Susceptibility of envelope-treated softwood to subterranean termite damage.
Two field trials were conducted to determine the aboveground effectiveness of envelope treatments of deltamethrin and permethrin for the protection of two softwood framing timbers, radiata pine, Pinus radiata D.Don, and slash pine, Pinus elliottii Englem., against damage by Australia's most economically important species of termite, Coptotermes acinaciformis (Froggatt). Specimens were treated with Tanalith[R] T (a novel solvent) to achieve 5-mm-depth envelopes. Details of a 12-month field trial in the wet/dry tropics of northern Australia (Darwin, Northern Territory) and of a 7-month trial in subtropical eastern Australia (Beerburrum, Queensland) using a different test method are presented. At the conclusion of the field trial in the Northern Territory, all timber specimens had evidence of contact by C. acinaciformis. Both the deltamethrin (0.002% mass/mass ovendried [m/m OD]) and permethrin (0.02% m/m OD) envelope treatments were completely successful. Similarly, the fully impregnated LOSP reference treatment containing permethrin (0.02% m/m OD) was also successful. Damage to the untreated and solvent (Tanalith[R] T) control specimens was variable due to the inclusion of both sapwood and heartwood specimens of radiata pine and slash pine in the trial. The Tanalith[R] T appeared to contribute to the overall effectiveness of the deltamethrin and permethrin envelope treatments. Similar results were obtained from the field trial in southeast Queensland using a different test protocol. C. acinaciformis and Schedorhinotermes seclusus (Hill) provided termite foraging pressure to most timber specimens. All treatments protected the test specimens. Termites did not cause damage to test specimens via untreated cut ends. Consequently, with regard to C. acinaciformis or S. seclusus, there appears to be no need to apply a supplementary treatment to exposed cut ends of Tanalith[R] T treated softwood framing material up to the profile dimension examined. The direction for further work is indicated.
Termites are generally found in the tropical and warm temperate regions of the world (Edwards and Mill 1986). In Australia, about 20 species of termite are of economic importance to timber in service in buildings (Watson 1990). Many countries, including Australia, are seeking suitable cost-effective methods to prevent damage to buildings by termites. Koppers Arch Wood Protection (Australia) Pty Ltd ("Koppers Arch") has developed a timber preservation system (International Patent Pending Application No. PCT/AU01/01625) whereby the carrier (Tanalith[R] T) remains mobile within the wood for a period of time, providing migration of the preservative within the treated wood. Treatment can be conducted using conventional pressure impregnation techniques. Unlike conventional batch systems, treatment can be conducted by an in-line process thereby providing an envelope treatment of dry softwood framing material (Cobham and Snow 2003). This method of treatment would be ideal for use in continuous production line facilities, such as sawmills. The envelope-treated material has a preservative penetration depth of at least 5 mm (Kennedy and Cobham 2003). Approval of envelopes for framing material is currently being assessed by the National Registration Authority (NRA) of Australia. Their approval would lead to 5-mm envelopes being included in Australian Standard AS 1604 (2000).
Prior to acceptance, the effectiveness of the envelope treatment to protect wood from damage by termites must be demonstrated. Koppers Arch engaged laboratories at CSIRO Forestry and Forest Products (CSIRO) and the Department of Primary Industries to conduct two independent field trials. Specimens of radiata pine, Pinus radiata D.Don, and slash pine, Pinus elliottii Englem., framing material (both heartwood and sapwood) envelope-treated with the synthetic pyrethroids deltamethrin or permethrin were evaluated for termite damage in two field trials with very different methodologies. Details of the work undertaken in the Northern Territory and in southeast Queensland, with Australia's most economically important species of termite Coptotermes acinaciformis (Froggatt) (Gay and Calaby 1970), are presented in this paper.
