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Following the commodity risk assessment of bonsai plants (Pinus parviflora grafted on Pinus thunbergii) from China performed by EFSA, the EFSA Plant Health Panel performed a pest categorisation of Pyrrhoderma noxium, a clearly defined plant pathogenic basidiomycete fungus of the order Hymenochaetales and the family Hymenochaetaceae. The pathogen is considered as opportunistic and has been reported on a wide range of hosts, mainly broad‐leaved and coniferous woody plants, causing root rots. In addition, the fungus was reported to live saprophytically on woody substrates and was isolated as an endophyte from a few plant species. This pest categorisation focuses on the hosts that are relevant for the EU (e.g. Citrus, Ficus, Pinus, Prunus, Pyrus, Quercus and Vitis vinifera). Pyrrhoderma noxium is present in Africa, Central and South America, Asia and Oceania. It has not been reported in the EU. Pyrrhoderma noxium is not included in Commission Implementing Regulation (EU) 2019/2072. Plants for planting (excluding seeds), bark and wood of host plants as well as soil and other growing media associated with plant debris are the main pathways for the entry of the pathogen into the EU. Host availability and climate suitability factors occurring in parts of the EU are favourable for the establishment and spread of the pathogen. The introduction and spread of the pathogen into the EU are expected to have an economic and environmental impact in parts of the territory where hosts are present. Phytosanitary measures are available to prevent the introduction and spread of the pathogen into the EU. Pyrrhoderma noxium satisfies all the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest. [ABSTRACT FROM AUTHOR]

Abstract Following the commodity risk assessment of bonsai plants (Pinus parviflora grafted on Pinus thunbergii) from China performed by EFSA, the EFSA Plant Health Panel performed a pest categorisation of Pyrrhoderma noxium, a clearly defined plant pathogenic basidiomycete fungus of the order Hymenochaetales and the family Hymenochaetaceae. The pathogen is considered as opportunistic and has been reported on a wide range of hosts, mainly broad‐leaved and coniferous woody plants, causing root rots. In addition, the fungus was reported to live saprophytically on woody substrates and was isolated as an endophyte from a few plant species. This pest categorisation focuses on the hosts that are relevant for the EU (e.g. Citrus, Ficus, Pinus, Prunus, Pyrus, Quercus and Vitis vinifera). Pyrrhoderma noxium is present in Africa, Central and South America, Asia and Oceania. It has not been reported in the EU. Pyrrhoderma noxium is not included in Commission Implementing Regulation (EU) 2019/2072. Plants for planting (excluding seeds), bark and wood of host plants as well as soil and other growing media associated with plant debris are the main pathways for the entry of the pathogen into the EU. Host availability and climate suitability factors occurring in parts of the EU are favourable for the establishment and spread of the pathogen. The introduction and spread of the pathogen into the EU are expected to have an economic and environmental impact in parts of the territory where hosts are present. Phytosanitary measures are available to prevent the introduction and spread of the pathogen into the EU. Pyrrhoderma noxium satisfies all the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest.

Brown root rot disease on Reevesia formosana was firstly found in Chiayi County, Taiwan. The infected trees with foliage wilting, leaf discoloration, brown mycelial mat on root and basal stem, and brown mycelial networks in rotten diseased wood were observed. The infected trees wilted eventually. Phellinus noxius was identified as the causal pathogen by the symptoms and signs shown on the trees. Also, morphological and molecular identification of the fungal colony isolated from the diseased tissue was carried out. P. noxius was inoculated to 6-year-old R. formosana seedlings with P. noxius grown on the oat grain medium in the greenhouse. Inoculated seedlings were infected. The symptoms and signs shown on the seedlings were the same as in the field. The fungus was then re-isolated from the diseased tissue. This is the first report of P. noxius on the host R. formosana in Taiwan. Since R. formosana is the main food source of Formotosena seebohmi, the outbreak of brown root rot disease on R. formosana deteriorates the habitat of F. seebohmi and may threaten the population of F. seebohmi when no proper mitigation is applied. [ABSTRACT FROM AUTHOR]

