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Antifungal activity of a stilbene glucoside from the bark of Picea glehnii
2001 - IRG/WP 01-10402
Stilbene glucosides are widely distributed as phenolic extractives in the bark of Picea glehnii, a commercially species planted in the northern area of Japan, and its content reaches to more than 10% by the dried weight of the bark. Although antifungal activities of these compounds have been reported, the mechanism of growth inhibition is still unclear. Isorhapontin (5,4'-dihydroxy-3'-methoxystilbene-3-ß-D-glucoside) is the major constituent of the stilbene glucosides in the bark of P. glehnii. In the present work, the relation between metabolism and antifungal activities of isorhapontin for the white-rot fungus Phanerochaete chrysosporium and the wood staining fungus Trichoderma viride was investigated. Inhibition of fungal growth was obviously depending on the conversion of isorhapontin to the aglycone isorhapontigenin (3'-methoxy-3,5,4'-trihydroxystilbene) by ß-glucosidic activities in the cultures. Exogenous addition of ß-glucosidase also enhances the antifungal activity of isorhapontin. Moreover, less than 100 ppm addition of the stilbene aglycone isorhapontigenin is sufficient to inhibit the growth of both fungi. However, further metabolism of isorhapontigenin was observed after prolonged incubation of the fungi and resulted in detoxification.
S Shibutani, M Samejima

Influence of bark damage on bluestain development in pine logs
1997 - IRG/WP 97-10197
Mechanized harvesting of conifers can lead to extensive bark damage, with the resulting wounds providing suitable entry points for bluestain fungi that are not associated with bark beetle vectors. However, the amount of bluestain colonisation can vary greatly between the different types of wound. To evaluate the effect of wound type seven different types of wounds were artificially created on freshly felled logs of Corsican pine. These ranged from barely visible punctures, to the removal of large strips of bark, simulating typical harvester damage. The logs were left in the field exposed to natural inocula of wood degrading fungi and assessed after 6 and 12 weeks. Results indicated that surface area of injury was not the best parameter for predicting the rate and extent of staining. Minor disruptions of the bark e.g. crushing and punctures, were sometimes associated with substantial amounts of stain development. Wounds with flaps of loosened but still attached bark were especially susceptible to bluestain colonization, but additional damage to exposed wood surfaces did not result in more stain. Stain development was strongly associated with the edges of wounds where the bark and exposed wood met. Excluding potential bluestain vectors such as bark beetles and weevils by enclosing the logs in netting did not markedly reduce stain, suggesting that micro-arthropods such as mites play an important part in disseminating bluestain fungi to wounds produced during harvesting and log extraction.
A Uzunovic, J F Webber, D J Dickinson

Feasibility of AE (Acoustic Emission) monitoring for the detection of the activities of wood-destroying insects
1992 - IRG/WP 92-2416
The feasibility of acoustic emission (AE) as a nondestructive testing method for the detection of the wood destroying insects was investigated. AEs were detected from the wood specimens under feeding attack of sugi bark borers or powder-post beetles. However, the feasible monitoring area of an AE sensor is influenced by the attenuation of AE amplitude, so that this could be a problem in the practical AE measurements, especially with wood specimens of higher moisture content.
Y Fujii, Y Imamura, E Shibata, M Noguchi

Influence of the peeling on the absorption in the sap displacement method
1990 - IRG/WP 3626
Results of tests on the Eucalyptus and pine fenceposts treated by sap displacement method are presented. Freshly cut post 2 m in length and 8 to 16 cm in diameter were placed for 6 days with their butt ends down in water soluble preservative solution (CCF) to a depth of about 65 cm, and these were inverted and kept in the same way for 3 days more. The treatment began a few hours after felling. The absorptions obtained in partially and totally barked fenceposts were compared. In both timber species, the barked fenceposts absorbed approximately two and a half times more preservative than the other fenceposts partially barked.
M V Baonza Merino

Anti-feedant activity of stilbenic components from bark of Picea glehnii against a subterranean termite, Reticulitermes speratus
2002 - IRG/WP 02-10447
Stilbenic components, one of polyphenolic groups, widely distributed in plant bodies have been known as anti-microbial agents, but not known whether to have anti-termite activities. A stilbene glucoside, isorhapontin, from the bark of Picea glehnii was examined on the anti-feedant activity against a subterranean Reticulitermes speratus. Isorhapontigenin, the aglycone of isorhapontin, induced from it by hydrolysis using ß-glucosidase was also tested for comparison. From the results of choice and no choice feeding tests using paper disks, anti-feedant activity was shown in both the compounds. Isorhapontigenin had a larger anti-feedant activity than isorhapontin.
S Shibutani, M Samejima, S Doi

