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Comparative response of Reticulitermes flavipes and Coptotermes formosanus to borate soil treatments
1991 - IRG/WP 1486
Eastern (Reticulitermes flavipes [Kollarl]) and Formosan (Coptotermes formosanus Shiraki) subterranean termite workers (Isoptera: Rhinotermitidae) were exposed to borate-treated sand in an indirect exposure tunneling assay in the laboratory. In the ten day assay period, both termite species readily penetrated sand containing 5000, 10000, or 15000 ppm (wt. of compound / wt. of sand) disodium octaborate tetrahydrate (Tim-BorÒ) or zinc borate (Firebrake ZB-FineÒ). With Reticulitermes flavipes, significant mortality (85-93%) resulted from workers tunneling through sand treated with 5000 ppm disodium octaborate tetrahydrate (higher concentrations were also effective), or 15000 ppm zinc borate. Responses of Coptotermes formosanus workers were lesser and more variable, with only concentrations of 10000 and 15000 ppm zinc borate resulting in mortality 70-89%) significantly different from that in the control groups. These results suggest that differences between these two species in tunneling behavior may reduce exposure of Coptotermes formosanus to the borate-treated sand.
J K Grace


Borate thermal treatments
1992 - IRG/WP 92-3715
Green, partially seasoned (air-dried, steam conditioned), or kiln-dried southern pine timbers were treated thermally using 15% disodiumoctaborate tetrahydrate solution. After treatment, sections were stored under non-drying conditions to allow for diffusion. Results showed that effective treatment meeting the AWPA minimum retention (0.17 B203 pcf [2.72 kg/m³] in the outer inch) and penetration (2.5-in [64-mm] or 85% of the sapwood) could be obtained only with certain combinations of seasoning, treatment, and diffusion storage. The best results in terms of both retention and penetration were obtained with material steamed and stored prior to treatment using a 10-min hot bath time. Kiln-dried timbers could not be treated effectively. The results suggest that non-conforming treatment of green or partially seasoned timbers will require higher solution concentrations, higher hot bath temperatures, and/or longer diffusion periods to meet required standards. Results also indicated that treatment of smaller stock in dimension sizes (up to 2-in [50-mm]) should be feasible.
H M Barnes, R W Landers, L H Williams


Treatment of Douglas fir heartwood with disodium octaborate tetrahydrate (Tim-BorÒ ) to prevent attack by the Formosan subterranean termite
1991 - IRG/WP 1487
Toxicity of disodium octaborate tetrahydrate (Tim-BorÒ) to Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), and termite feeding on treated Douglas-fir heartwood were evaluated in laboratory and field tests. Feeding on filter papers impregnated with Tim-BorÒ solutions reduced but did not eliminate termite gut protozoan populations. In a forced-feeding laboratory assay, Douglas-fir heartwood treated to Tim-BorÒ retentions ³0.35% BAE drastically reduced termite feeding and resulted in 100% termite mortality within three weeks. Gradual and significant mortality (49%) after four weeks of feeding at 0.16% BAE suggests that this or lesser concentrations may be useful in baits for remedial termite control. After 162 days of field exposure to an active Coptotermes formosanus colony in an accelerated field test, moderate feeding was noted at 0.65% BAE (13.6% weight loss) and 0.73% BAE (16.9% wt. loss), and only slight damage (2.5% wt. loss) at the highest retention field tested of 1.02% BAE. These results indicate that Tim-BorÒ provides protection from Formosan termite attack, but that some cosmetic damage occurs even at high retentions. This cosmetic damage is unlikely to create a structural hazard, but additional field evaluations are needed to determine the treatment requirements for timbers visible to the consumer.
M Tamashiro, R T Yamamoto, J K Grace


