Zoospores of the nematode-parasitic Catenaria anguillulae (Chytridiomycota) were studied by videomicroscopy in sealed films of water on microscope slides in the presence or absence of freeze-inactivated nematodes (Panagrellus redivivus). Zoospores swam for more than 1 h at a mean velocity of 104 μm s−1, interspersed with repeated phases (1–2 min) of amoeboid crawling on glass or nematode surfaces. They were attracted to and encysted near the mouth, excretory pore, and anus of nematodes, or eventually encysted at random on glass and nematode surfaces. The single posterior flagellum was immobile during amoeboid crawling but resumed rapid beating when the last pseudopodium was being retracted. Zoospores encysted by adhesion of the anterior of an amoeboid cell to a surface; then the cell posterior was raised above the anterior so that the flagellum projected perpendicular to the surface, and the flagellum was retracted by rotation of the cell contents. Cysts germinated within 20–60 min by a narrow germ-tube at the site of adhesion. The germ-tube grew a short distance, then formed an intercalary vesicle into which the cyst contents emptied by expansion of a cyst vacuole. In several cases the germ-tube penetrated a nematode and formed the vesicle inside the host. Rhizoids or assimilative hyphae developed from the vesicle or by growth of the germ-tube tip. An increasing proportion of zoospores that remained motile after 1 h in water films had a globose body in contrast to the normal elongated form. This seemed to be caused by damage during repeated transitions between the amoeboid and swimming phases, because pseudopodia sometimes remained firmly attached to a glass surface.

C. anguillulae showed consistent orientation (polarity) of zoospore encystment and cyst germination. This parallels the behaviour of other zoosporic fungi or fungus-like organisms (Plasmodiophora brassicae, Rozella allomycis, Pythium, Phytophthora and Saprolegnia spp.) suggesting that it is a common feature of zoosporic parasites. Surface-recognition for encystment by C. anguillulae was mediated by the zoospore soma, not the flagellum. In addition, we redefine the early development of C. anguillulae, including flagellar retraction by rotation of cell contents, non-specific adhesion of zoospores and cysts to surfaces, and evacuation of cyst contents into a vesicle from which further growth occurs.

The performance of isolates of the ectomycorrhizal fungi Coltricia perennis, Laccaria bicolor, Lactarius hepaticus and Paxillus involutus originating from Scots pine stands was studied on solid media with different concentrations of ammonium, glycine and glucose as inorganic nitrogen, organic nitrogen and carbon source. Laccaria bicolor was able to grow on both ammonium- and glycine-containing media. Biomass and growth rate of L. hepaticus and P. involutus on media with ammonium were generally higher than on media with glycine as nitrogen source. Coltricia perennis did not clearly show preference for either ammonium or glycine. Fractal dimensions, calculated from the biomass and radii of the fungi, were in the range 1–3. Fractal dimensions provided extra information about the foraging strategy of mycelia not obtained from growth rate and biomass production measurements, but cannot replace those because the use of fractal dimensions alone may lead to misinterpretation.

Phaeoramularia braunii sp. nov., P. trigonellae sp. nov., Stenella capparidiicola sp. nov. and S. hyptiantherae sp. nov., collected on Chloroxylum sp., Trigonella foenum-graecum, Capparis zeylanica and Hyptianthera stricta, respectively are described, illustrated and compared with related species.

The pathogenicity of two isolates of Verticillium lecanii towards non-target invertebrates and six species of aphid was tested in bioassays. There was no evidence of infection in any of the 20 non-target invertebrates. All target aphid species were susceptible to at least one isolate. The level of susceptibility varied between aphid species, with Myzus persicae and Brachycaudus helichrysi showing the greatest susceptibility.

