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• 41. [Article] Patterns of fungal attack in wood-plastic composites following exposure in a soil block test

  The ability of white and brown rot fungi to colonize wood-plastic composites was investigated by measuring weight loss and anatomical changes. Three composite materials were evaluated. The material containing ...

  Citation × Citation Citation Abstract Copy Title: Patterns of fungal attack in wood-plastic composites following exposure in a soil block test Author: Morrell, Jeffrey J., Mankowski, Mark The ability of white and brown rot fungi to colonize wood-plastic composites was investigated by measuring weight loss and anatomical changes. Three composite materials were evaluated. The material containing a 70/30 wood-high density polyethylene (HDPE) mixture was most susceptible to fungal attack, while two different 50/50 wood-HDPE composites experienced little or no attack. Scanning electron microscopic (SEM) examination of samples not exposed to fungus revealed the presence of voids between the wood and HDPE in all three materials. Similar examination of decayed samples of the composite with a higher wood content revealed that the fungi had thoroughly colonized the particles, particularly near the point of initial fungal exposure. Fungal hyphae were also prevalent in the voids deeper in the composite. The two composites containing higher HDPE levels had little evidence of fungal attack, despite the presence of voids. Title: Patterns of fungal attack in wood-plastic composites following exposure in a soil block test Author: Morrell, Jeffrey J., Mankowski, Mark The ability of white and brown rot fungi to colonize wood-plastic composites was investigated by measuring weight loss and anatomical changes. Three composite materials were evaluated. The material containing a 70/30 wood-high density polyethylene (HDPE) mixture was most susceptible to fungal attack, while two different 50/50 wood-HDPE composites experienced little or no attack. Scanning electron microscopic (SEM) examination of samples not exposed to fungus revealed the presence of voids between the wood and HDPE in all three materials. Similar examination of decayed samples of the composite with a higher wood content revealed that the fungi had thoroughly colonized the particles, particularly near the point of initial fungal exposure. Fungal hyphae were also prevalent in the voids deeper in the composite. The two composites containing higher HDPE levels had little evidence of fungal attack, despite the presence of voids. Close

• 42. [Article] Fungi colonizing redwood in cooling towers: Identities and effects on wood properties

  Heartwood from coastal redwood [Sequoia sempervirens (D. Don.) Endl.] is very durable and is often used untreated in harsh environments, such as cooling towers of power or chemical processing plants. Wood ...

  Citation × Citation Citation Abstract Copy Title: Fungi colonizing redwood in cooling towers: Identities and effects on wood properties Author: Morrell, Jeffrey J., Smith, Susan M. Heartwood from coastal redwood [Sequoia sempervirens (D. Don.) Endl.] is very durable and is often used untreated in harsh environments, such as cooling towers of power or chemical processing plants. Wood in this environment is often attacked by soft rot fungi. Some wood users attempt to bolster protection by including additives, such as chromium, in the water. Examination of sections cut from a redwood cooling tower revealed that most pieces were colonized by a variety of Fungi Imperfecti, in spite of surface chromium levels that averaged 0.26 lb/ft3. Eleven species were isolated from the material; soft rot tests of these fungi indicated that all of the isolates were capable of causing Type 2 soft rot attack (cell-wall erosion). These fungi caused little or no weight loss on redwood specimens, but did damage less durable ponderosa pine sapwood. The results suggest that the redwood cooling tower was colonized by a variety of fungi; however, the combination of redwood extractives and a shallow chromium barrier appears to protect against soft rot attack. Title: Fungi colonizing redwood in cooling towers: Identities and effects on wood properties Author: Morrell, Jeffrey J., Smith, Susan M. Heartwood from coastal redwood [Sequoia sempervirens (D. Don.) Endl.] is very durable and is often used untreated in harsh environments, such as cooling towers of power or chemical processing plants. Wood in this environment is often attacked by soft rot fungi. Some wood users attempt to bolster protection by including additives, such as chromium, in the water. Examination of sections cut from a redwood cooling tower revealed that most pieces were colonized by a variety of Fungi Imperfecti, in spite of surface chromium levels that averaged 0.26 lb/ft3. Eleven species were isolated from the material; soft rot tests of these fungi indicated that all of the isolates were capable of causing Type 2 soft rot attack (cell-wall erosion). These fungi caused little or no weight loss on redwood specimens, but did damage less durable ponderosa pine sapwood. The results suggest that the redwood cooling tower was colonized by a variety of fungi; however, the combination of redwood extractives and a shallow chromium barrier appears to protect against soft rot attack. Close

