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The accelerated field simulator (= fungal cellar)
1982 - IRG/WP 2170
G C Johnson, J D Thornton, H Greaves


Natural durability studies in an accelerated field simulator - A novel approach
1983 - IRG/WP 2197
A study of the natural durability of untreated timbers to both decay and termite attack is described. The work illustrates the versatility of the Accelerated Field Simulator as a novel approach to biodeterioration research.
G C Johnson, J D Thornton, J W Creffield, C D Howick


Performance trials of treated hardwood fences
2002 - IRG/WP 02-30281
This paper examines the performance of the traditional hardwood paling fence used in Australia, after preservative treatment. Unseasoned rails, palings and plinths of the low natural durability species Eucalyptus regnans (mountain ash) and E. obliqua (messmate) were treated with PEC (pigment emulsified creosote) or PROCCA (an oil emulsion of CCA). Treated posts of these species were also compared with a naturally durable species used for posts, E. camaldulensis (river red gum). As the sawn timbers were mostly heartwood, penetration depths achieved were generally poor. The effect of incising posts, and notching or cutting timbers before and after treatment were examined, along with alternative construction methods. Performance was compared in laboratory ‘agar trays’, an Accelerated Field Simulator, and the field, enabling correlation between the various test methods. Results, including five year field inspections, showed that the above ground portions of the fence were still sound, compared to an untreated model fence. PEC provided better protection than PROCCA to timbers cut after treatment, due to its ability to bleed across cut surfaces. After five years, PEC treated posts performed as well as untreated E. camaldulensis posts.
L J Cookson D Scown, B Iskra


The performance of chlorothalonil after 4.5 years in the accelerated field simulator
1994 - IRG/WP 94-30041
The decay resistance of chlorothalonil in oil was examined in an accelerated field simulator (AFS). Pinus radiata D. Don and Eucalyptus regnans F. Muell. sapwood stakes were treated, placed in soil in the AFS, and monitored over 4.5 years. CCA type C treated stakes were included for comparison. Water and toluene treated control stakes were heavily decayed after 1-2.5 years. Oil treated controls, though moderately decayed, were still serviceable after 4-4.5 years. At each equivalent retention, chlorothalonil performed better than CCA in treated Pinus radiata and Eucalyptus regnans stakes. Pinus radiata stakes treated to 3.6 kg/m³ with CCA were heavily decayed after 4 years, while 3.1 kg chlorothalonil/m³ treated stakes were only lightly decayed. Similary for Eucalyptus regnans, 6.6 kg CCA/m³ treated stakes were heavily decayed after 4 years, while 6.1 kg clorothalonil/m³ treated stakes were lightly decayed. Most of the decay was due to soft rot. When soil in the AFS was 1.5 years old, it had half to three-quarters the number of microbial propagules as could be cultured from fresh soil, that was collected from the same site as the AFS soil was originally taken.
L J Cookson


Field Liners as physical barriers to prevent wooden utility pole decay in soil: An accelerated field simulation trial
2008 - IRG/WP 08-20384
Field Liners (FL’s), plastic sleeves used to protect in-ground wooden poles from fungal and termite damage, have been tested before as physical barriers to prevent contact between soil and wood and to retain wood preservative treatment. These earlier studies concentrated mostly on creosote preserved poles and early generation FL’s which were cumbersome in their application. The newer generation Field Liners were designed for simpler installation. Renewed interest in their application has emerged in Australia in light of dwindling supplies of suitable timber to use as utility poles. In light of this, and previous ‘hurdle theory’ publications, some Australian utility distribution companies commissioned a study to determine whether these new generation FL’s would work under Australian conditions. An accelerated field simulation trial using posts (with and without Field Liners and/or H1 retentions of ACQ preservative treatment) in fungus-rich soil was conducted in a purpose-designed facility maintained at constant high temperature and humidity. Posts were examined periodically for decay over 19 months. Decay was first noticed at the six month inspection, when a treated Eucalyptus cladocalyx and an untreated Eucalyptus globulus control (without Field Liners) had decayed slightly. No E. cladocalyx or E. globulus posts with FL’s had any decay. After 19 months, all eight untreated control posts had significant soft rot throughout their sapwood. All eight ACQ-treated posts without FL’s had 1-8 mm decay through their sapwood. All four ACQ-treated posts with FL’s had no evidence of decay while two of the four unpreserved posts with Field Liners had slight decay adjacent to the small hole/vent at the bottom of the FL’s where post-soil contact occurred. It is not recommended that FL’s be used as sole protection for untreated poles. Reduced preservative retentions in poles with FL’s may be considered in order to reduce the amount of preservative used, or poles which have lower natural durability in the heartwood could also be considered.
A R Howgrave-Graham, L J Cookson, T Hale