Materials and methods
Commercially available framing material (cross section: 35 by 90 mm) of radiata pine and slash pine were sourced from various suppliers by Koppers Arch and treated at their Trentham, Victoria, plant. Four treatments were prepared: three envelope treatments (Tanalith T solvent only; deltamethrin 0.002% mass/mass ovendried [m/m OD]; and permethrin 0.02% m/m OD) using the in-line dipping process and light organic solvent preservative (LOSP) (permethrin 0.02% m/m OD) using vacuum-pressure impregnation. The LOSP treatment conformed to Hazard Class 2 (H2) requirements, for aboveground, weather-protected situations, in accordance with AS 1604.1-2000 Standards Australia (2000). Framing material included both heartwood and sapwood. Sixteen combinations of treatments and timber type were prepared and supplied to both laboratories as 1-m lengths.
Northern Territory trial
Ten, 1-m lengths of radiata pine sapwood, radiata pine heartwood, slash pine sapwood, and slash pine heartwood were treated with each of the above-mentioned four treatments. These treated lengths, together with 10 untreated 1-m lengths of each timber substrate were forwarded to CSIRO. Six lengths of each of the four treatments for each timber substrate, as well as the untreated substrates, were randomly selected and cut to a specified plan. The remaining four lengths of each treatment/untreated substrate were stored as reference material. A central 350-mm section was cut from each of the six selected lengths of each treatment/untreated substrate. Each 350-mm section was further cut to provide a 100-mm sample for chemical analysis to determine pyrethroid content and a 250-mm test specimen for field-testing against termites.
Samples of solutions containing deltamethrin and permethrin that were used to envelope treat the framing material were also forwarded to CSIRO. Subsequently, exposed cut ends (35 by 90 mm) of all 250-mm-long test specimens were dipped for five seconds in the respective solutions of all four treatments and allowed to air dry.
After air-drying, all untreated and treated test specimens were artificially weathered to H2 conditions (i.e., volatilization in vacuum ovens for five days at 40[degrees]C and -95 kPa) as specified in the Australasian Wood Preservation Committee (AWPC) Protocols for Assessment of Wood Preservatives (AWPC 1997). The volatilization schedule was used to remove any residual solvent and volatiles from test specimens that may be deleterious to termite health and vigour as well as to provide artificial ageing. At each stage, care was taken to ensure that test specimens of different treatments were kept separate.
The test method adopted for the field trial satisfies the minimum requirements as specified in AWPC (1997) for evaluating preservative-treated timber intended for H2 service conditions. Six replications of test specimens were exposed to termite damage in the field. For each replication, a layer of highly termite-susceptible timber (mountain ash, Eucalyptus regnans F. Muell.) was placed inside the base of a 200-1 steel drum. A total of 10 test specimens (treated and untreated) were then placed inside the drum separated by strips of mountain ash. These mountain ash strips linked test specimens together. The ratio of mountain ash material to test specimens was about 2:1 m/m. Test specimens were arranged in three tiers: two bottom tiers of four specimens and a top tier of two specimens. There was a minimum distance of 200 mm between each test specimen. The two 35 by 250 mm edges of each test specimen were in direct contact with the mountain ash strips. Additional mountain ash and radiata pine timber was placed around and on top of the test specimens to attract termites into the drum as well as maintain their presence throughout the test duration. A lid was used to seal the drum. Each of the six replications (drums) was connected to trees infested with C. acinaciformis. To allow easy access for the termites to enter the drums, a 25-mm-diameter borehole was drilled into the center of the infested trees at a height of approximately 300 mm. One end of a 250-mm length of hollow plastic piping (25-mm diameter) was then inserted into the borehole with the other end of the piping inserted into a 25-mm-diameter hole (300 mm above the base) that had been drilled through the sidewall of the drum. To act as a termite foothold, a thin length of moistened hardwood veneer was placed inside the plastic piping. For protection against excessive heat and grass fires, all drums were covered with aluminium foil insulation.
Three drums contained only heartwood test specimens of each timber species (radiata pine and slash pine), whereas the other three drums contained only sapwood test specimens of each timber species. That is, three drums contained radiata pine and slash pine heartwood specimens X four treatments plus two untreated heartwood controls (10 test specimens per drum). The remaining three drums contained radiata pine and slash pine sapwood specimens X four treatments plus two untreated sapwood controls (10 test specimens per drum). Each drum was exposed to termites from a different colony of C. acinaciformis. This was achieved by ensuring that the distance between drums exceeded the likely foraging range of 50 m expected of C. acinaciformis (Greaves 1962). The test site was located at Gunn Point (12[degrees]23'S, 131[degrees]10'E), near Darwin in the wet/dry tropics in the Northern Territory of Australia where C. acinaciformis is common. The duration of the field trial was 12 months, but the drums were inspected on several occasions, without disturbing the test specimens.