Preliminary evaluation of borate baits and dusts for eastern subterranean termite control
1990 - IRG/WP 1433
Borates are of potential use in the development of baiting systems for subterranean termite control. In the 15-day laboratory assays reported here, the oral toxicity of disodium octaborate tetrahydrate to Reticulitermes flavipes (Kollar) was evaluated under choice and no-choice conditions. These assays suggest a range of 2500 to 5000 ppm to be applicable in developing baits, and that concentrations greater than 5000 ppm may deter feeding. Laboratory assays with borate dusts (disodium octaborate tetrahydrate, zinc borate, and a fine-grain zinc borate) are also reported. In a toxic variation of mark-release methodology, these materials are passed among the test group by grooming foragers exposed to the dust. In these assays, 10% of the test group was exposed to the borate dust, then released placed in contact with unexposed workers in a simulation of a field release. Zinc borate treatment elicited the greatest mortality (99-100%), although disodium octaborate tetrahydrate also elicited mortality significantly greater than that in the control groups. These results suggest that less soluble borates may be more efficient dust toxicants, and that capture and dust-treatment of a portion of the foraging termite population could elicit high mortality among termites contacting the treated individuals after their release back into the colony.
J K Grace, A Abdallay, J M Sisson


Eastern subterranean termite responses to three soil pesticides
1990 - IRG/WP 1432
In laboratory assays simulating field conditions, tunneling and mortality of Reticulitermes flavipes (Kollar) workers were evaluated in sand treated with aqueous solutions of formulated chlorpyrifos, isofenphos, and disodium octaborate tetrahydrate. Chlopyrifos and isofenphos were evaluated at concentrations of 500 and 1000 ppm (weight of active ingredient / weight of sand), and disodium octaborate tetrahydrate at 2500 and 5000 ppm. No tunneling was observed in sand treated with chlorpyrifos, and high termite mortality suggested vapor and/or high contact toxicity. Tunneling was initiated in isofenphos-treated sand, and termites subsequently died in the tunnels from contact toxicity. At both concentrations, termite mortality from isofenphos exposure was equivalent to that with chlorpyrifos, but the shorter tunnel length at the higher isofenphos concentration (1000 ppm) indicated a concentration-dependent rate of mortality. Greatest tunneling was observed in sand treated with disodium octaborate tetrahydrate. Low and variable mortality with this compound at 2500 ppm are attributable to its slow toxic action and, possibly, difficulty in obtaining an homogenous distribution. Tunneling was not inhibited at 5000 ppm, but mortality was comparable to that observed with 1000 ppm chlorpyrifos, although slightly less than with 1000 ppm isofenphos. Termiticides having different repellency/mortality profiles are potentially useful in termite control.
J K Grace


Modelling the control of decay in freshly felled pine poles
1997 - IRG/WP 97-10206
In a recent study investigating control of decay in freshly felled pine utility poles, it became apparent that the efficacy of different treatment methods was strongly related to the size of the material being treated. A topical application of 5% w/v disodium octaborate tetrahydrate (DOT), brush applied to the cut surfaces of logs with otherwise intact bark was just as effective at excluding white rot colonisation in large diameter logs (greater than 30 cm) as it was in small diameter material (less than 15 cm diameter). In both instances, protection was effective for at least 12 months. In contrast, a biological treatment consisting of a spore suspension of a specially selected isolate of Trichoderma viride, was only effective in preventing white rot when applied to the small diameter logs. In larger logs, the extent of decay in biologically treated material was as high as that evident in the untreated controls. To ascertain why the effectiveness of the biological control was dependent on the diameter of material being protected, a simple mathematical model, describing both the growth of the Trichoderma and decay basidiomycetes, was devised. In addition to providing a valuable insight into the dynamics of biological control, this modelling exercise highlighted the benefits of applying such an approach to wood protection.
M W Schoeman, W Van der Werf, J F Webber, D J Dickinson


L-joint trials: Part 3: Relative performance of a range of preservative products
2002 - IRG/WP 02-30292
Long-term trials using the L-joints described in BS EN 330 and AWPA Standard E9-97 have been in progress at BRE since 1982. This paper records the current assessments of decay of L-joints in trials started between 1982 and 1994 with treatments applied to both Scots pine sapwood (Pinus sylvestris) and spruce (Picea sp.). Data are provided on a range of active ingredients including TnBTO, PCP, acypetacs zinc, azoles, isothiazolones, IPBC and disodium octaborate tetrahydrate.
J K Carey


