Disodium Octaborate Tetrahydrate Research Articles

Thermal analysis of Oriental beech wood treated with some borates as fire retardants

Wood is widely used as a construction material for many applications. To have knowledge about the thermal degradation characteristic of wood could be crucial for indoor and outdoor applications. Chemical treatments could improve the resistance of wood against fire and heat. In this study, to investigate the thermal properties of Oriental beech (Fagus orientalis) wood treated with 0,25%; 1% and 4,70% aqueous solutions of boric acid, borax, disodium octaborate tetrahydrate and mixtures of and in different proportions, thermogravimetric analysis, differential-thermogravimetry, and differentialthermal analysis were performed. Our results showed that borate treatment decreased the Tmax (maximum degradation temperature) and increased residual char amount. Higher concentration levels of borates resulted in higher char content of Oriental beech wood specimens. Residual char content of borate treated wood samples at fixed concentration of 4,70% ranked as in the following order: disodium octaborate tetrahydrate > boric acid + borax (7:3) > boric acid + borax (1:1) > boric acid > borax >Control. The highest residual char content was achieved for the sample impregnated with 4,70% disodium octaborate tetrahydrate among the all treated samples.

Insecticide Dip Treatments to Prevent Walnut Twig Beetle Colonization of Black Walnut Logs

Abstract The health, sustainability, and commercial viability of eastern black walnut (Juglans nigra) are currently under threat from thousand cankers disease. The disease is caused by an invasive bark beetle species, the walnut twig beetle (Pityophthorus juglandis), and its associated fungal pathogen (Geosmithia morbida). Range expansion of the beetle and pathogen has likely been facilitated by transport of infested walnut forest products. Preventing colonization of these products is crucial to limiting further spread of thousand cankers disease. This study evaluated three insecticides for their ability to induce walnut twig beetle mortality and prevent colonization of black walnut bolts, 3 to 5 cm in diameter, after dip treatment applications. Treatments included 0.003 percent azadirachtin, 15 percent disodium octaborate tetrahydrate (DOT), 0.5 percent permethrin, and water in Trial 1, and 0.013 percent azadirachtin, 30 percent DOT, 0.5 percent permethrin, and water in Trial 2. A total of 40 beetles, 4 beetles per sample, were exposed to treated samples and observed for 120 hours in each trial. Permethrin was the only treatment to achieve 100 percent mortality and prevent all colonization activity. The 30 percent DOT treatment increased mortality compared with the control; however, it did not reduce the mean number of attacks or mean gallery length. Azadirachtin was not effective at either concentration. Results suggest that insecticide dip treatments can prevent walnut twig beetles from colonizing cut black walnut logs. Treatments could be used in conjunction with phytosanitation to help prevent further spread of thousand cankers disease while allowing for the continued transport of bark-on walnut forest products.

An International Termite Field Test of Wood Treated with Insecticides in a Buffered Amine Oxide Carrier

Abstract A buffered amine oxide carrier has shown promise to deeply penetrate dry lumber with insecticides for termite control without using pressure treatment. Pine sapwood from trees attacked by mountain pine beetle (MPB) has increased permeability. In this study, short lengths of heavily blue stained, post-MPB lodgepole pine lumber (Pinus contorta) were treated with the buffered amine oxide carrier to borate levels less than the retentions recommended for protection against attack by the Formosan subterranean termite (average, 0.5% mass/mass boric acid equivalent ), with and without the addition of organic insecticides. Additional samples were pressure treated with alkaline copper quaternary type D carbonate (ACQ-D) and disodium octaborate tetrahydrate (DOT). The boards were installed in field tests in Hawaii and Japan at sites with confirmed populations of Formosan subterranean termites. They were inspected after 2 and 5 years. Dip plus kiln-conditioning treatment with imidacloprid, permethrin plus imidacloprid, and permethrin provided good protection to post-MPB lodgepole pine lumber against termite attack over 5 years in Hawaii and Japan. Dip plus kiln-conditioning treatment with the buffered amine oxide alone provided no protection because of the low loading of borate used as the buffer. Samples that were DOT pressure treated to below the retention required for Formosan termites in American Wood Protection Association standards did not perform as well, possibly as a result of poor heartwood penetration as well as below-standard retentions. Addition of permethrin to DOT pressure treatment improved performance. ACQ pressure-treated samples did not perform as well, with two failures in Hawaii. This was also likely associated with poor penetration in the heartwood because this material was not incised.

