Sapwood Blocks Research Articles

Biological resistance of Zn-Al metal-coated wood

Sapwood blocks of sugi (Cryptomeria japonica) and akamatsu (Pinus densiflora) were coated with Zn/Al (45%/55%) alloy metal at thicknesses of 20–30, 90–100, and 180–200μm by an arc spray gun. They were served for choice and no-choice tests with a brown rot fungus (Fomitopsis palustris), a white rot fungus (Trametes versicolor), and a pest termite (Coptotermes formosanus). Coating thickness of 20–30μm was enough to prevent attacks by both test fungi, whereas 90–100μm thickness was needed for protection against termite attacks. Exfoliation of the coating layers was observed during the wet-dry process in the tests. The results suggested that Zn-Al alloy metal coating treatment was applicable as an alternative method for the protection of timbers from biological deterioration when combined with an additional treatment creating a vapor barrier.

The wood preservative potentials of heartwood extracts of Milicia excelsa and Erythrophleum suaveolens

The ability of heartwood extracts of two very durable tropical hardwood species ( Milicia excelsa (Welw.) C.C. Berg. Syn Chlorophora excelsa (Welw.) and Erythrophelum suaveolens (Guill. & Perr.) Brenan Syn Erythrophleum guinensis) to suppress attack by Lenzites trabea (a brown rotter) or by Polyporous versicolor (a white rotter) was investigated. Air dry extracts were dissolved in 60% methanol and impregnated into sapwood blocks of Ceiba pentandra Gaertn. Extract dosages were 8.009, 24.778, 48.056 and 96.11 kg/m 3 (0.5, 1.5, 3.0 and 6.0 lb/ft 3). Treated blocks were exposed to L. trabea and P. versicolor attack for 14 weeks by the soil block method using the procedure set out in ASTM D 1413-72. Only extract dosages of 48.056 and 96.11 kg/m 3 (3.0 and 6.0 lb/ft 3) were found efficacious in suppressing fungal attack. A tukey studentized test found both dosages significant at 1% level.

Consumption of Sound and Decayed Ponderosa Pine and Douglas-Fir by Reticulitermes spp. (Isoptera: Rhinotermitidae) from Northern California

Survival, amount of wood consumed, and the feeding rate of workers of western subterranean termites, Reticulitermes spp., were assessed on sapwood blocks of ponderosa pine, Pinus ponderosa Dougl. ex Laws, and Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, that were sound or decayed by 1 of 2 brown-rot fungi, Gloeophylum trabeum (Fr.) Murr. or Postia placenta (Fr.) M. Lars & Lomb. Groups of 200 workers were confined separately on combinations of each wood and fungal species for 28 d. Mean survivorship of2 colonies was 89.5 and 96.1%, and were not significantly different, whereas 1 of these suffered significantly greater mortality when fed wood of either species decayed by G. trabeum. Groups of workers consumed an average of 293 mg or 25.5% of wood during the test period. The amount and percentage of wood consumed by termites was significantly greater when decayed by either fungus; however, 1 colony consumed significantly more wood of both species when decayed by G. trabeum. When corrected for mortality over the length of the test, feeding (milligrams wood per worker per 28 d) was not significantly different between colonies or wood species. Wood of either species was consumed at a significantly greater rate if decayed by G. trabeum (1.77 mg per termite per 28 d) than by P. placenta (1.55 mg per termite per 28 d); wood decayed by either fungus was consumed at a significantly greater rate than nondecayed wood (1.25 mg per termite per 28 d).

Colonization patterns and topochemical aspects of sap streak caused by Stereum sanguinolentum in Norway spruce

SummaryFresh sapwood blocks of Norway spruce (Picea abies) were exposed to 12‐ and 60‐day attack by Stereum sanguinolentum in pure culture and were examined with respect to structural, topochemical and colour alterations. Final stages of degradation by 5. sanguinolentum were studied on naturally decayed spruce wood after 1 year of fungal growth. The development of discoloration in the main anatomical directions of wood was assessed. Furthermore, microspectrophotometrical studies on the decomposition of cell wall polyphenols were performed. Initial signs of sap streak appeared already 8 days after fungal infection. Within the three‐dimensional decay pattern, mycelial aggregations associ‐ated with the ray tissue proved to be the major cause of discoloration. UV extinction measurements taken at 280 nm of different parts of cell wall transverse sections revealed a specific pattern of lignin distribution and its derivatives during fungal degradation.

