Soft Rot Decay Research Articles

Characterization of Culturable Mycobiome of Newly Excavated Ancient Wooden Vessels from the Archeological Site of Viminacium, Serbia.

Two ancient wooden vessels, specifically a monoxyle (1st century BCE to 1st century CE) and shipwreck (15th to 17th century CE), were excavated in a well-preserved state east of the confluence of the old Mlava and the Danube rivers (Serbia). The vessels were found in the ground that used to be river sediment and were temporarily stored within the semi-underground exhibition space of Mammoth Park. As part of the pre-conservation investigations, the primary aim of the research presented was to characterize the culturable mycobiomes of two excavated wooden artifacts so that appropriate conservation procedures for alleviating post-excavation fungal infestation could be formulated. Utilizing culture-based methods, a total of 32 fungi from 15 genera were identified, mainly Ascomycota and to a lesser extent Mucoromycota sensu stricto. Soft-rot Ascomycota of genus Penicillium, followed by Aspergillus and Cephalotrichum species, were the most diverse of the isolated fungi. Out of a total of 38 isolates, screened on 7 biodegradation plate assays, 32 (84.21%) demonstrated at least one degradative property. Penicillium solitum had the highest deterioration potential, with a positive reaction in 5 separate plate assays. The obtained results further broaden the limited knowledge on the peculiarities of post-excavation soft-rot decay of archaeological wood and indicate the biochemical mechanisms at the root of post-excavation fungal deterioration.

Characterization of Microbial Decay and Microbial Communities in Waterlogged Archaeological Wood Excavated from the Wetland

Anatomical and chemical changes due to microbial decay and microbial communities in three waterlogged archaeological woods, namely Dongnim 1, Dongnim 2, and Dongnim 3, excavated from the wetland of the Dongnim-dong archaeological site in Gwangju, were investigated. Dongnim 1−3 exhibited a maximum moisture content approximately 6 to 8 times higher than that of undecayed recent wood, and there was no correlation with the burial period. Chemical analysis revealed an increase in ash and hot water extractive content in Dongnim 1−3 compared to undecayed recent wood, while the solvent extractive content tended to decrease. Additionally, there was a significant decrease in holocellulose content with a relative increase in lignin concentration in Dongnim 1−3. Microscopic observations showed erosion bacteria decay and soft rot decay in Dongnim 1−3. The microbial community analysis of Dongnim 2 and 3 revealed the dominance of Ascomycota (98% to 99%) in the fungal community and Proteobacteria (34% to 55%) as the predominant bacterial phylum. Nonetheless, significant differences in microbial community structure and diversity were observed between Dongnim 2 and Dongnim 3.

Characterization of Microbial Decay and Microbial Communities in Waterlogged Archaeological Rosewood (Dalbergia Species)

While numerous studies have examined microbial attacks on waterlogged archaeological wood, limited information is available regarding microbial attacks in waterlogged tropical hardwoods submerged in marine environments. In this context, we explored microbial attacks in waterlogged archaeological rosewood (Dalbergia species), a tropical hardwood species that was submerged in the Yellow Sea for approximately 700 years, using various microscopic techniques and next-generation sequencing (NGS) methods. Based on morphological features, Type-I soft rot decay was identified as the main decay type. Most fibers in waterlogged archaeological rosewood studied were gelatinous (G) fibers of tension wood and the mode of soft rot decay differed from fibers without the G-layer. Differences in decay resistance between vessel/axial parenchyma cells and fibers were not obvious. Vestured- and simple pit membranes showed higher decay resistance than vessel and axial parenchyma cell walls, respectively. Microbial community analysis by NGS revealed the dominance of Ascomycota and Basidiomycota in the fungal community. Various bacterial communities were also identified, although no prominent signs of bacterial decay were noted. The identified bacterial communities markedly differed from those reported previously in terms of their composition and abundance. Together, our results offer detailed insights into the microbial types and communities responsible for degrading waterlogged archaeological rosewood, contributing to a better understanding of microbial attacks in tropical hardwoods exposed to marine environments.

