrates.
M V Baonza Merino, D Franco

Influence of aliphatic acids on spore germination of wood decay fungi
1984 - IRG/WP 2224
Influences of eight saturated fatty acids (C5-C10, C12 and C16) on spores of four isolates of wood decaying basidiomycetes (white rot fungi: Poria tenuis and Trametes hispida; brown rot fungus: Gloeophyllum trabeum [two isolates]) were observed in-vitro. Spore response after 24 hr on malt extract agar containing 10, 10² , or 10³ ppm of each fatty acid included: no effect on normal germination, delayed germination or restricted mycelial growth, vacuolation and degeneration of spore cytoplasm, or germination inhibition without loss of spore integrity. C7-C10 acids destroyed spores of all fungi at 10² ppm whereas spores remained 'intact' at 10³ ppm of the same acids. C12 destroyed spores of the brown rot isolates but not the white rot fungi, and C16 lacked effect on all fungi at all concentrations. C5 and C6 destroyed spores only at 10³ ppm.
E L Schmidt

Spore germination of Gloeophyllum trabeum on wood is related to the mass of the wood sample
1978 - IRG/WP 2118
E L Schmidt, D W French

Antagonism to spore germination in Scots pine
1990 - IRG/WP 1458
Germination of Lenzites trabea and Chaetomium globosum spores was observed directly on wood blocks, on water soluble extracts and on organic solvent soluble extracts from pine wood. In all cases pine heartwood was found to be antagonistic to spore germination but pine sapwood varied in its antagonism according to the method of drying. Chromatography revealed that extracts from antagonistic wood differed from those of non-antagonistic wood in their composition.
S M Gray

Ibuprofen inhibits in vitro growth of brown-rot fungi
1996 - IRG/WP 96-10160
Ibuprofen, a phenyl propionic acid derivative (2-(4-isobutylphenyl)propionic acid) inhibited growth in vitro of 17 brown-rot fungi at a concentration of 100 µg/mL, while exhibiting no growth inhibition for 8 white-rot fungi at the same concentration. Propionic acid did not inhibit fungal growth in vitro. Morphological changes were noted in fungi that were able to grow in the presence of ibuprofen.
C A Clausen

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

Targeting fungal proteinases to prevent sapstain on wood
1995 - IRG/WP 95-10097
Discoloration of wood, caused by a variety of sapstaining fungi, leads to periodic losses in the Canadian lumber export industry. Proteolytic enzymes are thought to be necessary for retrieval of nitrogen during fungal growth on wood. The major extracellular proteinase of Ophiostoma piceae, a representative sapstaining fungus, was purified to homogeneity and its inhibition pattern characterised. Classic serine proteinase inhibitors inhibited the activity of the purified proteinase in a dose-dependent manner. Several chelating agents, detergents, heavy metals and PQ-8, a currently used commercial antisapstain formulation, also caused a reduction in proteolytic activity in vitro. Selected inhibitory compounds were then tested for their effect on growth of Ophiostoma piceae in artificial media and on wood. Heavy metals and several chelators inhibited growth on media containing protein or inorganic nitrogen, suggesting that they were toxic to the fungus rather than specific to the proteinase. However, chymostatin and PQ-8 did appear to be specific proteinase inhibitors. These products caused a decrease in growth on a protein-supplemented medium which induces proteinase production, but had little effect on growth on medium containing inorganic nitrogen. Visual assessment of lodgepole pine sapwood samples inoculated with Ophiostoma piceae also identified PQ-8 as an effective inhibitor of fungal growth. Other pure chelators and serine proteinase inhibitors did not perform well on wood. While some compounds showed promise in these tests, definitive testing and commercial application are constrained by the current lack of stable, cheap, non-toxic, specific serine proteinase inhibitors.
L D Abraham, D E Bradshaw, A Byrne, P I Morris, C Breuil

