Thirty-one clonal isolates of U. necator were taken from diseased grapes from three different vineyards in France and Germany. Samples were collected in April from typical ‘flagshoot’ symptoms, and in July and August from the same plants. The mating-type and the sensitivity to the fungicide triadimenol were determined for all isolates. Techniques for obtaining and characterizing isolates are described. Two isolates in the first sampling and eight in the second were resistant to triadimenol, with resistance factors ranging from 3·4 to 11·8. All isolates in the first sampling and nine out of the 21 isolates in the second were mating-type (+), the remaining isolates were mating-type (−). Genetic variation between all isolates was assessed using the RAPD technique. Phenetic analysis based on the 364 RAPD fragments obtained revealed two very distinct groups, one group containing nine out of the 10 isolates from the first sampling, the second group containing all the remaining isolates. Isolates clustered in the first group displayed 58 RAPD fragments specific to them. These isolates did not exhibit 60 RAPD fragments present in all other isolates. Molecular and biological data suggested that isolates clustering in the two groups represent two different biotypes of U. necator, which are likely to be genetically isolated.

Four species of Linocarpon on Pandanus are described and illustrated. L. spathulatum and L. sulcatum spp. nov. have ascospores with grooved appendages and ascomata with eccentric ostioles. L. fasciatum sp. nov. is similar to L. pandanicola, but its ascospores lack appendages and the ascomata are smaller. A collection of L. elaeidis, not previously reported from Mauritius, has ascomata with distinct black papillate necks, in contrast to the type material which lacks these structures.

Crypticola is re-evaluated, following a commentary on the nature of its straminipilous ornamentation, zoosporogenesis and habitat range. Atkinsiella entomophaga is transferred to Crypticola, but because this species was made the type species of Halocrusticida, new names are required for Halocrusticida and species therein (Halodaphnea hamanaensis – type species; H. parasitica, H. awabi, H. okinawaensis, H. panulirata). A new family, the Crypticolaceae, is erected for Crypticola. The family is placed, with reservations, in the Myzocytiopsidales, Peronosporomycetes.

Universally primed PCR (UP-PCR) fingerprinting combined with UP-PCR product cross hybridization, and ITS1 ribotyping were used to study the genetic relatedness of strains of Trichoderma and Gliocladium for two purposes: (1) to evaluate the ability of the methods to discriminate closely related strains and as tools to group strains which is necessary to facilitate; (2) identification of markers for development of specific detection assays for selected strains. Included among the strains were one T. harzianum, two T. virens, and one G. roseum that had been selected previously for their antagonistic ability against soil-borne phytopathogens. Similarity among strains, found by cross dot blot hybridization using UP-PCR amplification products, was used to group them into 15 genetic entities. ITS1 ribotyping of the strains was performed by digestion of the PCR amplified rDNA spacer region and electrophoresis of the products. The differences obtained from ribotyping as well as the differences in mobility of the intact spacer region were used for grouping of the strains. The UP-PCR hybridization groups and the ITS1 based groups proved to be consistent, but the resolution of the UP-PCR based approach was superior. The results demonstrate that the combination of UP-PCR and ribotyping can aid in clarifying species distinction in Trichoderma and Gliocladium and has the potential to become a valuable tool for studies of diversity and genetic structure of populations of these fungi. Furthermore, identification of single strains by the specific UP-PCR fingerprint seems feasible.

A series of comparative physiological and morphological analyses are described for eighteen Dendryphiella isolates. Conidial characteristics of ten isolates showed relatively little variation as a result of different incubation conditions. Isolates were markedly tolerant to NaCl and KCl, although some variation between isolates was noted. A variety of nitrogen compounds could be utilized by most isolates although some grew poorly with certain nitrogen sources. Most isolates showed a wide pH growth range, particularly at alkaline values, and broad temperature growth profiles. The relevance of these physiological characteristics to the survival and fitness of Dendryphiella species in the marine environment is discussed.

Over 70% of zygospores of M. piriformis collected from 10 day-old cultures germinated in water and on acidified water agar. Germination originated either through a crack on the zygosporangial wall or through one of the suspensors. The germination percentage was highest when newly matured zygospores were used. Zygospores from cultures older than one month either did not germinate or germinated poorly. The mode of zygospore germination was affected by nutrients and germination condition. Germ-sporangial, germ-sporangial-mycelial and mycelial germination were observed on solid media while germination with an elongated germ-tube was observed in water. Zygospores of M. piriformis germinated under light as well as in darkness. Although low pH is not required for zygospore germination in water, zygospore germination on solid media is favoured by low pH.

The influence of Fosetyl-Al and Metalaxyl on the diversity of arbuscular mycorrhizal fungi (AMF) was evaluated on naturally established citrus plants. Thirteen AMF species were recovered from rhizospheres of Citrus sinensis/C. limon treated or not with Fosetyl-Al and/or Metalaxyl. Spores of AMF were obtained from 100 g of rhizospheric soil at two sites in São Paulo state, Brazil. The soil samples were treated by the wet-sieving technique and the spores were quantified and identified. The number of spores was low at both sites. Fosetyl-Al reduced the number of spores and the diversity of AMF in one site but not in the other. Metalaxyl at low concentration increased the diversity of species in some experiments, but at higher concentration it tended to reduce the number of spores of AMF. Scutellospora was the genus that presented the largest number of species (7) followed by Acaulospora (3), Glomus (2) and Gigaspora (1). Gigaspora ramisporophora was the dominant species in one site, Glomus macrocarpum and Scutellospora gilmorei were dominant at the other.