Comparison of disodium octaborate tetrahydrate‐based and tannin‐boron‐based formulations as fire retardant for wood structures

ABSTRACTBoron‐based formulations are used to improve the service life of timber. On the one hand, boron‐treated wood increases resistance to biological attacks (e.g. by fungi and insects), and on the other hand, it renders wood more resistant to burning. In the present study, we analyse the fire behaviour of some water‐borne formulations containing boron. A completely inorganic formulation (disodium octaborate tetrahydrate (DOT)) is compared with new‐generation tannin‐based wood preservatives in which the flavonoid network is used to fix the boron to wood. The study of the fire behaviour was carried out according to four specific fire tests: (i) dripping; (ii) short‐term exposure; (iii) long‐term exposure and (iv) the limiting oxygen index. The Scots pine (Pinus sylvestris L.) specimens treated with DOT have shown a complete efficacy against fire after all tests were completed. It should also be noted that very positive results have also been achieved by the tannin‐based solutions. DOT has to be preferred when high performance is required, but exclusively for interior applications. The use of tannin‐based formulations can be suitable for outdoor fire protection and also for indoor applications when specific aesthetic requirements should be fulfilled. Copyright © 2013 John Wiley & Sons, Ltd.

Hydrothermal conversion of woody biomass with disodium octaborate tetrahydrate and boric acid

In this study, Scotch pine (Pinus sylvestris L.) was used as a woody biomass in the form of sawdust. Hydrothermal conversion of the biomass was carried out in the absence and presence of disodium octaborate tetrahydrate and boric acid at the temperatures of 250, 300 and 350°C. The effects of temperature and catalysts on the product distributions and bio-oil compositions were investigated. The highest total bio-oil yield obtained at 300°C with disodium octaborate tetrahydrate was 34.9wt%, whereas the total bio-oil yields from the non-catalytic run and the run with H3BO3 at 300°C were 24.6wt% and 19.1wt%, respectively. Although the composition of bio-oils was similar in all runs, some compounds such as furfural and furfural derivatives were not observed in the light and heavy bio-oils produced from the non-catalytic run and the run with disodium octaborate tetrahydrate at 300°C. The light bio-oils from all runs contained mainly oxygenated hydrocarbons. The major compounds in HBOs were the following: 4-methyl-3-penten-2-one and 4-hydroxy-4-methyl-2-pentanone for disodium octaborate tetrahydrate, 4-hydroxy-4-methyl-2-pentanone and (Z,Z)-9,12-octadecadienoic acid for the non-catalytic run and (Z,Z)-9,12-octadecadienoic acid for the run with boric acid. The maximum heating values for the LBO and HBO were estimated to be about 25 and 28MJ/kg, respectively, and they were obtained with disodium octaborate tetrahydrate. SEM analysis of the bio-char obtained from the non-catalytic run at 250°C showed a semi-char formation. An increase in temperature from 250 to 300°C led to the formation of regular channels on the surface of the bio-char. These open channels closed when the temperature was increased from 300 to 350°C.