Synergistic effects between 2-HPNO, Irganox 1076 and EDTA on the inhibition of wood degradation by Coriolus versicolor
2004 - IRG/WP 04-30331
The efficiency of 2-hydroxypyridine-N-oxide (2-HPNO) as wood preservative has been investigated. As shown using classical experiments as well as using response surface methodology, the efficiency of 2-HPNO as wood preservative is strongly improved in presence a chelator like EDTA and/or of Irganox 1076 an industrial antioxidant. In these conditions, wood preservative efficiency of the mixture the three previous compounds is quite similar to that of tebuconazole used alone. 2-HPNO exhibits an hydroxamic acid function and is a susbtrate of fungal peroxidase. These properties could explain the observed synergy. The implications of these data for the design of new wood preservation strategies are also discussed.
A Mabicka, S Dumarçay, N Rouhier, M Linder, J P Jacquot, P Gérardin, E Gelhaye

Effect of sterilization method on germination of spores of wood decay fungi observed by contact agar block method
1978 - IRG/WP 2117
Previous studies of germination of spores of wood decay fungi on wood have generally concluded that method of wood sterilization has little significant effect on germination response. This study expands the numbers of test fungi as well as number of sterilization methods employed to determine the influence of sterilization method on spore germination response of decay fungi. Germination was assessed on agar discs fused by aqueous diffusion path to 1 cm³ samples of aspen and white spruce sapwood.
E L Schmidt, D W French

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

A rapid colorimetric assay for mold spore germination using XTT tetrazolium salt
2011 - IRG/WP 11-20462
A rapid colorimetric assay was developed to quantitate metabolic activity in mold spores during germination using 2,3-Bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[9phenyl-amino)carbonyl]-2H-tetrazolium hydroxide (XTT). The assay was used to demonstrate inhibition of spore germination following exposure to different biocides and variability in the inhibition of spore germination of different mold species to the same biocide.
C A Clausen, V W Yang

Mold inhibition on unseasoned southern pine
2003 - IRG/WP 03-10465
Concerns about indoor air quality due to mold growth have increased dramatically in the United States. In the absence of moisture management, fungicides need to be developed for indoor use to control mold establishment. An ideal fungicide for prevention of indoor mold growth on wood-based materials needs to specifically prevent spore germination and provide long-term protection under conditions of high humidity. Fungicides intended for indoor use must exhibit no mammalian toxicity, be odorless and emit no VOCs. Classes of compounds meeting one or more of these criteria include acids, phenolic compounds (antioxidants), pharmaceuticals, commercial and experimental wood preservatives, food preservatives, and plant essential oils. Wood preservatives and food preservatives were initially screened at various concentrations for inhibitory properties to mold fungi on 2% malt agar (MA). Many compounds that inhibited the test fungi on MA failed to substantially inhibit mold growth on unseasoned southern pine at higher concentrations than the minimal inhibitory concentration determined on MA. Subsequently, compounds were screened on unseasoned southern pine stakes. Pine stakes were dipped for 15 seconds in varying concentrations of the test chemicals according to the ASTM standard test method D4445 for controlling mold on unseasoned lumber. Stakes were challenged with Penicillium chrysogenum PH02, Aspergillus niger 2.242, and Trichoderma viride ATCC 20476 spore preparations. Following a 4-wk incubation, stakes were rated from 0-5 with 5 representing heavy mold growth. An inihibition rating of 0 to 1 is indicative of successful mold inhibition. The best overall average ratings for wood preservatives were seen in stakes treated with 5% Bor-A-plus or Cu+, which were highly inhibitory to all test fungi. High concentrations of ethanolamine (10%) and thujaplicin (10%) were inhibitory to all test fungi. Pine resin (50%) solely inhibited P. chrysogenum. Of the food preservatives tested, five percent sodium benzoate and potassium sorbate inhibited all test fungi, while calcium propionate selectively inhibited A. niger. Pharmaceutical antifungals such as voriconazole (2.5mg/mL), thiabendazole (25mg/mL), and miconazole (20mg/mL) completely inhibited all test fungi on unseasoned pine, while other azole-derivatives failed to inhibit mold growth. Nystatin (10,000 units/mL) inhibited only A. niger. A combination of effective chemicals should be considered as one strategy to provide long-term protection of wood-based building materials from mold establishment.
C A Clausen, V W Yang

