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Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 3: Full penetration of the refractory sapwood of white cypress
2000 - IRG/WP 00-40167
The heartwood of white cypress, Callitris glaucophylla, is renowned for its termite resistance and durability against decay. The sapwood, which can represent up to 30% of log volume, is non-durable and refractory to conventional preservative treatment. Previous work ascribes the lack of permeability to oily deposits within tracheids and ray cells. Environmental scanning electron microscopy was used to investigate ultrastructural aspects of sapwood permeability. Several pre-treatment processes to improve permeability were tested with limited success. Solvent drying allowed preservative penetration but damaged the structure of the timber. Neither, long term water soaking nor an oscillating pressure/vacuum cycle had any effect on porosity to water-borne treatments. Through extensive modifications to a standard VPI process we can now repeatedly achieve full penetration with organic solvent-based wood preservative solutions into white cypress sapwood. Effects of this process on the strength of the timber are being evaluated. Work is continuing as to the most effective and efficient treatment schedule and the latest results will be presented at IRG 31.
M J Kennedy, L M Stephens, M A Powell

Methodology challenges in developing a transfer of natural durability from sawmill residues, illustrated by experiences with white cypress (Callitris glaucophylla)
2000 - IRG/WP 00-20203
The transfer of durability-conferring extractives from durable to non-durable wood has been accomplished often, but usually as an educational exercise rather than as a commercially oriented process. In the latter environment, many factors previously overlooked become vitally important. How to study them, in the absence of well-developed methodology and given the shorter timeframes being demanded by industry research funding organisations, presents real challenges. These challenges will be illustrated by experiences with the development of such a process for the 'waste' durability components of white cypress. Factors to be considered include: identification of active components; quantification of their individual and collective activities against target organisms; optimisation of source material handling, storage and extraction techniques; extract standardisation and batch-to-batch reproducibility; compatible yet cost-effective carriers for the actives into treated wood; effects on durability and other wood properties such as strength and handling safety; regulatory obstacles including acceptance into wood preservation standards; and quality control methods for penetration and retention of the treated product.
M J Kennedy, M A Powell

Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 2: Laboratory fungal bioassays
2000 - IRG/WP 00-20204
Extracts from sawmill residues of the naturally durable white cypress, Callitris glaucophylla were tested for fungicidal activity in a series of laboratory bioassays. The effects of different extraction solvents, techniques and sources of material on the biocidal efficacy of the resultant extracts were evaluated. Soil jar decay tests were used initially however, contractual time constraints necessitated the development of a more rapid screening technique. A modified sapwood agar media was developed and found to be suitable for testing the extracts. It could be applied to other non-diffusible wood preservatives. Ground white cypress sapwood was impregnated with a range of concentrations of various extracts and gamma irradiated. The treated sterilised sawdust was suspended in water agar. The media were inoculated with a white rot, Lopharia crassa, or a brown rot fungus Polyporus verecundus. Growth of the isolates was monitored for four weeks, enabling dose responses to be accurately determined. Methanol was determined to be the most effective extracting solvent, and toxic threshold values of the methanol extracts were estimated. Fractions of the total extract were also compared. Most fungicidal activity was found in the most abundant fraction, which contained significant proportions of terpenes and other non-polar, low boiling point compounds.
M A Powell, L M Stephens, L Francis, M J Kennedy

Termite and decay resistance of particleboard composed of white cypress pine and radiata pine
1997 - IRG/WP 97-10200
Phenol-formaldehyde bonded particleboard was manufactured from blends of non-durable radiate pine (P. radiate) and heartwood of the naturally durable species, white cypress pine (C. glaucophylla). Board specimens were subjected to bioassays using two termite species, M. darwiniensis and C. acinaciformis, and the basidiomycete fungi, C. puteana and P. ostreatus, and the durability of specimens was compared with that of commercially manufactured particleboard specimens containing either insecticide or fungicide. The aims were to determine whether the natural durability of the boards was modified by the addition of cypress pine and if the durability of boards was comparable to that of boards containing insecticide or fungicide. Particleboard specimens containing cypress pine showed increased durability compared to specimens consisting entirely of radiate pine. There was an inverse relationship between the percentage of cypress pine and mass losses of specimens during the bioassays. During the M. darwiniensis bioassay mass losses of specimens containing 100 or 90% cypress pine heartwood were comparable to those of specimens containing insecticide. However, cypress pine particleboard specimens, irrespective of cypress pine content, were less resistant to attack by C. acinaciformis than specimens containing insecticide. Specimens containing 75% or more of cypress pine possessed similar decay resistance as specimens containing fungicide.
P D Evans, J W Creffield, J S G Conroy, S C Barry

