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Influence of moisture content of rubber wood on the growth of Botryodiplodia theobromae
1993 - IRG/WP 93-10029
Botryodiplodia theobromae is the main fungus causing sapstain on rubber wood (Hevea brasiliensis). The entry and establishment of the stain fungus is nighly influenced by the moisture content of the wood. To determine the optimum moisture content of wood required for maximum growth of Botryodiplodia theobromae wood blocks at different moisture contents were inoculated with the test fungus and incubated for a period of two weeks. The study showed if the moisture content of the wood was reduced to less than 24%, the wood can be protected from fungal sapstain.
E J M Florence, R Gnanaharan, J K Sharma

The utilization of preserved rubberwood
1982 - IRG/WP 3186
The paper examines the use of processed and kiln-seasoned rubberwood for manufacturing furniture and doors and windows, discusses methods tested and found acceptable for preserving the timber as well as for drying the treated timber in conventional kilns. It considers a type of furniture where narrow width timber of preserved and kilned rubberwood has been used with great success. It recommends that wherever rubberwood is available, its use could be very profitable to local entrepeneurs.
V R Sonti, B Chatterjee, M S Ashraf

In-situ pressure injection for preservation of rubber wood (Hevea brasiliensis Muel Arg.)
1992 - IRG/WP 92-3688
Rubber wood is widely used for the manufacture of furniture, doors for housing and packing cases. However in an untreated condition it is highley susceptible to sapstain and decay fungi and borers. Its utility gets considerably reduced if the wood is not treated well in time. Preservative treatment has to be given within the period of felling and transport to prevent not only loss of structural properties and wood material. Although Boucherie, hot-cold bath diffusion, pressure impregnation, vacuum-pressure impregnation processes for treating timbers have been successfully employed for protection, but the process in cumbersome and difficult to adopt at the site of extraction. Hence, it was found necessary to evolve a simple and convenient method to treat trees in-Situ. A simple pressure injection technique was adopted to treat the standing tree using an instrument designed at the Institute (IWST). This instrument is easy to operate and inexpensive. It was observed that the movement of preservatives was satisfactory and effective. Samples of wood taken from treated stem of such trees were subjected to attack by brown and white rot fungi in the laboratory. It was observed that wood samples treated with Borax, boric acid and Bavistin (1:1:0.2); Borax, boric acid and Sodium pentachlorophenoxide (1:1.5:1) and Bavistin and Ekalux (0.5:0.5) showed higher resistance to fungi and insect attack compared to boric acid and Borax (1:1) in both laboratory and field conditions. Treated wood also retained natural colour and was free from fungal and insect attack for over 24 months in storage. Studies in this method of treatment of plantations species are in progress.
H S Ananthapadmanabha, V R Sivaramakrishnan

Technique for monitoring absorption during a vacuum pressure process
1992 - IRG/WP 92-3696
A laboratory technique was developed and an apparatus constructed which allowed for the direct and continuous measurement and observation of volumetric uptake of water-borne preservative into wood samples throughout a controlled vacuum-pressure treatment process. Fractional filling of void space was calculated. Graphing (fractional saturation) against time allows prediction of optimum cycle lengths with respect to achievable saturation values. Treatability evaluations using this technique were carried out on heartwood samples of six Malaysian hardwood species, kapur, kempas, keruing, punah, rubberwood, simpoh and on sapwood samples of Scots pine as a control. Generally the graphs exhibited two quasi-linear zones showing rapid initial absorption followed by slow absorption over a long period.
A J Pendlebury, J A Petty

Preliminary note on the fungal problem of rubber wood
1983 - IRG/WP 3246
Susceptibility of rubber wood to fungal attack limits its wider utilisation. Fungal problems encountered in treating rubber wood with boron compounds by diffusion process have been discussed. Sodium pentachlorophenoxide and 2-thiocyanomethylthio benzothioazole (TCMTB) were investigated for possible control of fungal growth during diffusion storage and their performance has been reported.
R Gnanaharan