Contamination and spoilage of chilled lamb with Pseudomonas spp.

To define the decomposition patterns of wood cell wall, three economically important brown-rot fungi, Coniophora puteana, Postia placenta, and Gloeophyllum trabeum were studied. Degraded Scots pine (Pinus sylvestris L.) sapwood blocks were analysed using 13C NMR spectroscopy, chemical, and water vapor sorption methods. C. puteana caused the most wood decay (55%) after 50 days of exposure, while the destructive abilities of P. placenta and G. trabeum were 32 and 30%, respectively. Hemicellulose was removed preferably to cellulose, but the intensity of depletion depended on the fungus species rather than the mass loss. P. placenta and C. puteana removed 11.8 and 14.7% of the lignin, respectively, while G. trabeum removed 25.2%. The possible re-polymerization of lignin stopped any further lignin degradation during attack by C. puteana and P. placenta, while G. trabeum continued to degrade lignin until the end of the test. Removal of lignin metoxyl groups and formation of the reactive phenolic hydroxyl groups can be coupled to the reactions of Fenton reagents or other powerful oxidants in acidic conditions. Removal of hemicellulose and lignin (primarily methoxyl groups) will promote further access of fungal metabolites to cellulose fibers. A common regularity of the surface A accessible to water molecules and the losses of the wood weight was obtained. The mass hydrophilicity of sorbent am in brown-rotted wood tended to decrease as the share of lignin increased.

Borate protection of hoop pine(Araucaria cunninghamii)sapwood from attack by subterranean termites(Coptotermesspp., Isoptera: Rhinotermitidae)

Summary Field bioassays were conducted with two Australian Coptotermes species to determine protection of hoop pine sapwood afforded by borate compounds. Coptotermes lacteus (Froggatt) was examined in winter and Coptotermes acinaciformis (Froggatt) in winter, spring and late summer at two localities in the state of Queensland. Sapwood blocks were placed in plastic containers and attached to termite mounds or infested trees. Termite response was determined by mass loss over five weeks and modelled. C. lacteus was relatively benign in winter and for 1.0 and 2.5% mass loss, mean borate retentions of 0.20 and 0.06% m/m boric acid equivalent (BAE), respectively, were derived. With C. acinaciformis, for 1.0 and 5.0% mass loss, mean borate retentions ranged from 0.49 and 0.25% BAE. respectively, in winter, to 0.76 and 0.47% BAE. respectively, in late summer. These results support conclusions from earlier laboratory studies conducted elsewhere. Total prevention of damage by field populations of termites was not a...

Wood decay activity and cellulase production by freshwater lignicolous fungi

Wood decay activity and coupled cellulase production were examined for freshwater lignicolous Ascomycetes, Deuteromycetes and an Oomycete. Wood decay ability was assessed by weight changes in wood and bark blocks of ash and cottonwood colonized by test fungi. Changes in wood components were also measured. Production of coupled cellulases was determined by measurement of activity of culture filtrates. Except for early successional species, most fungi caused weight loss in sapwood blocks; all species caused weight loss in bark blocks. Bark blocks were decayed more rapidly than sapwood blocks and cottonwood blocks were decayed more rapidly than those of ash. For four species examined, cellulose and lignin disappeared simultaneously, with cellulose disappearing more rapidly than lignin. All species produced extracellular exoglucanase, endoglucanase and glucosidase when grown in liquid media containing crystalline cellulose. Enzyme production by most of the species was increased by the addition of glucose.