Performance of borate-treated sill plates (dodai) in a protected, above-ground field test in Japan
2002 - IRG/WP 02-30278
This document is supplemental to the previous IRG document (IRG/WP 2000-30239). An experiment to simulate the dodai (sill plate) of the Japanese houses was conducted at the termite field test site of the Wood Research Institute in Kagoshima, Japan where two economically important subterranean termite species [Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe)] are established. DOT(disodium octaborate tetrahydrate)-treated hem-fir samples [Tsuga heterophylla (Raf.) Sarg. and Abies amabilis (Dougl.) Forbes]- 105 x 105 x 400 mm in size were placed on concrete blocks 19 cm the above ground surface. The test samples were prepared from sound wood samples pressure treated to supply 10 replicates of shell-treated materials at target levels of 2% BAE and 3% BAE. The subsequent diffusion storage produced another set of through-treated samples at the same target levels. Feeder stakes within the block hollows extended into the soil to facilitate the access of the termites to the wood samples. The assembled sets were covered with plastic boxes to protect the samples from the weather. Samples were annually inspected for termite attack and decay and visually rated according to AWPA standards since installation on December 21, 1995. After 6 years’ exposure, one or two samples from each group of borate treatments (2% BAE shell, 3% BAE shell, 2% BAE through and 3 % BAE through treatments) were very slightly attacked by termites, though these treatments were free from termite attack for the first 5 years. Over the same period, slight termite attack was observed on the samples of 2% BAE plus DDAC (didecyldimethylammonium chloride) and CCA 4.0 kg/m3 treatments, the latter included as a reference preservative. Untreated hem-fir and hinoki (Chamaecyparis obtusa Endl.) controls showed progressive termite attack starting in the first year and were moderately to heavily attacked after 6 years’ exposure. Incipient decay was first found on 7 untreated hem-fir and sapwood portion of two untreated hinoki during the 5th year of exposure. Decay on the untreated controls progressed in the 6th year as expected.
K Tsunoda, A Adachi, A Byrne, P I Morris, J K Grace


Disodium octaborate tetrahydrate, alone and in conjunction with a selected isolate of Trichoderma viride, reduces decay of fresh felled pine independent of the effect of weathering
1994 - IRG/WP 94-10054
Unpeeled billets of Corsican pine were treated with the following: 5% aqueous disodium octaborate tetrahydrate (DOT) solution; 5% DOT solution with an isolate of Trichoderma viride with a low susceptibility to borate; the Trichoderma viride isolate alone. Half of the billets in each treatment group were also placed in large-diameter plastic pipes to protect the billets from the weather. All three treatments gave good control of decay. Sheltering had no effect on the efficacy of any of the treatments, despite a significant weathering and leaching being present for the duration of the eight-month trial. These results suggest that boron-based preservatives may be viable treatments for controlling pretreatment decay in the forest situation.
M W Schoeman, D J Dickinson, J F Webber


Borate-treated food affects survival, vitamin B12 content, and digestive processes of subterranean termites
1990 - IRG/WP 1448
Toxicity of boron compounds was studied by analyzing survival rates and vitamin B12 contents in Formosan subterranean termites, Coptotermes formosanus Shiraki, that were exposed to dietary treatments for 10 days. The dietary treatments applied in moistened cellulose were (a) 0.05% boric acid equivalent (BAE) of disodium octaborate tetrahydrate, (b) 0.05% BAE of anmonium pentaborate plus sodium sulfate, (c) antibacterial control 0.09% streptomycin D, (d) untreated control-moistened cellulose, and (e) starvation control-no food. The main effects - colony and treatment -, and their interaction were shown to be significant by analysis of variance (ANOVA) tests. Survival of termites on diets (c) and (d) was not significantly different (P <0.05). Survival of termites on diet (d) was significantly higher than survival of termites exposed to diets (a), (b), and (e). Vitamin B12 content of termites exposed to diets (a), (b), (c), and (e) was significantly less than that of termites exposed to diet (d). Ingestion of borate-treated (and molybdate-treated) food by Reticulitermes flavipes (Kollar) suppressed the rates of methane production and H2-dependent reduction of CO2 to acetate by hindgut microbiota, apparently by indirect means. The mechanisms of how borate-treated food affects digestive processes or vitamin B12 contents of termites remains undefined. Results are discussed in relation to termite gut microecology and borate use for wood protection.
L H Williams, S I Sallay, J A Breznak


