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Comparison of the agar-block and soil-block methods used for evaluation of fungitoxic value of QAC and CCA wood preservatives
1994 - IRG/WP 94-20039
The modyfied agar-block and soil-block methods were used for comparing the fungitoxic value of QAC and CCA type preservatives against Coniophora puteana and Coniophora olivacea The mass loss and moisture contents of wood were analysed.
J Wazny, L J Cookson

Comparison between agar-block and soil-block methods for wood-destroying Basidiomycetes
1992 - IRG/WP 92-2401
The object of this work is to compare these methods in order to provide some information to help in the choice between them. The comparison was made by a statistical analysis (factorial completely randomized design) and by a discussion about other aspects of each method. An evaluation of some fungi on attacking wood and a comparison between Picnoporus sanguineus isolated from carpophore and decayed wood were made. The results indicated that the loss of mass was greater in soil-block. Besides, the activity of the fungi in this method was more homogeneous than in agar-block. However the soil-block method presents some difficulties not found in the agar-block method. As related to the performance of Picnoporus sanguineus strains, the greater loss of mass occured when it was isolated from carpophore, no matter what method was used. These results give important indications about the biological characteristics and the source of the strains.
M B B Monteiro, S Brazolin, G Catanozi

Laboratory tests on the natural durability of timber methods and problems
1984 - IRG/WP 2217
In literature a large variety of test methods is mentioned to examine the natural resistance of timber against fungal attack. This concerns the kind of sampling as well as the test procedure, the test fungi, the duration of test, and the classification of the resistance according to the test results. These variations, however, are of great influence on the test result. Long term exposure will lead to a further differentiation of timber species to be generally known as "resistant".
H Willeitner

Laboratory methods for assessing the resistance of wood plastic composites to fungal attack.
2006 - IRG/WP 06-20340
Wood plastic composites (WPC’s) have many attractive material features including dimensional stability and resistance to moisture, but the wood in these materials remains susceptible to fungal attack. Assessing WPC decay resistance in laboratory trials has proven difficult because the slow moisture sorption characteristics of this material do not allow for sufficient fungal attack over the traditional test periods. In this report, the previous work on WPC durability is reviewed and the characteristics of these materials that might influence durability are discussed in relation to how the test methodology might be improved to produce more meaningful test data.
J J Morrell

Current state of world standardization in the toxicometric methods for testing of wood preservatives
2007 - IRG/WP 07-20354
The paper presents an outline of the history of forming standardized toxicometric methods for testing of wood preservatives in the world during last 100 years. Numerous studies resulted in three main methods which are currently used for official and basis assessment of biocides: - agar-block method in Europe (EN 113); - soil-block method in the USA and Pacific countries (ASTM D 1413); - modified soil-block method in the Russian Federation and the Commonwealth of Independent States (GOST 16712). Further on the paper compares the three methods and presents lines of their global standardization.
J Wazny

Contribution to the testing of wood based board material
1982 - IRG/WP 2176
R G Lea

New conception for shortering the duration of fungitoxic test on wood preservatives. Part 1: State-of-art
1994 - IRG/WP 94-20044
The review of agar-block and soil-block methods published during 90 years focused of shortening the duration of fungitoxic test of wood preservatives is presented. Special attention was given to miniaturisation of wood specimens.
J Wazny, P Witomski

Fungi used in standard tests on the toxicity value of wood preservatives in various European countries
1975 - IRG/WP 255
The aim of the present paper is to make the comparative analysis of test fungi used in various European countries in order to define the toxicity value of wood preservatives against fungi of the Basidiomycetes class. Only the methods with national standard rank, present on the currently binding standards list are taken for consideration. The analysis of similarities and differences in the choice of test fungi used in these methods should be a further step in the investigation on the unification of the test methods
J Wazny