Boron Diffusion in Surface-Treated Framing Lumber

Abstract The extent of boron penetration in framing lumber treated by spray applications during construction is not well quantified. This study evaluated the effect of formulation and concentration on diffusion of boron in lumber specimens that were equilibrated in conditions that produced wood moisture contents of 18 to 21 percent. One set of specimens was pressure treated with water before equilibration. Borate solutions were prepared from powdered disodium octaborate tetrahydrate (DOT) or from two commercial glycol-borate formulations and applied with a garden-type sprayer. The DOT solution was applied at a 15 percent concentration, while the glycol-borate formulations were applied at 15 and 23 percent concentrations. Boron penetration was evaluated after 6, 13, and 26 weeks and boron retention after 26 weeks of diffusion. Boron penetration was observed for all treatments and progressed for the duration of the study. There was no significant penetration difference between the powdered DOT and glycol-borate solutions when they were applied at the same (15%) DOT concentration. However, after 6 weeks, the glycol-borate solutions applied at the 23 percent DOT concentration produced significantly greater depth of penetration than the solutions applied at the 15 percent concentration. The exception was the 15 percent DOT solution applied to the specimens that had been wetted and then dried down to equilibrium conditions. These specimens had the greatest penetration, possibly as a result of their higher equilibrium moisture content. Retention analysis revealed that the glycol-borate solutions applied at the 23 percent DOT concentration yielded significantly greater boron retentions in the outer assay zone. This effect was less apparent for the inner assay zones. Although boron retentions in the outer assay zone were below those standardized for pressure-treated wood, in some cases they exceeded reported concentrations needed for protection against termites and decay fungi.

The effect of some wood preservatives on the thermal degradation of Scots pine

Wood has been a structural material for many years; however, its ability to burn has limited its use in some applications. This study aims to evaluate the effect of commercial wood preservatives having concentration of 4% on the thermal behavior of Scots pine wood, and compare the fire retardant effectiveness of these preservatives with that of boron compounds. Thermal degradation of treated and untreated wood samples was evaluated by thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA). Thermal behavior of treated wood differed from thermal behavior of untreated wood in terms of a high char yield. Results showed that weight loss of wood reduced while char yield increased in the charring phase of the pyrolysis in the boron containing preservative treated wood accompanying with pyrolysis temperature lowered. The highest char yield was obtained from the samples treated with disodium octaborate tetrahydrate in the all treated groups.

Effects of Postlayup Borate Treatment on Appearance and Flexural Properties of Douglas-Fir Glued Laminated Beams

Abstract Preservative treatments are required whenever glued laminated beams are exposed outdoors. Treatments can be either water-based systems applied to individual laminations prior to layup or organic solvent–borne systems applied after the beams are fabricated. Water-based systems are not recommended for posttreatment because of concerns over checking and the potential for reductions in flexural properties, but there are few data on the effects of these treatments. The effects of pressure treatment with disodium octaborate tetrahydrate (boron) on flexural properties, glue-line shear, and visual appearance were investigated using Douglas-fir (Pseudotsuga menziesii) glued laminated beams. While treatment did result in the presence of drying checks on some beams, boron treatment followed by air seasoning or mild kiln drying did not produce any significant effects on modulus of rupture, modulus of elasticity, or glue-line shear. The results indicate that boron treatment does not affect load-bearing properties.

Research on Fire Retardant Performance of Chinese Fir with the Compound of Disodium Octaborate Tetrahydrate and SiO<sub>2</sub> Gels

The environmental fire retardant mentioned in this paper was compounded of disodium octaborate tetrahydrate and silicon dioxygen(SiO2)gels. Specimens of Chinese fir were impregnated with the compound by pressure and its fire retardant performance was studied. Results showed that, the anti-loss performance of disodium octaborate tetrahydrate was improved obviously. Compared with the untreated specimen, total heat release of the treated specimens decreased by 44.5% on average, while heat release rate decreased by 50.85% on average and ignition time prolonged obviously, which indicates that this compound possess good fire retardancy effect

Water Vapor Sorption Isotherms for Southern Pine Treated with Several Waterborne Preservatives

