Water-based antimicrobial agents, used in environmentally friendly applications, are widely used in wood protection industries. Furthermore, nanomaterials as antimicrobial agents, because of their biocidal component, huge specific surface area, and unique nanoscale effect, have attracted attention in the field of biodurability. We employed aqueous dispersed nano-silver with a diameter of 10 nm~20 nm to treat poplar wood and evaluated its leaching resistance and anti-mold effect on the wood surface. The results revealed that the higher the retention of the nano-silver, the stronger the protection efficiency of the wood surface against three molds (Aspergillus niger V. Tiegh, Penicillium citrinum Thom, and Trichoderma viride Pers. ex Fr); and the leachability of the nano-silver presented a slowly growing trend with the increase in the retention. When the wood surface attained a silver retention of 0.324 g·m⁻², its anti-mold efficiency against Aspergillus niger V. Tiegh, Penicillium citrinum Thom, and Trichoderma viride Pers. ex Fr reached 80, 75, and 80%, respectively, which achieved or even exceeded the required standard value of effective mold inhibition (75%). Notably, the nano-silver leaching rate at this retention attained merely 4.75 %. The nanoparticle, well distributed on a wood surface, may promote sufficient contact with fungi as well as strong interaction with wood cell wall components, which probably contributed to the effective anti-mold efficiency and the leaching resistance. This study provided positive evidence for the anti-mold effect of nano-silver on wood surface.

Bamboo is rich in starch and sugars and can be infected by mold and stain fungi, degrading its performance, shortening its service life, and reducing its utilization value. It is crucial to investigate how to protect bamboo against mold and stain fungi. The zone of inhibition test was used to evaluate the antifungal activity of azoxystrobin, kresoxim-methyl, pyraclostrobin and 3-iodo-2-propynyl-butylcarbamate (IPBC) against stain fungi (Botryodiplodia theobromae, Fusarium moniliforme, and Alternaria alternate) and mold fungi (Aspergillus niger, Penicillium citrinum, and Trichoderma viride) to develop new chemicals to protect bamboo against stain fungi and molds. The inhibitory activity of the composite pyraclostrobin and IPBC with different ratios was evaluated. Water-based formulations of the fungi were used to treat the bamboo, and the mold and stain resistance of the bamboo was investigated at different chemical retention rates. The results showed that the antifungal activity of pyraclostrobin was significantly higher than that of azoxystrobin and kresoxim-methyl. Different degrees of inhibitory activities against the stain and mold fungi were observed, and the inhibitory activity was higher against stain fungi than against molds. The three stain fungi were completely inhibited at a 7:3 ratio of pyraclostrobin to IPBC and 0.1% concentration. As the ratio increased, the inhibitory effect against mixed mold strains improved. The control efficacy of the pyraclostrobin formulations Str-1 and Str-2 at 0.1% concentration was 100% against Alternaria alternate and 70.8% against Fusarium moniliforme. The control efficacy of the composite formulations SI-1 and SI-2 at 0.1% concentration was 100% against all three stain fungi and greater than 91.8% against the mixed mold strains. This study provides new insights into the utilization of pyraclostrobin and its composite formulations as new bamboo antifungal agents.

The diversity of stain fungi is important if wood is inhabited with various fungi, and the discoloration mechanism will be better understood. MiSeq amplicon high-throughput sequencing (Illumina^®) is able to detect species richness (the number of species within a community) and species evenness (the sizes of species populations within a community). This study detected fungal diversity in discolored Mongolian pine for the first time by the MiSeq approach, focusing on the nuclear ribosomal internal transcribed spacer-1 (ITS1). The results show that the discolored wood was inhabited by a combination of microorganisms, more than 90% of which belong toAscomycotafungi at the phylum level. The MiSeq method revealed not only all the inhabited fungal species but also their quantitative relation to each other. The dominant fungal species in sample A areHelotiales(34.1%) andHypocreales(20.7%). The dominant fungal species in sample B isNectriaceae(67.9%), whileHypocrea(34.7%) andSporothrix(27.6%) are the dominant fungal species in sample C. It was confirmed via core microbiome analysis that the following fungi were common stain fungi in the three discolored samples:Fusariumspp.,Aspergillusspp.,Sporothrixspp.,Penicilliumspp.,Trichodermaspp.,Alternariaspp. andCladophialophoraspp.

The modulus of elasticity (MOE) of wood is a sensitive indicator of rot-fungal attack. To develop an alternative method of rapid assessment of fungal decay in the laboratory, changes in static MOE of untreated and preservative-treated wood were measured during exposure to the brown-rot fungus, Gloeophyllum trabeum, and the white-rot fungus, Trametes versicolor, in a standard soil bottle assay. Static MOE loss was compared with mass loss. The results showed that the MOE of wood was a sensitive and reliable indicator of rot-fungal attack, regardless of fungus or wood species. The MOE analysis of untreated wood reduced the 12- to 16-week exposure time necessary for the standard mass loss measurement to four weeks. Also, the exposure time for preservative-treated wood was reduced to eight weeks. Untreated wood was determined to be susceptible to decay if the MOE loss was 40% or more after a four-week exposure, while treated wood was considered susceptible to decay if the MOE loss was 40% or more after an eight-week exposure.

High-throughput sequencing technology was used to analyze the fungal community structure and its association with the cause of decay on the wooden pillars of an ancient archway in Beijing. The dominant fungi on the rotten pillars belonged to Ascomycetes regardless of the sampling position. Compared with the fungal community composition of discolored wood previously studied, the proportion of Basidiomycetes in rotten wood pillars increased at the highest value of 37.9%. High-throughput sequencing showed that the main fungi in the first pillar were Ascomycetes ( Phoma , Lecythophora , and Scedosporium ) and Basidiomycetes (Sporidiobolales). Ascomycetes Lecythophora and Basidiomycetes Cryptcoccus and Postia were the main fungi in pillar 2. Phoma , Trichoderma, and Entoloma were isolated from pillar 1, whereas Alternaria and Phaeosphaeriaceae were obtained from pillar 2 using culture isolation. Traditional isolation failed to obtain all dominant fungi. The importance of high-throughput sequencing technology in ancient wooden structure building biodeterioration analysis was further explained. At the three sampling sites, the contact-ground fungal community composition was similar to that of in-ground wood, whereas above-ground fungal community composition was significantly different from the other two sites. The high moisture content of the wood caused decay. The bottom of the pillar was immersed in groundwater, whereas that cement coating prevents the evaporation of water,cause the wood moisture content to be high. By comparing the fungal diversities of decaying wood and discolored and dry, decayed wood, the relative content of Basidiomycetes may be used as an indicator of wood decay state.