Some data on the activity of alternative fungicides for wood preservation
1985 - IRG/WP 3333
Data from laboratory tests against basidiomycete fungi are presented for 9 alternative fungicides in organic solvent formulations and also in water for one product. Results are compared with data for reference preservatives, tributyltin oxide, copper and zinc naphthenates and pentachlorophenol. Of special interest is the apparently better than additive effect of mixing tributyltin naphthenate and Xyligen B, and the promising performance of Armoblen 480, a novel organic solvent formulation of n-alkyl coco-derived quaternary ammonium compounds.
A F Bravery, J K Carey

Evaluation of bacteria for biological control of wood decay
1990 - IRG/WP 1426
Laboratory soil-block and agar-block tests were carried out to evaluate the efficacy of bacteria as biological control agents against 5 brown-rot and 3 white-rot fungi. Pretreatment of Southern pine and sweetgum with a bacterial solution prevented decay in agar-block tests. However, the bacteria were generally ineffective in preventing decay in Southern pine, Douglas-fir, sweetgum and yellow poplar in soil-block tests. Wood blocks treated with an autoclaved bacterial solution were not decay resistant by either test method.
R Benko, T L Highley

Fungitoxic effect of the quaternary ammonium compounds preservatives against Basidiomycetes by using agar-plate and agar-block methods
1996 - IRG/WP 96-30118
Results of investigations on the fungitoxic value of three versions of wood preservatives based on the quaternary ammonium compounds (lauryldimethylbenzylammonium chloride, lauryldimethyl-benzylammonium bromide and alkylbenzyldimethylammonium chloride) and borates in relation to the wood destroying fungi have been presented. The agar-plate (screening) and agar-block method were applied. A wide range of the fungitoxic activity of all the three formulations and a very small leachability were proved.
J Wazny, P Rudniewski

Bestimmung der pilzwidrigen Wirksamkeit von Holzschutzmitteln gegen Moderfäule-Erreger
1977 - IRG/WP 2125
Ziel der vorliegenden Arbeit war der Vergleich der in verschiedenen Ländern zur Bestimmung der pilzwidrigen Wirksamkeit von Holzschutzmitteln gegen Moderfäule-Erreger angewandten Methoden. Als Vergleichsmaterial dienten drei normierte Methoden: die britische (42), skandinavische (45) und die in der DDR angewendete (47) sowie wichtige, von verschiedenen Fachleuten ausgeführte Arbeiten experimentellen Charakters. Die Analyse betraf vor allem folgende Probleme: Bereich der Anwendung der Methoden, Trägersubstanz, Testorganismen, Bewertungskriterien der Ergebnisse sowie andere Fragenkomplexe. Es wurden die aktuellen Untersuchungsmethoden zur Bestimmung der pilzwidrigen Wirksamkeit von Holzschutzmitteln gegen Moderfäule-Erreger, die in verschiedenen Forschungsarbeiten angewendet worden waren, durchgesehen. Festgestellt wurden sehr starke Unterschiede der methodischen Grundsätze, die sowohl zwischen den Methoden als auch im Rahmen der verschiedenen Typen von Methoden bestehen; diese Unterschiede betreffen vor allem die für die Pilzzucht angewandten Nährböden, die Ausmaße der Proben, die Auswahl der zu untersuchenden Organismen u. a. m. Von den drei Arten der Methoden: dem Agar-Klötzchen-, Erde-Klötzchen- und Vermiculit-Klötzchen-Verfahren scheint besonders das letzte hinsichtlich der Wiederholbarkeit als auch im Hinblick auf die Vergleichsmöglichkeiten der erhaltenen Ergebnisse geeignet zu sein.
J Wazny

Screening wood preservatives: Comparison of the soil block, agar block and agar plate tests
1993 - IRG/WP 93-20001
Several test procedures have been developed over the years to screen potential biocides for their value as wood preservatives. Each test has inherent advantages and disadvantages. In this paper the relative merits of the soil block, agar block and agar plate tests are compared. Eight commercially available biocides encompassing inorganic and organic systems were tested against four basidiomycete decay fungi. Each biocide was ranked according to its performance in the three tests. The results show that the relative efficacy of the different biocides is dependent on the screening test. Biocides can be separated on the basis of their chemistry. "Fixed" inorganic preservative systems perform better in tests which employ wood as a substrate material. Organic systems perform well in both the agar plate and wood-containing tests. Furthermore, the agar plate technique shows promise for detecting synergism between biocide components. It is concluded that all of these test methods should be considered to efficiently screen biocides for use as wood preservatives.
K J Archer, D D Nicholas, T Schultz