Four new species of Pseudocercospora are described, illustrated and compared with allied taxa. These are P. asiatica or Glochidion lanceolarum, P. melochiigena on Melochia corchorifolia, P. operculinae on Operculina terpethum and P. trewiae-nodiflorae on Trewia nodiflora.

Fungal cultures isolated from oil-polluted sea water near Mumbai, India have been studied for their capability to degrade crude oil. A yeast isolate identified as Yarrowia lipolytica was further investigated with respect to its dimorphic behaviour and alkane degradation. Y. lipolytica NCIM 3589 in the yeast form degraded the aliphatic fraction of crude oil and also pure alkanes (20–60% within 48 h) under aerobic conditions. Unlike most Y. lipolytica strains, our isolate required partial anaerobiosis for mycelium formation. Studies with two isolates suggested that mycelium to yeast transition may be the prerequisite for effective alkane degradation.

Enridescalsia gen. nov., characterized by synchronous, polytretic conidiogenous cells and brown euseptate conidia, is described and illustrated from submerged, decaying leaves of Terminalia cattapa from Cuba. Notes on similar genera are given.

Four rare microfungi, Dactylaria appendiculata, Exserohilum novae-zelandiae, Monacrosporium psychrophilum and Pleurocatena acicularis, were found when root pieces taken from wheat crops were incubated on low nutrient agar (SNA).

One hundred and thirty four dikaryotic isolates of Ganoderma, morphologically determined as G. adspersum, G. annulare, G. applanatum, G. brownii, G. lobatoideum, G. lobatum, G. lucidum, G. oerstedii, G. resinaceum, and G. tornatum, were examined by horizontal PAGE for eight enzymatic activities. A total of 94 bands were analysed. The objective was to evaluate the relatedness among the specific taxa by analysing numerically the isoenzymic patterns. To discern fungal individuals somatic incompatibility tests were used. Within each enzyme system several allozyme phenotypes could be observed. The enzymic systems analysed failed to yield diagnostic bands for each morphologically defined group, except the AKP system for G. resinaceum. Some bands were shared by all the isolates studied. On the other hand, diagnostic bands at the species complex level were encountered.

The ectomycorrhizal Laccaria bicolor, cultivated axenically in modified Pachlewski's medium, can use a broad spectrum of nitrogen and carbon sources. The fungus exhibited greater growth in the presence of ammonium or nitrate than with ammonium nitrate. With the latter salt, the drop in pH of the culture medium indicated that ammonium was taken up preferentially to nitrate. L. bicolor grew more poorly on amino acids such as glycine, alanine, aspartate and glutamate, the latter three being very poor carbon sources. By contrast, glycine was used as nitrogen and carbon sources. Glucose and maltose in mixture, with a 20[ratio ]5 ratio, were the most effective carbohydrates for promoting growth, followed by starch, dextrins, maltose, glucose and sorbitol. L. bicolor failed to grow in the presence of sucrose and galactose.

Isocitrate dehydrogenase (IDH), a key enzyme linking carbon and nitrogen metabolism, is present in L. bicolor as NAD- and NADP-dependent proteins. Both enzymes were stimulated in response to nitrogen starvation and appeared to operate in close association with the glutamine synthetase and NADP-dependent glutamate dehydrogenase of the fungus, indicating that 2-oxoglutarate produced by IDHs is probably utilized in the assimilation of inorganic nitrogen. The highest specific activities of NAD and NADP-IDH coincided in most cases with the rapid growth periods of the fungus, although in slow growing conditions obtained by addition of glycine or sorbitol to the culture media, only NADP-IDH activity increased in conjunction with growth. In addition, activity of the NADP-IDH was constantly higher than that of NAD-IDH. These results are indicative that the NADP-dependent enzyme plays a substantial biosynthetic role, possibly by an additional production of reduced nucleotides.

Proliferation of intraradical hyphae of the arbuscular mycorrhizal fungus Glomus fistulosum was observed and measured in surface disinfected mycorrhizal maize root segments in an aseptic cultivation system. The maximum growth of hyphae proliferating from the root segments was observed at pH 6·3, and low concentrations of buffering substances stabilized the pH of the incubation medium (0·9 mm MES, 1 mm BIS-TRIS). The proliferation of intraradical hyphae was not influenced but the germination of chlamydospores of the mycorrhizal fungus was inhibited by an artificial inorganic soil solution at lowest dilutions. The percentage of root segments bearing proliferating hyphae and the growth of hyphae decreased with increasing concentration of phosphate in the incubation medium. All reduced sulphur-containing compounds tested (sulphite, dithionite and metabisulphite) suppressed the proliferation of hyphae completely.