Inhibitory effect and possible mechanism of oregano and clove essential oils against Pectobacterium carotovorum subsp. carotovorum as onion soft rot in storage

Soft rot caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) is the most common bacterial disease of postharvest onion. This study aimed to determine the antibacterial activity of oregano and clove oils against Pcc and the control of stored soft rot decay in onion. Oregano oil had a minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC) of 200 μL L−1, whereas clove oil had a MIC and MBC of 400 and 500 μL L−1, respectively. Treatment with oregano and clove oil could significantly reduce Pcc cell viability and coincided with a gradient change with time. The inhibitory degree on biofilm synthesis was correlated with oregano and clove oil concentrations. Consequently, 1 × and 2 ×MIC treatments could distinctly reduce biofilm adhesion. With high concentrations of oregano and clove oil, abnormal cell morphology along with cell membrane rupture and cellular leakage were observed by scanning electron microscope (SEM), resulting in a substantial increase in extracellular conductivity. Meanwhile, secretion of extracellular cell wall degrading enzymes (CWDEs) of Pcc was declined in varying degrees, with pectinase (Pel) being significantly inhibited (29.82–100 %). In comparison to the control group, RT-qPCR data indicated that oregano and clove oil downregulated the expression of pathogenic genes, resulting in a decrease in bacterial pathogenicity. Under in vivo culturing, the soft rot decay of onion was reduced by 34.07–100 % in a concentration-dependent manner. In short, essential oils (EOs) may mitigate the severity of onion soft rot by inhibiting the Pcc virulence-associated factors such as activity, motility, toxicity, biofilm formation, and enzyme secretion to various degrees. Thus, oregano and clove oil may be used as alternative bio-fungicides to control and treat the severe disease of soft rot caused by Pcc in onions after harvest.

Biological Durability of Acetylated Hornbeam Wood with Soil Contact in Hungary

This test aimed to discover if industrially acetylated hornbeam can tolerate real-field conditions in Hungary, where various microorganisms can attack the wood separately or cooperatively. Untreated samples accompanied the modified wood to assess the degradation capacity of the soil. The test also focused on weather parameters, the Scheffer index, and soil properties. The untreated stakes showed insect damage, soft rot decay, white rot decay, wasp stripping, moss, and cracks. All of the beech and hornbeam stakes broke after 3.5 years, and the last Scots pine sapwood stakes broke after 6 years. To date, acetylated hornbeam exhibits stronger resistance than untreated hornbeam, beech, and Scots pine sapwood. The acetylated hornbeam stakes showed no decay after 6 years of exposure, and they became dry shortly after being taken from the soil. Acetylated hornbeam stake number 7 had superficial brown rot decay after 18 months, which gradually worsened over the years. The Fourier transform infrared spectroscopy analysis revealed that this stake had lower acetyl content. It was associated with hornbeam wood; it had a wet pocket or a part that was not as permeable and achieved a lower grade of acetylation.

Use of riboflavin to reduce decay and extend the shelf-life of fresh-cut sweet pepper

Riboflavin (vitamin B2) generally is recognized as a safe (GRAS) additive. It is used in food to fortify products with low natural content or compensate for the possible vitamin losses during processing. In this work, we studied the effect of pre-storage riboflavin dips on the quality maintenance of fresh-cut pepper (Capsicum annum L). We initially tested the efficacy of different riboflavin concentrations (0, control; 1; 10 and 100 μmol L−1) to reduce spoilage in fresh-cut green sweet pepper sticks (5 × 1 cm). Treatments with 100 μmol L−1 riboflavin effectively controlled pepper spoilage and were therefore selected for further evaluation along with refrigerated storage. Riboflavin dips reduced soft-rot decay incidence and severity and prevented the increase in electrolyte leakage, and respiration during storage. Riboflavin treatments preserved textural properties by preventing tissue hardness, stiffness, and resistance to bend losses. Treated peppers also presented lower yeasts and molds and aerobic mesophilic bacteria counts. Finally, riboflavin-dips improved antioxidant and phenolics retention without alterations in color, weight loss, sugar, or organic acids. Taken together, results show, for the first time, that riboflavin may be used as a postharvest preservative agent to extend the shelf-life of fresh-cut vegetables.

Hallmarks of Basidiomycete Soft- and White-Rot in Wood-Decay -Omics Data of Two Armillaria Species.