Pathogenic root/wood rot fungal species infect multiple urban tree species in Singapore. There is a need for sustainable and environmentally friendly mitigation. We report the local Trichoderma strains as potential biocontrol agents (BCAs) for pathogenic wood rot fungal species such as Phellinus noxius, Rigidoporus microporus, and Fulvifomes siamensis. Isolated Trichoderma strains were DNA-barcoded for their molecular identities and assessed for their potential as a BCA by their rate of growth in culture and effectiveness in inhibiting the pathogenic fungi in in vitro dual culture assays. Trichoderma harzianum strain CE92 was the most effective in inhibiting the growth of the pathogenic fungi tested. Preliminary results suggested both volatile organic compound (VOC) production and direct hyphal contact contributed to inhibition. SPME GC-MS identified known fungal inhibitory volatiles. Trichoderma harzianum strain CE92 hyphae were found to coil around Phellinus noxius and Lasiodiplodia theobromae upon contact in vitro and were possibly a part of the mycoparasitism. In summary, the work provides insight into Trichoderma inhibition of pathogenic fungi and identifies local strains with good potential for broad-spectrum BCAs against root/wood rot fungi in Singapore. [ABSTRACT FROM AUTHOR]

Ocean Expo Park, established in 1976 on subtropical Okinawa Island, Japan, has approximately 8000 planted or naturally grown trees in an area of 77.2 ha. Windfall of these trees occurs mainly due to typhoons; wood chips made from the trunks and roots of windfall trees are commonly used as mulching material throughout the park areas, despite possible infection by pathogenic fungi such as Phellinus noxius, the pathogen causing brown root rot. P. noxius is distributed in tropical and subtropical areas worldwide and has a broad host range. The fungus can infect host plants with mycelia via root‐to‐root contact or with basidiospores. Here, we report the current status of tree damage caused by brown root rot in the park and infer the infection routes of P. noxius based on microsatellite markers. Among a total of 294 trees surveyed in the park, P. noxius was isolated from 13 trees of five species. P. noxius was observed more frequently on Ficus microcarpa than on other tree species. Ficus superba var. japonica was identified as a new host species, and Bombax ceiba was first recorded as a host plant of P. noxius in Japan. Among the 13 P. noxius isolates from the diseased trees, 2 isolates from adjacent diseased trees were considered to be of the same genet, while the other 11 isolates were different genets, indicating that infection by basidiospores occurred frequently among trees in the entire park, although spread via root systems also occurred between at least two adjacent trees. An identical genet was not detected at distant locations, which suggests that the disease does not spread via chips. However, mulching with chips can lead to wood decay due to decaying fungi other than P. noxius. Therefore, in accordance with the precautionary principle, the park currently prohibits the chipping and mulching of windfall or damaged trees and is considering disposal methods such as burning. [ABSTRACT FROM AUTHOR]

Mature tropical urban trees are susceptible to root and trunk rot caused by pathogenic fungi. A metagenomic survey of such fungi was carried out on 210 soil and tissue samples collected from 134 trees of 14 common species in Singapore. Furthermore, 121 fruiting bodies were collected and barcoded. Out of the 22,067 OTUs (operational taxonomic units) identified, 10,646 OTUs had annotation information, and most were either ascomycetes (63.4%) or basidiomycetes (22.5%). Based on their detection in the diseased tissues and surrounding soils and/or the presence of fruiting bodies, fourteen basidiomycetes (nine Polyporales, four Hymenochaetales, one Boletales) and three ascomycetes (three species of Scytalidium) were strongly associated with the diseased trees. Fulvifomes siamensis affected the largest number of tree species surveyed. The association of three fungi was further supported by in vitro wood decay studies. Genetic heterogeneity was common in the diseased tissues and fruiting bodies (Ganoderma species especially). This survey identified the common pathogenic fungi of tropical urban trees and laid the foundation for early diagnosis and targeted mitigation efforts. It also illustrated the complexity of fungal ecology and pathogenicity. [ABSTRACT FROM AUTHOR]

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Brown Root Rot Disease (BRRD) is one of the most devastating urban tree diseases in tropical and subtropical areas, including Hong Kong. It can result in tree death in a few months and is difficult to detect in the early stages of development. Fungal isolation and PCR methods are currently the most widely adopted methods to diagnose the disease. However, they are both time and technically demanding. Loop-mediated isothermal amplification (LAMP) is a superior molecular-based diagnostic method with great specificity, accessibility, and effectivity. In this study, 15 BRRD-positive and 15 BRRD-negative trees were sampled from 19 roadside slopes in Hong Kong from the end of 2020 to the middle of 2021. The wood tissues were isolated and cultivated in PN3 and PDA agars for the disease diagnosis. The mycelium samples in PDA were directly conducted in LAMP kits (mLAMP) to substitute the purified DNA materials. Wood tissues were also used in LAMP kits (wLAMP) as impurified and highly contaminated samples. The results of mLAMP and wLAMP were compared with the results of isolation to evaluate the specificity and sensitivity of LAMP method. The results showed that mLAMP had 100% sensitivity and 73.3% specificity. For wLAMP, both the sensitivity and specificity were 73.3%. For symptomless trees, 85.7% and 64.3% congruencies were found in mLAMP and wLAMP, respectively. Based on the results of this study, the co-application of LAMP in the current tree management work was also discussed. We envisaged LAMP is a sensitive, prompt, and user-friendly method to diagnose BRRD and it could favor the BRRD diagnosis in fields by accelerating and promoting large-scale screening. [ABSTRACT FROM AUTHOR]