At the conclusion of the trial, test specimens were removed from each drum and their surfaces carefully checked for evidence of contact by termites, such as mudding, mud tubing, faecal spotting, or damage. Test specimens were then cleaned and visually assessed for termite damage using the rating system shown in Table 1. The rating system was developed specifically for envelope treatments to assess whether damage of the envelope treatment occurred and, if so, an estimation of the amount of specimen remaining.
One hundred and forty test specimens (35 by 90 by 190 mm long) were evaluated in the trial; one test specimen cut from each 1-m length. Exposed cut ends of 80 test specimens (16 combinations of treatments and timber type by five replicates) were dipped for 5 seconds in their respective treating solutions and allowed to air-dry. Sixty test specimens (12 combinations of envelope treatments and timber type by five replicates) were not dipped. Radiata pine sapwood material ("studs", 35 by 70 by 2,400 mm) were cut into specimens ("control specimens", 35 by 70 by 190 mm and "feeder specimens", 15 by 70 by 190 mm long). The initial mass of each specimen was recorded. Peters and Allen (1995) demonstrated enhanced termite feeding on wood that had been oven-dried at 105[degrees]C for 24 hours. To avoid this enhanced feeding and termiticide denaturation and movement, the oven-dry mass of each specimen, as described in Peters and Fitzgerald (1998), was estimated. The mean estimated OD mass for the test specimens was 339.9 g (standard deviation [SD] = 63.5, number of samples [n] = 140), for the control specimens: 202.3 g (SD = 25.8, n = 64), and for the feeder specimens: 104.6 g (SD = 14.6, n = 168).
Test specimens (five per treatment) were exposed with radiata pine feeder specimens in plastic test containers, 90 mm deep by 210 mm wide by 310 mm long. Test specimens and feeder specimens were separated by corrugated cardboard. One treatment, with five replicates and six feeder specimens were used in each of 28 test containers. Radiata pine control specimens were also exposed in eight test containers to monitor termite foraging vigour.
Four trenches (Trench 1-4: each 300 by 300 by 10,000 mm long) were used. Each trench was filled with slash pine off-cuts and backfilled with soil to facilitate sustained foraging by termites. Nine concrete brick assemblies (about 100 mm thick) were placed on each trench. Radiata pine stakes (20 by 35 by 150 mm long) were driven into the ground within the gaps of the bricks to allow access by termites from the ground to the test specimens. Seven test containers, each holding five test specimens and six feeder specimens, were placed on each trench. Two test containers, each holding eight control specimens, were also placed on each trench. Each test container was then covered with heavy-duty black plastic and secured with soil. This method is based on Peters and Fitzgerald (1998) and is a modification of Protocol H2.2 Lunchbox Technique (AWPC 1997). C. acinaciformis and Schedorhinotermes spp. occur commonly in the trial site at Beerburrum (26[degrees]58'S, 152[degrees]54'E), in southeast Queensland, Australia. Following exposure for seven months, mass losses of the specimens were estimated. Termite activity in each test container was recorded at the time of harvest.
Results and discussion
Northern Territory trial
At the conclusion of the Northern Territory field trial, all test specimens had evidence of contact by C. acinaciformis. Mountain ash and radiata pine timbers had been destroyed. A summary of the ratings assigned to each test specimen after 12 months of exposure to C. acinaciformis and the range between the ratings that encompass each mean are given in Table 2. Whether or not a treatment was successful in protecting the radiata pine and slash pine specimens from significant damage by C. acinaciformis is also included in Table 2. In this study, deltamethrin and permethrin were applied as envelope treatments with an expected penetration depth of at least 5 mm. Therefore, to be deemed successful against C. acinaciformis, all six replicate specimens of a given treatment should each be rated as either 1 (sound) or 2 (superficial damage or grazing), i.e., damage by termites should not exceed a depth of 5 mm.
