A survey of fungicide resistance among isolates of the mushroom pathogens Cladobotryum mycophilum and C. dendroides Types I and II was undertaken, with respect to the active ingredients thiabendazole, carbendazim (benzimidazoles) and prochloraz manganese following an epidemic in Britain and Ireland in 1994/95. The majority of isolates (41/57) were strongly resistant to thiabendazole (ED50 > 200 ppm) and were exclusively C. dendroides Type II. All C. mycophilum and C. dendroides Type I isolates, and four C. dendroides Type II isolates, were weakly resistant to thiabendazole (ED50 1–10 ppm). Thiabendazole-resistant C. dendroides Type II isolates were only weakly resistant to carbendazim (ED50 2–10 ppm) and isolates which were weakly resistant to thiabendazole were carbendazim-sensitive (ED50 < 1 ppm), demonstrating a lack of complete cross resistance between these two benzimidazole fungicides. The ED50 values for all isolates with respect to prochloraz manganese ranged from 0.14 to 7.8 ppm. Benzimidazole resistance was considered to have been an important factor influencing the severity of the 1994/95 cobweb epidemic but 25% of isolates collected were benzimidazole sensitive.

Ultrathin sections of five spore stages of C. ribicola were incubated with wheat germ agglutinin (WGA), which binds to chitin, followed by an ovomucoid-gold complex, which binds to WGA and examined by TEM. Labelling experiments showed the presence of chitin in all five stages of the fungus, although the distribution of chitin varied among spore stages. Competitive inhibition studies with triacetyl chitotriose showed that WGA bound to cell walls of basidiospores much more strongly than other spore types, requiring a 10-fold increase in concentration over that required for the other spore types to achieve complete inhibition.

The white rotting Armillaria mellea induced a spatially very distinctive pattern of degradation in sycamore wood, under both natural and artificial conditions. Degradation began preferentially within groups of fibres containing intercellular spaces, whereas fibre regions lacking such spaces were undegraded and remained largely intact even when decay had become advanced elsewhere. The two types of fibre region differed not only in the presence of intercellular spaces, and hence in the potential for gas exchange, but also in their degree of lignification. This was higher in the more resistant type, as shown by staining of undecayed wood with toluidine blue-O, by microspectrometry after staining for the Mäule colour reaction, and by uv-microscopy. A spatially similar pattern of cellulose degradation was induced by the brown rotting Laetiporus sulphureus, which is known to cause preferential degradation of less strongly lignified cell walls. By contrast, the white-rotting Ganoderma pfeifferi showed a tendency to degrade the stronger lignified cell walls. Thus, in combination with the application of conventional histological methods, the wood degradation modes observed give additional evidence for stronger and weaker lignified fibre regions within the wood of sycamore.

Seed samples of maize (Zea mays ssp. mays) from Mexico and of teosintes (Zea spp.), the nearest wild relatives of maize, from Mexico, Guatemala, and Nicaragua were assessed for infection with Fusarium species. Strains similar in morphology to Fusarium moniliforme and F. subglutinans were the most frequent isolates from maize and from teosinte species including Z. diploperennis, Z. luxurians, Z. mays ssp. mexicana, and Z. mays ssp. parviglumis. Analysis of fertility, vegetative compatibility and mycotoxin production identified 63% of the 70 F. moniliforme strains from teosinte as genetically diverse members of Gibberella fujikuroi mating population A, a common pathogen of maize. The F. subglutinans strains from maize and teosinte were similarly genetically diverse, but were not fertile with standard testers of G. fujikuroi mating populations B and E, common pathogens of Poaceae, or of mating population H, which causes pitch canker disease of pine. Fifty-four percent of the 80 F. subglutinans strains were fertile when crossed with female tester strains from teosinte and maize collected in a field at Netzahualcoyotyl in the state of Mexico. These strains from Mexico and Central America may comprise a new and distinct G. fujikuroi mating population, but a strain from the Netzahualcoyotyl field site was fertile with a strain of G. fujikuroi mating population H from California. Thus, F. subglutinans from teosinte and maize may have a close relationship to mating population H from pine.