Efficacy of Didecyl Dimethyl Ammonium Chloride (DDAC), Disodium Octaborate Tetrahydrate (DOT), and Chlorothalonil (CTL) against Common Mold Fungi
2004 - IRG/WP 04-30338
The fungitoxic properties of four fungicides, alone and in combination, against four different mold fungi commonly associated with indoor air quality problems were evaluated on two different wood species and sheetrock. The fungicides were chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) (CTL) in a 40.4% aqueous dispersion, disodium octaborate tetrahydrate (DOT) in two different forms - a 40% glycol solution and a 98% wettable powder, and didecyl dimethyl ammonium chloride (DDAC) in an 80% solution. The fungi were Aspergillus niger, Cladosporium cladosporioides, Penicillium brevicompactum, and Stachybotrys chartarum. All fungicide treatments on wood reduced growth, sporulation and discoloration of the mold fungi when compared to nontreated specimens. No single fungicide provided total control of all four fungi on wood. CTL provided the best single-agent protection by totally preventing the growth of C. cladosporioides and S. chartarum and reducing growth of A. niger and P. brevicompactum to low levels. DOT in both forms was very effective against A. niger, but provided only sporadic protection against other fungi. DDAC provided good protection against S. chartarum but was not as effective against the other molds. Combinations of the different biocides were more effective than any single agent. DOT + DDAC totally prevented or greatly reduced growth of A. niger, P. brevicompactum and S. chartarum. Cladosporium cladosporioides was the most difficult organism to control, but even this was achieved when DDAC was increased to 1.0% with DOT. The most consistent control of discoloration, sporulation, and growth of the fungi on wood was obtained with the combination of DOT and CTL. DOT, alone or in combination with DDAC or CTL, was also very effective against the fungi on sheetrock. The results suggest that by using appropriate products, during construction or after water damage, problems associated with the growth of common molds and their potential health effects can be avoided.
J A Micales-Glaeser, J D Lloyd, T L Woods


Resistance of borate-treated lumber to subterranean termites in the field
1998 - IRG/WP 98-10255
Borate-treated wood samples were tested for their resistance against subterranean termites in the field. Wood samples (10.5x10.5x40cm3) of western hemlock were pressure impregnated with disodium octaborate tetrahydrate (DOT) and didecyldimethylammonium chloride (DDAC), and assigned into two groups on the basis of boron contents:high retention (1.5-2.2%BAE) and low retention(O.7~1.3%BAE). Eight replicates were prepared for each retention level. Four untreated controls were also included in the field evaluation for comparison. Each sample was placed on a concrete block 19cm above ground surface and covered with plastic box in Kagoshima, Japan on July 1, 1993. Four boxes were employed so that 5 samples (two each of treated groups and one untreated sample) were in each box. After two years of exposure, three of all the treated samples exceptionally sustained very slight attacks, while in general untreated controls were moderately to severely attacked. Borate-treatment was proved to be satisfactorily effective in protecting lumber in above ground situations from subterranean termites. Further trials have been set up to determine the long-term efficacy of the treatment compared to chromated copper arsenate treated and naturally durable wood.
K Tsunoda, A Adachi, T Yoshimura, A Byrne, P I Morris, J K Grace