Accelerated H3 above-ground decay trials in Australia
2009 - IRG/WP 09-20411
An above-ground H3 fungal field trial was installed at five sites (3 in Australia, 2 in New Zealand), with the aim of finding a method that would shorten the time required for evaluating new preservatives and protection systems. One-quarter of the H3 preservative retentions were mostly installed, as first results suitable for registration occur when these reach 70% soundness. Chemical analysis of spare treated specimens gave retentions that averaged 9% lower than determined by solution uptake. This paper provides the exposure results from Australia after one year. At Clayton near Melbourne, untreated Pinus radiata test specimens had highest moisture content in the ‘rot box’ design, followed by the ground proximity and ‘embedded test’, while ‘flat panels’ were driest. Most extensive decay occurred in tests where wood separators between test specimens had been pre-inoculated with Gloeophyllum abietinum (brown rot) or Perenniporia tephropora (white rot). At Innisfail in frames not intentionally pre-inoculated, water-treated P. radiata was extensively decayed when ‘flat panels’ were placed on an aged test frame. Minor decay to water-treated P. radiata occurred in the ground proximity, deck-on-ground and rot box tests. In comparison, no decay was found in the embedded, flat panel (new frame), raised deck, modified double layer and peg tests. The treatments under test included CCA, copper chromate, alkaline copper high quat (AChQ), copper azole, azoles, kerosene, boron, TBTN, and copper naphthenate. Untreated Corymbia maculata heartwood was included as an example for natural durability.
L J Cookson, J Carr


Accelerated H3 above-ground decay testing
2013 - IRG/WP 13-20520
An above-ground H3 fungal field trial was installed at two sites in Australia and one in New Zealand, as well as in two Accelerated Field Simulators. The aim was to find a method that would shorten the time required for evaluating new preservatives and protection systems. One-quarter H3 retentions were installed, as first results suitable for registration occur when these reach 70% soundness. Twelve test methods were examined, some established and others developed for the project. In two methods, feeder blocks pre-inoculated with laboratory-raised fungi were placed next to test specimens in an effort to accelerate decay. The treatments examined were CCA, alkaline copper high quat (AChQ), azoles, kerosene, TBTN, and water. Untreated Corymbia maculata heartwood was included for natural durability. Inspection was annual for four years. The fastest test was the ‘rot box’ at Innisfail, followed by the ground proximity, deck-on-ground and embedded tests. The most reliable tests giving expected relative order of failure were those allowing diversity of fungi rather than those that became dominated by a few, and included those placed close-to-ground or those with increased volume of untreated wood substrate in frames. Pre-inoculation with Gloeophyllum abietinum gave more representative results than those pre-inoculated with Oligoporus placenta.
L J Cookson, D Page, T Singh


A rapid field bioassay technique with subterranean termites
1983 - IRG/WP 1188
Details are summarised of a field procedure which is designed to ensure continuous exposure to a replenishing termite biomass. After pre-baiting to determine the presence and identification of a termite hazard, test specimens (35 x 35 x 250 mm³) are installed vertically in the ground adjacent to and in contact with bait specimens of the same dimensions and interconnected by susceptible feeder strip.
C D Howick, J W Creffield