• 43. [Article] The effect of pH on decomposition of Mylone (dazomet) and tridipam to fungitoxic methylisothiocyanate in wood

  Mylone@ and tridipam are two solid chemicals that decompose to produce methylisothiocyanate (MIT), a highly effective wood fumigant. In this study, two techniques -- a rapid, test-tube method and small-scale, ...

  Citation × Citation Citation Abstract Copy Title: The effect of pH on decomposition of Mylone (dazomet) and tridipam to fungitoxic methylisothiocyanate in wood Author: Lebow, Stan, Morrell, Jeffrey J., Sexton, Camille M. Mylone@ and tridipam are two solid chemicals that decompose to produce methylisothiocyanate (MIT), a highly effective wood fumigant. In this study, two techniques -- a rapid, test-tube method and small-scale, wood-block assay -- were used to determine the effect of the pH of various chemical buffers on the decomposition of Mylone@ and tridipam in Douglas-fir heartwood samples colonized by Poria carbonica. Both chemicals were sensitive to pH, and higher levels of MIT were produced as the pH of the buffers increased. In general, fungal survival was not affected 1 week after chemical treatment. Complete control of P. carbonica, however, resulted after 4 weeks of exposure to 50 mg Mylone@/block or 150 mg tridipam/block, when each chemical was combined with a pH-12 buffer. These results suggest that regulating fumigant treatments according to the degree of fungal attack can substantially improve the precision of decay control in wood maintenance programs. Title: The effect of pH on decomposition of Mylone (dazomet) and tridipam to fungitoxic methylisothiocyanate in wood Author: Lebow, Stan, Morrell, Jeffrey J., Sexton, Camille M. Mylone@ and tridipam are two solid chemicals that decompose to produce methylisothiocyanate (MIT), a highly effective wood fumigant. In this study, two techniques -- a rapid, test-tube method and small-scale, wood-block assay -- were used to determine the effect of the pH of various chemical buffers on the decomposition of Mylone@ and tridipam in Douglas-fir heartwood samples colonized by Poria carbonica. Both chemicals were sensitive to pH, and higher levels of MIT were produced as the pH of the buffers increased. In general, fungal survival was not affected 1 week after chemical treatment. Complete control of P. carbonica, however, resulted after 4 weeks of exposure to 50 mg Mylone@/block or 150 mg tridipam/block, when each chemical was combined with a pH-12 buffer. These results suggest that regulating fumigant treatments according to the degree of fungal attack can substantially improve the precision of decay control in wood maintenance programs. Close

• 44. [Article] Interactions of ammoniacal copper zinc arsenate (ACZA) with Douglas-fir

  Tests were conducted to determine the effect of ACZA composition on fixation and the roles of adsorption and precipitation in fixation. The sites of copper and zinc adsorption within the treated wood and ...