Axenic cultures of the aspen rust Melampsora larici-tremulae were established for the first time by seeding aeciospores artificially produced on larch onto three chemically defined media. Cultures were maintained for 9 months and evaluated for their appearance, growth rates and sporulation ability. Two types of colonies were observed. One, white and fluffy tending to felty, did not sporulate in culture. The other, white-orange with a more compact aerial mycelium, sporulated profusely producing various spore like bodies and other unusual structures. An initial lag phase, with reduced growth, characterised primary rust cultures in the first 4–5 weeks. After about one month, cultures seemed adapted to utilising exogenous nutrients for sustained growth and their development rate increased substantially. As a result of selection under unusual growing conditions, fast-growing genetic variants were also observed in the nutrient agar. Growth on all the three test media, containing different organic and inorganic constituents, suggested that nutritional requirements were non-specific. The importance of axenic cultures in the study of the nutritional requirements of aspen rust and the potential of these investigations to elucidate some physiological and genetic aspects of the host-parasite relationship are discussed.

Ophiostoma setosum is described as a new species commonly associated with exposed sapwood of Tsuga heterophylla in western North America. It is characterized by the production of a typical ophiostomatoid teleomorph, a Pesotum anamorph with conspicuous, dark seta-like hyphae on the synnema stipes and apices, and a Sporothrix mycelial anamorph with solitary or short-catenate conidia. Mating experiments demonstrate that the species has two mating types controlled by two alleles at a single locus and is reproductively isolated from similar biological species of the O. piceae complex. Phylogenetic analysis of DNA sequences from the ITS2 and 5′ end of the large nuclear subunit (26S) of the ribosomal DNA supports the close relationship of O. setosum and O. piceae.

Schizophyllum commune produces a variety of mycelial proteolytic enzymes. The specific functions of many of these enzymes are unknown, but several have elevated activity when the mycelium is grown in nitrogen-limiting conditions, suggesting a role in mycelial autolysis. We have purified one of these nitrogen-limitation induced enzymes, a small serine protease, ScPrI, from S. commune mycelial extracts. ScPrI has an apparent molecular mass of 22 kDa and is active against classical substrates for chymotrypsin and subtilisin proteases. The pH optimum for activity is neutral to slightly alkaline and the protein denatures above 50 °C. The enzyme is inhibited by PMSF, TPCK and chymostatin, and it shows little dependence on metal ions. Hydrolysis of oxidized insulin B-chain peptide by ScPrI demonstrated cleavage following aromatic amino acids and leucine. Kinetic analysis of hydrolysis of N- succinyl-AAPF-pNA and N-succinyl-AAPL-pNA revealed similar Kms for both substrates but the Vmax was nearly 3-fold higher for the substrate with phenylalanine in the P1 position.

Host-parasite interactions of Agaricus bisporus and Verticillium fungicola were studied in paired-cultures. Different growth reactions were found according to the culture medium used, but no apparent alterations could be detected by light and electron microscopy in A. bisporus vegetative mycelia. In vitro, different hydrolytic enzymes are produced by V. fungicola in cultures with A. bisporus vegetative mycelial cell walls as the only carbon source. In vitro, this enzyme preparation is able to partially digest isolated A. bisporus vegetative mycelial cell walls. These results suggest that although apparent attachment of the mycoparasite to the host cell surface seems to occur, there is no in vivo A. bisporus vegetative mycelial cell wall degradation.