Japan's comments on ISO/DIS 12583-1/2
1996 - IRG/WP 96-20100
The paper describes an accelerated field test for the evaluation of timber preservative formulations against subterranean termites. The method has been adopted by the South African wood preservation industry as a screening method for the approval of wood preservatives for use under SA conditions. The method which is based upon the fungal cellar test offers a rapid means of evaluating the comparative performance of new wood preservative formulations in an environment that accurately reflects field conditions.
P Turner, D Conradie


Short-term field test method with accelerated infection of Basidiomycetes in wood
1981 - IRG/WP 2155
In the ŠIPAD - IRC Wood Protection Laboratory an attempt has been made to develop a simple short-term method for field testing out-of-ground contact wood using accelerated infections with Basidiomycetes. This method makes it possible to obtain a preliminary assessment of a preservative's quality and to estimate the possibility of achieving promising results in more expensive long-term tests. The idea was to use water traps (reservoirs) and 50 x 25 x 15 mm³ laboratory infected pine blocks as the substrate to improve the possibility of inoculation of L-joints.
N Vidovic


Are fungal cellar tests really necessary?
1989 - IRG/WP 2333
During the past decade the range of methodology used to evaluate wood preservative potential has significantly expanded. At the forefront of these new tools available to the scientist·is the fungal cellar. This technique, as currently applied, involves the exposure of treated and untreated samples to conditions of moisture and temperature which ensure optimum fungal attack. By comparison data with that obtained on similar preservative systems in conventional stake tests, acceleration factors for predicting performance have been developed. This discussion paper examines the philosophy influencing the development of fungal cellar testing, and provides an alternative viewpoint.
J N R Ruddick


Leaching of Active Components from Preservative Treated Timber. Stage 1: Semi-Field Testing
2004 - IRG/WP 04-20302
The project is aiming at finding realistic leaching rates from preservative-treated wood in use class 3 (above ground). The project focuses on developing a field trial method for investigating leaching. Panels are subjected to outdoor exposure under natural weather conditions at a test field at the Danish Technological Institute. The leachate is collected and monitored by chemical analysis of the active ingredients. The project is ongoing and the paper presents results from approximately 12 months’ of exposure. The study includes commercially available organic and inorganic fungicides using 4 different application methods: vacuum-pressure-, double-vacuum-, flow coat and supercritical treatment. Different test set-ups examine the influence of a number of different parameters. The results obtained from outdoor exposure will be compared with a laboratory test method (proposal of CEN/OECD, DOC TC38 WG 27 N039). The method investigated has proved to be useful in characterising the leaching behaviour from preservative-treated wood. The results from the present project are intended to serve as part of the basic documentation according to Directive 98/8/EC (The Biocidal Products Directive, BPD) for leaching of active ingredients in use class 3.
N Morsing, B Lindegaard


Accelerated wood decay in a soil bed test under greenhouse conditions compared with a stake test under field condition
1991 - IRG/WP 2384
The rate of decay of oak, beech, Douglas fir, pine and spruce stakes in an outside test field were compared with the decay rate of the same species in a greenhouse soil-bed test. Strength loss after four and six months respectively was measured by determining the compression strength parallel to the grain. The results show that all species, strength loss in the greenhouse was 2 to 4 times higher than under field conditions. The rate of strength loss correlates with the rate of weight loss.
J E Polman, S G Michon, H Militz


A new accelerated field test for termites
1983 - IRG/WP 1178
A new accelerated field test method for termites is described. Two series of tests were conducted with this accelerated method and the results were very encouraging.
W E Conradie, A Jansen


Ground contact performance of wood treated by the MSU process
1990 - IRG/WP 3609
Environmental concerns have prompted a renewed interest in accelerated fixation schemes for CCA-treated wood. Results from stake tests of southern pine (Pinus sp.) treated using a conventional Bethell cycle are compared with matched stakes treated using the MSU Process. The effects of adding boric acid to the preservative formulation are also discussed. Differences among test plots are discussed.
H M Barnes, T L Amburgey, R W Landers