Wood-decaying Basidiomycetes are among the most efficient degraders of plant cell walls, making them key players in forest ecosystems, global carbon cycle, and in bio-based industries. Recent insights from -omics data revealed a high functional diversity of wood-decay strategies, especially among the traditional white-rot and brown-rot dichotomy. We examined the mechanistic bases of wood-decay in the conifer-specialists Armillaria ostoyae and Armillaria cepistipes using transcriptomic and proteomic approaches. Armillaria spp. (Fungi, Basidiomycota) include devastating pathogens of temperate forests and saprotrophs that decay wood. They have been discussed as white-rot species, though their response to wood deviates from typical white-rotters. While we observed an upregulation of a diverse suite of plant cell wall degrading enzymes, unlike white-rotters, they possess and express an atypical wood-decay repertoire in which pectinases and expansins are enriched, whereas lignin-decaying enzymes (LDEs) are generally downregulated. This combination of wood decay genes resembles the soft-rot of Ascomycota and appears widespread among Basidiomycota that produce a superficial white rot-like decay. These observations are consistent with ancestral soft-rot decay machinery conserved across asco- and Basidiomycota, a gain of efficient lignin-degrading ability in white-rot fungi and repeated, complete, or partial losses of LDE encoding gene repertoires in brown- and secondarily soft-rot fungi.

Fungal attack on archaeological wooden artefacts in the Arctic\u2014implications in a changing climate

Climate change is expected to accelerate the microbial degradation of the many extraordinary well-preserved organic archaeological deposits found in the Arctic. This could potentially lead to a major loss of wooden artefacts that are still buried within the region. Here, we carry out the first large-scale investigation of wood degradation within archaeological deposits in the Arctic. This is done based on wooden samples from 11 archaeological sites that are located along a climatic gradient in Western Greenland. Our results show that Ascomycota fungi are causing extensive soft rot decay at all sites regardless of climate and local environment, but the group is diverse and many of the species were only found once. Cadophora species known to cause soft rot in polar environments were the most abundant Ascomycota found and their occurrence in native wood samples underlines that they are present locally. Basidiomycota fungi were also present at all sites. In the majority of samples, however, these aggressive and potentially very damaging wood degraders have caused limited decay so far, probably due to unfavorable growth conditions. The presence of these wood degrading fungi suggests that archaeological wooden artefacts may become further endangered if climate change leads to more favorable growth conditions.

Three-Dimensional Exploration of Soft-Rot Decayed Conifer and Angiosperm Wood by X-Ray Micro-Computed Tomography

X-ray micro-computed tomography (XμCT) was used to explore the decomposed structure of conifer and angiosperm wood after colonization by soft-rot fungi. The visualization of degradation features of soft-rot decay was challenging to achieve through XμCT. Difficulties in visualization emerged due to a decreased grayscale contrast (i.e. X-ray density) of the degraded wood. Nevertheless, we were able to image fungal-induced cell deformations in earlywood and cavities in the thick wall of latewood cells in three-dimensions (3D). Unlike the organic wood material, the higher X-ray density of inorganic deposits, identified as mainly calcium-based particles by energy-dispersive spectroscopy, allowed a facilitated 3D survey. The visualization of inorganic particles in 3D revealed a localized distribution in certain cells in conifer and angiosperm found mostly in earlywood.

Method for characterizing extracellular proteins from the cell wall proteome of the copper tolerant fungus Phialophora malorum

Phialophora malorum is a well-known copper tolerant fungus causing soft rot decay of copper-treated wood in-service in ground contact situations worldwide. The aim of the present work was to develop a method that allowed studies of the mechanism(s) behind extracellular copper tolerance by examining the profile of proteins expressed by P. malorum in the cell wall/slime (subproteome) environment in mycelia grown in Cu-supplemented media. The study involves development of a novel non-destructive approach using mild extraction, concentration, separation (SDS-PAGE electrophoresis) and characterization (MALDI-TOF MS/MS) of the proteins present. Studies revealed differential protein profiles and expression in Cu-supplemented (0.1% CuSO4) vs control shake cultures after 10 days growth. Twelve proteins including several hydrolytic (i.e. glucosidases, pectinase, polygalacturonase) enzymes were either unique or over-expressed in Cu-cultures compared to controls. The cell wall location of the proteins was consistent with a role in copper tolerance and detoxification by binding Cu-ions extracellularly. Several of the proteins (e.g. hydrolases, pectinase) are also involved in wood cell wall biomineralization. It is proposed that the concentration of metabolites (organic acids) slowly released in close vicinity of hyphal surfaces by weakly bound enzymes over-expressed through Cu-stress may function to reduce levels of free non-chelated Cu (II) ions entering the cell cytoplasm and therefore provide a first level of defense against copper toxicity.