Studies on initial spore deposition, retention and germination on two susceptible aphid species and four resistant non-target insects revealed differences in the behaviour of the pathogen between the two groups. Spore density mm−2 was greater on susceptible insects both immediately post-inoculation and following 24 h incubation. There was no loss of spores from M. persicae over 24 h. All other species showed more than 50% spore loss in the same period. However, even after 90% spore loss, large numbers of spores remained on the bigger insects such as Agonum dorsale. Germination and germ-tube growth were possible on such resistant non-target insects, indicating that resistance to infection occurs after this stage. There was little difference in rate of germination on the two groups. However, differences in germ-tube growth were evident, with the production of longer and narrower germ-tubes on the resistant insects.

Two new species, Pseudocercosporella arcuata and P. woodfordiana, on Rubus ellipticus and Woodfordia floribunda, respectively, are described and compared with related taxa.

Following the Chernobyl accident in 1986, sporocarps of Suillus variegatus in Sweden showed a large amount of individual variation in concentration of 137Cs activity. Our aim was to determine the degrees to which this variability in sporocarp 137Cs levels could be explained by differences between (i) local populations, (ii) fungal genets and (iii) locations within genets. Five populations in a 100-yr-old Scots pine forest, located within a 1 km2 area, and two populations in Scots pine/Norway spruce forest, located 40 km north-west of Uppsala, were investigated. In total, 154 sporocarps were analysed to determine their 137Cs content. Of these, the genetic affiliations of 86 were successfully characterized using somatic incompatibility reactions. Twenty-six genets were found which, on average, consisted of 6·5 sporocarps. The genets averaged 7·5 m in size, measured as the length between the most distant sporocarps. The mean sporocarp 137Cs level was 67·1±2·8 kBq kg−1D.W. (range between 13·6 and 182). According to analyses of variance, within-population variation accounted for 60% of the total variation in 137Cs levels, while 40% was ascribed to variation among populations. Within a population, 137Cs levels did not generally differ significantly between genets. Plausible reasons for intraspecific variation in radiocaesium content in sporocarps are discussed.

The content of phenolic substances in freshly collected fruit bodies of several basidiomycete genera varied in the range 2·35–9·05 mg g−1, following closely the trend of a normal function.

It was necessary to use a polyphenoloxidase-inhibiting substance to obtain reliable analysis. The content of phenolics decreased, during 3 d at room temperature and following freezing at −20°C.

Eighty-eight isolates of Gremmeniella abietina var. abietina belonging to the Asian, European and North American races were cultivated on agar plates and their fatty acids and sterols were extracted and analysed.

Fourteen fatty acids and seven sterols were detected by gas chromatography. Multivariate discriminant analysis revealed distinct differences between the contents of fatty acids and sterols (FAST-profiles) of the three races; the most distinct was the Asian race. Additionally, the presence of two ecologically different types in Finland, the large tree and small tree type (LTT and STT, respectively) was confirmed on the basis of their significantly different FAST-profiles. The FAST-profiles of European STT more closely resemble the American race than the European LTT. The diversity of North American isolates of the European race, which were supposedly initially introduced from Europe in the 1960s, were considerably higher than the diversity of the European LTT or STT isolates.

Analysis of Phytophthora cactorum using Random Amplified Microsatellites (RAMS) revealed considerable variation among isolates, most of which correlated with the original host plants. The lack of variation among isolates originating from strawberry suggests that crown rot of strawberry is caused by a single clone within the geographical area studied. It was also shown that P. cactorum isolates form a unique group different from other Phytophthora spp. from Group I.

P. cactorum isolates from necrotic stem lesions on Betula pendula seedlings or Fragaria × ananassa plants suffering from crown rot were highly pathogenic to their original host plants. P. cactorum isolates from strawberry inoculated via wounds also caused necrotic lesions on B. pendula. On the other hand isolates from B. pendula did not cause disease symptoms on strawberry plants. On Alnus glutinosa the percentage of successful inoculations with a birch isolate was 40.