Clearly, the deltamethrin (0.002% m/m OD) and permethrin (0.02% m/m OD) envelope treatments were successful in protecting both radiata pine and slash pine specimens from significant damage by C. acinaciformis (mean ratings: deltamethrin, radiata pine = 1.2, slash pine = 1.2; permethrin, radiata pine = 1.2, slash pine = 1.5) (Table 2). An examination of the raw data showed that the deltamethrin and permethrin envelope treatments protected radiata pine and slash pine specimens from damage regardless of whether they contained heartwood or sapwood (Table 2). The fully impregnated LOSP treatment containing permethrin (0.02% m/m OD) (reference control) was also successful, with all test specimens being rated as either 1 (sound) or 2 (superficial damage/grazing) (Table 2). Observations throughout the field trial showed that the envelope treatments of deltamethrin and permethrin acted as strong repellents to C. acinaciformis.
As expected, the untreated radiata pine and solvent controls (both heartwood and sapwood) were substantially damaged by C. acinaciformis (Table 2). In contrast, slash pine heartwood is known to be highly resistant to damage by termites (Standards Australia AS 3660.1-2000). However, two specimens designated as heartwood were recorded as significantly damaged by C. acinaciformis. Examination of the specimens revealed that only 10 percent and 50 percent of their volume was heartwood. Termites heavily damaged the sapwood component, but did not damage the heartwood. The untreated slash pine specimens designated as sapwood were substantially damaged with the exception of one specimen that was unusually dense.
Data for the solvent controls of each timber substrate were variable. Many were destroyed whereas others had only superficial damage. Ratings ranged from 2 (superficial damage/grazing) to 7 (destroyed) (Table 2). However, much of the variability was due to the presence of sapwood in heartwood specimens and vice versa. Solvent-treated heartwood specimens of slash pine were highly resistant to damage by termites.
Mean ratings for the solvent controls of each timber substrate were lower than the corresponding untreated controls. It can be concluded therefore that the Tanalith T solvent appeared to contribute slightly to the overall effectiveness of the deltamethrin and permethrin envelope treatments. More detailed work needs to be conducted to confirm this conclusion.
At the time of harvest, termites (C. acinaciformis) were active in all but one test container on Trench 1; termites (Schedorhinotermes seclusus [Hill]) were active in all but two test containers on Trench 2; and termites (S. seclusus) were active in all test containers on Trench 4. C. acinaciformis was active with Heterotermes paradoxus (Froggatt) in one test container on Trench 1 and in one test container with S. seclusus on each of Trenches 2 and 4. Termites did not forage on Trench 3.
C. acinaciformis damaged all control specimens on Trench 1 (mean mass loss g = 133.8, SD = 41.4) apparently initiating foraging from the radial and tangential faces, preferentially in the early wood. Foraging on these faces usually stopped before the ends of the specimens. Where damage occurred to the ends of the specimens, foraging from within the specimen was implicated. The majority of the damage to control specimens on Trench 2 (mean mass loss g = 66.5, SD = 39.0) was caused by S. seclusus. Foraging by S. seclusus typically results in broad undulations across the earlywood and latewood and is usually distinctly different from that of C. acinaciformis. S. seclusus was also active foraging on control specimens on Trench 4 (mean mass loss g = 20.0, SD = 14.8) and feeding on the end grain was initiated.
Termite damage to feeder specimens and test specimens is presented in Table 3. Termites damaged feeder specimens in 19 test containers. Damage ranged from slight mass loss to almost complete destruction. Most damage occurred in test containers with untreated or solvent control specimens. One test container without damage to feeder specimens was on Trench 1; the other was on Trench 2.