MDF manufactured from blends of cypress pine and radiata pine shows enhanced resistance to subterranean termite attack
2001 - IRG/WP 01-40214
Medium density fibreboards consisting of blends of the naturally durable wood species white cypress pine (Callitris glaucophylla) and non-durable wood species were manufactured in a commercial plant and subjected to a bioassay using the subterranean termite species, Coptotermes lacteus. A board composed of 30% cypress pine, 30% slash pine (Pinus elliottii) and 40% of the naturally durable hardwood species spotted gum (Corymbia maculata) was also manufactured and bioassayed against C. lacteus. The aims were to determine (i) whether boards containing cypress pine possessed increased resistance to termite attack compared to a control manufactured entirely from non-durable wood species; (ii) the relationship between the cypress pine content of boards and their resistance (if any) to termite attack; (iii) whether the termite resistance of boards containing cypress pine could be further enhanced by the addition of spotted gum fibre. There was an inverse relationship between the cypress pine content of MDF specimens and mass losses of the specimens during the bioassay, the percentage mass losses of specimens containing 11.4, 16.2 and 34.2% cypress pine being 20.3, 13.4 and 8.8%, respectively, compared to 32.8% for the control, which consisted of non-durable slash pine (80%) and hoop pine (Araucaria cunninghamii) (20%) fibre. There was strong evidence that the inverse relationship between the cypress pine content of boards and mass losses during the bioassay was linear, although a statistically significant quadratic (curvilinear) effect was also apparent. The addition of spotted gum fibre to boards did not increase their resistance to termite attack. Cypress pine heartwood contains a variety of extractives that are either toxic or repellent to termites, and the increased termite resistance of MDF containing cypress pine compared to the control is probably due to the insecticidal effect of such chemicals on C. lacteus. The incorporation of cypress pine fibre into MDF shows promise as an alternative to chemical biocides for increasing the resistance of MDF to termites. However, the response of termites to heartwood extractives varies between species, and therefore further experimentation is needed to test the resistance of MDF containing cypress pine fibre to attack by greater range of wood destroying termites under test conditions that more closely simulate field conditions.
P D Evans, S Dimitriades, C Donnelly, R B Cunningham

A field method for determining the above-ground resistance of wood and wood products to attack by subterranean termite
1994 - IRG/WP 94-20035
A method for determining the above-ground resistance of wood and wood products to subterranean termites in the field is described. Termites are aggregated in 20-litre steel drums, each containing a highly susceptible timber substrate. At the centre of each drum, specimens of the test material under evaluation are sandwiched, using circular sections of wire mesh, between two layers of the substrate. The drums are connected by plastic piping to infested trees or to other drums which have previously aggregated target species of termites. Preliminary results in the use of this method are presented in a study comparing the resistance of eight untreated timber species and one species treated with a copper-chromium-arsenic (CCA) formulation to Mastotermes darwiniensis Froggatt and Coptotermes acinaciformis (Froggatt) in the Northern Territory of Australia. Advantages of this field method are discussed
J W Creffield

Examination of algal and wood extracts for the control of marine borers
1999 - IRG/WP 99-10306
Extracts obtained from a marine alga and white cypress pine (Callitris glaucophylla J. Thompson & L.J. Johnson) were examined for their ability to control marine borers. In a two week laboratory bioassay, filter papers were soaked in 0-8% extract concentrations, dried, and placed with Limnoria quadripunctata Holthuis in Petri dishes containing seawater. The 8% algal extract virtually prevented L. quadripunctata from boring holes through the paper. However, papers soaked in lower algal extract concentrations were attacked. Similar concentrations of C. glaucophylla extract failed to protect the filter papers from L. quadripunctata, despite some initial inhibition. Small blocks of Pinus radiata D. Don treated with the extracts and exposed in the sea were all destroyed within 13 months, except those blocks treated with the 8% algal extract which were just moderately attacked by Limnoria and Teredinids.
D Scown, L J Cookson, R De Nys

Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 1: Optimisation of the extraction conditions
2000 - IRG/WP 00-30238
As the first phase of a large project aimed at recovering 'waste' durability components from sawmill residues of Callitris glaucophylla, several solvents and extraction methods were evaluated, initially in the laboratory and then at pilot industrial scale. Extracts were compared by crude total dissolved solids content, by chemical analysis using GC-MS and LC-MS, and by laboratory bioassays against termites and decay fungi. Solvent polarity was more important than extraction method: polar solvents extracted greater total amounts, and were comparable to non-polar solvents in extract activity against decay. The latter produced greater specific activity against termites. Drying of sawdust before extraction reduced the yield of some volatile extractive components, but activity was not seriously affected. Extractive components fractionated by column chromatography exhibited a wide range of bioactivities. GC-MS and LC-MS analytical techniques were used to characterise the most active fractions, in which l-citronellic acid and several terpenoids were abundant.
M J Kennedy, Hui Jiang, L M Stephens

Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 4: Analysis of extracts and treated wood for active components
2000 - IRG/WP 00-20215
In order to facilitate the commercial implementation of a large project aimed at recovering 'waste' durability components from sawmill residues of Callitris glaucophylla, it has been essential to develop analytical methodology for the important bioactive components of the heartwood extract. This methodology will be used 1) to standardise the activity of successive production batches, ensuring that batch-to-batch variation is controlled, and 2) to monitor the penetration and retention of active components in extract-treated wood, ensuring that treatment quality is controlled. Analytical techniques used through the project have included both LC/MS and GC/MS, but as most of the extract activity against termites and fungi has now been demonstrated to reside in the lighter fractions, we have concentrated on GC/MS for the routine methodology for both extract activity and wood retention. Penetration is monitored by the application of a chromazurol S spot-test to a freshly cut transverse section. Both cypress heartwood and penetrated sapwood turn red-purple under the conditions of the test, which is not necessarily specific for cypress extractives, but nevertheless useful for routine monitoring of penetration of cypress extracts.
Hui Jiang, M J Kennedy, L M Stephens

An aquaria test of the natural resistance against marine borers of some commercial timbers available in Australia
1996 - IRG/WP 96-10145
The natural resistance of the heartwood of 22 different timbers grown or commercially available in Australia was examined. Radiata pine sapwood both untreated, and treated with 5.4 kg/m³ CCA salt, was included for comparison. Small timber blocks were exposed for one year in tanks containing either Limnoria tripunctata or Lyrodus pedicellatus. Four softwood species tested were heavily attacked and non resistant: radiata pine sapwood, Douglas fir, Huon pine and King William Pine. The latter two species are moderately durable in ground contact. Both white and black cypress pine were lightly attacked. Most hardwoods examined that are durable on land, also performed well in the aquaria, although none were immune from marine borer attack. Blocks in aquaria with Lyrodus pedicellatus were generally more decayed by marine microorganisms than blocks placed with Limnoria tripunctata. Limnoria is able to leave its burrow, and probably grazes on surface mycelia.
L J Cookson

Wood characterization of Tetraclinas articulata and evaluation of its resistance against lignilolytic fungi
2009 - IRG/WP 09-10697
Coniferous trees of the Tetraclinis articulata known under the Common name thuja from Berberie, is an endemic species from North Africa. The solid wood is much appreciated for its natural beauty and homogeneity and its quality for marquetry and furniture. The aim is to improve Tetraclinis articulate uses. At present, its wood is widely underestimated and sub-used compared to its announced qualities. Previous studies have shown that the Cupressaceous, to which the thuja belongs, possesses extractable compounds called tropolones considered as being responsible for their natural durability. A first objective is to analyse the inherent characteristics of Tetraclinis articulatasolid, a solid wood originated from Morocco, based on its physical and mechanical properties because there is little scientific data in the literature related to the quality of this species of wood. A second one is to assess the anti fungus potentials of thuja sawdust or woodchip recovered at the end of processing the timber. Indeed, the extraction of tropolones can be expensive and unprofitable, it seems therefore interesting to test the anti fungal activities and consider the possibility of incorporating them into particle board and test their durability. We have performed physical and mechanical tests and conducted biological degradation tests. Microbial resistance properties have been investigated to show any possible decay zones in the samples. Preliminary results of the biocides activities in sawdust show that rates from 1 to 2 % of sawdust, incorporated in the culture medium, limit the development of degradation agents as Coriolus Versicolor. In this context, the use of sawdust in an industrial scale in Morocco would be an environmental challenge and an answer to the challenges required, among others, by evaluation of local biomass and the reduction of the use of organic and mineral biocides.
F El Bouhtoury-Charrier, A Hakam, A Famiri, M Ziani, B Charrier

Wart Morphology can Distinguish White Cypress Pine from the Less Durable Species, Black Cypress Pine
2009 - IRG/WP 09-20406
White cypress pine (Callitris glaucophylla) wood is durable enough to be used outdoors, but occasionally there are reports of its premature failure in ground contact, which may be due to its substitution by the less durable species, black cypress pine (C. endlicheri). It has been difficult to prove this, however, because the woods of both species are very similar in structure and cannot be separated using conventional anatomical features. This study examined whether differences in the size and morphology of warts on tracheid walls in the two species could be used to identify them. There were significant differences in the height, width and shape of warts in the two species, but there was considerable overlap in the distribution of these parameters between specimens. Warts in C. endlicheri were more likely to be bent-over near their tops than those in C. glaucophylla, and the angle bending of warts was greater in C. endlicheri. Quantification of these parameters produced complete separation of multiple specimens of the two species, and could potentially be used to help determine whether premature failure of C. glaucophylla heartwood in ground contact is the result of its substitution by C. endlicheri.
R Heady, R Cunningham, P Evans