Fruiting colonies of Phellinus contiguus growing on an agar medium and explants from competent regions of dark-grown colonies were used to investigate differentiation of setae, which are a component of the hymenium. The majority of setae arose laterally from intercalary hyphal compartments. The first sign of seta differentiation was generalized swelling of a portion of the hyphal compartment. On explants 50% of the seta population reached the ensuing rounded tip, pointed tip and brown point stages 36, 52 and 68 h post-excision respectively. The distribution of setae on cut surfaces of explants after incubation for three days was in general similar to that of the much larger total hyphal population. However hyphae close to the source outer surface and on explants from older parts of source colonies had reduced capacity for seta differentiation. The spatial density of setae after three days was increased by addition of glucose to the explantation medium and reduced by addition of ammonium chloride. It is concluded that many of the hyphae near to cut surfaces of explants are competent to form setae and that the number which do so is limited by environment, possibly energy supply.

Ophiostoma piceaperdum and O. europhioides are well-known, first described from conifers in Canada. They have been considered to be synonymous. After studying the type material, as well as a collection of isolates of O. piceaperdum and O. europhioides, we have concluded that they cannot be distinguished from each other, so we support the synonymy of O. europhioides and O. piceaperdum and provide a description for the Leptographium anamorph of O. piceaperdum. Ceratocystis pseudoeurophioides has previously been distinguished from O. europhioides based on differences in anamorph morphology. This species has also been reduced to synonymy with O. penicillatum, which was reported to have cucullate ascospores. Later descriptions of O. penicillatum reported it to have allantoid ascospores. We conclude that C. pseudoeurophioides cannot be distinguished from O. piceaperdum and is, therefore, reduced to synonymy with that species.

The ITS region of ribosomal DNA was sequenced for 30 isolates or sporocarps (including five type specimens) representing ten European taxa of Antrodiella. Phylogeny was inferred from the sequences by parsimony with Steccherinum ochraceum as an outgroup. The phylogram is discussed in relation to morphological and ecological characteristics of the species. On the basis of both morphological and molecular data Antrodiella pallasii sp. nov. is described. The study did not support the separation of A. beschidica and A. farinacea from A. semisupina. A. faginea is reported from Fennoscandia.

Several fungi associated with leaf spots and stem cankers of Proteaceae are reported. The new species Kabatiella proteae, Phloeosporella protearum, Septoria grandicipis, Stilbospora proteae and Trimmatostroma elginensis are described. Several new teleomorph-anamorph connections are reported, including Mycosphaerella stromatosa and Pseudocercospora stromatosa, Teratosphaeria microsporum and Trimmatostroma microsporum, and Lembosia proteae and Clasterosporium proteae. Additional species described are Lophiostoma fuckelii and Verrucisporota proteacearum which are also newly recorded associated with leaf spots of Proteaceae in South Africa.

A new keratinophilic species, Chrysosporium fluviale sp. nov., isolated from river sediments in Catalonia, Spain, is characterized by having small, slender and verrucose conidia borne on slightly swollen conidiogenous cells. Morphological and molecular characters obtained by sequencing of the corresponding ITS-5.8S rDNA regions and of the RFLPs support the separation of Chrysosporium fluviale from the morphologically closest C. evolceanui, C. indicum and the Chrysosporium anamorph of Arthroderma curreyi.

Results of a transmission and scanning electron microscopy study of the mitosporogenous process in Cercosporella ugandensis are given. The details hitherto deduced from light microscopy concerning mitospore initiation, maturation and secession are confirmed. In addition, an ultrastructural basis, in terms of wall layer deposition, is provided for mitospore maturation, scar structure and development, and mitospore secession. This implies a quite separate mode of delimitation and liberation in comparison to other fungi in the Cercospora-like generic assemblage.