  Citation × Citation Citation Abstract Copy Title: Interactions of ammoniacal copper zinc arsenate (ACZA) with Douglas-fir Author: Lebow, Stan T., Morrell, Jeffrey J. Tests were conducted to determine the effect of ACZA composition on fixation and the roles of adsorption and precipitation in fixation. The sites of copper and zinc adsorption within the treated wood and the bonding environment of adsorbed copper were also examined. The results generally support the finding that arsenic fixation occurs by precipitation of metal/arsenate complexes. Arsenic leaching was minimized with high solution ratios of metal oxide:arsenic pentoxide, and with formulations containing zinc. Zinc precipitated the majority of arsenic when ammonia was allowed to evaporate from the treating solution. The metal cations were leach-resistant regardless of ACZA formulation because of their low water solubility and their ability to adsorb to the wood. Copper was readily adsorbed by lignin and by model compounds that possessed phenolic hydroxyl groups, which suggests that phenolic hydroxyl groups were the primary reaction sites. Fourier Transform Infrared (FTIR) and Fast Atom Bombardment (FAB) mass spectroscopy analysis also supported this conclusion. Multiple copper species and increased free radical content were detected within lignin that had adsorbed copper. Adsorption of copper and zinc has important ramifications for arsenic fixation. Title: Interactions of ammoniacal copper zinc arsenate (ACZA) with Douglas-fir Author: Lebow, Stan T., Morrell, Jeffrey J. Tests were conducted to determine the effect of ACZA composition on fixation and the roles of adsorption and precipitation in fixation. The sites of copper and zinc adsorption within the treated wood and the bonding environment of adsorbed copper were also examined. The results generally support the finding that arsenic fixation occurs by precipitation of metal/arsenate complexes. Arsenic leaching was minimized with high solution ratios of metal oxide:arsenic pentoxide, and with formulations containing zinc. Zinc precipitated the majority of arsenic when ammonia was allowed to evaporate from the treating solution. The metal cations were leach-resistant regardless of ACZA formulation because of their low water solubility and their ability to adsorb to the wood. Copper was readily adsorbed by lignin and by model compounds that possessed phenolic hydroxyl groups, which suggests that phenolic hydroxyl groups were the primary reaction sites. Fourier Transform Infrared (FTIR) and Fast Atom Bombardment (FAB) mass spectroscopy analysis also supported this conclusion. Multiple copper species and increased free radical content were detected within lignin that had adsorbed copper. Adsorption of copper and zinc has important ramifications for arsenic fixation. Close

• 45. [Article] Interactions between sodium N-methyldithiocarbamate and Douglas-fir heartwood

  Vapam(r) (NaMDC) is the fumigant most commonly used to arrest and control decay of utility poles. While volatile fungitoxins are detectable only 1 to 2 years after treatment, poles treated with Vapam(r) ...

  Citation × Citation Citation Abstract Copy Title: Interactions between sodium N-methyldithiocarbamate and Douglas-fir heartwood Author: Miller, D. B., Morrell, Jeffrey J. Vapam(r) (NaMDC) is the fumigant most commonly used to arrest and control decay of utility poles. While volatile fungitoxins are detectable only 1 to 2 years after treatment, poles treated with Vapam(r) remain free of decay fungi for 6 to 17 years. Vapam(r) decomposes to produce volatile fungicides as well as a number of nonvolatile products that may provide long-term protection. The degree and rate of decomposition of NaMDC were evaluated by using a gas chromatograph and a high-performance liquid chromatograph to analyze extracts from Vapam(r) mixtures with wood, cellulose, vanillin, starch and glass. Compounds similar to those produced from Vapam(r)-soil mixtures were found in the mixtures tested. Of the materials identified, sulfur was the most abundant nonvolatile product in wood mixtures and may play a role in long-term wood protection. Sulfur was present only at low levels in cellulose mixtures. These results, coupled with the low levels of volatile MIT produced in the cellulose mixtures, suggest that lignin is an important site for Vapam(r) decomposition reactions. Further studies are suggested to determine the role of nonvolatile decomposition products in arresting decay away from the point of application. Title: Interactions between sodium N-methyldithiocarbamate and Douglas-fir heartwood Author: Miller, D. B., Morrell, Jeffrey J. Vapam(r) (NaMDC) is the fumigant most commonly used to arrest and control decay of utility poles. While volatile fungitoxins are detectable only 1 to 2 years after treatment, poles treated with Vapam(r) remain free of decay fungi for 6 to 17 years. Vapam(r) decomposes to produce volatile fungicides as well as a number of nonvolatile products that may provide long-term protection. The degree and rate of decomposition of NaMDC were evaluated by using a gas chromatograph and a high-performance liquid chromatograph to analyze extracts from Vapam(r) mixtures with wood, cellulose, vanillin, starch and glass. Compounds similar to those produced from Vapam(r)-soil mixtures were found in the mixtures tested. Of the materials identified, sulfur was the most abundant nonvolatile product in wood mixtures and may play a role in long-term wood protection. Sulfur was present only at low levels in cellulose mixtures. These results, coupled with the low levels of volatile MIT produced in the cellulose mixtures, suggest that lignin is an important site for Vapam(r) decomposition reactions. Further studies are suggested to determine the role of nonvolatile decomposition products in arresting decay away from the point of application. Close