Pathogenic root/wood rot fungal species infect multiple urban tree species in Singapore. There is a need for sustainable and environmentally friendly mitigation. We report the local Trichoderma strains as potential biocontrol agents (BCAs) for pathogenic wood rot fungal species such as Phellinus noxius, Rigidoporus microporus, and Fulvifomes siamensis. Isolated Trichoderma strains were DNA-barcoded for their molecular identities and assessed for their potential as a BCA by their rate of growth in culture and effectiveness in inhibiting the pathogenic fungi in in vitro dual culture assays. Trichoderma harzianum strain CE92 was the most effective in inhibiting the growth of the pathogenic fungi tested. Preliminary results suggested both volatile organic compound (VOC) production and direct hyphal contact contributed to inhibition. SPME GC-MS identified known fungal inhibitory volatiles. Trichoderma harzianum strain CE92 hyphae were found to coil around Phellinus noxius and Lasiodiplodia theobromae upon contact in vitro and were possibly a part of the mycoparasitism. In summary, the work provides insight into Trichoderma inhibition of pathogenic fungi and identifies local strains with good potential for broad-spectrum BCAs against root/wood rot fungi in Singapore.

Emerging plant pathogens have been increasing exponentially over the last century. To address this issue, it is critical to determine whether these pathogens are native to ecosystems or have been recently introduced. Understanding the ecological and evolutionary processes fostering emergence can help to manage their spread and predict epidemics/epiphytotics. Using restriction site‐associated DNA sequencing data, we studied genetic relationships, pathways of spread and the evolutionary history of Phellinus noxius, an emerging root‐rotting fungus of unknown origin, in eastern Asia, Australia and the Pacific Islands. We analysed patterns of genetic variation using Bayesian inference, maximum‐likelihood phylogeny, population splits and mixtures measuring correlations in allele frequencies and genetic drift, and finally applied coalescent‐based theory using Approximate Bayesian computation (ABC) with supervised machine learning. Population structure analyses revealed five genetic groups with signatures of complex recent and ancient migration histories. The most probable scenario of ancient pathogen spread is movement from an unsampled population to Malaysia and the Pacific Islands, with subsequent spread to Taiwan and Australia. Furthermore, ABC analyses indicate P. noxius spread occurred thousands of generations ago, contradicting previous assumptions that this pathogen was recently introduced to multiple geographical regions. Our results suggest that recent emergence of P. noxius in eastern Asia, Australia and the Pacific Islands has probably been driven by anthropogenic and natural disturbances, such as deforestation, land‐use change, severe weather events and/or introduction of exotic plants. This study provides a novel example of applying genome‐wide allele frequency data to unravel the dynamics of pathogen emergence under changing ecosystem conditions. [ABSTRACT FROM AUTHOR]

Phellinus noxius causes brown root rot (BRR) of diverse trees. Basidiospores and diseased host tissues have been recognized as important sources of P. noxius inoculum. This study aimed to understand whether P. noxius could occur or survive in soil without host tissues in the natural environment. Soil was sampled before and after the removal of diseased trees at eight BRR infection sites (total of 44 samples). No P. noxius colonies were recovered in soil plating assays, suggesting that no or little viable P. noxius resided in the soil. To know whether P. noxius could disseminate from decayed roots to the surrounding soil, rhizosphere and non-rhizosphere soils were sampled from another two infection sites. Although P. noxius DNAwas detectable with specific primers, no P. noxius could be isolated, even from the rhizosphere soils around decayed roots covered with P. noxius mycelial mats. The association between viable P. noxius and the presence of its DNA was also investigated using field soil mixed with P. noxius arthrospores. After P. noxius was exterminated by flooding or fumigation treatment, its DNA remained detectable for a few weeks. The potential of onsite soil as an inoculum was tested using the highly susceptible loquat (Eriobotrya japonica). Loquats replanted in an infection site that had been cleaned up by simply removing the diseased stump and visible residual roots remained healthy for a year. Taken together, P. noxius is not a soilborne pathogen, and diseased host tissues should be the focus of field sanitation and detection for BRR. [ABSTRACT FROM AUTHOR]