Genetic relationships were investigated among several populations of Pleurotus tuberregium from Nigeria, Papua New Guinea and New Caledonia. Intrastock mating compatibility studies using progeny from two collections demonstrated a tetrapolar mating system for P. tuberregium. Interstock matings among the geographically distinct populations were compatible. All isolates were found to be intersterile with tester strains of other Pleurotus species, showing that P. tuberregium represents a unique intersterility group in Pleurotus. Nucleotide sequences of the ITS region of the rDNA gene were determined for 30 isolates and used to infer phylogenetic structure of populations. Phylogenetic analysis shows that African and Australasian-Pacific isolates form at least two distinct evolutionary lineages. Higher genetic divergence was observed among ITS sequences from the Australasian-Pacific region than among African isolates, which suggests a possible origin of P. tuberregium in the Australasian-Pacific region.

A revision of Amorphomyces was carried out based on an examination of the author's and type material. Detailed study of the development of the female thallus of Amorphomyces italicus revealed a small, lobate, free, external primary appendage. A free appendage appeared to be lacking in all other known species of the genus. The generic circumscription of Amorphomyces is therefore emended. The new species A. hernandoi, parasitizing the marine aleocharid Diglotta mersa, is described from Portugal. Amorphomyces stipitatus and A. trogophloei are synonymized with A. italicus. With additions and changes, Amorphomyces currently includes ten species. All taxa are illustrated with photographs and line drawings, and a key for their determination is provided.

This work tested the hypothesis that the abundance of fungal species on coniferous needles is correlated to climatic factors at a regional scale. The proportions of Pinus sylvestris needles colonised by Lophodermium pinastri, Cyclaneusma minus and Verticicladium trifidum were examined along two altitudinal transects in 2 successive years. L. pinastri and C. minus colonisation increased with altitude, whereas that of V. trifidum decreased. The data are discussed in relation to the importance of climatic controls on species distributions.

Haptoglossa dickii is a biflagellate zoosporic parasite of bactivorous nematodes. The walled encysted zoospores germinate more or less synchronously to produce specialised infection cells known as gun cells. This paper documents the changes in the main cytoplasmic organelles, namely the nucleus, Golgi body, mitochondria, lipid droplets and dense-body vesicles, from the onset of encystment until the formation of the mature gun cell. The septum-delimited gun cells show a marked polarity in the distribution of their organelles from their inception, which seems in part determined by the temporal order by which the main organelles migrate out of the cyst and into the gun cell initial. In this species the majority of dense-body vesicles and mitochondria precede the nucleus and lipid droplets. The nucleus remains more or less central throughout the remaining course of gun cell differentiation. The single nucleus associated Golgi body changes its orientation to track (possibly even determining) the spatial position of the ingrowing injection tube. The mitochondria fuse to form one or more complex reticulate structures which are aligned close to the injection tube throughout its formation and which in the mature cells form a fine network entwined around the fully differentiated tube. The vesicles containing electron-dense inclusion granules (dense-body vesicles) are initially concentrated towards the gun cell anterior, but later migrate to the posterior end of the cell and fuse to give rise to the basal vacuole. Some of the likely functional aspects of these cytoplasmic changes are discussed.

A key to six taxa of Hygrocybe, subgenus Hygrocybe, sections Chlorophanae and Hygrocybe is provided. One species is new and four species are reported for the first time from the Greater Antilles. The new species is H. chimaeroderma (section Chlorophanae). Hygrocybe acutoconica, H. calyptriformis and H. incolor (section Hygrocybe) are reported for the first time, and two new varieties, H. konradii var. antillana and H. calyptriformis var. domingensis (section Hygrocybe) are described. Three new combinations are made: H. acutoconica var. microspora, H. conica var. brevispora and H. luteistipes (section Hygrocybe).

A morphological study of Mexican collections of Crepidotus cinnabarinus, C. croceitinctus, C. palmarum and C. quitensis is provided. The relationships of these species with close allies are examined and discussed. Microscopical observations on the type collections of C. carpaticus, C. cinnabarinus, C. croceitinctus, C. luridus vars luridus, minor and oaxacae, C. macedonicus, C. palmarumm, C. quitensis, C. subcroceitinctus and C. unicus are included. Illustrations of the microscopic features of all taxa are presented.