Sapstain development on Jack pine logs in Eastern Canada
2000 - IRG/WP 00-10358
During 1998-99, a study was initiated to investigate the influence of seasons, log types and storage time on the sapstain development on jack pine logs at two sites in Eastern Canada. Jack pine trees (Pinus banksiana) were harvested into whole-tree and cut-to-length logs in spring and in autumn. Sapstain development was examined in these logs at 2 to 4 week intervals after felling. The mean stain coverage and maximal radial penetration of stain in wood were measured from the discs of the sampled logs. The spring trial showed that sapstain did not develop significantly on jack pine logs within four weeks after trees were cut; however, the severity of stain increased proportionally with the storage time. For both test sites, the full-tree stems were stained more than the cut-to-length logs. All logs were seriously stained after the three months summer storage. The main fungus isolated from stained wood was Ceratocystis coerulescens. Bark beetle attack was found in logs within four weeks after the trees were cut. The bark beetle was Ips pini. After three months in the summer storage, decay started to develop among these logs and the main causal species was Schizophyllum commune.
Dian-Qing Yang, R Beauregard

The relationship between blue-stain and bark beetles
1971 - IRG/WP 19
The attack of bark beetles on standing or in newly-felled stems provides special growth conditions to wood-inhabiting fungi. In the wood attacked by bark beetles, a specific and rich fungus flora is found, and from these fungi the economically important group of blueing fungi has been more thoroughly investigated. These fungi live on nutritive substances present in the cells, especially in the medullary rays and other parenchymatous cells. They attack lignified cell walls only to a limited extent but in the ray cells they may cause considerable destruction. Some of these fungi may attack the secondary cell walls where they develop cavities. The blueing fungi attack standing trees when their moisture content is low as well as timber at different stages of storage before it is completely seasoned. They spread very quickly both radially and longitudinally and thus they may cause rapid discolouration and considerable financial losses. The greatest losses are caused by blueing fungi which attack newly felled timber in the forest simultaneously with the infestation of bark beetles. Von Schrenk (1903) has already pointed out the relationship between the attack of the bark beetles and the blueing of the wood which at this time was thought to be caused by one fungus Ceratocystis pilifera. Later.the number of known Ceratocystis species which are, over the whole world, the most common fungi associated with the attack of bark beetles, have amounted to 80-90 at the present time, and they have been studied most thoroughly by R W Davidson (numerous papers between 1935 and 1970) in the USA. The greatest number of species has been found in North America, where the variability in host trees and in climatic conditions is greater than in North Europe.
A Käärik

Anti-fungal properties of pyrolytic oils derived from softwood bark
2000 - IRG/WP 00-30218
Thermal decomposition of balsam fir and white spruce mixed bark residues at 450°C and under vacuum (< 20 kPa abs.) results in high yields of pyroligneous liquors rich in phenolic content. This vacuum pyrolysis process has been scaled-up to a pyrolysis plant with a feed capacity of 3.5 t/h of softwood bark, which is the largest plant of this type in the world. The pyrolytic aqueous condensates have been tested for their anti-fungal properties. One of the major objectives of this study was to identify which groups of chemical compounds were the most active to inhibit the growth of wood decay fungi. The fractionation of the pyrolytic aqueous phase in four distinct parts was accomplished by a liquid-liquid extraction method. The four fractions were named F1 (ether extractibles), F2 (ethyl acetate extractibles), F3 (neutral compounds) and F4 (phenolic compounds). Petri tests were conducted using two brown rot fungi (P. placenta and G. trabeum) and two white rot fungi (I. lacteus and T. versicolor). The composition of these fractions was analysed by GC/MS. Fraction F1, with concentrations of organic acids, phenols and derivatives (3.0% by weight), benzenediols (3.9% by weight), and a variety of other products (quinones, furans, etc.), was the most promising to inhibit the growth of decay fungi, while fraction F3 showed no inhibitive effect in the Petri dish agar test. C. versicolor was most sensitive to these fractions, while I. lacteus was the least. The addition of CuSO4 to the water soluble organics improved their ability against decay.
D Mourant, Dian-Qing Yang, Xiao Lu, C Roy