Evaluation of an alkyl ammonium compound as a fungicide to control sapstain and mould during diffusion storage
1984 - IRG/WP 3282
An alkyl ammonium compound ('Akzo' ES 255) was evaluated for its effectiveness against mould and sapstain during diffusion storage of boron-treated rubber wood. Though ES 255 at 1.0% concentration was effective against mould (71%) and sapstain (89%) it is less satisfactory compared to 0.5% sodium pentachlorophenoxide against mould (92%) and sapstain (98%).
R Gnanaharan

Biodeterioration and preservation of rubberwood (Hevea brasiliensis)
1994 - IRG/WP 94-10084
Plantation-grown rubber trees (Hevea brasiliensis) in the tropics is fast emerging as a significant provider of quality hardwood for a variety of non-structural products, as the aesthetics of the timber is its creamed colour resembling perhaps the priced but depleting Ramin wood or even American beechwood. However rubberwood logs and sawn materials are highly sensitive to sapstain, fungal decay and insect damage. Ensuring high added value of rubberwood products requires stringent control of biodeterioration using preservation treatment or immediate seasoning. This paper attempts to review studies on biodeterioration and preservation of this favoured wood material in the tropics.
L T Hong, A H H Wong

Degradation of the normal fibre walls of rubberwood (Hevea brasiliensis) by the tropical blue-stain fungus Botryodiplodia theobromae
1998 - IRG/WP 98-10286
Rubberwood was examined by light microscopy and transmission electron microscopy (TEM) after exposure to the common tropical sapstain fungus Botryodiplodia theobromae for four weeks to study hyphal colonisation of wood cells and to determine if this fungus also degraded lignified normal fibre cell walls in addition to the walls of non-lignified elements. Light microscopy revealed relatively large diameter hyphae to be abundantly present in parenchyma cells. The hyphae were also present in other types of wood cells, including fibres. TEM provided evidence of fibre wall degradation in the normal rubberwood in the form of lumen wall erosion (type-2 soft rot decay). These observations suggest that the ability of B. theobromae to degrade lignified wood cells walls should be viewed with concern when utilising rubberwood which has been severely sapstained, particularly after prolonged exposure to this fungus.
A A H Wong, A P Singh

Degradation of the gelatinous-layer in aspen and rubber wood by the blue stain fungus Lasiodiplodia theobromae
1996 - IRG/WP 96-10168
Studies on the degradative ability of the blue stain fungus Lasiodiplodia theobromae Pat. have shown several strains to cause significant weight losses (i.e. ca 20%) in the temperate and tropical wood species, aspen (Populus tremula) and rubber wood (Hevea brasiliensis). In addition to the consumption of soluble carbohydrates and extractives, major changes in the ultrastructure of fibre cell walls was apparent with rapid attack of the gelatinous layer noted. In both wood species following G layer degradation, early wood fibres showed true cell wall degradation with pronounced erosion attack suggesting that prior destruction of the G layer afforded greater accessibility and ease of attack of the outer secondary cell layers.
O Encinas, G F Daniel

Efficacy of deltamethrin associated with TCMTB and MBT for the temporary protection of timbers immediately following their sawing, in tropical countries
1987 - IRG/WP 1321
K-Othrine bois 2.5 "sciage"Ò containing 2.5 g/l of deltamethrin, 50 g/l of TCMTB and 50 g/l of MBT used at a 6% dilution controls effectively during the drying process of the freshly sawn wood, the insects attacking wet wood, the staining fungi and the rots. The protection lasts 4 months. The efficacy trials carried in 1985 and 1986 in the CTFT ("Centre Technique Forestier Tropical") of Abidjan, Ivory Coast, confirms the dilution rate of 6%. The fungicidal efficacy can be strengthened when necessary and according to climatic or storage conditions by adding to K-Othrine bois 2.5 "sciage"Ò the adequate quantity of a ready mixed formulation of TCMTB and MBT.
J S Duguet, V Dartigues