Isolates of Pithomyces chartarum obtained from pasture samples originating from Australia, Brazil, New Zealand and Uruguay were evaluated for their ability to produce sporidesmin. Only isolates that produced enough spores to confirm the presence or absence of sporidesmin were evaluated. Samples from the countries examined gave proportions of sporidesmin-producing isolates of: Australia, 67% of 207 isolates; Brazil, 2% of 51 isolates; New Zealand, 86% of 391 isolates and Uruguay, 28% of 182 isolates. Considerable variations in the ability to produce sporidesmin were found, not only between countries but between samples taken from the same country.

Xylaria species are common endophytes in tropical plants. It is not known, however, whether transmission of Xylaria occurs horizontally or vertically, whether individual Xylaria strains have wide host ranges or are host-specific, or how they are dispersed. We compared frequency of Xylaria endophytes in leaves and seeds of two tree species in Puerto Rico, Casuarina equisetifolia (Australian pine) and Manilkara bidentata (ausubo). These trees were chosen because they differ markedly in morphology, habitat, distribution, and origin. In C. equisetifolia Xylaria was significantly more frequent in leaves than in seeds. Xylaria was isolated from seeds of trees in inland parks, but never from seeds of trees growing on beaches. This suggests that vertical transmission of Xylaria may be possible but is not necessary for infection. In M. bidentata, Xylaria was isolated from 97% of leaves but was never isolated from seeds, suggesting that transmission is entirely horizontal. Seedlings raised in a greenhouse far from other M. bidentata trees had a level of Xylaria infection as high as seedlings in the forest, suggesting that inocula can come from other sources and endophytic strains are not host-specific.

Ophiostoma ulmi and O. novo-ulmi are partly reproductively isolated, morphologically, behaviourally and molecularly distinct species responsible for the first and current pandemics of Dutch elm disease, respectively. Among >11000 isolates sampled from Dutch elm disease sites across Eurasia and North America since 1973, nine could not be assigned to O. ulmi or O. novo-ulmi. Of these isolates one (P129) was from Poland and eight (d10, d11, e12, e27, e28, e37, f30 and g3) were from a single bark sample in Portugal. These nine isolates were termed ‘fast-waxy’ isolates because of their unusual cultural characteristics. The possibility that they were interspecific hybrids was investigated. When compared with O. ulmi and O. novo-ulmi for colony pattern, growth-rate, optimum temperature for growth, vascular wilt ability, elm bark colonizing ability, cerato-ulmin toxin production, ability to fertilize (as [male ]) O. novo-ulmi, and ability to be fertilized (as [female]) by O. ulmi, they exhibited a combination of O. ulmi-like, O. novo-ulmi-like, intermediate or novel characters (female sterility) consistent with their being hybrids. P129 and representative Portuguese isolates d10 and e27 each exhibited a different combination of characters, indicating each was a different hybrid genotype. When d10 and e27 were independently crossed to the same O. novo-ulmi isolate, differences in their F1 progeny sets for growth-rate and pathogenicity distributions were consistent with their being different recombinant genotypes. A molecular analysis of P129, d10 and e27 using RAPDs of genomic DNA, rDNA RFLPs and cerato-ulmin gene sequences confirmed that each was a unique interspecific hybrid. The mechanism of origin of these hybrids and their evolutionary significance are discussed. Combined experimental and circumstantial evidence indicates that they are relatively unfit, rare and probably transient, and that they arise when O. novo-ulmi invades territory occupied by O. ulmi and replaces it. Nonetheless, the possibility that the hybrids act as a genetic bridge, facilitating transfer of novel vegetative compatibility loci and other loci form O. ulmi to O. novo-ulmi at recent epidemic fronts, requires investigation.

Arthrobotrys chazarica sp. nov. and Nematophagus tabrizicus sp. nov., which capture nematodes by means of adhesive networks, are described and illustrated.

Soil samples from six sites in Provence, France, were flooded with water and baited with cellophane, specifically to obtain Rhizophlyctis rosea; all proved positive. By standardizing the cellophane addition and counting the R. rosea thalli that grew on it, derivations of thallus recovery g−1 of soil (TRG) were possible. Where aliquot soil samples for assay were small, sterilized soil leachate was used to chemically reinforce the flood water. Mean TRG was 395 for a grassland soil and 1293 following drying and removal of small stones from it. Separated leaf humus from the same dried soil had a mean TRG of 1105. Thought was given to what these figures might represent, in terms of sporangia of R. rosea present in the soil at the time of its collection. These are the first quantitative results in soil ecology for the Chytridiales.

Ophiostoma europhioides and O. huntii are two very similar fungi known to cause blue-stain of timber. Both species have been isolated from pine and spruce in Canada and are characterized by Leptographium anamorphs and hat-shaped ascospores. The aim of this study was to compare isolates of O. huntii and O. europhioides from various parts of the world. These isolates were compared morphologically using light and scanning electron microscopy. Sexual compatibility was determined using mating studies. O. huntii isolates from the different geographical areas were similar to each other but distinct from O. europhioides. A new Ophiostoma species, O. aenigmaticum, is described for the Japanese isolates; Leptographium aenigmaticum, its anamorph, is described as a new species.