Abstract Equilibrium moisture content (EMC) was measured over a range of relative humidities at 22.5°C to determine whether certain wood preservatives increase the hygroscopicity of southern pine (Pinus sp.) The treatments studied were alkaline copper quaternary (ACQ) at a retention of 6.6 kg⋅m−3, chromated copper arsenate (CCA) at 6.9 kg⋅m−3, and disodium octaborate tetrahydrate (DOT) at 3.8 kg⋅m−3 (equivalent to 2.6 kg⋅m−3 as B2O3). All treatments examined increased the EMC at relative humidities above 60 %. Wood treated with DOT was the most hygroscopic. At high relative humidities, the ratio of the EMC of ACQ-treated wood to CCA-treated wood was 1.08. It is unlikely that the higher corrosiveness of ACQ compared with CCA is due to this slight increase in hygroscopicity.

INFLUENCE OF FOLIAR FERTILIZATION ON MINERAL COMPOSITION, SUGAR AND ORGANIC ACID CONTENT OF SWEET CHERRY

The influence of a three-year-long foliar fertilization programme on mineral composition of leaf, content of sugars (glucose, fructose, galactose and sucrose) (Prunus avium L.) and organic acids (citric, malic and fumaric acid) of sweet cherry fruits was studied. The experiment was conducted during 2005-2007 in West Hungary on mature 'Germersdorfi 3' grafted on Prunus mahaleb rootstock, planted in 1999 and grown in a calcareous chernozem soil. Trees were foliar-fertilized with potassium (K) as KNO 3 , calcium (Ca) as Ca(NO 3 ) 2 and boron (B) as disodium octaborate tetrahydrate (Na 2 B 8 O 13 4H 2 0). Boron spraying was conducted at blooming time and 35 days later. Potassium spraying was carried out 21 and 35 days after full bloom while calcium was applied 21, 35 and 42 days after full bloom. Besides fruit analysis, complete soil and leaf analyses were carried out to study the rate of nutrient uptake and its effects on fruit quality. The applied treatments (except K 1 ) increased leaf K significantly as compared to the control till ripening. Treatments had no consequent effect on leaf Ca till ripening. After ripening, B was present in significantly higher amounts in treated leaf samples. From all applied treatments only boron had a significant effect in increasing sugar contents as compared to the control. Furthermore, repeated Ca spraying had significant effect on the contents of organic acids while B applications led to significantly lower acid contents in the fruit.

Effects of polyvinyl alcohol on leachability and efficacy of boron wood preservatives against fungal decay and termite attack

In this study, the use of polyvinyl alcohol (PVA) as boron fixative agent was investigated. Two levels of PVA (2.5 and 4%) were evaluated with disodium octaborate tetrahydrate (DOT) at three concentrations (1, 2 and 4% boric acid equivalent (BAE)) using a double vacuum impregnation process on Scots pine sapwood specimens. Leaching was performed according to a laboratory leaching procedure. Boron analysis using atomic absorption spectrometer showed a significant reduction in boron leachability for the samples treated with both concentrations of PVA when compared to the stand-alone boron treatment leading to boron retentions capable of preventing wood biological degradations. Decay resistance of the leached specimens was evaluated using the brown rot fungus Poria placenta. Even if complete protection was not fully achieved, an improvement in decay resistance was observed for the samples treated with DOT in presence of PVA. This leak of efficacy was attributed to a decrease in the biological activity of the complexed boron against fungi. Durability of treated wood against termite attack, evaluated using Reticulitermes santonensis, indicated a significant enhancement for the samples treated in presence of the fixative agent compared to the pure boron treatment.

Efficacy and Economic Benefits of Prophylactic Treatments of Newly Felled Bamboo

Bamboo (Bambusa spp.) users in Laguna and Rizal, Philippines, were surveyed regarding their willingness to accept varying degrees of bamboo powderpost beetle, Dinoderus minutus (F.) (Coleoptera: Bostrichidae), damage. The efficacy of deltamethrin, permethrin, or disodium octaborate tetrahydrate in water or in kerosene was then assessed against beetles on freshly cut bamboo (Bambusa vulgaris Schrader ex Wendland). Adult D. minutus in groups of 100 were capable of inflicting 50% cross-sectional damage on 30-cm-long bamboo samples within a 4-wk test period. Deltamethrin (0.01% [AI]). in water or kerosene provided significantly better protection against D. minutus attack on bamboo for 5 wk than did all other treatments. The results from a survey were then used to assess the cost/benefit ratio for each prophylactic treatment. Successful prophylactic treatment provided up to a 12:1 return, illustrating the benefits of such treatments.