Protection of freshly felled timber against attack by bark boring insects
1981 - IRG/WP 1143
This report describes two experiments with the insecticide formulation Perigen, which contains the synthetic pyrethroid permethrin. At 0.2% w/v active ingredient individual logs were protected against bark boring beetles for 18 weeks. At 0.3% w/v active ingredients Perigen gave similar protection against insect attack to stacks of recently felled unbarked pine logs. This protection was at least equivalent to that obtained with a 5% w/v aqueous DDT emulsion.
J Dominik, P R Skidmore

Development of bluestain in commercially harvested logs in Britain
1996 - IRG/WP 96-10150
In Britain, mechanised harvesting of conifer forestry crops is now the preferred method of felling where terrain and access allows. However, use of mechanised harvesters can lead to excessive debarking, loosening of the bark and wood splintering with, on average, about a third of the bark removed from the more severely damaged logs. More bark has also been observed to be lost from logs harvested early in the summer (June) than later in the season (August). In an experiment which ran from June October in 1993, mechanically harvested logs with only relatively small amounts of bark damage (mean 12%) were found to be much more susceptible to attack by bluestain fungi than those processed manually, and the damaged areas were associated with extensive bluestain development around the log circumference. The most dramatic staining was produced by Ceratocystis coerulescens and Leptographium wingfieldii. Bark beetles which act as vectors of some bluestain fungi were excluded from the experimental logs, but other insect genera were found to act as casual vectors of the staining fungi. Harvester design and improved skills of harvester operators cannot significantly reduce the potential amount of blue stain degrade as significant reduction of stain only comes with the very low amounts of bark damage (0-10% of circumference) and this is practically unachievable with mechanised methods. Thus rapid delivery of logs for further processing remains the safest way of minimising the opportunity for fungal attack.
A Uzunovic, J F Webber, D J Dickinson

Preliminary indications of the natural durability of Spruce bark board
1999 - IRG/WP 99-10312
A board material made from pressed bark, with no added adhesive, has been developed by Forintek&apos;s composites group and tested for durability by Forintek&apos;s treated-wood group and the University of Hawaii. This material was also manufactured with veneers in a one-step process. Since one role of bark on the tree is protection against pests and diseases, barkboard was expected to have some natural durability. Samples from the first boards made, were therefore subjected to a two-hour boil test, a soil-block test, a soil-bed test and two-choice and no-choice termite tests. Preliminary findings suggest that barkboard is dimensionally stable and has considerable natural durability against brown rot, white rot, soft rot, and the Formosan subterranean termite. This durability can be partially transferred into veneer in a one-step pressing process and is virtually unaffected by leaching. More work will be required to fully define the natural durability of barkboard, with and without veneer.
P I Morris, J K Grace, G E Troughton

Efficacies of an insecticide and a fungicide for preventing blue-stain of Japanese red pine logs
2006 - IRG/WP 06-20329
We examined blue-stain fungi on Japanese red pine at 3 forests and 2 saw mills in Iwate Prefecture, Japan. The isolated ophiostomatoid fungi were Leptographium sp and Ophiostoma sp. There were 3 routes of the blue-stain; fungal growth from the spore or hypha stuck on the cross cut surfaces, fungal spread through the inner bark by bark beetles and fungal invasion around whorled knot. The larger extensions of blue-stain in summer and spring seasons were mainly caused from infestations of bark beetles. Efficacies of an insecticide and a fungicide for preventing blue-stain were also evaluated. For preventing blue-stain through the year, it was required to treat logs with the insecticide against bark beetle attacks and with the fungicide to inhibit fungal growth on the cross cut surface.
H Taniuchi, T Koiwa, H Masuya, S Doi

Efficacies of physical barriers for preventing blue-stain of Japanese red pine logs
2007 - IRG/WP 07-20359
This paper deals with field trials on physical barriers to prevent blue stain on Japanese red pine logs using a fly screen, bark and leaves of Japanese cedar as covering materials. These barriers arrested blue stain and bark beetle attacks to low levels than control for 1 month except covering with a small amount of bark. Covering with the fly screen and a large amount of bark permissibly suppressed blue stain for more than 1 month. The fly screen will be enough for practical use to prevent blue stain of pine logs.
H Taniuchi, T Koiwa, H Masuya, S Doi