Natural durability of wood in ground contact - A correlation between field and laboratory tests
1985 - IRG/WP 2182
A field test is being carried out to evaluate the natural durability of 20 hardwoods. The resistance to decay and termite attack was evaluated in accelerated laboratory tests. The results of the field test after 6 years and 8 months indicate that there is not necessarily agreement between results from laboratory and field tests. It is pointed out that apart from the artificiality of the laboratory tests, a possible cause of the discrepancies can be the different performance of the same wood species in different test sites.
M S Cavalcante, G A C Lopez, R G Montagna, M E S Fosco Mucci


Fungus cellar testing as an evaluation method for performance of treated timber in ground contact
2001 - IRG/WP 01-20227
A fungus cellar method for the accelerated evaluation of performance of treated wood in ground contact is described. The test soil comprised of sandy loam, vermiculite and Japanese horticulture soil "Kanumatsuchi" in a ratio of 6:2:2 by volume. The soil was inoculated with the dominant test fungus isolated with selective medium from decayed wood samples. Pairs of treated and untreated wood specimens Japanese cedar in contact with each other were buried vertically for two thirds their length. Assessment of the specimens was carried out periodically using the FFPRI graveyard damage index six- grade scale. Important factors for accelerating decay were the moisture control of the mixed soil, temperature and relative humidity, and the maintenance of fungus activity. The fungus used for inoculation favored a soil water holding capacity (WHC) of 50-80%. Under these conditions the untreated control specimens had a damage index in six months equivalent to three years FFPRI graveyard test service life, the decay accelerating rate by the fungus cellar to the graveyard test was 6 times. Under higher soil moisture conditions (WHC>80%) in the fungus cellar, soft rot was dominant and the decay rate was slower. DDAC treated specimens (8.4kg/m3) had a damage index of 2.6 in three years and 3.0 in four years. DDAC treated specimens (8.2kg/m3) in the graveyard test have been shown to be durable for 12 years (damage index of 2.3 in ten years and 2.6 after 12 years). This fungus cellar method has been shown to accelerate decay in DDAC treated specimens 3 times or more in comparison to the FFPRI graveyard test. On the other hand specimens treated with Copper-azole (6.0kg/m3 as retention of actives) had a damage index of 0 after eight years. The average service life in the FFPRI graveyard test is not decided as the Copper-azole treated specimens are in sound condition so it is not yet possible to evaluate the accelerating rate for the Copper-azole by the fungus cellar method. The fungus cellar method will be an useful method for the accelerated evaluation of performance of treated wood in ground contact provided the test conditions can be controlled.
Y Nagano


Attempt for developing a new method for above ground field testing of wood durability
2000 - IRG/WP 00-20199
Field testing remains the most appropriate way for evaluation of wood preservatives or natural durability of wood species. Above ground tests are designed to answer specific questions concerning the outdoor utilisation of wood. Such methods supply additional information and confirm or reject preliminary laboratory results. The European standard (ENV 12037, "lap-joint") for assessment of the durability of preservative treated wood in above ground testing has recently been proposed. It may also be used to assess the natural durability of wood. The objective of the present paper is to bear some discussion on alternative above ground test methods. The existing lap-joint field test corresponds to the real exploitation conditions of timber, but shows no decay after 2-3 years of exposure. This could be misleading when assessing the efficiency of preservatives. The method suggested acts more quickly compared to the lap-joint method with regard to mould, stain and, presumably, decay fungi. It is an accelerated above ground field test providing conditions favourable for fungal growth, but following close the fluctuations of climate. Results are shown where samples treated with preservatives for above ground use and untreated samples were exposed to the accelerated above ground test for several months. Fungal discoloration of the timber surface was classified by visual examination according to a seven-grade scale. The field test described here may be recommended for quickly testing of the natural durability of wood in above ground conditions as well as for approval of preservatives.
N Terziev, M-L Edlund