Effects of monoglycerides on leachability and efficacy of boron wood preservatives against decay and termites

Borates are well known for their ability to protect wood against fungal and insects attacks. However, their use in outdoor applications is limited due to their high leachability from treated wood. In this study, monoglycerides were investigated as fixative agents to reduce boron depletion from Scots pine using a double vacuum impregnation process involving impregnation with disodium octaborate tetrahydrate (DOT) followed by a second impregnation with the fixative agent. Significant reduction in boron leachability in samples treated with monoglycerides was observed compared to the standalone boron treated specimens. Evaluation of decay resistance of treated blocks using the brown rot fungus Poria placenta indicated a slight increase of durability, while resistance to termites attacks was strongly improved as demonstrated by the low weight losses and the high termites mortality levels observed. Monoglycerides could therefore be valuable additives to reduce boron depletion for outdoor applications in which wood is exposed to natural leaching conditions.

Metal loss from treated wood products in contact with municipal solid waste landfill leachate

The research presented in this paper evaluates the potential impact of municipal solid waste (MSW) landfill leachate quality on the loss of metals from discarded treated wood during disposal. The loss of arsenic (As), chromium (Cr), copper (Cu), and boron (B) from several types of pressure-treated wood (CCA: chromated copper arsenate, ACQ: alkaline copper quaternary, CBA: copper boron azole, and DOT: disodium octaborate tetrahydrate) using leachate collected from 26 MSW landfills in Florida was examined. The toxicity characteristic leaching procedure (TCLP), the synthetic precipitation leaching procedure (SPLP), and California's waste extraction test (WET) were also performed. The results suggested that loss of preservative components was influenced by leachate chemistry. Copper loss from CCA-, ACQ- and CBA-treated wood was similar in magnitude when in contact with landfill leachates compared to synthetic TCLP and SPLP solutions. Ammonia was found as one of the major parameters influencing the leaching of Cu from treated wood when leached with MSW landfill leachates. The results suggest that disposal of ACQ- and CBA-treated wood in substantial quantity in MSW landfills may elevate the Cu concentration in the leachate; this could be of potential concern, especially for a bioreactor MSW landfill in which relatively higher ammonia concentrations in leachate have been reported in recent literature. For the As, Cr and B the concentrations observed with the landfill leachate as the leaching solutions were over a range from some sample showing the concentrations below and some showing above the observed value from corresponding SPLP and TCLP tests. In general the WET test showed the highest concentrations.