Termites damaged test specimens in four test containers. Damage ranged from slight mass loss to almost complete destruction; damage occurred in three test containers with untreated specimens. The five untreated slash pine sapwood test specimens were destroyed. The untreated slash pine specimens designated as heartwood actually had high sapwood content. Termites foraged on this sapwood, leaving the heartwood undamaged. Termites damaged one radiata pine sapwood solvent control test specimen. Most of the mass loss, however, in this specimen was due to fungal decay, including brown cubicle rot. Similar fungal decay was recorded only in two other test containers.
On three of the four trenches, C. acinaciformis or S. seclusus, or both, provided termite foraging pressure. On these trenches, the termites entered the vast majority of test containers, but essentially damaged only untreated test specimens and feeder specimens. All Tanalith T envelope treatments, containing either permethrin or deltamethrin, protected the radiata pine and slash pine specimens (both sapwood and heartwood). Termites did not initiate damage to the exposed cut untreated ends of test specimens. With regard to C. acinaciformis, it appears unnecessary to apply a supplementary treatment to the cut ends of envelope-treated radiata pine and slash pine framing material for timber up to the profile dimension examined. Larger profiles may require end sealing. Peters and Fitzgerald (1998) noted that C. acinaciformis does not appear to initiate damage through the end grain of timber specimens whereas Mastotermes darwiniensis Froggatt can. It now seems likely that S. seclusus also can initiate such damage on untreated timber. More feeder specimens were damaged in test containers with untreated test specimens than in other test containers. Generally the damage on individual feeder specimens was greater in test containers with untreated test specimens. A slightly repellent effect of the treated test specimens on termites was evident.
Wood continues to be the most commonly used framing material for the construction of residential properties in Australia, as in North America. However, softwood framing timbers, such as radiata pine, slash pine, and Caribbean pine, P. caribaea Morelet, are susceptible to termite damage. The Queensland Building Act 1975 (and similar legislation in most other States and Territories of Australia) requires that buildings in Queensland be constructed in accordance with the provisions of the Building Code of Australia (BCA) (Australian Building Codes Board 1996). These provisions specify that all susceptible structural members of buildings be protected from damage by subterranean termites. If the materials and construction comply with Australian Standard AS 3660.1 (2000), the requirements of the BCA and the Queensland Building Act 1975 are satisfied. The use of other methods that will prevent damage to buildings by termites is also permitted in the Act. The decision to accept these preventative methods, which are not nominated in AS 3660.1 (2000), is at the discretion of each local government council.
For the purposes of the BCA, susceptible structural timbers treated with preservative in accordance with the provisions of Australian Standard AS 1604 (2000), are deemed 'not susceptible' to damage by subterranean termites. For aboveground, weather-protected situations H2, AS 1604 specifies approved preservatives, penetration patterns, and minimum preservative retentions. The carriers currently available to provide for penetration of the preservative are waterborne or organic solvent-borne systems. Both carrier systems have deficiencies. Waterborne carriers swell wood. Thus, treated timber needs to be re-conditioned prior to in-service use. While organic solvent-borne carriers do not swell wood, their main disadvantages are the high cost and the environmental concerns of volatile organic compounds being released into the atmosphere. Both systems require pressure plants, which are expensive to construct. Since they are batch processes, they do not compliment continuous sawmill production and require a high level of operator control to contain costs.
At the conclusion of the Northern Territory aboveground H2 field trial, all test specimens (treated, solvent-treated, and untreated) had evidence of contact by C. acinaciformis, as indicated by damage to the specimens, 'mudding', 'mud tubing', and/or faecal spotting by termites on one or more surfaces of each specimen. Both the deltamethrin (0.002% m/m OD) and permethrin (0.02% m/m OD) envelope treatments with Tanalith T were completely successful in protecting all radiata pine and slash pine specimens (heartwood and sapwood) from significant damage by C. acinaciformis. All test specimens were rated as either 1 (sound) or 2 (superficial damage/grazing). Similarly, the fully impregnated LOSP treatment containing permethrin (0.02% m/m OD) (reference control) was also successful in protecting all radiata pine and slash pine specimens (both heartwood and sapwood) from significant damage by C. acinaciformis, with all test specimens again being rated as either 1 or 2.