Délavabilité de bois ronds traités avec un sel CCA dans des conditions réelles de stockage. Incidence pratique de la fixation accélérée par étuvage. Impact effectif sur l'environnement
1993 - IRG/WP 93-50001-23
Un essai de terrain a été organisé pour mesurer concrètement, dans des conditions aussi proches que possibles des conditions réelles de terrain, les pertes effectives en produit de traitement lorsque le bois traité est soumis à des intempéries. L'essai a été conduit sur des bois ronds (poteaux), traités en autoclave par procédé Bethell avec un sel CCA de type C, avec comme finalité l'évaluation de la nature et des quantités de composés délavés en pratique, pour évaluer ainsi leur impact réel sur l'environnement au niveau du site de traitement. Compte-tenu des propriétés fixantes de ce type de produit, il était interessant d'identifier ces pertes à différents stades de la fixation, ainsi qu'après fixation compléte. Utilisant également les divers travaux et constats disponibles à ce jour sur les possibilités d'accélérer la fixation par l'étuvage, nous avons voulu observer et quantifier cette amélioration dans les mêmes conditions de terrain. Cet essai a été organisé et exécuté conjointement par le CTBA et la société FRANE BOIS IMPREGNES. Il conduit à 3 constatations principales: - Les pertes pratiques sont quantitativement nettement moins importantes que celles obtenues à partir des méthodes et échantillons de bois utilisés en laboratoire. - A l'issue et surtout au cours de la fixation les divers métaux se comportent de façon très différente, et on peut penser que la nature de la formulation a une importance notable sur ce comportement, même si dans tous les cas les quantités concrètement délavées restent faibles. - L'éuvage en sortie de traitement et dans des conditions adaptées permet d'obtenir spontanément, un résultat analogue à celui obtenu par un cycle de fixation traditionnel.
M Rayzal, F Larroze


A comparison between different accelerated test methods for the determination of the natural durability of wood
1996 - IRG/WP 96-20099
According to the European standard EN 350-1 the natural durability of wood is defined as: "the inherent resistance of wood to attack by wood destroying organisms". This standard also describes how, for certain hazard classes, the durability is determined. The two methods described in this standard are the kolleflask method (EN 113) and the field-stake-test method (EN 252). The EN 113 test gives results within a short period of time by using isolated fungi cultures. A good prediction from the test results to the natural durability of timber in use is a problem. In contrary, the test results of EN 252 in outdoor field tests show the durability of timber species under certain soil and climate conditions, but the test takes a long period of time (years to decades) before an evaluation can be done. In different countries in Western-Europe a discussion is going on about the use of tropical hardwoods and timber from fast growing plantages. The impact of this is that there is a growing need for alternative timbers, which can substitute well known durable species. Quite often the durability of the alternative species is not well known. To give a reasonable prediction of the durability of wood species within a short period of time, a reproducible, reliable and fast test method for predicting durability is needed. Previous research on this subject (Polman et al. 1992) showed that with the aid of an accelerated stake-test, useful results can be achieved. The research described here was done to develop such a method. For this reason, results from an accelerated soil bed test were compared with EN 113 fungal tests and a modified field-test EN 252. For a further comparison, softrot tests following the standard ENV 807 were performed.
H Militz, S G L Michon, J E Polman, M Stevens


Termite resistance of Malaysian and exotic woods with plantation potential: Field evaluation
1998 - IRG/WP 98-10289
An in-ground resistance of selected Malaysian and exotic timbers to attack by a representative aggressive subterranean Coptotermes termite was evaluated as part of an on-going collaborative research between the Forest Research Institute of Malaysia and the University of Hawaii on termite control of building timbers under humid tropical conditions. A test site at FRIM, highly susceptible to the subterranean termite Coptotermes curvignathus was chosen for study. The accelarated test protocol consisted of burying small (2 x 2 x 2 cm3) wood blocks of the following timber species at 15-20 cm below-ground with the immediate environment manipulated by addition of residues from oil palm fibres and venners of decay susceptible woods and concealed with forest top soil: Casuarina equisetifolia, Azadirachta excelsa, Tectona grandis (both Malaysian-grown and Burmese material), Hevea brasiliensis, Acacia mangium, Albizia falcataria, Araucaria cunninghamii, P. sylvestris, Koompassia malaccensis and K. excelsa. After 28 days, it was found that the results of the subterranean termite resistance test are consistent with the known/expected termite resistance of these woods when compared with previous natural durability stake test records of FRIM.
A H H Wong, J K Grace, L H Kirton