Since 2007, a comprehensive survey of the occurrence of brown root rot disease has been conducted in Taiwan. The rare basidiocarps of the pathogen Phellinus noxius (Corner) Cunningham were also investigated throughout Taiwan and on outer islands. To 2018, a total of 2287 disease cases of brown root rot were recorded, and 164 cases were found with basidiocarps on diseased trees. These 164 cases included 33 newly discovered tree hosts on which were borne the fruiting body of P. noxius. Most of the basidiocarps were of the flat type which is inconspicuous, while some belong to bracket type. Generally, basidiocarps were found in most counties of Taiwan and on the outer islands, but they exhibited higher frequencies in the central and southern parts of Taiwan. They tended to occur more at elevations of 200~300 m in the hills, but gradually disappeared at the elevation increased to 800 m. To compare variations in growth rates, 34 single-basidiospore isolates were obtained and grown on both potato dextrose agar (PDA) and malt extract agar medium (MEA). Results showed three levels of significant growth differences on PDA, and four levels of differences on MEA, indicating growth rate variations among these sexual basidiospores. The abundance of P. noxius basidiocarps in nature suggests that genetically variable basidiospores are involved in long]distance dispersal of this fungus which is responsible for serious tree diseases. [ABSTRACT FROM AUTHOR]

The role of basidiospores of Phellinus noxius in nature has not been clearly elucidated since brown root rot disease was discovered. Previously, it was reported that P. noxius rarely produces basidiocarps in nature, while a total of 33 new tree host species bearing basidiocarps were recently found in Taiwan. The more-abundant basidiospores were collected for germination and infection studies in this paper. Fresh basidiospores were collected from live basidiocarps growing on a small-leafed banyan (Ficus microcarpa), and the basidiospores were rinsed out. The germination experiment revealed that they could germinate in all kinds of liquids including rainwater, with germination rates usually exceeding 50%. The direct inoculation of basidiospore suspensions at concentration of 105~106 spores/mL on four tree species was consistently unsuccessful. The same spore suspension was used to inoculate wood chips from Taiwan zelkova (Zelkova serrata) sapwood. After 2 months, some of the wood chips had been colonized by basidiospores, showing dark-brown line or network symptoms. Using these colonized wood chips, we successfully inoculated wounded roots of Taiwan zelkova seedlings within 3 months, proving the virulence and role of basidiospores in nature. Since 2007, 13 cases of twig or stem infection by P. noxius were found in the field, confirming transmission by basidiospores. In Taiwan, due to the high frequency of typhoon damage to trees, abundant stem wounds should act as important sites for basidiospore deposition and infection. This could facilitate the long-distance dispersal of this disease in nature. [ABSTRACT FROM AUTHOR]

The antifungal activity of leaf oils from different provenances of Cinnamomum osmophloeum was evaluated against Phellinus noxius and their chemical polymorphism. C. osmophloeum leaf oils of 15 provenances and their relative contents were classified into eight chemotypes, namely cinnamaldehyde, cinnamaldehyde/linalool, linalool, cinnamaldehyde/cinnamyl acetate, linalool/camphor, camphor/bornyl acetate, 1,8-cineole/p-cymene, and mixed types according to GC-MS, CA, and PCA. It was found that leaf oils of both cinnamaldehyde and cinnamaldehyde/cinnamyl acetate types had excellent inhibitory effects against P. noxius, and their IC50 values were 119.5 and 154.1 µg/ml, respectively. Furthermore, trans-cinnamaldehyde possessed the strongest antifungal activity among the constituents against P. noxius, and its IC50 values were 116.0 µg/ml. [ABSTRACT FROM AUTHOR]