Compared to the performance of the untreated controls, the Tanalith T solvent controls appeared to exhibit some termite-repellent properties. This suggests that the solvent contributes slightly to the overall effectiveness of the deltamethrin and permethrin envelope treatments. Observations throughout the field trial showed that both deltamethrin and permethrin envelope treatments were repellent to C. acinaciformis.
Similarly, in the Queensland H2 field trial, the envelope-treated test specimens containing either permethrin or deltamethrin were not susceptible to termite damage by either C. acinaciformis or S. seclusus and appeared to be repellent. Unlike the Northern Territory trial, some test specimens in the Queensland trial had untreated exposed cut ends. Results appear to negate the need to apply a supplementary treatment to the exposed cut ends of radiata pine and slash pine specimens envelope-treated with either permethrin or deltamethrin. However, larger profiles may require end sealing.
Using specimens of sapwood only, further work should be undertaken to determine more conclusively the contribution of the Tanalith T solvent to the overall efficacy of the insecticidal formulations used for the envelope treatment of radiata pine and slash pine framing material. The need for re-sealing of cut ends with insecticidal formulation should be further investigated, especially on larger profiled timbers. If deltamethrin and permethrin are substituted by alternative actives, the collection of additional efficacy data is strongly recommended.
Table 1. -- Rating system employed for the assessment of termite damage on test specimens in the Northern Territory field trial. Rating Condition of specimen 1 Sound 2 Superficial damage or grazing by termites 3 Surface damage by termites > 5 mm in depth 4 Damage (slight) 10 to 25 percent mass loss 5 Damage (moderate) 25 to 50 percent mass loss 6 Damage (severe) 50 to 75 percent mass loss 7 Damage (destroyed) 75 to 100 percent mass loss Table 2. -- Mean ratings, the range, and whether the deltamethrin, permethrin, and LOSP treatments were successful in protecting radiata pine and slash pine specimens (heartwood and sapwood) from significant damage by C. acinaciformis in the Northern Territory field trial. (a) Mean Success Treatment Timber (b) rating (c) Range (pass or fail) Untreated control Radiata pine 6.3 5 to 7 Fail Slash pine 5.3 2 to 7 Fail Envelope-Tanalith Radiata pine 4.8 2 to 7 Fail solvent only Slash pine 3.8 2 to 7 Fail Envelope-deltamethrin Radiata pine 1.2 1 to 2 Pass 0.002% m/m (d) Slash pine 1.2 1 to 2 Pass Envelope-permethrin Radiata pine 1.2 1 to 2 Pass 0.02% m/m Slash pine 1.5 1 to 2 Pass LOSP (e)-permethrin Radiata pine 1.2 1 to 2 Pass 0.02% m/m Slash pine 1.0 1 to 1 Pass (a) To be deemed successful, all six replicate specimens of a given treatment must be rated as either 1 (sound) or 2 (superficial damage/ grazing). Key: 1 = sound; 2 = superficial damage/grazing; 3 = surface damage (> 5 mm in depth); 4 = slight damage; 5 = moderate damage; 6 = severe damage; 7 = destroyed. (b) For each timber substrate, means given comprise data for both heartwood and sapwood designated specimens. (c) Means of six replicate specimens. (d) Retentions (mass/mass) are based upon the ovendried mass of the treated wood. (e) Light organic solvent preservative (LOSP) conformed to Hazard Level 2 (H2) requirements in accordance with AS 1604.1-2000, Standards Australia (2000). Table 3. -- Mean mass loss and the range for damaged feeder specimens and test specimens and whether the deltamethrin, permethrin, and LOSP treatments were successful in protecting