Do insects infest wood packing material with bark following heat-treatment?
2007 - IRG/WP 07-10633
As a result of international trade, many bark- and wood-infesting insects are inadvertently transported in wood packing materials (WPM) such as crating, dunnage, and pallets. WPM is suspected as the likely pathway for most of these borers, although the exact mode of entry into the USA is unknown for all 25 borers. The top 10 countries of origin were, in decreasing order, Italy, Germany, China, Spain, Belgium, Russia, India, Mexico, France, and United Kingdom. We initiated studies in 2004 and 2005 to evaluate post-treatment insect colonization of logs and lumber with varying amounts of bark. Acer rubrum (red maple), Carya glabra (pignut hickory), Pinus resinosa (red pine), and Quercus rubra (northern red oak) were selected. All bark was retained on the logs. The logs were either heat treated according to ISPM-15 standards (56°C core temperature for 30 minutes) or left as untreated control logs. Overall, bark- and wood-boring insects (primarily Cerambycidae and Scolytidae) colonized and successfully reproduced in all treated and untreated logs of all four tree species tested. Although our studies indicated that borers will infest barked surfaces of WPM after heat treatment under ideal field conditions, it was not known to what degree treated WPM contains bark, and how often borers live are associated with the bark. A survey revealed that about 0.11% of all marked WPM entering the USA harbored live borers. The results of the surveys and studies may help regulators to judge the relative risk of bark associated with WPM and whether there is justification to require that WPM be manufactured from bark-free wood.
R A Haack, T R Petrice, P Nzokou, D P Kamdem

Run-off quality from sprinkled debarked logs and logs with bark from Picea abies and Pinus contorta
2007 - IRG/WP 07-50248
Storage of roundwood is necessary for efficient industrial production at sawmills and pulpmills. The need for wood storage becomes even more critical when large storm fellings create huge volumes of wood that is at risk for deterioration. In Scandinavia, the technique of sprinkling of water on roundwood is used to protect stored wood from fungal and insect infestation and drying during the summer. Depending on the sprinkling regime, the contributions to log yard run-off might be considerable. Log yard run-off is polluted and can therefore be harmful to downstream water recipients due to eutrophication and oxygen depletion. It is therefore desirable to find solutions for minimising the pollutants, i.a. organic material and phosphorus, in the run-off. A large portion of these pollutants probably originate in the bark. In Scandinavia, the majority of all logs are debarked after storage and sprinkling. Debarking the logs before storage might help to reduce the amount of pollutants. In this study, two storage experiments were conducted to investigate the importance of bark during sprinkled storage. Experimental piles of debarked logs and logs with bark from Norway spruce (Picea abies) and Lodgepole pine (Pinus contorta) were sprinkled for 10 to 12 weeks during the summer at two locations in central Sweden. Run-off was collected below the piles. pH, total organic carbon (TOC), total phosphorus, total nitrogen, and phenols in the log yard run-offs were analysed and compared. The possibility of using this method for reducing the concentrations of pollutants in log yard run-off are discussed as well as the suitability of its use in Sweden.
M Jonsson

The Comparison of Fixation and Leachability of Bark, Fruit and Leaf Tannin Extracts with Boron Minerals
2008 - IRG/WP 08-30473
Tannins extracted from several plants have natural durability properties. Due to these properties, some of the researchers have studied them for protecting wood. In this study, Scots pine (Pinus sylvestris) and beech (Fagus orientalis) wood samples were treated with bark, fruit, and leaf extracts as well as water-based wood preservative salts at various concentrations to increase fixation. The penetration, fixation, and antifungal properties of different treatment solutions were compared. Retention levels were generally higher for Scots pine wood than beech wood. The highest retention levels were seen in wood treated with valex and sumex, which are extracts of oak fruits and sumac leaves, respectively. Leaching tests indicated that both wood types treated with sumac extracts showed higher retention levels than wood treated with the other fruit and bark extract solutions. Adding 1% water-based wood preservative salts to valex and sumac extracts increased the retention levels. Higher concentrations of wood-preserving salts accelerated and increased the amount of leaching. We found that the extract alone was resistant to leaching. Mycological tests showed that bark extract solution was the most effective at preventing mycelium penetration and that adding water-based wood-preservative salts to all extract solutions significantly affected the resistance of the wood against fungal infection.
S Sen, C Tascioglu, K Tirak