Association of contents of nitrogen and sugars in rubberwood (Hevea brasiliensis) clones with susceptibility to sapstain by Botryodiplodia theobromae, Aureobasidium pullulans and Aspergillus niger
1999 - IRG/WP 99-10307
The purpose of this study was to determine if nitrogen and sugar contents in rubberwood from three selected varieties (clones) rubber trees would affect the rate of colonisation by Botryodiplodia theobromae (a tropical sapstain fungus), Aureobasidium pullulans (a temperate sapstain fungus) and Aspergillus niger (a common mould fungus). Sapstain growth was rated daily until at least 50% mycelial coverage was achieved for 40x20x5mm3 samples from three rubberwood clones (GT1, PB217 and RRIM600) inoculated with the test fungi and incubated in a humidified petri dish assembly under aseptic conditions. All samples had more than 50% coverage of mycelium after 9 days of incubation. The results indicate that the nitrogen content of clone RRIM600 (1.06lmg/g) was significantly higher when compared to that of clone GTI (0.73mg/g) and clone PB217 (0.78mg/g). After oven drying (45°C), clone PB217 contained significantly higher amounts of fructose (5.55mg/g), glucose (2.30mg/g) and total sugar (13.15mg/g), as compared to clone GTI and RRIM600. Clone GTI had the lowest fructose (0.23mg/g), glucose (0.14mg/g), sucrose (2.20mg/g) and total free sugar (2.56mg/g). RRIM600 however had the highest amount of sucrose. B. theobromae spread significantly faster on RRIM600 (4.3 days when >50% mycelial coverage is achieved) than PB217 (5.6 days) or GTI (5.8 days) which is associated with the overall higher nutrient availability in clone RRIM600. Light sanding (down to 1-2mm depth) of sapstain infected samples revealed that deep sapstain typical of B. theobromae remained in the wood, contrasting with the absence of stain by A. pullulans and A. niger (both are typical superficial stainers) in the sanded material.
A J Ashari, J W Palfreyman, A H H Wong

Optimun storage period for the boron diffusion treatment of rubber wood
1996 - IRG/WP 96-30121
The study determined the maximum thickness of rubber wood that can be diffusion treated and the effect of diffusion storage period on the distribution of chemicals in treated wood of various thicknesses. Wood of thickness up to 50 mm can be easily diffusion treated with 10% boric acid equivalent (BAE) solution to adequate loading of chemicals. The optimum diffusion storage period to get uniform and adequate distribution of chemicals in the treated wood is two, three, nine and twelve weeks for 25, 50, 75 and 100 mm thick wood respectively.
T K Dhamodaran, R Gnanaharan

Decay resistance of densified ammonia-plasticized stems of oil palm (Elaeis guineensis)
1991 - IRG/WP 3673
When wafers of oil palm stems (Elaeis guineensis) were plasticized with 28% aqueous ammonia and immediately compressed mechanically, the treated material, gained 73% in basic density (average basic density, 0.695 g/cm³), and was highly resistant to decay by wood rot basidiomycetes. Compared with the control specimens (density, 0.403 g/cm³), resistance to decay of the densified specimens by Coriolus versicolor increased by 55%, and Gloeophyllum trabeum, 74%. Fungal decay was significantly correlated with basic density (densification effect) (r-value, between -0.77 and -0.92), mediated in part by a similar pattern of correlation (-0.86) between densification and decaying tissue moisture content. Mass losses of specimens which were plasticized but not subsequently densified, did not differ significantly (P<0.05) from the controls while basic density of such treated specimens decreased slightly (density, 0.358 g/cm³). Total nitrogen contents for the controls, specimens plasticized without densification, and densified plasticized specimens were respectively; 0.24, 0.65 and 0.63% (g/g), the control differing significantly from the rest. Substrate pH were similar among the three samples. It appeared that artificial densification (rather than total nitrogen levels) assumed an overriding influence on decay resistance of compressed ammonia-plasticized oil palm stems
A H H Wong, M P Koh