A laboratory evaluation of tributyltin ethanesulphonate as an aqueous fungicide in wood preservation
1983 - IRG/WP 3229
Toxic limit data, using both leached and unleached wood test blocks, are reported for aqueous solutions of tributyltin ethanesulphonate against four Basidiomycete fungi, Poria placenta, Gloeophyllum trabeum, Coriolus versicolor and Coniophora puteana. An in situ study of the tributyltin compound in Scots pine and ponderosa pine sapwood has been carried out, using the technique of 119mSn Mössbauer spectroscopy.
R Hill, P J Smith, J N R Ruddick, K W Sweatman

Effects of the specimen position on fungal colonisation and wood decay by en 113 test fungi
1998 - IRG/WP 98-20136
For testing wood preservatives according to EN 113 it is common practice to plant the test blocks on neutral supports in order to prevent (1) a diffusion of chemicals into the agar medium and (2) an excessive moistening of the specimens. The procedure was employed in EN 350-1 for testing the natural durability of solid wood. It turned out to be of problematic nature because of the individual requirements of the test fungi. A certain degree of moisture can stop the virulence of one species, but - on the other hand - favour the virulence of another, so that different ratings of durability can be expected. In order to clarify this relation, blocks of durable and non-durable wood species were planted on different support materials and directly on the mycelial mat. Coniophora puteana, Coriolus versicolor, Gloeophyllum trabeum, and Poria placenta were used as test fungi. The results reveal a wide range with respect to the rate of colonisation and decay of the respective wood species if supports or no supports are used.
G Kleist, M-T Lenz, R-D Peek

Antagonistic properties of Gliocladium virens against wood attacking fungi
1996 - IRG/WP 96-10162
Gliocladium virens has shown good antagonism against decay fungi in agar medium and in wood blocks. Gliotoxin produced by Gliocladium virens is associated with biocontrol of some plant diseases, but its importance to biocontrol of wood-attacking fungi is unknown. We investigated the ability of gliotoxin-producing (GLT+) isolates of Gliocladium virens and gliotoxin-deficient (GLT-) mutants of Gliocladium virens to inhibit growth of wood-attacking fungi in agar medium and to prevent decay in wood. The brown-rot fungi, Postia placenta and Neolentinus lepideus and the white-rot fungi, Trametes versicolor and Phlebia brevispora were completely inhibited by the GLT+ isolate and the GLT- mutants in agar medium. The GLT+ isolate also completely inhibited the growth of the brown-rot fungus, Gloeophyllum trabeum and the white-rot fungus, Irpex lacteus but the GLT- mutants caused lesser inhibition. The GLT+ isolate and GLT- mutants were ineffective in preventing growth of mold and stain fungi in dual agar culture. Pretreatment of wood blocks with a GLT+ isolate or GLT- mutant prevented decay by Postia placenta. Likewise, the GLT+ isolate prevented decay by Irpex lacteus but the GLT- mutants did not. Gliocladium virens (GL-21) was grown on a sulfur containing medium at pH 3.5 to enhance antibiotic production. However, inhibition of growth of decay fungi on agar medium containing culture filtrates was not enhanced. Decay was reduced in blocks treated with the culture filtrates but was not completely stopped. The filtrates were also ineffective in preventing growth of mold and stain fungi on wood.
T L Highley, H S Ananthapadmanabha, C R Howell