EVAULATION OF INSECTICIDES FOR WESTERN DRYWOOD TERMITE CONTROL, 2008

Six insecticides were tested for their effectiveness as localized treatments against Incisitermes minor populations contained in naturally infested boards. Candidate boards were collected from homes and decks from several cities in California. Boards were determined active for drywood termites using portable detection equipment that included termite feeding sensing devices (acoustic emission, AE) (Termite Tracker, Dunegan Engineering, Midland, TX) and X-ray (XR200, Golden Engineering, Centerville, IN). Boards with visual signs of damage were determined to be active with drywood termites by drilling a 2.4 mm dia hole and inserting the AE sensor probe roughly 8 mm deep and taking three one-min readings of termite feeding activity. This process was repeated every 45 cm down the entire length of the board. Additionally, X-ray images were taken for the entire length of each board. Three different board dimensional sizes (e.g., 2 by 4 & 2 by 6; 2 by 8 & 4 by 4; and 4 by 6 & 4 by 10) were stratified within treatment groups. Prior to treatment, all chemically treated and water only boards were drilled (2.4 mm dia) in a pattern that consisted of two diagonal holes spaced approximately 5 cm apart, down the entire length of the board for board dimensional sizes of 2 by 8 or less. For larger dimensional lumber sizes, two opposite sides of the board were drilled and treated. A State licensed structural pest control applicator conducted all drilling of holes and pesticide applications. Label instructions were followed and maximum insecticide rates were used. AIs included in laboratory tests were the following: Bora-Care® (disodium octaborate tetrahydrate (DOT) 40%, Nisus Corp., Rockford, TN), OptigardTM ZT (thiamethoxam 21.5%, Syngenta Crop Protection, Inc., Greensboro, NC), Premise Foam® (imidacloprid 0.05%, Bayer Environmental Science, Research Triangle Park, NC), Termidor SC (fipronil 9.1%, BASF Corp., Research Triangle Park, NC), Tim-bor® (DOT 98%, Nisus Corp., Rockford, TN), and XT-2000 (92% d-limenone, Xtermite, Inc., San Diego, CA and bottled by Speer, Memphis, TN). The Bora-Care was diluted with water 1:1 (20% final solution DOT). The Optigard ZT was prepared according to the label directions at a 15:1 ratio and applied with the Optigard ZT Foamer Kit. The Premise foam came as ready-to-use foam in a pressurized aerosol can equipped with an applicator tip. The Termidor SC was injected as an aqueous preparation at 0.12% final solution. The Tim-bor was mixed in water at a final 15% DOT solution. The XT-2000 was injected directly from the container into treated boards. All chemical treatments were randomized. In addition, two untreated checks were included in the study: treatments with water and no treatment. In total there were eight treatments, replicated three times. After treatment, boards were maintained in the laboratory at ambient temperature and humidity conditions for three months at the University of California Richmond Field Station. Post-treatment evaluations included dissection of all boards and counts of dead and alive termites. Data table contains treatment, board volume, number drilled holes, volume of product injected (ml) per cm, and percentage mortality. Differences in percentage mortality among treatments were conducted using ANOVA and Tukey HSD multiple comparisons test.

The response and recovery of the Formosan subterranean termite (Coptotermes formosanus Shiraki) from sublethal boron exposures

Controlling the Formosan subterranean termite, a cosmopolitan pest and the most structurally damaging pest in the state of Hawaii, is an important priority for homeowners and commercial builders alike. Boron-treated lumber is often part of an effective integrated pest management (IPM) strategy, owing to its effect of reducing attack by subterranean termites and preventing wood decay due to fungi and bacteria. Termites from field colonies maintained in Honolulu were collected and exposed to one of four composite boards: zinc borate (ZB)/disodium octaborate tetrahydrate (DOT) (boric acid equivalent or BAE 0.75%), anhydrous boric acid (B2O3) (BAE 0.75%), or an untreated composite board control; after 5 days the wood pieces were replaced with untreated composite boards. The effect of 5 days of boron exposure was examined by comparing the wet weight of termites, wood consumption, survival, and termite boron content. The analyses at both 5 and 10 days revealed significantly more boron in the termites exposed to treated timber than those not exposed, and decreased weight in those termites exposed to borates. The general trend was for the ZB treatment to have less of an effect on the termites than the DOT treatment, while were both less harmful than boric acid in these experiments. The boron content of the exposed termites declined by 66–74% after 5 days of feeding on untreated wood, indicating that termites can excrete or metabolize ingested boron over time. This ability to recover from sublethal exposure to boron may explain the gradual avoidance of borate-treated wood noted by other authors, and has implications for the inclusion of borate-treated timber in an IPM programs for preventing infestation by subterranean termites.