Performance of Borate-treated lumber in a four-year, above-ground termite field test in Hawaii
2001 - IRG/WP 01-30265
We report the fourth year of field study results from a protected above-ground field test in Hawaii simulating the sill plate (dodai) used in conventional Japanese housing construction. Field tests were established in both Hawaii and Japan to examine the efficacy of disodium octaborate tetrahydrate (DOT, 2% and 3% shell and through) wood treatments. In Hawaii, chromated copper arsenate (CCA, 4 kg/m3) and ammoniacal copper zinc arsenate (ACZA, 4 kg/m3) were included in the test, along with untreated western hemlock and Pacific silver fir controls. Both field sites support active Formosan subterranean termites, Coptotermes formosanus Shiraki, although termite pressure is greater in Hawaii due to the uniformly favorable environmental conditions. This report updates the three-year results previously reported to IRG (Grace et al. 2000). After four years, minor damage (visual rating of 7, where 10 = sound and 0 = failure) has been noted to five individual treated dodai (out of a total of 10 boards from 7 treatments) as follows: 2% BAE shell treatment (2 boards), 2% BAE + DDAC through treatment (2 boards), and CCA treatment (1 board). Between the third and fourth years of the test, only four treated boards progressed to lower visual ratings: one 2% BAE shell treatment (from 10 to 7), one 3% BAE shell treatment (from 10 to 9), and two 3% BAE through treatments (from 10 to 9). In contrast, all untreated control boards were virtually destroyed during the past 11 months of exposure. Mean ratings for all wood treatments ranged from 9.2 to 10. These four-year results suggest that each of the DOT, CCA and ACZA treatments would provide long-term protection of dodai from termite attack.
J K Grace, R J Oshiro, A Byrne, P I Morris, K Tsunoda


Six-year Report on the Performance of Borate-treated Lumber in an Above-ground Termite Field Test in Hawaii
2004 - IRG/WP 04-30343
We report the fifth and sixth years of field study results from a protected above-ground field test in Hawaii simulating the sill plate (dodai) used in conventional Japanese housing construction. Field tests were established in both Hawaii and Japan to examine the efficacy of disodium octaborate tetrahydrate (DOT, 2% and 3% BAE shell and through) wood treatments. In Hawaii, chromated copper arsenate (CCA, 4 kg/m3) and ammoniacal copper zinc arsenate (ACZA, 4 kg/m3) were included in the test, along with untreated western hemlock and Pacific silver fir controls. Both field sites support active Formosan subterranean termites, Coptotermes formosanus Shiraki, although termite pressure is greater in Hawaii due to the uniformly favorable environmental conditions. To date, all wood treatments have performed well, with mean visual damage ratings ranging from 10 (ACZA) to 8.5 (DOT, 2% BAE shell treatment) on the AWPA 10 - 0 scale after six years. This report updates the four-year results previously reported in IRG/WP 01-30265 (Grace et al. 2001).
J K Grace, A Byrne, P I Morris, K Tsunoda


Remedial wood preservative efficacy of BORA-CARE against the Formosan subterranean termite and eastern subterranean termite (Isoptera: Rhinotermitidae)
1991 - IRG/WP 1504
When a spruce board (3.8 cm x 8.8 cm x 2.4 m) was surface-sprayed with BORA-CARETM solution (containing 23% disodium octaborate tetrahydrate) and stored in an air-conditioned room (24 ± 2°C and 60 ± 5% RH) for eight months, ca. 40% of the wood (measured by the cross section surface proportion) contained borates at the rate of >2,500 ppm BAE (boric acid equivalent). In a choice bioassay, termite feeding on wood treated with BORA-CARETM was significantly reduced compared to untreated wood. The majority of tested termites died at the end of the one month choice bioassay. In addition to the high ambient moisture in the bioassay units, water brought in by the subterranean termites may have contributed to the rapid diffusion of borates into the surface-treated board.
N-Y Su, R H Scheffrahn


Resistance of borate-treated lumber to subterranean termites under protected, above-ground conditions
2000 - IRG/WP 00-30239
An experiment to simulate the dodai (sill plate) of the Japanese houses was conducted at the termite field test site of Wood Research Institute in Kagoshima, Japan where two economically important subterranean termite species [Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe)] are established. DOT(disodium octaborate tetrahydrate)-treated hem-fir samples [Tsuga heterophylla (Raf.) Sarg. and Abies amabilis (Dougl.) Forbes] in a dimension of 105 x 105 x 400 mm3 were placed on concrete blocks 19 cm above ground surface. The test samples were prepared from sound wood samples pressure treated to supply 10 replicates of shell-treated materials at target levels of 2% BAE and 3% BAE. The subsequent diffusion storage produced another set of through-treated samples at the same target levels. Feeder stakes within the block hollows extended into the soil to facilitate the access of the termites to the wood samples. The assembled sets were covered with plastic boxes to protect the samples from the weather. Samples were visually inspected for termite attack and decay and rated according to AWPA standards. After 4 years&apos; exposure, borate-treated samples (2% BAE shell, 3% BAE shell, 2% BAE through and 3% BAE through treatments) were free from termite attack, while one replicate each of 2% BAE with DDAC (didecyldimethylammonium chloride) and CCA 4.0 kg/m3 treatments, the latter included as a reference preservative, were slightly attacked. Untreated hem-fir and hinoki (Chamaecyparis obtusa Endl.) controls were slightly to heavily attacked during the same test period. No sign of decay was found on any sample, although moisture contents were well above fiber saturation points in some samples.
K Tsunoda, A Adachi, T Yoshimura, A Byrne, P I Morris, J K Grace