Brown root rot disease (BRRD), caused by Phellinus noxius , is an important tree disease in tropical and subtropical areas. To improve chemical control of BRRD and deter emergence of fungicide resistance in P . noxius , this study investigated control efficacies and systemic activities of fungicides with different modes of action. Fourteen fungicides with 11 different modes of action were tested for inhibitory effects in vitro on 39 P. noxius isolates from Taiwan, Hong Kong, Malaysia, Australia, and Pacific Islands. Cyproconazole, epoxiconazole, and tebuconazole (Fungicide Resistance Action Committee [FRAC] 3, target-site G1) inhibited colony growth of P. noxius by 99.9 to 100% at 10 ppm and 97.7 to 99.8% at 1 ppm. The other effective fungicide was cyprodinil + fludioxonil (FRAC 9 + 12, target-site D1 + E2), which showed growth inhibition of 96.9% at 10 ppm and 88.6% at 1 ppm. Acropetal translocation of six selected fungicides was evaluated in bishop wood ( Bischofia javanica ) seedlings by immersion of the root tips in each fungicide at 100 ppm, followed by liquid or gas chromatography tandem mass spectrometry analyses of consecutive segments of root, stem, and leaf tissues at 7 and 21 days posttreatment. Bidirectional translocation of the fungicides was also evaluated by stem injection of fungicide stock solutions. Cyproconazole and tebuconazole were the most readily absorbed by roots and efficiently transported acropetally. Greenhouse experiments suggested that cyproconazole, tebuconazole, and epoxiconazole have a slightly higher potential for controlling BRRD than mepronil, prochloraz, and cyprodinil + fludioxonil. Because all tested fungicides lacked basipetal translocation, soil drenching should be considered instead of trunk injection for their use in BRRD control., Competing Interests: The author(s) declare no conflict of interest.

The avocado industry was established in New Zealand from several importations dating back to 1907. Several serious pathogens found elsewhere in the world were not imported. A literature review and internet search were conducted to determine what serious avocado pathogens are not present in New Zealand and the potential impact they could have if they established. Relevant information was summarised for six pathogens determined to be the most serious of avocado and not known to be present in New Zealand: avocado sunblotch viroid (ASBVd); Pseudocercospora purpurea (cercospora spot); Raffaelea lauricola (laurel wilt); Fusarium sp. (fusarium dieback); Phellinus noxius (brown root rot); and Sphaceloma perseae (avocado scab). Laurel wilt, brown root rot, cercospora spot and fusarium dieback could become established in New Zealand if the climate here becomes warmer but establishment of ASBVd and avocado scab (which are not restricted to hot climates) is more likely. [ABSTRACT FROM AUTHOR]

Taiwania ( Taiwania cryptomerioides Hayata) is a native and plantation species in Taiwan, and its heartwood has demonstrated excellent decay resistance. Brown root rot fungus Phellinus noxius has caused severe damage to more than 100 tree species in Taiwan. The aims of this study were to investigate the antifungal activities of Taiwania heartwood extracts against P. noxius and to identify the antifungal compounds. Antifungal activities were examined using the agar dilution method (a direct contact assay) and the inverted lid method (a vapor contact assay). Active compounds were purified using liquid-liquid partition, open-column chromatography and HPLC. Among four soluble fractions ( n-hexane, ethyl acetate, n-butanol and water soluble fractions), results showed that n-hexane soluble fraction (HSF) can significantly inhibit the growth of P. noxius via the agar dilution method. Moreover, active compounds present in HSF were obtained using antifungal assay-guided fractionation. Results showed that ferruginol, T-cadinol, α-cadinol and T-muurolol were found to exhibit excellent antifungal activities against P. noxius, and their IC values were 16.9, 25.8, 33.8 and 50.6 μg/mL, respectively. According to the current findings, phytochemicals (ferruginol, T-cadinol, α-cadinol and T-muurolol) of Taiwania heartwood had the potential to be used as environmentally benign antifungal agents against P. noxius in place of synthetic or inorganic fungicides. [ABSTRACT FROM AUTHOR]

Background: Analysis of phylogenetic relationship of 91 isolates of Phellinus noxius obtained from 46 plant species in Taiwan did not show distinct grouping based on ITS sequences. Results: However, the ITS nucleotides showed 20 different kinds of variations including single nucleotide polymorphisms, deletion and insertion in ITS1 and ITS2, but none in 5.8 S. The Taiwanese isolates of P. noxius were dividable into long (type L), median (type M) and short (type S) groups based on ITS sequence length. Two isolates with identical ITS sequence belonged to types L. Type M with 72 isolates was further divided into 33 subtypes, while types S with 17 isolates was further divided into two subtypes. Conclusion: Phylogenetic analysis of ITS sequences among Phellinus species showed that isolates of P. noxius were in the same clade distinctly separated from other Phellinus species. [ABSTRACT FROM AUTHOR]