Erynia neoaphidis is the most widespread aphid pathogen in temperate regions. A few authors have identified this species as infecting some non-aphid hosts. It exhibits high variability with respect to morphology and cultural characteristics that underlines the need for assessment of the genetic variability within this species. We used size of PCR-amplified ribosomal DNA internal transcribed spacer (ITS) coupled with RAPD-PCR pattern in order to investigate genetic variability within a sample of 30 isolates identified as E. neoaphidis and one isolate of E. kondoiensis from diverse countries and hosts. Isolates fell into four discrete ITS size groups: 575 base pairs (bp) in isolates from non-aphid hosts, 1000 (including the E. kondoiensis isolate), 1100, or 1450 bp in those from Aphididae. The 1100-type seems to be the one of most widespread, since two-thirds of the isolates from diverse locations belong to this type. ITS types can be correlated with morphological and physiological characteristics. A great deal of genetic variability exists within ITS types, as shown by RAPD-PCR. RAPD groupings could be related with geographical origin in some cases. There was no apparent relationship between host and ITS type or RAPD pattern among isolates from Aphididae. PCR-based technologies provide evidence that could be used to clarify the taxonomy of E. neoaphidis and closely related species, and will help identify markers related to epidemiological characteristics.

We report the first successful culturing and confirmation of identity (via sodium dodecyl sulphate polyacrylamide gel electrophoresis, SDS–PAGE) of Serpula lacrymans (the dry rot fungus) derived from basidiomes and mycelia growing in the ‘wild’. The fungus was found growing on well decayed coniferous wood within the Narkanda region of the Western Himalayas at between 2800 and 3100 m above sea level (a.s.l.). The ‘wild’ habitat of the fungus is described, as is the isolation of Serpula himantioides also found in these regions. Temperature, osmotic potential, initial pH and air-current influenced the average colony extension rate of ‘wild’ and a selection of building isolates on 2% malt extract agar. The ‘wild’ and building isolates behaved as two separate cohorts; the ‘wild’ isolates appeared to be less affected by extremes of temperature, whereas building isolates extended more rapidly at the moderate microenvironmental regimes.

Sclerotinia homoeocarpa is a common and severe fungal pathogen responsible for dollar spot disease on turfgrasses. The RAPD–PCR technique was used to identify genetic variation among 26 isolates of S. homoeocarpa. DNA polymorphisms were detected among different isolates using 15 oligonucleotide primers and a dendrogram was constructed using the unweighted pair-group method with arithmetic averages (UPGMA) for cluster analysis. Isolates from different geographical locations in the United States were separable into three distinct groups based on RAPD profiles and the cluster analysis. These three groups, however, were clearly more closely related to each other than to the isolate from Belize which was unique compared to the other S. homoeocarpa isolates examined. RAPD profiles suggest that transport of the pathogen from east coast to west coast locations in the U.S.A. may account for the recent identification of the disease in the Pacific Northwest. The results indicate that RAPD–PCR is a valuable method for differentiating isolates of S. homoeocarpa.

Maple leaf disks were exposed in a softwater stream for two weeks and then aerated for 2 d in water to induce spore production by aquatic hyphomycetes. Sporulation was inhibited by the addition of yeast extract or leaf leachate (up to 2·5 g l−1) to the sporulation water. With leaf leachate, but not with yeast extract, this effect was neutralized by the addition of 50 mg l−1 of CaCl2. Sporulation increased at intermediate concentrations of several inorganic compounds (CaCl2; KH2PO4/K2HPO4; NaNO3; NaCl). It increased at low concentrations (1–3 g l−1) of an artificial seasalt mixture, was much reduced at 7·5 g l−1 and absent at 15 g l−1.

Of the two potato glycoalkaloids, α-chaconine and α-solanine, α-chaconine was the more inhibitory on spore germination in Alternaria brassicicola and Phoma medicaginis, and on growth in liquid culture of these species and also Ascobolus crenulatus and Rhizoctonia solani. At 50 μM or less, solanine caused little (<20%) or no inhibition but, in combination with comparable concentrations of chaconine (which were sometimes also below the activity threshold), synergistic inhibitory effects (up to 100% inhibition) were apparent. A scanning electron microscopic examination of agar-grown cultures of P. medicaginis revealed that both glycoalkaloids at 100 μM inhibited hyphal extension, but that chaconine particularly increased branch formation (three-fold) as well as hyphal thickness and ‘beading’. Glycoalkaloid-containing liquid medium from R. solani cultures did not contain glycoalkaloid hydrolysis products. There was a 17% reduction in the solanine content of the medium, but the chaconine level was not significantly different from that in uninoculated controls. Neither glycoalkaloids nor their hydrolysis products were detectable in the washed mycelium of such cultures.