Carvacrol and eugenol inhibit postharvest soft rot disease by enhancing defense response in peaches during storage

Peaches are in high demands because of their nutritional value and delicious flavor, but often become unmarketable due to the fungus infection. In this study, carvacrol and eugenol were used to preserve peaches. Rhizopus stolonifer growth was completely inhibited by carvacrol at 32 µl/Lair and eugenol at 64 µl/Lair. Carvacrol at 0.5 µl/Lair and eugenol at 1 µl/Lair significantly reduced the incidence and severity of soft rot decay in artificially inoculated peaches. Also, carvacrol and eugenol significantly reduced the natural incidence of soft rot disease and maintained high sensory acceptance and quality of peaches during storage. The activities of defense-related enzymes were enhanced by carvacrol and eugenol fumigation, and the contents of phenolics, flavonoids, lignin, and hydroxyproline-rich glycoprotein in these two oils treated fruit, were much higher than untreated control during storage. These observations indicted that carvacrol and eugenol could preserve peach fruit during postharvest storage. Practical applications Carvacrol and eugenol showed great potential application in the preservation of peach fruit during postharvest storage, exhibiting high antifungal activity against Rhizopus stolonifer and enhancing defense response to soft rot disease.

Fungal wood-decay strategies in Nothofagaceae woods from Miocene deposits in southern Patagonia, Argentina

Carlos Daniel Greppi, Juan L. García Massini, Roberto R. Pujana and Sergio A. Marenssi, May 2018. Fungal wood-decay strategies in Nothofagaceae woods from Miocene deposits in southern Patagonia, Argentina. Alcheringa xxx, xxx -xxx.Decayed woods from the Miocene, Rio Leona Formation, Santa Cruz, Argentina having simultaneous decay patterns consistent with soft- and white rot characteristics are described. Samples were previously identified as Nothofagoxylon scalariforme. At low magnification, the permineralized woods appear mottled, with discoloured, degraded areas, scattered in apparently robust tissue, consistent with white-rot decay. At greater magnification, the woods reveal several micromorphological features, including differential decay of cellulose-rich cellular components that match soft-rot decay by extant ascomycetes and some basidiomycetes. In addition, decayed woods either appear differentially delignified or show simultaneous decay of all cellular components (lignin- and cellulose-rich), which are by-products of white-rot fungal decay. Additional anatomical characteristics of the decayed woods are consistent with a host response to the fungal attack. Co-occurrence of these two decay patterns suggests soft-rot decay and white-rot fungal decay. In addition, co-occurrence of all the decay features observed also suggests facultative soft rot by white-rot fungi, such as in some extant species that switch between these two types of decay strategies as a means to circumvent plant defences. These data indicate that fungi with soft-rot capacity for wood decay can be traced back to the early Miocene (ca 19 Ma). In addition, this report adds to the distribution and diversity of fungi in the geological record and underscores the ecological importance of wood as a preferred substrate for the association and interactions between fungi with different saprotrophic abilities, which have been fundamental for nutrient recycling in terrestrial ecosystems during the Cenozoic.Carlos Daniel Greppi [greppi.carlos.d@gmail.com] Museo Argentino de Ciencias Naturales-CONICET, Av. Ángel Gallardo 470, (1405) Ciudad Autónoma de Buenos Aires, Argentina; Juan L. García Massini [massini112@yahoo.com.ar] Centro de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR), Provincia de La Rioja, UNLaR, SEGEMAR, UNCa, CONICET, Entre Ríos y Mendoza s/n (5301) Anillaco, La Rioja, Argentina; Roberto R. Pujana [rpujana@gmail.com] Museo Argentino de Ciencias Naturales-CONICET, Av. Ángel Gallardo 470, (1405) Ciudad Autónoma de Buenos Aires, Argentina; Sergio A. Marenssi [smarenssi@hotmail.com] IGEBA-CONICET, Departamento de Geología, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Guiraldes 2620, (1428) Buenos Aires, Argentina.

Resistance of the S1 layer in kempas heartwood fibers to soft rot decay

Naturally durable heartwoods, where available, continue to be used as support structures in environments considered hazardous, particularly in ground contact. However, durability of heartwoods against wood decay microorganisms varies. Therefore, it is important to evaluate heartwood products for their in-service performance in order to maximise benefits derived from this valuable natural resource of limited supply. In the work presented, wood pieces from a kempas (Koompassia malaccensis) utility pole that had been placed in service in an acidic soil in Malaysia, and in time had softened at the ground-line position, were examined by light and transmission electron microscopy to evaluate the cause of deterioration.Light microscopy (LM) provided evidence of extensive attack on fibre cell walls by cavity-producing soft rot fungi. Transmission electron microscopy (TEM) revealed in greater detail the distribution and micromorphologies of cavities as well as their relationships to the fine structure of fibre cell walls, which consisted of a highly electron dense middle lamella, a moderately dense S1 layer and a multilamellar S2 layer with variable densities, reflecting differences in lignin concentration. The resistance of the moderately dense S1 layer to soft rot was a feature of particular interest and is the main focus of the work presented. The resistance appeared to be correlated with high lignification of the outermost region of the S2 wall, interfacing with the S1 layer, an unusual cell wall feature not previously described for normal wood.