Effect of juglone from Juglans mandshurica bark activity of wood decay fungi
2009 - IRG/WP 09-30502
Juglone was extracted from Juglans mandshurica bark via vacuum-assisted steam stripping. The extract was characterized by Fourier Transform Infrared Spectroscopy (FTIR), 1H Nuclear Magnetic Resonance (NMR) and Gas chromatography/mass spectrometry (GC-MS). The extraction process was easy to perform and produced excellent yields (0.22 g juglone/100 g of bark) of a high purity extract (96.42% juglone). The yield was much higher than those of previous studies. The biological activity of the extract was assessed in vitro against Aspergillus niger, Paecilomyces variotii, Trametes versicolor and Gloeophyllum trabeum. Juglone showed good anti-fungal activity, even at concentrations as low as 500 ppm. The results suggest that Juglone may show promise as a natural wood protectant and further studies are planned.
Dongmei Yang, Shuangyue Li, Shujun Li, Wenqiang Su, Yan Jin, Molong Sun

Antifungal Effect of Bark and Wood Extracts of Condalia hookerii (Rhamnaceae), Ebenopsis ebano (Fabaceae) and Helietta parvifolia (Rutaceae) on Trametes versicolor
2010 - IRG/WP 10-30532
This research detail the growing inhibition effect on Coniophora puteana and Trametes versicolor fungi caused by hot water sawdust and bark extracts of three semi-arid land species Condalia hookerii, Ebenopsis ebano and Helietta parvifolia diluted in malt extract agar medium at 2000 ppm and 10000 ppm. After 12-14 days incubation the inhibition growing effect was measured based on the difference between extracts and the control (fungi growing in malt extract agar medium without-extract). The highest growing inhibition was obtained from the fungi Trametes versicolor on malt extract agar medium from bark water extracts of Helietta parvifolia at 10000 ppm concentration. The second highest growing inhibition was amounted to 45 ± 12 for Trametes versicolor at the same species from sawdust water extracts.
A Carrillo, J G Marmolejo, F Garza, V Bustamante, M Garza

Preference of Reticulitermes flavipes (Kollar) for Southern Pine Blue-Stained Sapwood from Beetle-Killed Trees
2012 - IRG/WP 12-10763
Bark beetles and their associated Ophiostomatiod fungi are the major pests of pine forests in the southeastern USA, and termites are the major insect decomposers of dead trees and wood products in the southeastern USA. While both are the principal destructive insects of southern pine trees and southern pine lumber, respectively, no relationship between the two has apparently been reported in the literature. While recently inspecting bark beetle-killed southern pine trees, we noticed that subterranean termites were often present in the lower trunk of pines with incipient bark beetle infestations and always present in trees that had been dead for several months. This unusually rapid termite infestation suggested a possible attraction of termites to beetle-killed wood. AWPA E1 choice termite tests with three colonies of the subterranean termite Reticulitermes flavipes (Kollar) always showed a significant feeding preference for both air-dried and kiln-dried blue-stained southern pine sapwood compared to unstained southern pine sapwood. These initial results indicate that subterranean termites play a significant role in the ecosystem of southern pine forests and carbon recycling, and termite attack on southern pine lumber cut from beetle-killed trees may be associated with the death of the host tree. As the implications of these results may be of major importance to forest health, ecology, and utilization of wood products from the southern pines, we are conducting additional laboratory and field studies.
N S Little, J J Riggins, A J Londo, T P Schultz, D D Nicholas

Anti-Fungal Activity on Some Wood extracts as a Wood Protectant
2016 - IRG/WP 16-30684
In this study, six different wood barks were used, where obtained bark extracts were blended with potato-agar in order to investigate their antifungal properties. To determine the inhibition effectiveness of extractives, two different fungi; Coniophera puteana and Trametes versicolor were selected. Fungal activity was carefully observed for the duration of seven days. Following biological testing, extracts showed a significant inhibition against each fungus. Selected extract concentration is known to be more efficient on inhibition. As concentration increased, fungal growth slowed down and hindered. Bark extracts used in this study showed great efficiency against white-rot fungus, T. versicolor at low concentration. However, efficiency against fungal activity of extracts remained the same at high concentration. These bark extracts have a favorable chance to be used as a natural wood preservative according to results.
Ö Özgenç, S Durmaz