The aim of the present in-vitro studies was to identify Trichoderma strains from Hong Kong with highly antagonistic potential against the basidiomycete Phellinus noxius. Dual culture and interaction tests using samples of balsa wood (Ochroma lagopus) as well as studies on fungal growth at different temperatures and water activities were conducted. The impact of Trichoderma strains on wood colonisation and decomposition by three P. noxius isolates were quantitatively analysed by measuring dry weight loss and rate of eradication of the pathogen from the test wood. Most Trichoderma strains revealed antagonistic potential against P. noxius. In the wood blocks incubated with P. noxius and then treated with Trichoderma T-TMS1 for 24 weeks, 100% eradication of three P. noxius isolates was recorded. The results indicated that application of Trichoderma strains might be a promising and environmentally benign method of eradicating P. noxius from wood debris in soils. [ABSTRACT FROM AUTHOR]

In this study, the effect of phenazine-1-carboxylic acid (PCA) on morphological, physiological, and molecular characteristics of Phellinus noxius has been investigated, and the potential antifungal mechanism of PCA against P. noxius was also explored. The results revealed that PCA showed in vitro antifungal potential against P. noxius and completely inhibited P. noxius hyphae at concentrations >40 μg/mL. PCA inhibited both mycelial growth and the loss of mycelial biomass in vitro in a dose-dependent manner. Morphological changes in PCA-treated P. noxius hyphae, such as irregularly swollen mycelia as well as short hyphae with increased septation and less branching, were observed by optical microscopy. The intracellular reactive oxygen species (ROS) levels were significantly increased in PCA-treated P. noxius cells as compared to control groups. Induced hyperpolarization of the mitochondrial membrane potential (MMP), repressed superoxide dismutase (SOD) activity and up-regulated gene expression of seven tested genes were also found in PCA-treated P. noxius groups. Thus, the present results suggested that the mechanism of action of PCA against P. noxius might be attributed to direct damage of mycelium and high intracellular ROS production, and indirect induction of genes involved in cell detoxification, oxidation-reduction process, and electron transport of the respiratory chain. [ABSTRACT FROM AUTHOR]

Phellinus noxius is a pathogenic fungus that causes brown root rot disease in a variety of tree species. This fungus is distributed in tropical and sub-tropical regions of Southeast and East Asia, Oceania, Australia, Central America and Africa. In Japan, it was first discovered on Ishigaki Island in Okinawa Prefecture in 1988; since then, it has been found on several of the Ryukyu Islands. Recently, this fungus was identified from the Ogasawara (Bonin) Islands, where it has killed trees, including rare endemic tree species. For effective control or quarantine methods, it is important to clarify whether the Japanese populations of P. noxius are indigenous to the area or if they have been introduced from other areas. We developed 20 microsatellite markers from genome assembly of P. noxius and genotyped 128 isolates from 12 of the Ryukyu Islands and 3 of the Ogasawara Islands. All isolates had unique genotypes, indicating that basidiospore infection is a primary dissemination method for the formation of new disease foci. Genetic structure analyses strongly supported genetic differentiation between the Ryukyu populations and the Ogasawara populations of P. noxius. High polymorphism of microsatellite loci suggests that Japanese populations are indigenous or were introduced a very long time ago. We discuss differences in invasion patterns between the Ryukyu Islands and the Ogasawara Islands. [ABSTRACT FROM AUTHOR]

Since the 1990s, brown root rot caused by Phellinus noxius (Corner) Cunningham has become a major tree disease in Taiwan. This fungal pathogen can infect more than 200 hardwood and softwood tree species, causing gradual to fast decline of the trees. For effective control, we must determine how the pathogen is disseminated and how the new infection center of brown root rot is established. We performed Illumina sequencing and de novo assembly of a single basidiospore isolate Daxi42 and obtained a draft genome of ~40 Mb. By comparing the 12,217 simple sequence repeat (SSR) regions in Daxi42 with the low-coverage Illumina sequencing data for four additional P. noxius isolates, we identified 154 SSR regions with potential polymorphisms. A set of 13 polymorphic SSR markers were then developed and used to analyze 329 P. noxius isolates collected from 73 tree species from urban/agricultural areas in 14 cities/counties all around Taiwan from 1989 to 2012. The results revealed a high proportion (~98%) of distinct multilocus genotypes (MLGs) and that none of the 329 isolates were genome-wide homozygous, which supports a possible predominant outcrossing reproductive mode in P. noxius. The diverse MLGs exist as discrete patches, so brown root rot was most likely caused by multiple clones rather than a single predominant strain. The isolates collected from diseased trees near each other tend to have similar genotype(s), which indicates that P. noxius may spread to adjacent trees via root-to-root contact. Analyses based on Bayesian clustering, FST statistics, analysis of molecular variance, and isolation by distance all suggest a low degree of population differentiation and little to no barrier to gene flow throughout the P. noxius population in Taiwan. We discuss the involvement of basidiospore dispersal in disease dissemination. [ABSTRACT FROM AUTHOR]