Performance of Two Imidacloprid-Treated Malaysian Hardwoods in an Accelerated Aboveground Termite Test
2005 - IRG/WP 05-30389
The performance of the chloronicotinyl insecticide imidacloprid as a wood protecting termiticide, under a simulated Malaysian biological hazard class H2 (exposure aboveground indoors against termites and wood borers), was evaluated by a novel termite field test protocol. Replicate end-grain sealed air dried test blocks (20 x 20 x 20 mm) of two Malaysian hardwoods, Kembang Semangkok (Scaphium spp.) and Rubberwood (Hevea brasiliensis) were vacuum-atmospheric pressure-impregnated in the laboratory in butanolic solution of imidacloprid to target retention of 0 (control), 1 and 3 g/m3. Halve the replicated blocks were then subjected to a prescribed water-leaching cycle, and conditioned blocks then installed in a novel aboveground H2 hazard class-type termite field test where Coptotermes curvignathus are prevalent. After 8 weeks exposure, untreated hardwoods were severely (termite ratings 1-2) or moderately attacked (ratings: 6.3-7.5), while, with the exception of occasional light grazing, none of the leached nor non-leached test blocks treated with imidacloprid to both target termiticide retention were regarded to be attacked (ratings: 9.8-10).
A H H Wong


Leaching of active components from preservative-treated timber. Stages 2 & 3: Laboratory testing and comparison with semi-field testing
2004 - IRG/WP 04-20303
This part of the project is focussed on leaching from preservative-treated wood obtained by the laboratory test method CEN/OECD draft guideline, February 2003 ”OECD guideline for the testing of chemicals proposal for new guideline XXX. Estimation of Emissions from Preservative-treated Wood to the Environment: Laboratory Method for wood held in the storage yard after treatment and for wooden commodities exposed in Use Class 3 (not covered, not in contact with the ground).” Preservative-treated test specimens are emerged in water. The specimens are immersed two days a week in a 60 days period. On each immersion day 3 immersions are carried out. One sample is immersed in water 18 x 3 times. Each immersion takes one minute. Between each immersion the specimens are stored in climate chambers. Water (emissate) is retained for chemical analysis for active ingredient to determine the leaching. The study includes commercially available organic fungicides using vacuum-pressure treatment as an application method. The preservative used is the preservative used in Nordtest project 1582-02 named M1. The investigation includes two different periods of fixation, one with a long fixation period and one with a short fixation period of the active ingredient before the immersion testing. The results obtained from laboratory testing are compared with the semi-field exposure. The method developed for in-service testing has proved to characterise the leaching behaviour from preservative-treated wood. However, there is no good correlation between field-testing and the CEN/OECD laboratory testing method for the product involved.
N Morsing, B Lindegaard