Growth of two selected sapstain fungi and one mould on chitosan amended nutrient medium
2003 - IRG/WP 03-10466
In vitro studies were undertaken to investigate the effect of chitosan on growth of Leptographium procerum, Sphaeropsis sapinea and Trichoderma harzianum. Chitosan was tested at three molecular weight (MW) ranges and different concentrations formulated as either a powdered suspension or as a solution. The results generally showed that low MW chitosan produced a greater inhibitory effect on growth of test fungi than medium and high MW, irrespective of the chitosan formulation used. However, chitosan was more effective when applied in solution with much lower concentrations exerting inhibition of test fungi than chitosan suspensions. Furthermore, susceptibility of test fungi to chitosan differed, with T. harzianum being the most tolerant and S. sapinea the most sensitive species irrespective of chitosan formulation used.
C Chittenden, R N Wakeling, B Kreber

Inhibition of termite feeding by fungal siderophores
1992 - IRG/WP 92-1558
Siderophores are iron-chelating extracellular fungal metabolites which may be involved in initiating wood decay. A purified siderophore extract isolated from the brown-rot decay fungus Gloeophyllum trabeum (Pers. ex Fr.) Murr. (Basidiomycetes: Polyporaceae) was found to deter feeding by Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). This fungus has previously been associated with preferential feeding on decayed wood by subterranean termites, and solvent extracts have been reported to induce termite trail-following, arrestment, and/or aggregation. This is the first report of Gloephyllum trabeum metabolites or fungal siderophores having a negative behavioral effect on subterranean termites.
J K Grace, B Goodell, W E Jones, V Chandhoke, J Jellison

Inhibition of wood decay and termite damage by calcium precipitation
1996 - IRG/WP 96-30111
Fungal decay of wood in service, especially brown rot, results in billions of dollars (US) of losses annually. Recent environmental restrictions, both U.S. and international, are limiting or eliminating the use of broad spectrum biocides for wood preservation, primarily due to problems with disposal. In order to design new, environmentally benign methods for control of wood decay fungi, it is essential to understand the precise sequence of biochemical events as wood is colonized. The production of polygalacturonase (PG) and hydrolysis of bordered pit membranes during incipient brown-rot decay has recently been described by our laboratory. One key to pectin hydrolysis by plant pathogens has been shown to be fungal production of oxalic acid which lowers the pH of the substrate and chelates calcium ions. Production of oxalic acid may serve a similar role during incipient wood decay as calcium oxalate has been visualized by scanning electron microscopy during both brown-rot and white-rot decay. Therefore, it was hypothesized that in situ precipitation of existing calcium ions in wood may prevent the cascade of biochemical events involved in colonization of wood by brown-rot fungi, expecially hydrolysis of bordered pit membranes. Preliminary experiments in our laboratory have shown that brown-rot fungi, white-rot fungi, and termites are inhibited from effecting weight loss of wood following pretreatment of wood blocks with the selective water soluble calcium precipitating agent N,N-naphthaloylhydroxylamine (NHA).
F Green III, T A Kuster, L Ferge, T L Highley

Inhibition of termite damage by N'N-napthaloylhydroxyamine (NHA): Reticulotermes flavipes (Kollar) vs. Coptotermes formosanus Shiraki
2000 - IRG/WP 00-10354
The calcium precipitating agent NHA has been shown to protect southern yellow pine (SYP) from wood decay and termite damage comparable to CCA in field tests (Gulfport, MS) for two years (Crawford and Green, 1999). In a collaborative study, SYP wood blocks were vacuum treated with three concentrations of aqueous NHA and exposed in a no-choice test to Eastern subterranean termites (FPL, USA) and Formosan subterranean termites (WRI, Japan) to determine protection against termite damage. Individual blocks (leached and unleached) were exposed to R. flavipes (AWPA) or C. formosanus (JWPA) for 3-4 weeks. Mean weight loss of wood blocks after termite exposure ranged from 0.0 to 18.0% for R. flavipes and 6.0 to 20% for C. formosanus. Wood blocks exposed to R. flavipes were completely protected by 0.5 and 1.0% NHA, but weight loss in similar blocks challenged by C. formosanus were 6.0% and 6.2% respectively at the same concentrations. NHA acted as an effective termiticide for R. flavipes with 100% mortality after 3 weeks, but only soldiers were preferentially killed in C. formosanus. Formosan subterranean termite workers showed enhanced resistance to NHA treatment when compared to Eastern subterranean termites.
F Green III, S T Lebow, T Yoshimura

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