• 46. [Article] Steady-state diffusion of chloropicrin in Douglas-fir heartwood

  The effects of moisture content, flow direction, concentration, and temperature on the diffusion of chloropicrin in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) heartwood were investigated. Diffusion ...

  Citation × Citation Citation Abstract Copy Title: Steady-state diffusion of chloropicrin in Douglas-fir heartwood Author: Peralta, Perry N., Morrell, Jeffrey J. The effects of moisture content, flow direction, concentration, and temperature on the diffusion of chloropicrin in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) heartwood were investigated. Diffusion coefficients were strongly affected by wood moisture content. Coefficients for radial and tangential diffusion at the fiber-saturation point were twice as high as those at the oven-dry condition. Longitudinal diffusion coefficients, however, increased only 12.5% when the moisture content was increased over the same range. Longitudinal diffusion coefficients were about three orders of magnitude higher than those in the transverse directions, while there was no significant difference between radial and tangential diffusion coefficients. Diffusion coefficients were independent of concentration, showing the validity of Fick's law of diffusion in characterizing the flow of the fumigant in wood. Diffusion coefficients were always higher at 35 C than at 20 C; however, the difference was not statistically significant, suggesting that the flow of the fumigant is not a temperature-activated process. Title: Steady-state diffusion of chloropicrin in Douglas-fir heartwood Author: Peralta, Perry N., Morrell, Jeffrey J. The effects of moisture content, flow direction, concentration, and temperature on the diffusion of chloropicrin in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) heartwood were investigated. Diffusion coefficients were strongly affected by wood moisture content. Coefficients for radial and tangential diffusion at the fiber-saturation point were twice as high as those at the oven-dry condition. Longitudinal diffusion coefficients, however, increased only 12.5% when the moisture content was increased over the same range. Longitudinal diffusion coefficients were about three orders of magnitude higher than those in the transverse directions, while there was no significant difference between radial and tangential diffusion coefficients. Diffusion coefficients were independent of concentration, showing the validity of Fick's law of diffusion in characterizing the flow of the fumigant in wood. Diffusion coefficients were always higher at 35 C than at 20 C; however, the difference was not statistically significant, suggesting that the flow of the fumigant is not a temperature-activated process. Close

• 47. [Article] Potential for Using Essential Oils to Protect Viscoelastic Thermal Compression–Treated Hybrid Poplar

  The potential for using pretreatment with cinnamon leaf oil or juniper foliage oil to improve the durability of viscoelastic thermal compression (VTC)–treated hybrid poplar was explored in a field termite ...