A comparison of fungal strains used in the bioassay of wood preservatives
1984 - IRG/WP 2220
Previously published data are presented relating to a number of strains of wood-destroying basidiomycetes (Coniophora puteana, Coriolus versicolor, Gloeophyllum abietinum, Gloeophyllum sepiarium, Gloeophyllum trabeum, Lentinus lepideus, Poria placenta, Fibroporia vaillantii and Serpula lacrymans) commonly used as test fungi in the bioassay of wood preservatives. The data, which has not been statistically compared, consists of mycelial growth rates, decay capacities, and toxic values using agar, agar-block and soilblock methods based on data published over a period of almost 50-years. In many cases a large variation can be observed between strains originating from the same geographical region and between strains from different climatic-geographical zones. The differences between individual sub-cultures of the same strain, as used in various laboratories - or even in the same laboratories - are noted. Many of the published bioassay methods contain insufficient detail to make statistical assessments. Therefore, the authors have not attempted a definitive comparison of the numerous data. A proposal is presented to organize an international resource of pure cultural strains used as test organisms in bioassays of wood fungus may be dictated by local requirements.
J Wazny, H Greaves

Standard Test Methods for Wood Preservatives by Laboratory Agar-Block Test
2006 - IRG/WP 06-20350
Wood is one of the most valuable and versatile resources for all sorts of constructional purposes. But timber in its various forms is subjected to several types of deterioration. This standard lays down the method for the laboratory determination of threshold value of wood preservatives against fungi. Most chemicals are initially tested for their ability to control decay fungi in agar-block tests. In an agar-block test, blocks of wood containing a pre-determined retention level of chemical are exposed to wood-destroying species of both brown-rot and white-rot fungi. The blocks along with the fungi inoculums are placed within a sealed dish containing agar. Efficacy is measured as a loss of block weight. The test fungus to a medium containing known concentrations of the test chemical, or soaking filter paper in the test chemical and placing this on the surface of a previously inoculated plate. The presence of the fungus and its growth rate are used as a measure of chemical effectiveness. These results are then compared with results of similar tests on accepted preservatives. Whereas this method provides a relative measure of toxicity, the growth of fungi on artificial media is markedly different from growth in wood. This test method varies widely between laboratories. The efficacy of wood preservatives provide valid data, the time required to obtain definitive results is too long because reliable decisions on efficacy against wood decay organisms must rely on long-term field test data. This goal will not be realized until we develop a better understanding of the many variables that influence microbial decay rates, develop improved methods for detecting and quantifying the extent of wood decay and couple these developments with improved designs for test specimens and methods. The main objection to the malt-agar toxicity test is that the substrate is not wood. But this testing method takes minimum time among other methods which is save the time, money and labor of the users.
P K Sarker, M A Rahman, M R Bulbul, T Das, G N M Ilias

Modern Instrumental Methods to Investigate the Mechanism of Biological Decay in Wood Plastic Composites
2014 - IRG/WP 14-40674
Various instrumental techniques were used to study the fungal decay process in wood plastic composite (WPC) boards. Commercial boards exposed near Hilo, Hawaii (HI) for eight years in both sun and shadow locations were inspected and tested periodically. After eight years of exposure, both boards were evaluated using magnetic resonance imaging (MRI), while a selected area of the board exposed in shadow was additionally tested using microscopy and micro x-ray computed tomography (CT). Experimental boards exposed to either exterior conditions in Vancouver, British Columbia (BC) or a laboratory decay process were used for verification of MRI and CT results obtained from the commercial board. MRI detected the presence of free water and its distribution in the exposed commercial board samples tested. Fibre saturation in the experimental board was found to be about 22%, in comparison to 27 – 30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Reconstructed volumes from CT scans of the tested boards allowed for the WPC microstructure to be observed in various planes of view and for void analysis of the material to be conducted. A significantly higher average percentage volume of voids was detected in the exposed sample compared to its reference unexposed counterpart. CT scans and subsequent void analysis of the experimental soil block culture test samples of known weight loss in wood demonstrated this technique to be reasonably accurate in the detection of voids created due to biological decay. No obvious relationship was established between the presence of free water detected by MRI and the average volume of voids detected by CT. Scanning electron microscopy (SEM) confirmed the presence of fungal mycelia in the exposed commercial board cross-section imaged by both MRI and CT. It was confirmed that both MRI and micro CT could be used for non-destructive evaluations of WPC materials, including their decay process. This work also found that many different decay fungi species could colonize and internally damage WPC, and that fungal decay in WPC seems to be a self-propagating process requiring an initiation time period where no obvious decay damage is observed.
G Sun, R Ibach, M Gnatowski, J Glaeser, M Leung, J Haight