radiata pine and slash pine specimens (heartwood and sapwood) from significant damage by C. acinaciformis on Trenches 1, 2, and 4 in the Queensland field trial. Damaged Damaged feeder test Treatment/timber specimens Mean mass loss specimens g (range) Untreated control Radiata-heart 6 54.5 (31.1 to 76.9) 5 Slash-sap 6 46.9 (27.7 to 59.4) 5 Slash-heart 6 54.5 (18.1 to 97.8) 5 Envelope-Tanalith T solvent only (a) Radiata-sap 1 44.9 (b) 1 Slash-heart 1 1.3 (b) 0 Envelope-deltamethrin 0.002% m/m (c) Radiata-heart 3 2.2 (0.8 to 2.9) 0 Slash-sap 2 1.9 (1.2 to 2.7) 0 Slash-heart 0 0 0 Envelope-deltamethrin (a) 0.002% m/m Radiata-sap 0 0 0 Slash-sap 1 43.7 0 Slash-heart 4 52.4 (43.1 to 61.6) 0 Envelope-permethrin 0.02% m/m Radiata-heart 1 1.1 0 Slash-sap 4 16.5 (0.8 to 59.3) 0 Slash-heart 4 10.3 (1.9 to 33.3) 0 Envelope-permethrin (a) 0.02% m/m Radiata-heart 3 14.1 (1.2 to 36.8) 0 Slash-sap 4 51.1 (15.5 to 77.0) 0 Slash-heart 4 25.1 (12.1 to 56.5) (b) 0 LOSP (d)-permethrin 0.02% m/m (a) Radiata-sap 5 3.9 (0.6 to 9.7) 0 Radiata-heart 6 51.3 (1.4 to 105.9) 0 Slash-sap 4 16.0 (0.7 to 60.2) 0 Slash-heart 5 74.2 (47.9 to 86.9) 0 Success test Treatment/timber Mean mass loss specimens g (range) Untreated control Radiata-heart 96.4 (60.6 to 146.9) Fail Slash-sap 231.2 (183.2 to 262.5) Fail Slash-heart 45.1 (16.2 to 86.5) Fail Envelope-Tanalith T solvent only (a) Radiata-sap 61.1 (b) Fail Slash-heart 0 Pass Envelope-deltamethrin 0.002% m/m (c) Radiata-heart 0 Pass Slash-sap 0 Pass Slash-heart 0 Pass Envelope-deltamethrin (a) 0.002% m/m Radiata-sap 0 Pass Slash-sap 0 Pass Slash-heart 0 Pass Envelope-permethrin 0.02% m/m Radiata-heart 0 Pass Slash-sap 0 Pass Slash-heart 0 Pass Envelope-permethrin (a) 0.02% m/m Radiata-heart 0 Pass Slash-sap 0 Pass Slash-heart 0 Pass LOSP (d)-permethrin 0.02% m/m (a) Radiata-sap 0 Pass Radiata-heart 0 Pass Slash-sap 0 Pass Slash-heart 0 Pass (a) Test specimens with ends dip-treated. (b) Includes mass loss due to fungal decay. (c) Retentions (mass/mass) are based upon the ovendried mass of the treated wood. (d) Light organic solvent preservative (LOSP) conformed to Hazard Level 2 (H2) requirements in accordance with AS 1604.1-2000, Standards Australia (2000).
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Kennedy, M.J. and P.R.S. Cobham. 2003. Controlled envelope treatments of Pinus sapwood achieved by modifications of impregnation process and carrier solvents. Paper presented at the 34th International Research Group on Wood Preservation Annual Meeting, Brisbane. Australia. Doc. No. IRG/WP 03-40258. 4 pp.
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___________ and C.J. Fitzgerald. 1998. Field exposure of borate-treated softwood to subterranean termites (Isoptera: Rhinotermitidae, Mastotermitidae). Material und Organismen. 32(1):41-66.
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The authors are, respectively, Forest Products Entomologist, Dept. of Primary Industries, Indooroopilly Sciences Center, Gate 3, 80 Meiers Rd., Box 631, Indooroopilly, Queensland 4068, Australia and Forest Products Entomologist, CSIRO Forestry and Forest Products, Private Bag 10, Clayton South, Victoria 3169, Australia. The authors acknowledge Peter Cobham and Dr. Joely Taylor (Koppers Arch Wood Protection (Australia) Pty Ltd.) for funding, useful criticism, and supply of treated material. This paper was received for publication in June 2003. Article No. 9688.
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|Author:||Peters, Brenton C.; Creffield, James W.|
|Publication:||Forest Products Journal|
|Date:||Dec 1, 2004|
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