This study examined the occurrence of macrofungi and the decay of roofs thatched with water reed, Phragmites australis. Sampling from 20 north- and 20 south-facing roof sides showed that several ascomycetes usually associated with reed in situ are common on thatch. The only basidiomycetes recorded were Mycena species. There was no significant difference in the representation of macrofungi on north- and south-facing roof sides, but Mycena spp. only produced basidiomes on surfaces facing north, suggesting that the dry environment of the south side prevents fruiting. Eleven species were recorded in total, and the average of 2·4 species per roof did not increase with the age of thatch or degree of decay. The same species were generally present on young and old thatch, and no successional stages of fungal communities could be distinguished with increasing roof age.

Deterioration of thatch occurs at the exposed surface of the roof and progresses inwards. Within the layer of reeds outer, middle, and inner zones develop representing different stages in the decay. The zones move inwards as thatch deteriorates. A comparison of the rate of decay among roofs with pitch 30°, 45° and 60° showed that the innermost zone appeared ca 20 cm from the exposed reed butts in both of the steeper roofs, whereas it was no longer present in the roof with low pitch. This suggests that the depth of the zones depends upon the roof slope, and the outer and middle zones move inwards at a higher rate in roofs with a low pitch, resulting in an increased rate of deterioration.

Phragmites thatch appears to harbour its own characteristic macrofungal community, with certain Mycena species likely to represent the principal decomposers. A common feature of fungi occurring on thatch is that they must endure unfavourable conditions.

Halosarpheia kandeliae sp. nov. collected on intertidal bark of Kandelia candel is described and its unique ascus morphology illustrated. It is compared with other Halosarpheia spp. and Aniptodera salsuginosa.

This listing covers the period September 1, 1997 through to October 31, 1997. Citations are arranged in groups which roughly correspond with the British Mycological Society's Special Interest Committees. All correspondence about this item should be addressed to the Executive Editor. Reprints of this feature will not be available.

As part of an investigation into the factors influencing the colonization of the rhizosphere and the root tissues of host plant, by pathogenic and non-pathogenic strains of Fusarium oxysporum, the effect of a range of carbon (C) sources on the growth habits of five strains of F. oxysporum were compared. The strains used were two F. oxysporum f. sp. lycopersici (Fol strains), two F. oxysporum f. sp. radicis-lycopersici (Forl strains) pathogenic on tomato and strain Fo47, a non-pathogenic strain of F. oxysporum, currently used as a biocontrol agent to reduce severity of fusarium diseases on several crops. Radial extension rates on solid media were measured using soluble saccharides (glucose, xylose and D galacturonic acid), polysaccharides (carboxymethyl cellulose, xylan and pectin) and soluble and insoluble extracts of tomato roots as C sources. Growth parameters were estimated by fitting a logistic equation to biomass data recorded from liquid culture using the same C sources.

The strains were characterized by means of the pattern of radial extension rates on the various C sources, and the two Forl strains were discriminated further from the other strains. The growth parameters were unique features of each F. oxysporum strains, whatever the C source. The pathogenic strains did not exhibit particular abilities in degrading the cell wall components. It was concluded that growth habits related to carbohydrate utilization are unique to each strain of F. oxysporum and that these traits are not related to pathogenicity.

The adhesion of conidia of Drechmeria coniospora to the nematode Panagrellus redivivus was reduced after treatment of the conidia with Pronase E, or the detergents sodium dodecyl sulphate (SDS) and dodecyltrimethylammonium bromide (DTAB) suggesting involvement of proteinaceous compounds in the adhesion process. In the TEM the thick extracellular pad covering the adhesive bud of the conidia was completely removed after treatment with Pronase E. After treatment with SDS or DTAB the proteinaceous compounds appeared to be dissolved leaving mainly carbohydrates in the pad as observed on OsO4 without and OsO4 with Ruthenium red-stained material, respectively. The detergent extracts after SDS and DTAB treatments contained nine and seven peptides, respectively, with molecular masses in the range from 6 to 80 kDa on SDS-PAGE gels, and five biotinylated peptides were found in each extract, after blotting to nitrocellulose membranes, indicating that these were surface proteins. None of the detergent extracts was able to reduce adhesion of the conidia after treatment of the nematodes. The detergent extracts contained protease- and phosphatase activity. The protease inhibitor, chymostatin, inhibited infection of nematodes and growth of the conidia, suggesting the involvement of chymotrypsin-like proteases in the infection process. On gelatin-containing substrate gel electrophoresis two proteases were clearly chymostatin sensitive.

The Cainiaceae is revived to accommodate Atrotorquata, Arecophila, Cainia, Ceriophora and Reticulosphaeria, all of which are described and illustrated. Ommatomyces is also included in the family and discussed. The essential characteristics of the family are ascomata which are usually immersed under a clypeus, unitunicate asci with a complex, J+, apical apparatus comprising a series of rings, and brown ascospores which may have longitudinal germ slits, striations, reticulate ornamentations and/or germ pores.