A laboratory study on effect of coating materials on leaching of copper from CCA treated wood
2001 - IRG/WP 01-50176
Components of CCA preservatives can leach into surrounding soil and water and have some effect on germination and growth of some plants. In this report, the effect of coating materials in reducing chemical concentration in the leachate were evaluated. Rubber wood blocks (Hevea brasiliensis) treated with CCA were fixed at room temperature at high humidity. After air dried, they were painted with coating materials, then followed by leaching procedure. The concentration of copper in the leachate was analysed by atomic absorption spectrophotometry. The results showed that coating materials could reduced the concentration of copper in leaching water. In addition, the resistance of treated wood against destroying fungi was studied. After painted with coating materials, wood specimens were exposed to fungi for the periods of time and results were discussed.
A Veenin, T Veenin

Laboratory evaluation of six commercial termiticides against subterranean termite, Coptotermes gestroi Wasmann
1994 - IRG/WP 94-30034
Small specimens of Heavea brasiliensis (10 x 10 x 20 mm³) were exposed to the laboratory colony of Coptotermes gestroi Wasmann for 4 months after dip- or brush-treatment with six commercially available emulsifiable termiticides (alpha-cypermethrin, cypermethrin, permethrin, bifenthrin, chlorpyrifos and chlordane). Synthetic pyrethroids and chlorpyrifos were effective as well as 1% treatment of chlordane at lower concentrations. No marked difference in effectiveness was noticed between dip- and brush-treatments. Field trials will be planned to examine their efficacy in the actual conditions in the search for alternative termiticides.
Y Sornnuwat, C Vongkaluang, T Yoshimura, K Tsunoda, M Takahashi

Some studies on fungal deterioration of rubber wood (Hevea brasiliensis)
1980 - IRG/WP 2140
For the sreening of anti-stain chemicals trials with selected agricultural fungicides and new chemicals were carried out. Botryodiplodia theobromae, Aspergillus sp. and Penicillium sp. were used at test organisms. For testing the durability of rubber wood (Hevea brasiliensis) suitable local rotting fungi (Basidiomycetes), based on high degrading power, which may later be employed in standard tests, were isolated: Trametes corrugata, Schizophyllum commune, Lentinus blepharodes, Lenzites palisotii, Ganoderma applanatum, Fomes senex and Polyporus zonalis. Several of the fungicides screened, such as benomyl, thiram, quintozene and captafol, are effective against the blue stain fungus Botryodiplodia theobromae, at fairly low concentrations. However at the levels required, none of them is cost-effective compared sodium pentachlorophenoxide, the preservative currently used for blue stain control in rubber wood. Of the seven Basidiomycetes tested, two of them - Lenzites palisotii and Ganoderma applanatum - were shown to give a high degree of degradation in rubber wood. These species could perhaps be used as test organisms for evaluating wood preservatives in Malaysia.
A Sujan, A G Tan, M Stevens

Laboratory Evaluation of the Formosan Subterranean Termite Resistance of Borate-treated Rubberwood Chipboard
2004 - IRG/WP 04-30359
Both no-choice and two-choice 4-week AWPA laboratory tests were performed to evaluate the resistance of borate-treated rubberwood (Hevea brasiliensis) chipboard prepared from a commercial mill run, against the Formosan subterranean termite Coptotermes formosanus. Boric acid (technical granular) was incorporated into the boards during manufacture to achieve loadings of 1.0% or 1.1% boric acid equivalents (BAE). In the no-choice test, both the untreated chipboard and solid rubberwood controls sustained heavy termite attack (respective mean visual ratings of 4.6 and 2.7 on a 10-point AWPA scale), while the two retentions of borate-treated chipboard showed only light grazing (mean rating 9.2). The two-choice test demonstrated a preference of termites for solid rubberwood (mean rating 2.4) instead of untreated chipboard (rating 8.4), and for untreated (mean rating 8.4 and 8.8) instead of borate-treated (mean ratings 9.8 & 9) chipboards. Complete termite mortality in the presence of borate-treated chipboard in both laboratory tests demonstrates the toxicity of borates to Formosan subterranean termites.
A H H Wong, J K Grace