Double-stranded RNA (dsRNA) elements of 8·3 and 5·5 kbp were detected in three of five geographically distinct isolates of Alternaria solani. Variation with respect to the number of dsRNA segments was detected among isolates of the fungus. No virus-like particles were purified from the mycelium, or observed in ultra-thin sections of hyphae. Utilizing differential centrifugation or density gradient centrifugation for subcellular fractionation, dsRNA was found associated specifically with fractions containing 80–100 nm spherical membrane vesicles. Similar vesicles were observed in cytoplasm of hyphae by electron microscopy. Treatment of dsRNA-containing fractions with ribonuclease A did not degrade the dsRNA, suggesting that it is located inside the vesicles. There was no correlation between the radial growth of the isolates in laboratory media and the presence or absence or dsRNA.

Four ascomycete species with brown 1-septate ascospores with wall ornamentation were identified from palms in Ecuador and Brunei. Asci were long cylindrical, relatively thick-walled, bitunicate with non-fissitunicate dehiscence, and the hamathecium was composed of trabeculae. These fungi are referred to Roussoëlla, and are described and illustrated in this paper, including two new species. A key to accepted species of Roussoëlla is provided.

Eighty-four isolates of Penicillium chrysogenum and related species were examined by isozyme analysis. Four main groups could be defined by cluster analysis; P. chrysogenum var. chrysogenum, P. flavigenum sp. nov., P. chrysogenum var. dipodomyis and P. nalgiovense. P. flavigenum is described as new species, and P. chrysogenum var. dipodomyis raised to species level as P. dipodomyis. The genetic distance between these groups was calculated by employing a formula that accounts for the differences in alleles and loci obtained by isozyme analysis of these fungi. The genetic distances and cluster analysis suggest that the groups should be considered as four separate species. The practical implication of the separation and the ecological characteristics of the four species are discussed.

Comparison of type specimens of A. gerdemannii and A. appendicula revealed the spores to be identical in organization and subcellular structure, indicating they are conspecific. The Glomus morph of A. appendicula was not assigned a name in the protologue, but 11 living cultures started from or producing spores of A. gerdemannii also generated Glomus-like spores of identical morphology to those in type specimens of Glomus leptotichum. These spores were indistinguishable from those in type specimens of G. fecundisporum, indicating they are conspecific. Both species were described in the same paper, so the name G. leptotichum is given priority because type specimens are in better condition and specimens from a reference culture have been identified by an author of both prologues. Absence of a teleomorph and confirmation of dimorphism from single and multiple-spore inoculations of host plants in culture provide the basis for designating A. gerdemannii and G. leptotichum as synanamorphs of one vesicular-arbuscular mycorrhizal fungus.

The production of basidia from individual teliospores of Sporisorium formosanum and Ustilago affinis is described. In S. formosanum the upper portion of the basidium separates as a conidium-like body the two cells of which either conjugate or produce sporidia, whilst the lower portion remains unicellular and gives rise to sporidia. In U. affinis the basidium is four-celled and remains intact, its cells either conjugating or producing sporidia, sometimes on the same basidium. These patterns of teliospore germination are compared with one another and other members of the Ustilaginaceae, notably Ustilago trichophora.

A new species of Boerlagiomyces is described from submerged wood collected from a freshwater river in the Philippines. Boerlagiomyces grandisporus is compared with previously described species in the genus and is shown to possess greatest similarity with B. websteri. Selected ultrastructural characteristics of the ascospores of B. grandisporus are illustrated and discussed in relation to other fungi. The taxonomic relationship of the genera Boerlagiomyces and Garethjonesia are reassessed and shown to be congeneric; the new combination B. lacunosispora is accordingly validated.