  Citation × Citation Citation Abstract Copy Title: Potential for Using Essential Oils to Protect Viscoelastic Thermal Compression–Treated Hybrid Poplar Author: Morrell, Jeffrey J., Scouse, Adam, Kamke, Frederick A. The potential for using pretreatment with cinnamon leaf oil or juniper foliage oil to improve the durability of viscoelastic thermal compression (VTC)–treated hybrid poplar was explored in a field termite test and a laboratory mold test. The addition of oils prior to VTC processing had variable effects on resistance to both mold and termite attack. Subsequent gas chromatography–mass spectroscopy assessment of residual oil components in VTC processed material suggested that the heating associated with the process was associated with substantial degradation of oil components that might help explain the lack of protective effect. The results suggest that further attempts to use essential oils to improve the durability of VTC processed materials must first explore less aggressive heating conditions to reduce the potential for thermal degradation of oil components while still achieving the attractive gains in physical properties associated with the process. Title: Potential for Using Essential Oils to Protect Viscoelastic Thermal Compression–Treated Hybrid Poplar Author: Morrell, Jeffrey J., Scouse, Adam, Kamke, Frederick A. The potential for using pretreatment with cinnamon leaf oil or juniper foliage oil to improve the durability of viscoelastic thermal compression (VTC)–treated hybrid poplar was explored in a field termite test and a laboratory mold test. The addition of oils prior to VTC processing had variable effects on resistance to both mold and termite attack. Subsequent gas chromatography–mass spectroscopy assessment of residual oil components in VTC processed material suggested that the heating associated with the process was associated with substantial degradation of oil components that might help explain the lack of protective effect. The results suggest that further attempts to use essential oils to improve the durability of VTC processed materials must first explore less aggressive heating conditions to reduce the potential for thermal degradation of oil components while still achieving the attractive gains in physical properties associated with the process. Close

• 48. [Article] Production of fungal protoplasts from selected wood-degrading fungi

  Studies of the effects of various chemicals on fungal growth are difficult to perform on filamentous fungi because of the difficulty of observing the protoplasm through the rigid hyphal wall, and because ...

  Citation × Citation Citation Abstract Copy Title: Production of fungal protoplasts from selected wood-degrading fungi Author: Rui, Chen, Morrell, Jeffrey J. Studies of the effects of various chemicals on fungal growth are difficult to perform on filamentous fungi because of the difficulty of observing the protoplasm through the rigid hyphal wall, and because most activity occurs in the region near the hyphal tip. However, hyphae can be exposed to certain enzymes that degrade the cell walls, producing protoplasts. There are few reports of protoplast production from economically important wood decayers. In this report, protoplasts were produced from hyphae of the common wood-degrading fungi Phanerochaete chrysosporium, Postia placenta, Gloeophyllum trabeum, and Trametes versicolor with a commercially prepared mixture of cell-wall degrading enzymes (Novozyme 234). Protoplasts were more readily produced from young hyphae; however, regeneration was better with older hyphae. Magnesium sulfate and mannitol (0.5 M) performed comparably well as osmotic stabilizers. Title: Production of fungal protoplasts from selected wood-degrading fungi Author: Rui, Chen, Morrell, Jeffrey J. Studies of the effects of various chemicals on fungal growth are difficult to perform on filamentous fungi because of the difficulty of observing the protoplasm through the rigid hyphal wall, and because most activity occurs in the region near the hyphal tip. However, hyphae can be exposed to certain enzymes that degrade the cell walls, producing protoplasts. There are few reports of protoplast production from economically important wood decayers. In this report, protoplasts were produced from hyphae of the common wood-degrading fungi Phanerochaete chrysosporium, Postia placenta, Gloeophyllum trabeum, and Trametes versicolor with a commercially prepared mixture of cell-wall degrading enzymes (Novozyme 234). Protoplasts were more readily produced from young hyphae; however, regeneration was better with older hyphae. Magnesium sulfate and mannitol (0.5 M) performed comparably well as osmotic stabilizers. Close

• 49. [Article] Nutritional Quality of Douglas-fir Wood: Effect of Vertical and Horizontal Position on Nutrient Levels

  The chemical composition of the boles of 14 Douglas-fir trees growing in the central Willamette Valley of western Oregon was examined to determine whether differences in various chemical component levels ...