Performance of Tuff Brite C™ and other formulations against blue-stain, mold and brown-stain in freshly-sawn rubberwood (Hevea brasiliensis) in the humid tropics of Peninsular Malaysia
1997 - IRG/WP 97-30163
The relative anti-sapstain and anti-mold efficacies, including brown-stain development in freshly-sawn rubberwood (Hevea brasiliensis) in the Malaysian tropics, between selected water-based product concentrations of formulations Tuff Brite CTM without/with added Borax (at 1.5/0, 1/1.5, 1.5/1.5 and 2%/1.5%), PQ8TM without/with added Borax (at 2.5/0, 1.5/1.5, 2/1.5 and 2.5%/1.5%) and NeXgenTM/NeX-BriteTM combination (at 1/0.25, 1.5/0.25 and 2%/0.25%) were assessed visually. Rubberwood boards, dipped in these concentrations for 1 min. were subjected to an 8 weeks sapstain trial in a FRIM sawmill shed. Sodium pentachlorophenate/Borax combination (at 2/1.5 and 2%/2%) was the reference anti-sapstain chemical. The rough-sawn boards were rated for blue-stain and mold weekly, while both the planed and the internal faces of the boards, sawn lengthwise into two-halves, were rated for blue-and brown-stain only after 8 weeks. Results for the rough-sawn boards, planed boards and the internal faces of the boards revealed a generally consistent excellent performance of Tuff Brite CTM without/with Borax against blue-stain and mold in rubberwood, protection being marginally better than that of NaPCP/Borax. Over a range of concentrations, performance by the remaining fomulations PQ8TM without/with Borax and NeXgenTM/NeX-BriteTM were variable: rated satisfactory (generally <10% surface infected) and/or poor (31-50% of surface infected) against sapstain and/or mold. Against brown-stain development (i.e. to conserve the natural cream/yellow hue in rubberwood), Tuff Brite CTM without/withBorax also appeared to be relatively better (generally yellow-to-light brown hue) than the other formulations, but perhaps only marginally so than NaPCP/Borax (light blue as well as yellow-to-light brown hue observed).
A H H Wong, T L Woods

Preservative treatment of rubber wood (Hevea brasiliensis) to increase its service life
2005 - IRG/WP 05-40320
Rubber wood (Hevea brasiliensis) possess excellent properties for interior designing, wood working and furniture making. But it is very much susceptible to sap stain and mould fungi which decreases the service life. For profitable uses , it is necessary to increase the service life of rubber wood. To protect the rubber wood from wood degrading agents, the sawn timber were treated with Borax – boric acid solution and Copper-chrome -boron solution by soaking process and Lowry empty cell pressure process following moderate treatment schedule. It was found that rubber wood can be treated satisfactorily by both the processes with acceptable penetration and retention.
K Akhter

Treatment of rubberwood (Hevea brasiliensis)
1997 - IRG/WP 97-40081
In this study treatability of rubberwood, timber from rubber trees (Hevea brasiliensis) was investigated by using both pressure and non-pressure methods. Samples with 4 cm by 4 cm cross section were sawn from the logs which were harvested from a plantation located in Batu Pahat, Johor, Malaysia. Full-cell and cold soaking methods were employed using Copper Chrome Arsenate (CCA) for the experiments. Samples were treated with 10% concentration of CCA for the cold soaking method while 5% concentration was used for the full cell method. Retention, penetration, characteristics of the samples treated with both methods and the effect of pressure treatment on mechanical properties of specimens were evaluated. Average retention values for cold soaking methods ranged from 1.47 kg/m3 to 12.58 kg/m3. These values were found to be 31.84 kg/m3, 32.58 kg/m3, and 34.15 kg/m3 as a result of 2 hours, 4 hours, and 6 hours pressure treatments, respectively. Static bending properties of rubberwood reduced as pressure treatment time increased. Six hour treatment resulted in approximately 30% reduction in modulus of rupture of the specimens. Modulus of elasticity also decreased with increasing pressure treatment time.
S Hiziroglu