Distribution of boron from fused borate rods in Douglas-fir transmission poles
1996 - IRG/WP 96-30112
The diffusion of boron from fused borate rods (disodium octaborate tetrachydrate) was monitored over 42 months in CCA-treated Douglas-fir transmission poles. The boric acid equivalent was estimated by the curcumin/salicylic acid color test on increment cores removed from the poles. Moisture content of the poles was quite variable but was always above 20 percent. The percent of increment core length showing boron was also variable with time of sampling from individual poles and between poles. Diffusion of boron increased until 18 months then decreased slightly at 30 and 42 months. Boron was almost always detected downward from the treatment holes at a distance of 25 cm. Likewise, boron was usually detected laterally from the insertion hole at a distance of 7.6 cm. Movement of boron upward from the insertion holes was often nil and not exceeding 5 cm. Thus, because of the variable penetration of boron in the Douglas-fir heartwood, untreated areas are present that are susceptible to decay.
T L Highley, F Green III, W F Finney


A technique for determining the efficacy of water diffusible preservative plugs for implanting in joinery in service
1987 - IRG/WP 2291
A technique is described for determining the efficacy of soluble, diffusible preservative plugs for eradicating decay in joinery. It uses blocks of Scots pine sapwood or heartwood adjusted to known moisture contents prior to the establishment of the test fungus Coniophora puteana, from a single longitudinal dowel and the subsequent introduction of the preservative plugs. Prevention of decay, eradication of the test fungus and movement of the preservative were monitored after exposure periods of up to 24 weeks. Movement of boron from borate-based plugs along the grain varied with moisture content and was largely independent of sapwood or heartwood or the type of preservative plug used; movement across the grain was more restricted. The zones protected from decay varied with moisture content and in sapwood were approximately 30 mm along the grain at 25% moisture content and over 100 mm at 50% moisture content; the protected zones in heartwood were somewhat greater than in sapwood. Generally the fungus was eradicated from the zones protected from decay but sometimes live fungus was still present; the long term significance of this needs further study.
J K Carey, A F Bravery


Life Cycle Assessment of borate treated wood
2005 - IRG/WP 05-50224-12
Life Cycle Assessment (LCA) is being used increasingly around the world by decision-makers to help incorporate the environmental component of sustainability into their activities. U.S. Borax regularly assesses how its products contribute to sustainable development. Using data gleaned from LCA of its products, the company recently completed its first ISO 14040 compliant cradle-to-grave LCA of lumber treated with Tim-bor® Industrial (Disodium Octaborate Tetrahydrate) and Oriented Strand Board treated with Borogard ®ZB (Zinc Borate). The goal of this research is to give architects and builders better information to determine the environmental sustainability of using borate-treated building materials in their construction projects.
M J Manning