Evaluation of the protective means of some wood preservatives by means of accelerated tests
1973 - IRG/WP 232
In site conditions of the eastern site in the forest-steppe part of the Krasnovarsk region, the relative effectiveness of a series of wood preservatives was obtained by means of field tests. To obtain a more accurate evaluation of the protective qualities of these accelerated tests were carried out in laboratory conditions. In 9 boxes filled with non-sterile soil taken from the site, 72 samples of pine wood (in sizes of 20x20x30 and 20x20x5 mm³) soaked in copper naphthenate, pentachlorophenol and the compound FHM-7751 in three different concentrations were placed. In 3 boxes decay was mainly due to fungi causing limited rotting. In the other 6 boxes the soil was infected with the basidiomycete fungi Hymenochaete sp. and Coniophora cerebella in order to obtain more reliable results of the protective properties of the wood preservatives. Uniform distribution of infection was insured by placing cubes of wood infected with a pure culture of the fungi under test between the faces of two adjacent samples. Tests were carried out in an air temperature of 20-24°C with a relative air humidity of 70-80%. Soil humidity relative to its absolute dry weight was maintained at 30%. The decay of wood was measured by weight loss. Duration of tests was from 1 to 3.5 years. The advantage of the method used lies in the uninterrupted action of micro-organisms in the course of a long period while in field tests samples are subjected to attack only during the short Siberian warm period of the year. Moreover in field tests the samples do not always find themselves in the fungus infected zone and the decay is caused by imperfect fungi having only a moderate effect. A drawback of this method is the isolation of the sample as a result of which the soil zone around the treated samples is deprived of the influx of new micro-organisms, while available micro-organisms find themselves in severe conditions which become worse with the increase in the concentration of the wood preservative. As in field tests the accelerated tests have shown pentachlorophenol (PCP) to give the best protection. Samples after 6 months in the soil and with an absorption of 3 kg/m³ begin to be attacked by staining fungi, non-spore carrying bacteria and spore yeasts. With an absorption of 8 kg/m³ the samples are practically immune to micro-organisms. Analysis carried out a year after placing the samples in the soil has shown the samples to be in a good condition whether they have been treated with the maximal or minimal dose of PCP. The condition of the samples in analogous when subjected to the action of not only fungi causing moderate decay but also the basidiomycete fungus Hymenochaete sp. Samples treated even with minimal doses of wood preservative showed no signs of decay while the weight of untreated samples fell by 74 and 92% according to size. In non-sterile soil, together with fungi causing soft rotting, there develops to a sufficient extent mycelium of the basidiomycete fungus Lentinus lepideus. Nevertheless, after 2.5 years of accelerated tests, and in spite of the fairly high development of Lentinus lepideus in the soil, the condition of treated samples corresponded to a preservation (durability) index 100. The treated samples were immune to mycelium of Lentinus lepideus even in spite of the fairly strong attack at the beginning of the test by ammonia-forming bacteria and wood-staining fungi. Tests with Coniophora cerebella were the longest (3-5 years). Visual inspection showed decay of controls only. Treated samples, irrespective of the amount of PCP used, showed no signs of decay or weight loss. The results of accelerated tests agree with field tests. But sometimes there are found on the surface of samples mycelium and white well-branched wafts (fans) of Hymenochaete sp. The appearance of hymeno-mycetes seems to indicate their adaptation to PCP and the beginning of decay. Much attention is now given to the study of the reduced effect of PCP due to the adaptation of micro-organisms. The weakening of the protective action of wood preservatives leads also to their depletion in the wood while in service. The study of the microflora of samples in laboratory and field conditions has shown that in both cases bacterial flora predominates in the process of decay of wood treated with PCP. It is represented by spore-carrying as well as spore-free forms. With the increase of wood preservative loadings the spore-free forms predominate. The species composition of fungal flora has little variety on wood samples treated with PCP. The species resistant to it are, in field tests, Trichoderma lignorum and Fusarium sp.
I A Petrenko


Accelerated testing for out of ground contact using natural biological preconditioning
1996 - IRG/WP 96-20088
Small blocks made of Scots pine sapwood were treated, buried in vermiculite and exposed to natural microbial colonisation during outdoor exposure prior to laboratory decay testing. Periodic microbial isolations, moisture content, permeability and weight loss tests were also conducted. Bacteria and moulds colonised the vermiculite and miniblocks well. Aureobasidium pullulans was common on TnBTO treatments. Basidiomycetes were isolated from the control miniblocks at 3 months. Controls showed slightly increased permeability compared with treated samples after 1 month. At 3 months, controls, all TnBTO treated blocks and the lower retentions of DDAC showed permeability increases. Weight loss in the field was low up to three months, even in the controls (3.5%). Agar block trials with no natural pre conditioning showed all preservative treatments were effective, but, after only 1 month's field exposure the lowest retentions no longer provided adequate protection. Further studies are in progress.
S Molnar, D J Dickinson, R J Murphy


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