Tropic Responses of Fungi to Wood Volatiles

Sapwood blocks of lime (Tilia vulgaris) and pine (Pinus sylvestris) placed to one side of growing colonies of several wood decay fungi markedly influenced their hyphal extension patterns, particularly by causing positive or negative tropic responses. A method was devised to measure and quantify these responses and analyse them statistically. Chemotropic responses were demonstrated by Chaetomium globosum, Trichoderma viride, Serpula lacrymans and Coniophora puteana in the presence of air-dried and heat-dried wood but not by Coriolus versicolor or Humicola grisea. The implications of chemotropism as a factor influencing the invasion and colonization of wood are discussed.

Effect of sound and Lenzites-decayed wood on the amino acid composition of Reticulitermes flavipes

In hydrolysates of the eastern subterranean termite, Reticulitermes flavipes, the most abundant protein amino acids (μmoles) were glycine, alanine, and glutamic acid; the least abundant were methionine and histidine. Sawdust from both sound and Lenzites trabea-decayed sapwood blocks of sugar maple, loblolly pine, and slash pine was force-fed to termites. A diet of decayed rather than sound wood had little effect on protein amino acid composition of the termites; glycine content varied the most. In contrast, diet affected the free amino acid composition. Except for glutamic acid, the major protein amino acids of the termites were not the predominant free amino acids. Tyrosine and histidine were relatively more abundant as free than as protein amino acids. Greatest differences in protein amino acid compositions of sound and decayed wood were in contents of glycine, leucine, lysine, and arginine.

Ethylene production in xylem of Pinus radiata in relation to heartwood formation

The production of ethylene by xylem tissues of Pinus radiata was monitored throughout the year. Statistically, significantly greater quantities of ethylene were produced during the winter by transition zones separating sapwood from heartwood than by transition zones during the rest of the year and by middle and inner sapwood during the entire year. Ethylene (5 ppm in air), but not carbon dioxide (27.5% in air), stimulated the production of pinosylvin in sapwood blocks. Phenol synthesis appeared to be preceded by desiccation during both heartwood formation and wound response. Tests with cycloheximide indicated that transition zones are capable of protein synthesis. It was suggested that the auxin-ethylene balance could contribute to quantitative and seasonal differences in ethylene production between the wound and senescent responses (heartwood formation). These and other results suggest that (i) ethylene is involved in stimulation of respiration and phenol synthesis during the wound and senescent responses of xylem tissues of this species, and (ii) heartwood formation takes place mainly in the dormant season during increased metabolic activity in the transition zone.

Growth and enzyme production by Bacillus subtilis and Flavobacterium pectinovorum in Picea sitchensis

When Sitka spruce (Picea sitchensis) is stored in water, an increase takes place in the permeability of the wood. This increase is due to bacterial degradation of the tori and bordered pit membranes and partial degradation of the crossfield pits. It has been demonstrated that two bacteria—Bacillus subtilis and Flavobacterium pectinovorum—isolated from this water stored wood, grow and produce amylase, xylanase and pectinase in sapwood blocks suspended in sterile pond water. Since these organisms have also been shown to increase the permeability of sapwood blocks, it has been concluded that they are primarily responsible for the permeability changes that occur when spruce poles are stored in lake water.

Kinetics of Growth of Filamentous Fungi with Particular Reference to Wood Decay

THE decay of wood blocks by fungi has been described1–4 in terms of a progressive and characteristic decrease of dry weight, and Wilcox5 has correlated these weight losses with the microscopic changes which occur in the decay of sapwood blocks of the hardwood sweetgum (Liquididamber styraciflua L.), and the softwood southern pine (Pinus sp.). Fungi used were Polyporus versicolor L. ex Fr., causing a white rot, and Poria monticola Murr., causing brown rot. Wilcox confirmed that fungi rapidly become established throughout soil blocks6 so that hyphae are numerous in the early stages of decay. During later stages, however, the hyphal concentration decreased considerably and was sparse when 50 per cent of the thin wood samples remained. We have a quantitative theory to describe the relationship between residual wood weight and decay period, which might form the basis of a more general theory which would facilitate widespread attempts to protect wood from decay with preservatives.