  Citation × Citation Citation Abstract Copy Title: Nutritional Quality of Douglas-fir Wood: Effect of Vertical and Horizontal Position on Nutrient Levels Author: Morrell, Jeffrey J., Schowalter, Timothy D. The chemical composition of the boles of 14 Douglas-fir trees growing in the central Willamette Valley of western Oregon was examined to determine whether differences in various chemical component levels might help to explain arthropod or microbial colonization patterns. Levels of nearly all cations as well as N and P tended to be highest in the inner bark. Nitrogen levels were similar in sapwood and heartwood, but both were lower than those in the inner bark. Levels of N, P, Mg, Fe, and Zn tended to be significantly higher farther up the tree, suggesting that this zone might be a more suitable substrate of colonization. Water-soluble sugars tended to be present at higher levels closer to the live crown, a finding that implies that these compounds may be allocated to cells closer to the regions where active photosynthesis is occurring. Water-soluble sugars tended to be present at higher levels in the heartwood, an unexpected finding since these compounds are presumed to be consumed during heartwood formation. A broader sample of Douglas-fir boles is recommended to confirm these results. Title: Nutritional Quality of Douglas-fir Wood: Effect of Vertical and Horizontal Position on Nutrient Levels Author: Morrell, Jeffrey J., Schowalter, Timothy D. The chemical composition of the boles of 14 Douglas-fir trees growing in the central Willamette Valley of western Oregon was examined to determine whether differences in various chemical component levels might help to explain arthropod or microbial colonization patterns. Levels of nearly all cations as well as N and P tended to be highest in the inner bark. Nitrogen levels were similar in sapwood and heartwood, but both were lower than those in the inner bark. Levels of N, P, Mg, Fe, and Zn tended to be significantly higher farther up the tree, suggesting that this zone might be a more suitable substrate of colonization. Water-soluble sugars tended to be present at higher levels closer to the live crown, a finding that implies that these compounds may be allocated to cells closer to the regions where active photosynthesis is occurring. Water-soluble sugars tended to be present at higher levels in the heartwood, an unexpected finding since these compounds are presumed to be consumed during heartwood formation. A broader sample of Douglas-fir boles is recommended to confirm these results. Close

• 50. [Article] Bioassaying wood preservatives with Aspergillus niger

  The bioassay with Aspergillus niger is a simple way of determining the presence and amount of pentachlorophenol or tributyltin oxide in wood, but it does not appear useful for measuring strongly fixed ...

  Citation × Citation Citation Abstract Copy Title: Bioassaying wood preservatives with Aspergillus niger Author: Morrell, Jeffrey J. The bioassay with Aspergillus niger is a simple way of determining the presence and amount of pentachlorophenol or tributyltin oxide in wood, but it does not appear useful for measuring strongly fixed chemicals such as chromated copper arsenate, borate, and fluoride. Its effectiveness in detecting other preservatives has not been reported. Accordingly, the bioassay was evaluated for its ability to detect various concentrations of 15 preservatives introduced into blocks of ponderosa pine. These results were compared with those from modified soil-block tests involving the same chemicals. Several of the formulations-three quaternary ammonium compounds, copper naphthenate, and Folpet imparted some decay resistance to the blocks but were not detectable with the bioassay. The remaining chemicals were all detectable, although sensitivities varied. These results suggest that the Aspergillus bioassay can be useful for detecting many wood preservatives. Title: Bioassaying wood preservatives with Aspergillus niger Author: Morrell, Jeffrey J. The bioassay with Aspergillus niger is a simple way of determining the presence and amount of pentachlorophenol or tributyltin oxide in wood, but it does not appear useful for measuring strongly fixed chemicals such as chromated copper arsenate, borate, and fluoride. Its effectiveness in detecting other preservatives has not been reported. Accordingly, the bioassay was evaluated for its ability to detect various concentrations of 15 preservatives introduced into blocks of ponderosa pine. These results were compared with those from modified soil-block tests involving the same chemicals. Several of the formulations-three quaternary ammonium compounds, copper naphthenate, and Folpet imparted some decay resistance to the blocks but were not detectable with the bioassay. The remaining chemicals were all detectable, although sensitivities varied. These results suggest that the Aspergillus bioassay can be useful for detecting many wood preservatives. Close