Performance of borate-treated lumber in a protected, above-ground field test in Japan
2004 - IRG/WP 04-30344
This document is supplemental to the previous IRG document (Tsunoda et al., 2002). An experiment to simulate the sill plate (dodai) of the Japanese houses was conducted at the termite field test site of the Wood Research Institute in Kagoshima, Japan where two economically important subterranean termite species [Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe)] are established. DOT(disodium octaborate tetrahydrate)-treated hem-fir samples [Tsuga heterophylla (Raf.) Sarg. and Abies amabilis (Dougl.) Forbes]- 105 x 105 x 400 mm in size were placed on concrete blocks 19 cm the above ground surface. The test samples were prepared from sound wood samples pressure treated to supply 10 replicates of shell-treated materials at target levels of 2% BAE and 3% BAE. The subsequent diffusion storage produced another set of through-treated samples at the same target levels. Feeder stakes within the block hollows extended into the soil to facilitate the access of the termites to the wood samples. The assembled sets were covered with plastic boxes to protect the samples from the weather. Samples were annually inspected for termite attack and decay and visually rated according to AWPA standards since installation on December 21, 1995. All treated samples still remained free from decay after 8 years’ exposure, although slight progress in termite attack was observed on a few samples of 5 treatments within the last two years. Three samples with a target retention of CCA 4 kg/m3 were slightly attacked. On the other hand, 3% BAE through treatment performed best with mean rating of 9.8 against termite attack. After 8 years’ exposure, 2-4 samples from each group of borate treatments (2% BAE shell, 3% BAE shell, 2% BAE through and 3 % BAE through treatments) were slightly attacked by termites. Untreated hem-fir and hinoki (Chamaecyparis obtusa Endl.) controls showed progressive termite attack starting in the first year and were heavily attacked after 8 years’ exposure. Incipient decay was first found on 7 untreated hem-fir and sapwood portion of two untreated hinoki during the 5th year of exposure, whereas 9 and 4 sustained slight to heavy decay after 8 years’ exposure, respectively.
K Tsunoda, A Byrne, P I Morris, J K Grace


Laboratory evaluation of disodium octaborate tetrahydrate (TIM-BORÒ ) as a wood preservative or a bait-toxicant against the Formosan and eastern subterranean termites (Isoptera: Rhinotermitidae)
1991 - IRG/WP 1513
A no-choice bioassay indicated that termite feeding was significantly reduced when wood was treated with TIM-BORÒ at retentions of >3600 ppm and >900 ppm (w/w) for Coptotermes formosanus and Reticulitermes flavipes, respectively, and thus these wood preservative retention rates may be considered for these termite species. Results of a choice bioassay suggested retention rates of 450-1800 ppm and 450-900 ppm may be considered for Coptotermes formosanus and Reticulitermes flavipes, respectively when TIM-BORÒ is used in a bait-toxicant application.
N-Y Su, R H Scheffrahn


Termite resistance of borate-treated lumber in a three-year above-ground field test in Hawaii
2000 - IRG/WP 00-30236
A protected above-ground field test simulating the sill plate (dodai) used in conventional Japanese housing construction was established in both Hawaii and Japan to examine the efficacy of disodium octaborate tetrahydrate (DOT, 2% and 3% shell and through) wood treatments. In Hawaii, chromated copper arsenate (CCA, 4 kg/m3) and ammoniacal copper zinc arsenate (ACZA, 4 kg/m3) were included in the test, along with untreated western hemlock and Pacific silver fir controls. Both field sites support active Formosan subterranean termites, Coptotermes formosanus Shiraki, although termite pressure is greater in Hawaii probably due to the uniformly favorable environmental conditions. After three years, minor damage (visual rating of 7) has been noted to four individual treatment dodai (out of a total of 10 boards per treatment) as follows: 2% BAE shell treatment (1 board), 2% BAE + DDAC through treatment (2 boards), and CCA treatment (1 board). These same individual boards had been also rated 7 in the second year of the study; and, although at year 3 termites are still present on the boards in each case, there has been no further visible deterioration. This supports an hypothesis of delayed deterrence from termite exposure to these nonrepellent treatments. In contrast, untreated control boards in Hawaii were completely destroyed within one to two years. Overall, all treatments have provided very good protection from termite attack over the three years of the study, with 9.3 representing the lowest mean rating. These results support the use of DOT, CCA or ACZA treatments to protect dodai from termite attack.
J K Grace, R J Oshiro, A Byrne, P I Morris, K Tsunoda