This listing covers the period November 1, 1997 through to December 31, 1997. Citations are arranged in groups which roughly correspond with the British Mycological Society's Special Interest Committees. All correspondence about this item should be addressed to the Executive Editor. Reprints of this feature will not be available.

A new nematophagous hyphomycete is described from the Canary Islands as Arthrobotrys hertziana. It has branched conidiophores with slightly swollen tips, mostly three-septate conidia, and sticky knobs as trapping devices. A key to Arthrobotrys species forming sticky knobs is presented. Among six nematode and two springtail species tested as hosts only the nematode Panagrellus redivivus was trapped. The results are discussed with reference to taxonomical problems and the possibly limited host range.

Four species of Biflagellospora are reported from submerged wood samples in Thailand. They are characterized by simple, cylindrical, mostly geniculate, brown conidiophores with one or more sub-hyaline to light-brown conidia bearing long filiform appendages on each of two terminal cells. B. japonica is a new record for Thailand. B. siamensis, B. papillata and B. gracilis are described as new species.

The phylogenetic relationships of two Meliola spp., one Meliolina sp., and 36 other ascomycetes were inferred from sequences of the nuclear small subunit ribosomal RNA gene. Phylogenetic analyses revealed that the Meliolaceae are members of the unitunicate Pyrenomycetes, and are not closely related to the bitunicate ascomycetes. The Meliolaceae have been hypothesised to be closely related to the Erysiphaceae, but the cladistic analyses showed that the two families are not closely related. The phylogenetic position of Meliolina is found amongst the bitunicate ascomycetes making it distantly related to the Meliolaceae.

The effects of a prescribed fire on the presence of ectomycorrhizal fungi on the root tips of ponderosa pine were investigated one year after a prescribed ground fire. Ectomycorrhizas were sampled within 1 m2 plots before and one year after the fire, and in nearby control plots that were not burned. The cores were divided into litter/organic, upper mineral, and lower mineral layers. The total ectomycorrhizal biomass in the control plots did not differ between year one and year two samples for any core layer, while in the fire plots the destruction of the litter/organic layer resulted in an eight-fold reduction in total ectomycorrhizal biomass. Mycorrhizal biomass in the two mineral layers was not significantly reduced by the fire. We used molecular tools to identify fungi directly from the ectomycorrhizas. In unburned plots members of the Russulaceae and Thelephoraceae were among the most frequent and abundant ectomycorrhizal types; species of most other taxa were rare. In the control plots these two families were among the dominant species in both years, but patchiness on a fine spatio-temporal scale caused some major changes in ranking of individual species between sample years. Rhizopogon subcaerulescens was the most pronounced example; its biomass in the control plot samples was seven times greater in year two than in year one because of an exceptionally large cluster of mycorrhizas encountered in a single core. The effect of fire on individual species was difficult to assess because of this patchiness and because all species were low in abundance after the fire. The most abundant pre-fire species were reduced to undetectable post-fire levels, while several less abundant species, including R. subcaerulescens, Cenococcum geophilum, and several unknown types were not substantially reduced by the fire. We speculate that the more abundant species, Martellia sp., thelephoroid 1, and Tomentella sublilacina, were differentially affected because their dominance was most prominent at the litter and organic layers. In any case, a short-term effect of this fire appears to be increased species evenness.

The patterns of mycelial development (length and branching) of five strains of Fusarium oxysporum were measured in the vicinity of tomato and wheat roots. Two strains were of f. sp. lycopersici, two of f. sp. radicis-lycopersici and the fifth was a non-pathogenic strain currently used as a biocontrol agent. Hyphal extension and branching were measured microscopically using a CCD camera and an image analyser. Furthermore, the role of soluble root exudates, insoluble root materials, glucose supply, and nitrogen supply (casamino acids) on mycelial development was investigated. Each strain had its own pattern of development in the absence of a root. Fungal development of all five strains was stimulated in the vicinity of roots irrespective of plant species but there was no chemotropic response towards or away from the root. Both pathogenic and non-pathogenic F. oxysporum populations exhibited their own characteristic growth and development features which were not related to their pathogenicity. Growth stimulation was mainly related to the presence of organic nitrogen in the soluble exudates. It is proposed that signalling and recognition mechanisms between the host plant and the pathogenic or non-pathogenic strains are likely to occur on or in the root rather than external to the root.

Emericella indica sp. nov. and a peculiar morphological variant of E. quadrilineata are described and illustrated. The former is characterized by large, smooth, violet ascospores and the latter by apparently budding ascospores. Analysis of the sequences of the nuclear rDNA ITS region gene of these species and E. nidulans and E. variecolor support our concepts based on morphological criteria.