Basal root rot of teak was first reported from Sabak Bernam, Selangor making this the first report of the disease on teak in Peninsular Malaysia. The fungus found associated with the disease was Phellinus noxious. The disease aggressively killed its host irrespective of the host health status. Bark depression at the root collar which was visible from a distance was the characteristic symptom and the main indicator in identifying the disease in the plantation since above ground symptoms of the canopy could not be differentiated from crowns of healthy trees. However, although above ground symptoms were not easily discernible, the disease was already advanced and the trees mostly beyond treatment; 3.4 % of the trees in the plantation were affected and the disease occurred both on solitary trees and in patches. Below ground, infected trees had rotted root systems, mainly below and around the collar region with brown discolored wood and irregular golden-brown honeycomb-like pockets of fungal hyphae in the wood. Pathogenicity tests showed that the fungus produced symptoms similar to those observed in the plantation and killed two year-old teak plants. The disease killed all the inoculated hosts within three months, irrespective of wounded or unwounded treatments.

The distribution of Phellinus noxius is currently limited to tropical and subtropical regions of Southeast and East Asia, Oceania, Central America, and Africa. The ability of this pathogen to produce disease in temperate climates is unknown. We examined the pathogenicity of Phellinus noxius on four important conifer plantation species grown under temperate conditions in Japan. The inoculation experiment with two isolates of P. noxius from Japan demonstrated clear fungal pathogenicity on the four conifer species, 3 months post-inoculation. Typical disease symptoms ranged from wilting, leaf chlorosis and necrosis, and defoliation resulting in the eventual death of most saplings. Mortality rate varied depending on tree species and the fungal isolate used. The results suggest that the possibility of serious damage if P. noxius invades the temperate zone of Japan (e.g., Kyushu and/or Honshu) from subtropical areas of Japan such as the Ryukyu Islands or foreign countries as global warming progresses. [ABSTRACT FROM AUTHOR]

The chemical compositions and anti-tumor activities of the petroleum ether fraction (PE), from mushroom Pyropolyporus fomentarius, were studied. Upon gas chromatography–mass spectrometry (GC–MS) analysis, nine major constituents were identified in the fraction. In vitro, the PE showed cytotoxic activity against murine sarcoma S180 (S180) cells in a dose- and time-dependent manner, and the cytotoxic effects were associated with apoptosis. The mitochondrial membrane potential loss and the intracellular ROS generation were greatly increased in the Pyropolyporus fomentarius PE treated group, suggesting cell apoptosis, induced by the PE in S180 cells, might be mitochondria dependent and ROS mediated. Consistent with in vitro findings, the in vivo study showed that the Pyropolyporus fomentarius PE was also effective in inhibiting the tumor growth induced by S180 cells and had lower immune organ toxicity. We found that the Pyropolyporus fomentarius PE has significant anti-tumor activity and great potential in screening anti-tumor drugs. [ABSTRACT FROM AUTHOR]

The extent and location of decay in a damaged standing hazel bottle tree (Sterculia foetida) infected with brown root rot (Phellinus noxius) were determined using non-destructive evaluation (NDE) techniques, namely, visual inspection, stress wave tomography, drilling resistance and crushing strength. The stress wave velocity, drilling resistance and crushing strength of the infected tree were lower than those of the uninfected tree. Greater decay and damage as well as weaker strength properties were found near the root and bark of the trunk at the base of the infected tree. Observation in the ield showed that decay and wood deterioration due to brown root rot developed from the root upwards to the trunk and from the bark penetrating inwards to the pith. Various NDE techniques can be used in combination to detect decay in living tree infected with brown root rot. [ABSTRACT FROM AUTHOR]