Performance of borate-treated lumber after 8 years in an above-ground termite field test in Hawaii
2006 - IRG/WP 06-30390
We report eight years of field study results from a protected above-ground field test in Hawaii simulating the sill plate (dodai) used in conventional Japanese housing construction. Field tests were established in both Hawaii and Japan to examine the efficacy of disodium octaborate tetrahydrate (DOT, 2% and 3% BAE shell and through) wood treatments. In Hawaii, chromated copper arsenate (CCA, 4 kg/m3) and ammoniacal copper zinc arsenate (ACZA, 4 kg/m3) were included in the test, along with untreated western hemlock and Pacific silver fir controls. Both field sites support active Formosan subterranean termites, Coptotermes formosanus Shiraki, although termite pressure is greater in Hawaii due to the uniformly favorable environmental conditions. To date, all wood treatments have performed well, with mean visual damage ratings ranging from 10.0 (ACZA) to 8.2 (DOT, 2% BAE shell treatment) on the AWPA 10 - 0 scale after six years. This report updates the six-year results previously reported in IRG/WP 04-30343 (Grace et al. 2004).
J K Grace, A Byrne, P I Morris, K Tsunoda


Performance of borate-treated lumber in a protected, above-ground field test in Japan
2006 - IRG/WP 06-30395
This document is supplemental to the previous IRG document (Tsunoda et al. 2004). An experiment to simulate the sill plate (dodai) of the Japanese houses was conducted at the termite field test site of the Research Institute for Sustainable Humanosphere of Kyoto University in Kagoshima Pref., Japan where two economically important subterranean termite species [Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe)] are established. DOT(disodium octaborate tetrahydrate)-treated hem-fir samples [Tsuga heterophylla (Raf.) Sarg. and Abies amabilis (Dougl.) Forbes]- 105 x 105 x 500 mm in size were placed on concrete blocks 19 cm above the ground surface. The test samples were prepared from sound wood samples pressure treated to supply 10 replicates of shell-treated materials at target levels of 2% BAE and 3% BAE. The subsequent diffusion storage produced another set of through-treated samples at the same target levels. Feeder stakes within the block hollows extended into the soil to facilitate the access of the termites to the wood samples. The assembled sets were covered with plastic boxes to protect the samples from the weather. Samples were annually inspected for termite attack and decay and visually rated according to AWPA standard since installation on December 21, 1995. All treated samples still remained free from decay after 10 years’ exposure. In contrast, slight progress in termite attack was observed on a few treated samples within the last two years. Four samples with target retention of CCA 4 kg/m3 were slightly attacked with mean rating of 9.6 against termite attack after 10 years. This meant that the extent of termite attack did not develop after the first attack. Through treatment at 3% BAE performed as well as CCA 4 kg/m3 after 10 years with mean rating of 9.5. Although mean ratings of termite attack on the treated samples ranged from 8.8 to 9.6, statistical analysis showed no significant differences among all treatments. Untreated hem-fir and hinoki (Chamaecyparis obtusa Endl.) controls showed progressive termite attack starting in the first year and were heavily attacked after 10 years’ exposure. Decay was found on 9 and 6 untreated hem-fir and hinoki, respectively.
K Tsunoda, A Byrne, P I Morris, J K Grace


The Development of a novel method to preserve reeds using an environmentally friendly timber preservative and a unique engineering design.
2006 - IRG/WP 06-40335
Reeds are used in the construction of bush lodges in Northern Kwa- Zulu Natal, South Africa. Fungal, insect and ultra-violet damage to these reeds is posing a severe problem. Within a space of two years, the reeds are attacked and have to be subsequently replaced; a time consuming and costly exercise. A novel method has been used to successfully preserve these reeds with an environmentally friendly preservative containing disodium octaborate tetrahydrate in a water-based polymer system. The polymer allows for uninhibited diffusion of boron into the reeds, whilst the polymer cures to form a continuous protective film. By making use of two strategically drilled holes, which are 2 mm in diameter, the preservative is introduced into the reed shafts and nodes. The boron successfully diffuses into the walls of the reeds and is prevented from leaching out of the reeds. The water-based polymer provides sufficient protection against excessive ultra-violet damage. The test site, which is situated in the Hluhluwe Game Reserve in Northern Kwa-Zulu Natal – South Africa, has been monitored for nearly two years and there are no sign of insect or fungal damage to the reeds. Over the two-year period, the reeds were periodically inspected for deterioration in colour and deterioration in structural integrity.
K Govender, K G Moodley


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