Carvacrol and eugenol effectively inhibitRhizopus stoloniferand control postharvest soft rot decay in peaches

This study aimed to investigate the antifungal mechanism of carvacrol and eugenol to inhibit Rhizopus stolonifer and the control of postharvest soft rot decay in peaches. To investigate the antifungal mechanism, the effects of carvacrol and eugenol on the mycelium growth, leakages of cytoplasmic contents, mycelium morphology, cell membrane and membrane composition of R. stolonifer were studied. Carvacrol and eugenol both exhibited dose-dependent antifungal activity against R. stolonifer, carvacrol at a concentration of 2μl per plant and eugenol at a concentration of 4μl per plant inhibited fungal growth completely. The two essential oils (EOs) increased cell membrane penetrability and caused the leakage of cytoplasm, nucleic acid and protein content. The observation using scanning electron microscopy andfluorescent microscopy showed modification of the hyphal morphology and breakage of the cell plasma membrane. Decreased ergosterol contents confirmed that the two EOs could destroy the membrane of R. stolonifer. For the invivo test, the inhibition of soft rot disease and the induction of defence-related enzymes were investigated. Carvacrol and eugenol significantly reduced the incidence and severity of soft rot decay in inoculated peaches. The best treatments for controlling soft rot decay were obtained at 0·5μll-1 for carvacrol and 1μll-1 for eugenol. The activities of defence-related enzymes in peaches were also enhanced by fumigation with two EOs. This study showed that carvacrol and eugenol could effectively inhibit the growth of R. stolonifer invitro and successfully control the incidence of soft rot decay in honey peaches. The above findings may be the main antifungal mechanism of carvacrol and eugenol on R. stolonifer. Furthermore, carvacrol and eugenol are helpful for their commercial application on the preservation of fresh fruit.

A Microscopic Study of Paper Decayed by Trichoderma harzianum and Paecilomyces variotii

The current study is interested in evaluating the decay of cotton, Whatman and chemical pulp caused by Trichoderma harzianum and Paecilomyces variotii. The structural changes of the paper were evaluated by Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The SEM results show differences in hyphae colonization and paper decay patterns between studied species under the current study; P. variotii caused an eroded structure in the cotton (cavity forming), whereas the initial T. harzianum colonization produced rupture and erosion (soft-rot decay type II) for the three types of paper ,the gaps were elongated with sharp pointed ends, which consisted either of individual cavities or in chains. Moreover, FTIR results confirmed that there a relationship could be observed between fungal decay and crystalline cellulose content because the intensity of peaks at 1335 and 1111 cm−1 significantly decreased due to the fungal decay. Furthermore, the intensity of O–H stretching absorption slightly decreased, and this may be attributed to hydrolysis of cellulose molecules.

Performance of waterborne copper/organic wood preservatives in an AWPA E14 soft-rot laboratory soil bed test using modified soil

Abstract Soil chemistry is known to have a major effect on the degradation of treated wood by basidiomycete fungi in laboratory and exterior ground-contact exposures. However, this topic received little attention from a soft-rot (SR) decay perspective. In the present paper, laboratory SR tests were performed with two different types of forest soils, which were also modified. Test samples, made of Pinus glabra (Walt.) (pine) were treated with four commercial copper/organic waterborne preservatives. In addition, soluble or particulate copper and the organic co-biocides quarternary ammonia compound or tebuconazole, were individually examined. After 19 months of soil bed exposure, moderate to severe degradation was observed in all treated samples in both soils. Surprisingly, microscopic examination showed minimal SR decay. Samples in the neutral soil had extensive tunneling bacterial deterioration and the best performance was observed with both copper/quaternary commercial formulations. Samples in the acidic soil appeared to have some white-rot and bacterial deterioration and all four commercial copper/organic formulations showed good statistically equivalent efficacy. For samples treated with only copper, the particulate copper samples performed statistically equivalent or slightly better than amine copper, while samples treated with only the organic quarternary or tebuconazole performed poorly in both soils.

Does copper tolerance provide a competitive advantage for degrading copper treated wood by soft rot fungi?