Pycnidiospores of Phyllosticta ampelicida germinate only after they become attached to a hydrophobic substratum. They do not readily attach or germinate on hydrophilic surfaces or on nutrient-rich media. The properties of the spore surface that function in attachment and signal mediation for germination were investigated in this study. Pycnidiospores were surrounded by a sheath that bound Concanavalin A (Con A)-TRITC and only weakly bound wheat germ agglutinin (WGA)-FITC. Galanthus nivalis lectin-FITC selectively bound primarily to the apical region of the sheath associated with the appendage. Con A, but not WGA or GNL, disrupted spore attachment. The Con A effect on spore attachment was significantly reduced when the lectin was pre-mixed with methyl-D-α-mannoside. The sheath as well as the associated appendage was removed with either Novozym 234 or crude β-glucuronidase. Such sheathless spores were initially adhesion incompetent but, by 40 min, the spores regained their ability to adhere to hydrophobic surfaces through the secretion of material that had an affinity toward colloidal gold. Non-treated pycnidiospores surrounded by sheath remained spatially separate; however, sheathless spores readily agglutinated. Addition of cations enhanced attachment to both hydrophobic and hydrophilic surfaces presumably through the masking of electronegative groups on the sheath or by reduction of the ordered water-shell surrounding the sheath. In particular, Ca2+ induced both attachment and germination on normally non-inductive hydrophilic surfaces, suggesting an additional role for Ca2+ in signal mediation for germination.

Cryptovalsa mangrovei is described and illustrated as a new species from a wood test block submerged in the intertidal zone of Mai Po Mangrove in Hong Kong and compared with C. halosarceiicola, another mangrove species, and C. suaedicola from an intertidal salt marsh plant.

The hyphal wall protects the pressurized cell against lysis, physical abrasion, chemical damage, and probably from other microorganisms and predatory invertebrates. Against these assets we can hypothesize costs for a cell that are associated with a wall. For example, phagocytosis is impossible, and the release of secreted molecules is complicated by the diffusional challenge presented by the mesh of microfibrils and interleaving wall polymers. A more controversial idea is that once delimited by a tough integument, growth becomes dependent upon the exertion of internal force to cause wall yielding, and most mycologists have posited turgor pressure as the origin of this force. In relation to growth then, it seems logical to suggest that fungal walls evolved to meet a multitude of needs, and that once a cell became walled, osmosis would automatically generate the turgor it required for growth.

Primordia formation and basidiocarp maturation have separate requirements for light. Both show maximum activity in the 440–470 nm range but with slightly different peak values. Maturation requires over 2 orders of magnitude longer exposures to light than does initiation. Fluence–response relationships of primordia initiation are complex and do not show reciprocity.

The mode of hyphal interaction and parasitism of Coemansia spp., mainly C. aciculifera and C. thaxteri, by Gliocladium roseum, Fusarium flocciferum and Verticillium psalliotae, species that occurred with the Coemansia spp. in wheat rhizospheres, was observed in mixed cultures on low nutrient medium. Two types of interaction occurred. G. roseum and F. flocciferum coiled round, penetrated and grew within the host's hyphae. V. psalliotae grew parallel to and along the host's hyphae, coiling only rarely, and sometimes formed thick mycelial layers on the host's sporangiophores. After infection by each fungus, the host's hyphae became narrower, collapsed and then disintegrated. The observations suggest parasitism followed by lysis rather than the involvement of antibiotics.

Several hyaline-spored coelomycetes placed in Ascochyta, Phoma and Phyllosticta have been recorded from spots on leaves and pods of soybean. Comparison of herbarium material, pathogenicity tests and in vitro studies have demonstrated that Phoma sojicola comb. nov. (syn. Ascochyta sojicola) was predominantly involved as a pathogen of soybean. The diagnostic characters and history of this fungus and other hyaline-spored coelomycetes occurring on soybean are described.

Some Armillaria species cause major disease problems in both forestry and gardens. In order to determine routinely and rapidly the identity of an isolate, a PCR-based method was investigated. A fragment, approx. 900 bp, of the IGS region of the ribosomal DNA was amplified from 96 different isolates of six species of Armillaria collected from the U.K. and mainland Europe. Armillaria mellea, A. gallica and A. tabescens produced unique digestion patterns when the PCR fragment was restricted with Alu I. A. ostoyae could be distinguished from A. borealis and A. cepistipes when the PCR fragment was restricted with Bsm I. Previously unreported RFLP patterns were determined for A. mellea and A. gallica. The existence of A. gallica isolates which are putative heterozygotes for the rDNA cluster is also reported. Based on differences in banding patterns. A. mellea, A. gallica, A. cepistipes and A. borealis were subdivided further into groups which correlated with differences in cultural morphology.