Protection of rubberwood timber. Part 1: Impregnation with boron preservatives
1989 - IRG/WP 3551
Rubberwood (Hevea brasiliensis) were treated with a 3% proprietary mixture of borax/boric acid using three different treatment schedules i.e. full-cell, full-cell to refusal and full-cell with 12 cycles of vacuum/pressure. Freshly cut samples had mean preservative retentions of 187 kg/m³, 214 kg/m³ and 178 kg/m³ respectively. Pre-air dried samples for one week had retentions of 252 kg/m³, 308 kg/m³ and 282 kg/m³ respectively. An increase of pressure time from 45 minutes to 90 minutes allowed for slightly higher retention values. Preservative retentions of the core (20 mm² around the centre) from freshly sawn samples were 0.08-0.13% m/m BAE (boric acid equivalent), 0.04-0.19% m/m BAE and 0.04-0.21% m/m BAE for the full-cell, full-cell to refusal and full-cell with 12 cycles vacuum/pressure treatment respectively. Retention values of similar samples from the surface up to a depth of 10 mm were 0.36-1.51% m/m BAE for the 3 different treatments.
L T Hong, C C K Liew

Rubberwood anatomy and its influence on gaseous permeabilit
1993 - IRG/WP 93-40005
The anatomical structure in several rubberwood (Hevea brasiliensis Muell. - Arg.) samples was examined by use of a Cambridge Stereoscan 600 scanning electron microscope. A series of electron micrographs is presented which illustrate those features anticipated as having an influence on permeability. A series of gas permeability experiments were performed on oven dried samples of rubberwood to determine the relative longitudinal, radial and tangential gaseous permeabilities. The results indicated that the permeability in the different directions examined was in the descending order longitudinal > tangential > radial. Graphs of specific flow rate as a function of mean pressure demonstrated that flow was essentially through one component in the longitudinal direction whereas in the tangential and radial directions it was through more than one.
A J Pendlebury, J A Petty

Resistance of two commercial cement-bonded rubberwood particle composites to decay and termites
2000 - IRG/WP 00-10338
Two types of cement-bonded rubberwood (Hevea brasiliensis) particle composites (tradenames: Cemboard and Primaflex in Malaysia), were evaluated for termite resistance (prevalent termite: Coptotermes curvignathus) in the field, and decay resistance (test white rot fungi: Schizophyllum commune and Pycnoporus sanguineus; test brown rot fungus: Gloeophyllum trabeum; test soft rot fungi: Phialophora fastigiata and compost-Chaetomium globosum mixed inocula) in the laboratory. Three termite- or decay- susceptible wood materials [rubberwood, kempas (Koompasia malaccensis) and radiata pine (Pinus radiata) pressed pulp] were also included for comparison. Both types of wood-cement composites were consistently shown to be immune to decay fungi and subterranean termites, recording also much lower final moisture contents of the composites compared with rubberwood, kempas and radiata pine pressed pulp. These wood-cement composites are therefore suitable for use in a severe decay and termite hazard.
A A H Wong

Economical schedule for boron treatment of rubber wood: Pilot plant investigations
1993 - IRG/WP 93-40002
An economical treatment schedule (15 minutes initial vacuum of 85 kPa; 15 minutes pressure of 1000 kPa; 5 minutes final vacuum of 85 kPa) was arrived at for treating air-dried rubber wood (Hevea brasiliensis) in a pilot plant cylinder. Treating with 3% BAE (boric acid equivalent) solution resulted in a dry salt retention of 13.1 kg/m³. Also, the study showed that green rubber wood can be treated to required chemical retention level by employing the above treatment schedule and by increasing the concentration of the treatment solution to 6% BAE.
R Gnanaharan, T K Dhamodaran

Performance of proprietary formulations of anti-sapstain preservatives on Hevea brasiliensis timbers in laboratory tests
1989 - IRG/WP 3532
A total of 10 proprietary and two experimental formulations were assessed for their effectiveness against sap-stain caused by Botryodiplodia theobromae on Rubberwood (Hevea brasiliensis). Sterilized wood samples 5x20x40 mm³ were dipped in the test chemicals for 60 seconds and then inoculated with 0.5 ml of culture filtrate of Botryodiplodia theobromae for incubation in sterile, damp petri dishes. Two formulations, Kemicide 1009 and stainguard gave good control at 1% strength while the experimental formulation ES AS11, was effective at 0.05%. NP-1 was effective at 1.0-2.0% while TBP gave some control at 3%.
L T Hong

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