The ability of soft rot fungi possessing strong (Phialophora malorum), medium (Phialophora mutabilis) and poor copper tolerance (Chaetomium globosum) to degrade untreated and CuSO4 and micronized copper treated birch- and pine wood was assessed using ENV 807 standard tests. The aim was to determine whether an ability to grow on Cu-agar and copper in liquid cultures can be transcribed into a competitive advantage to degrade Cu-treated wood. An ability to tolerate high copper levels in-vitro was not correlated with increased decay by the fungi but rather reflected the native chemistry of the wood cell walls. Both untreated and Cu-treated wood were degraded by the three fungi and showed aggressiveness in the order C. globosum > P. mutabilis > P. malorum Higher mass loss was recorded for birch than pine and decreased progressively as the copper loadings increased with statistically insignificant difference noted between Cu-treatments. Microscopy showed decay at the cell wall level to reflect degree of lignification with parenchyma cells degraded first in both untreated and Cu-treated wood. Results indicate presence of copper and its toxicity is unlikely to be the main reason for preventing soft rot decay of wood but rather the additive effect of copper binding to the wood material.

Histological changes in the cell wall structure during wood decay by Trametes hirsuta and Trametes versicolor in neem (Azadirachta Indica A. Juss)

ABSTRACTStructural alterations in the wood cell walls of neem inoculated with by Trametes hirsuta and T. versicolor were studied by microscopic methods. In vitro decayed wood showed extensive weight loss of test blocks (26.7 and 41.38% by T. versicolor and T. hirsuta, respectively) at the end of 3 months. Selective delignification in the initial phase followed by simultaneous removal of lignin was evident in test blocks inoculated with both the species. The separation of middle lamellae and patches of cellulosic polysaccharides stained blue with Astra blue in the delignified region of the fiber wall during early stages indicates selective mode of decay. In contrast, the occurrence of erosion troughs with characteristic U-notch in tangential sections is a characteristic feature of simultaneous rot that was apparent after 3 months of incubation. The decay pattern occurred concomitantly in all the xylem elements irrespective of general resistance pattern shown by vessel and axial parenchyma cells. At an advance stage, both species of Trametes showed formation of erosion channels along the microfibrils angle of cellulose which is considered as characteristics of soft rot decay type. The sharing of white rot and soft rot decay pattern by both the fungi suggest a phylogenetic link between both groups of fungi.

Durability of untreated and thermally modified reed (Phragmites australis) against brown, white and soft rot causing fungi

Reed (Phragmites australis (Cav.) Trin. ex Steud.) has been used for thatching roofs since centuries in many regions around the globe. Reed is a renewable resource and provides excellent thermal insulation properties. It is an appealing and very traditional material with known performance when applied as house roofing. However, during recent years an alarmingly high number of prematurely failing roofs were observed in different European countries, but the reason for drastically reduced service lives of thatched roofs is not understood, yet. This study aims therefore on comparative and comprehensive resistance tests to white, brown, and soft rot causing fungi to be performed with reed of different origin. Furthermore, thermal modification of reed was applied as potential environmental friendly technique to improve the durability of reed. Untreated reed of different origin as well as thermally modified reed (TMR) was found to be susceptible to white, brown, and soft rot decay. The latter caused most severe damage to the reed samples, i.e. >40% mass loss, and should therefore be addressed for future studies more in detail. The resistance of reed against the various decay fungi differed slightly between origins and culm sections. Thermal modification significantly improved the durability of reed. Mass loss caused by fungi was reduced by up to 80% at highest treatment intensity. However, the required treatment intensity did not become evident from the results yet. This should be determined in more detailed experiments including further target properties such as water exclusion efficacy, color, brittleness, and further strength properties to assure processing of the material for thatch.

Modelling timber decay caused by brown rot fungi

Decay models are key elements for service life prediction and performance classification of wooden products and timber structures. Available models differ in terms of data sources used and prevailing decay types considered. Comparative studies on performance models are therefore rare. In this study we applied data sets from field tests dominated by brown rot decay to a model developed on the basis of white and soft rot decay. Differences in time till colonization, onset of decay and subsequent decay progress between the rot types were found. Brown rot decay turned out to be initiated earlier and proceed faster compared to white and soft rot decay. Microclimate was influenced by shading within this study, whereby the moisture and temperature induced dose was affected as well as the progress of brown rot decay itself. Consequently, for obtaining a more conservative decay model only data sets dominated by brown rot and unaffected by shading were used. The brown model shortened the expected lifetime by 50 % compared to the previous white and soft rot model for a given dosage.