Improvement of wood properties by impregnation with liquefied spruce bark based resins
2016 - IRG/WP 16-40761
In this paper, biobased phenolic thermosetting resins are designed to be used as wood stabilization treatment. The originality of the study stands in substituting part of phenol by spruce (picea abies) bark: this is achieved by a liquefaction process in phenol in the presence of sulfuric acid as catalyst. Next, thermosetting resins are synthetized from liquefied bark by condensation on formaldehyde and further used for impregnation in beech blocks and curing. Two kinds of spruce barks -unmodified and pretreated ones- are used as starting material and characterized. Concerning pretreatment, a hydrolysis has been applied to spruce bark in order to enhance phenolic part. Two liquefaction processes are compared: the first one a simple heating under reflux in presence of phenol. A second one consists in heating at 200°C in closed reactor in phenol/ethanol/water solvent (20/50/30). For the different systems attempted, liquefaction yields are determined and analyzed regarding FT-IR analysis. 91% yield was obtained for liquefied spruce bark under reflux, but the highest bark to solvent ratio (50%) was obtained for process lead in closed reactor. Reactivity of liquefied bark resins is found to be better than control phenolic-formaldehyde resin. Impregnations in beech (Fagus sylvatica) wood blocks are performed using different dried matter content (10%, 20% and 30%). After curing, weight percent gain (WPG), leaching rate, anti-swelling efficiency (ASE) and resistance to decay of different systems are compared. It is shown that liquefied bark based resins confers to wood significant dimensional stabilization and resistance to decay against brown rot and white rot fungi. Concerning the impact of the different processes attempted such as hydrolysis pretreatment or liquefaction at 200°C in closed reactor, final properties of treated wood are decreased compared to liquefied bark resins.
X Duret, E Fredon, E Masson, P Gérardin

The Protective Effect of Different Tree Bark Extractives against Decay Fungi
2017 - IRG/WP 17-30707
There are various modification methods which increase the resistance of wooden materials. Due to recent environmental regulations, there is a need for new and environmentally-friendly wood preservatives. In this study, six different tree bark extractives were evaluated for their wood resistance against fungal degradation. For this purpose, the white rot fungi (Tramates versicolour) and brown rot fungi (Coniophera puteana) were used to determine the level of resistance of the tree bark extractives. The tree bark extractives demonstrated high resistance to fungi decay. Different tree bark extractives prevented fungus degradation for both fungi. SEM images also exhibited this phenomenon. The wood samples treated with extractives were covered with less hyphae as compared to the control samples. The tree bark extractives can be evaluated in a wood protection area.
Ö Özgenç, S Durmaz

Chemical composition and termiticidal activity of Khaya ivorensis stem bark extracts on woods
2018 - IRG/WP 18-30723
The genus Khaya is extractives rich, but the extractives in the stem bark are among the most abundant, accessible and utilised materials in Nigeria. These extractives are of considerable interest for wood protection because of their pesticidal properties. In this study, the chemical constituents of Khaya ivorensis stem bark (KISB) and their termiticidal activity were investigated on Triplochiton scleroxylon and Vitex doniana woods. Spectrophoto-metric and Forlin-Ciocalteu analyses showed that KISB contained total: alkaloids 38.98±0.02 mg/g, flavonoids 0.37±0.02 mg/g, phenol 50.62±0.11 mg/g, saponins 156.31±0.76 mg/g, and tannins 59.95±0.54 mg/g. Field tests demonstrated that the extract from KISB had significant termiticidal activity at tested concentrations compared to the control. The results indicated that KISB has potential as a natural agent for termite control.
G A Adedeji, O Y Ogunsanwo, F S Eguankun, T O Elufioye

Application of suberin fatty acids extracted from birch bark for wood coating
2021 - IRG/WP 21-40914
It is well known that chemical modifications to improve decay resistance also reduce the equilibrium moisture content (EMC) of wood. The mechanism of this action, however, has been the subject of much debate. Several groups have suggested that decay resistance is a result of lower diffusion rates of fungal degradation agents through the wood cell wall. A recent paper explained the fundamental principles governing diffusion through the wood cell wall. This current paper summarizes the findings in that paper with respect to decay resistance of modified wood. In short, large scale motions of the amorphous polysaccharides of the wood cell wall are necessary for diffusion of degradation agents during incipient decay. Many wood modifications are likely preventing decay by preventing these motions. Water promotes large scale motions of cell wall polysaccharides by increasing free volume, increasing the distance between polymer chains, and reducing the number of hydrogen bonds between polymer chains.
A Kumar, Risto Korpinen, Veikko Möttönen