The fungus Phellinus noxius has a broad host range and causes brown root rot in a variety of tree species of various ages, irrespective of their original health. The fungus is widely distributed in tropical countries of Southeast Asia, the Pacific Islands and Australia, Central America and Caribbean, and Africa. Since 1988, when brown root rot was first found on Ishigaki Island, Okinawa Prefecture, the disease has been reported on several islands in Okinawa and Kagoshima Prefectures, and it has been causing serious problems to shade, windbreak, ornamental and landscape trees in the Ryukyu Islands, located in the subtropical region of southern Japan. Here, we report on the current status of P. noxius-caused brown root rot in the Ryukyu Islands, Japan, including symptoms, occurrence, dispersal, distribution and host tree species of the disease, pathogenicity and/or virulence of the pathogen, and disease management based on our surveys and previously published reports from Japan. Brown root rot has been confirmed in 53 tree species from 32 plant families at different sites on 10 of the 12 islands surveyed. Among the 53 tree species, 34 were first recorded in Japan as host plants of P. noxius. The disease occurs mainly in shade, ornamental and windbreak trees at sightseeing places, parks, roadsides, agricultural land such as sugar cane fields, and around residences or other places associated with human activities. [ABSTRACT FROM AUTHOR]

BACKGROUND: Brown root rot disease caused by Phellinus noxius is widespread in approximately 216 tree and plant species in tropical and subtropical countries. No direct means of protection against P. noxius infection have thus far been developed. Therefore, in this field survey, a method was developed for preventing and controlling brown root rot disease using fumigation with dazomet. RESULTS: Tracers were used to monitor the effect of dazomet fumigation. The results from field surveys and phytotoxicity tests showed that dazomet is able to kill P. noxius without any side effects on plants. CONCLUSION: The use of an environmentally friendly agent to control brown root rot disease is needed, and prevention of the disease is more important than treatment. Hence, chemical fumigation with 60 g m−2 of 98% dazomet may be a possible means of preventing P. noxius incursion in agriculture, gardening and agroforestry. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: The objective of these in vitro studies was to identify a Trichoderma strain that reduces the rate of wood decomposition by the white rot fungus Phellinus noxius and Ganoderma australe. For this purpose, dual culture and interaction tests in wood blocks of three hardwoods, Delonix regia, Ficus benjamina, Jacaranda mimosifolia, and one softwood, Araucaria bidwillii, as well as investigations of fungal growth under different environmental conditions, were performed. The effect of Trichoderma ghanense, two strains of T. harzianum and T. reesei on wood colonization and decomposition by four P. noxius strains and G. australe were quantitatively analyzed by measuring the dry weight loss of wood. All Trichoderma species and wood-decay fungi showed optimum growth at a mean temperature of 25–35°C and a high water activity (aw ) of 0.998. At 35°C and aw 0.928, no growth was recorded for any of the wood-decay fungi after 1week, whereas most Trichoderma species were still actively growing. The different Trichoderma species all showed an antagonistic potential against P. noxius in the in vitro studies. The species of wood-decay fungi showed significant differences in their sensitivity when challenged by the volatile organic compounds (VOCs) of Trichoderma species. Reduction in the rate of wood decomposition by different Trichoderma species against all wood-decay fungi varied strongly according to the specific plant host. T. harzianum 121009 and T. atroviride 15603.1 showed the highest reduction in weight losses. P. noxius 169 strongly decomposed untreated and pretreated wood of D. regia, whereas weight losses of F. benjamina and J. mimosifolia pretreated with Trichoderma strains were significantly lower. Weight losses by G. australe were significantly reduced for A. bidwillii, D. regia and F. benjamina by all Trichoderma species, but no affect was recorded for J. mimosifolia. The in vitro studies show that only after careful monitoring (i.e. selecting the appropriate strain for the target pathogen and its niche (wood species) can Trichoderma species be used to significantly reduce the growth and rate of wood decomposition by different P. noxius strains. [Copyright &y& Elsevier]

Serratia marcescens (TRS-1), either as aqueous suspensions or in bioformulations of sawdust, rice husk and tea waste, promoted growth in tea seedlings as evidenced by increase in height, emergence of new leaves and branches, as well as increase in leaf biomass. Survival of S. marcescens in soil after application was determined by ELISA and Dot-Blot using PAb raised against the bacterium. S. marcescens solubilized phosphate in vitro and in vivo. Following application of the bacterium, soil P content decreased, root and leaf phosphate increased, and soil phosphatase activities were enhanced. The bacterium was antagonistic to a number of fungal pathogens in vitro. It also reduced brown root rot of tea caused by Fomes lamaoensis. Significant increase in phenolics, as well as peroxidase, chitinase, β-1,3-glucanase and phenylalanine ammonia-lyase, were observed in tea plants on application of S. marcescens alone or followed by F. lamaoensis. [ABSTRACT FROM AUTHOR]