LIQUID BORATE BAIT FOR CONTROL OF THE ARGENTINE ANT, LINEPITHEMA HUMILE, IN ORGANIC CITRUS (HYMENOPTERA: FORMICIDAE)

Abstract A liquid bait delivery system containing borate was evaluated for controlling the Argentine ant, Linepithema humile (Mayr), in an organic citrus orchard. Two concentrations of disodium octaborate tetrahydrate (1% and 0.5%) were tested in 500-mL capacity bait stations placed at the base of trees. Both concentrations significantly reduced ant activity over the 11-wk duration of the test when compared with controls. However, the 1% concentration of borate significantly reduced ant activity up to 76 m away from the treatment, whereas the 0.5% did not. Compared to ant control with contact insecticides, the bait delivery system uses less insecticide and is more target-specific, reducing environmental contamination.

Comparison of Localized Injections of Spinosad and Selected Insecticides for the Control of <I>Cryptotermes brevis</I> (Isoptera: Kalotermitidae) in Naturally Infested Structural Mesocosms

We investigated the efficacy of various chemical injections against Cryptotermes brevis (Walker) (Isoptera: Kalotermitidae) in hardwood shipping pallets. We had three principle interests: efficacy in whole structures, relative efficacy of the active ingredients, and whether acoustic evidence augmented treatment site selection. Infested pallets were delineated into boards with four monitoring sites each. Six chemical treatments were compared: chlorpyrifos aerosol, aqueous disodium octaborate tetrahydrate (DOT), resmethrin aerosol, distilled water (control), and two treatments of spinosad SC (one treatment applied based upon visual and the other treatment upon acoustic [AE] evidence). Individual boards were split apart; efficacy was determined by percentage mortality and pre- and posttreatment AE counts. Injections were constrained to a single point per board with the greatest level of termite activity. In whole pallets, mean percentage mortality ranged from 53.3 to 58.7% for the visual and AE spinosad treatments, respectively, whereas water averaged 6.8%. Remaining treatment mortalities were 33.2, 30.4, and 18.1% for chlorpyrifos, DOT, and resmethrin, respectively. Analysis of whole-pallet data indicated that none of the insecticides produced commercially acceptable mortality; localized injections of insecticides were not comparable with whole-structure treatments. We delineated independent groups of board sections (sectional aggregates; SA) that were connected by galleries. When treated SA were analyzed, spinosad and DOT treatments were significantly different from controls, whereas remaining treatments were not different from controls or spinosad and DOT. AE readings and visual termite evidence were compared with presence or absence of termites in SA, and it was determined that both AE and visual evidence were effective predictors of termite presence.

Vetiver oil and nootkatone effects on the growth of pea and citrus

Studies have indicated that vetiver oil and one of its components, nootkatone, possess insecticidal and herbicidal activities. The compounds appear to be good candidates as novel pesticides for substrate (soil, wood, and mulch) treatments. Phytotoxicity is a concern for substrate treatment agents against soil dwelling organisms. Using treated potting media the phytotoxic effect of vetiver oil and nootkatone was evaluated on the pea plants ( Pisum sativum L.; cv, “Kelvedon Wonder”) in the laboratory and on citrus trees ( Citrus unshiu Marcovitch) under field conditions. All the tested chemicals at various concentrations (20, 500, and 2000 μg/g soil) reduced the pea plant growth (plant height, root length, dry weight). Nootkatone treatments had the lowest inhibitory effect on growth, followed by vetiver oil and disodium octaborate tetrahydrate (Tim-bor ®), a registered pesticide with known phytotoxicity. The most inhibitive and injurious effects occurred with Tim-bor ® at concentrations of 500 and 2000 μg/g soil, causing plant mortality of up to 38.9%. No pea plant mortality was observed in nootkatone and vetiver oil treatments. Vetiver oil and nootkatone treatments at the rates of 30 and 100 μg/g potting media had no adverse effect on the citrus plant growth rates. These results support the possible usage of the two chemicals around buildings and in nurseries for the management of termites, ants, and weeds; or in the nursery industry where quarantines may be in place to prevent the movement of invasive pests.