Co-operative studies on determining toxic values against wood-destroying Basidiomycetes: Progress report to May 1989
1989 - IRG/WP 2339
This document reports progress on the co-operative study between nine laboratories set up following the proposals contained in Document IRG/WP/2316. Results have been received from two laboratories. Toxic values data have been established successfully using the test fungus Coniophora puteana but problems have been encountered with the other test fungi.
A F Bravery, J K Carey

Laboratory decay test of Burmese in and kanyin treated with three wood preservatives
1982 - IRG/WP 3210
Laboratory decay tests were performed on samples of In (Dipterocarpus tuberculatus Roxb.) and Kanyin (Dipterocarpus alatus Roxb. and Dipterocarpus turbinatus Gaertn f.) pressure treated with three wood preservatives - copper arsenic additive (CAA - a variation of ammoniacal copper arsenate), Arquad C-33 (a waterborne quaternary ammonium formulation), and tributyltin acetate (TBTA) dissolved in ethanol. Pressure treatments with each preservative involved a 0.5 - 1 hour vacuum followed by a 4 hour period of pressure. This resulted in a very variable treatment because of the inherent difficulty in treating these woods. The decay tests entailed a slightly modified form of the AWPA M10-77 standard soil-block test using three brown-rot and three white-rot fungi. The untreated In and Kanyin samples were moderately susceptible to decay though weight losses were very variable and some samples of Kanyin (usually the densest and least permeable) were naturally resistant. At the concentrations tested CAA was the most effective in reducing weight losses incurred in the soil-block tests. TBTA was successful in controlling decay caused by all but two of the test fungi. It is suggested that preservative retentions for TBTA conforming to those included in the Candadian standard for bis (tributyltin) oxide would exceed the toxic limit for all the fungi tested
J N R Ruddick, R S Smith, A Byrne

Discussion of diiodomethyl p-tolyl sulfone (Amical® 48) as a fungicide for wood preservatio
1987 - IRG/WP 3425
The effectiveness of diiodomethyl-p-tolyl sulfone (Amical® 48) as a fungicide for preservation of wood is supported by a discussion of results from the literature and current research programs.
J M Stamm, K J Littel, F M H Casati, M B Friedman

Biological control of Serpula lacrymans using Trichoderma spp
1994 - IRG/WP 94-10069
The effectiveness, or otherwise, in killing Serpula lacrymans, of a range of Trichoderma spp. in a variety of media and using two different incubation systems has been tested. In agar based systems with normal nutrients or minimal nutrients with high or low nitrogen contents and high or low iron content Trichoderma harzianum 25 proved to be the most efficient and killing Serpula lacrymans. Other species, such as Trichoderma hamatum 150, were effective in some media but not in others. Initial observation on partially decayed small wood blocks suggested that actively growing Serpula lacrymans could not be killed by Trichoderma spp.. Experiments undertaken on a specially designed system, however, indicated that certain Trichoderma spp. can act as effective antagonists even in wood based systems.
A J Score, J W Palfreyman

Soil blocks versus field test for evaluating and standardizing wood preservatives: A commercial view
1994 - IRG/WP 94-20024
On the basis of technical considerations, experience, costs and applicability, the author concludes that the soil block test and other laboratory tests have little meaning in a wood preservative standardization process and almost no merit in the commercialization of a wood preservative system. Field tests at sites known to be aggressive to preservative treated wood are strongly recommended.
W S McNamara

Essais mycologiques sur poteaux traités à la Wolmanit C B
1974 - IRG/WP 339
D Ollier, C Jacquiot

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