Previously undescribed features on the surfaces of powdery mildew conidia were revealed by the scanning electron microscope (SEM), reinforcing differences observable by light microscopy (LM). Four distinct patterns were observed on the septa and 10 on the outer wall, thus categorizing 15 anamorph taxa. Anamorphs of Leveillula, Phyllactinia and Pleochaeta, all had smooth to moderately verrucose septa, but each bore a different distribution of warts on their verrucose outer wall. Annular septa and an echinulate outer wall were unique for the Oidium anamorph of Blumeria. The remaining powdery mildews, all with Oidium states, had either whorled or fibrillar septa. Those with whorled septa are separated into three newly proposed subgenera: Fibroidium for the anamorphs of Podosphaera and Sphaerotheca having conidia with fibrosin bodies and a smooth outer wall; Octagoidium for the dendritic patterned, eight-sided conidia of Sawadaea; and Setoidium for the anamorph of Cystotheca reflecting the setae on the mycelium. Three new subgenera are proposed for those with fibrillar septa: Reticuloidium for conidia with a roughcast outer wall of Erysiphe sect. Golovinomyces; Graciloidium for the unswollen conidia of Arthrocladiella; Striatoidium for conidia of E. sect. Galeopsidis with a striate outer wall. The name Pseudoidium is retained as a subgenus for the anamorphs of E. sect. Erysiphe, Microsphaera and Uncinula which had conidia with a scaly, fibrous outer wall. The patterns on the outer wall of conidia were frequently modified by secondary creasing. These wrinkling patterns, also observable under the LM, proved useful in identification of anamorphs, especially on herbarium specimens. SEM, LM and host range data were used to construct keys for the prediction of the anamorphs of all the powdery mildew genera found in the U.K. The findings, together with teleomorph criteria, also prompted a revision of the Erysiphaceae.

Competition and replacement interactions between species of wood-decomposing basidiomycetes were studied with a culture technique using various sized pieces taken from 6 cm diam. wood discs as a substrate. Based on field studies, 17 species of basidiomycetes, either primary decayers or late successional saprotrophs which show strict dependencies on certain preceding pioneer decayers in the field, were isolated and inoculated on the wood sectors. After precolonization, the sectors were attached to each other pairwise in various species combinations and incubated on water agar. The discs were regularly inspected and photographed for detection of mycelial overgrowth. After 6 months, samples were taken from the wood of the sectors and cultured for identification of prevailing mycelia. Measured by the replacement of opposing fungi, the selective late successional species are more combative than the primary decayers. Species of Antrodiella had the greatest competitive success. The results of our experiment corresponds well with field observations and explain, at least partly, the physiological background of the interactions.

Three new species of smut fungi (Ustilaginales) on grasses from Western Australia are described and illustrated: Sporisorium ordense sp. nov. on Brachiaria pubigera, Sporisorium paraneurachnes sp. nov. on Paraneurachne muelleri and Ustilago xerochloae sp. nov. on Xerochloa imberbis and X. laniflora. Smut fungi new to Australia are: Sporisorium heteropogonicola comb. nov. (based on Sorosporium heteropogonicola) on Heteropogon contortus, Sporisorium iseilamatis on Iseilema vaginiflorum (matrix nova), Tilletia opaca on Spinifex longifolius (matrix nova), Ustilago spermophora on Sporobolus australasicus (matrix nova). Sporisorium mitchellii, known hitherto from South Australia on Iseilema mitchellii, was collected on Iseilema dolicotrichum (matrix nova).

Banksia brownii plants treated with a range of potassium phosphonate solutions were examined histologically to determine the mechanism of resistance to invasion by Phytophthora cinnamomi. Reaction zones in plants treated with the chemical compartmentalized P. cinnamomi in both bark and woody tissues, similar to acquired host resistance. Compartmentalization corresponded with the CODIT model of decay in trees. Reaction zones analogous to walls 2 and 3 of CODIT were actively rather than passively formed, and were associated with the ray and axial parenchyma, respectively. While the anatomical evidence of resistance in Australian native flora to this pathogen has been reported previously, this is the first report of enhanced compartmentalization responses of a susceptible native species after treatment with phosphonate.

Two new species of Hymenochaetaceae, Phellinus fushanus sp. nov. and Inonotus fushanus sp. nov., found growing saprotrophically on the stem of Persea zuilhoensis and Quercus longinus, respectively, in Taiwan, are described and illustrated.

The forest pathogen Dothistroma pini, which produces the polyketide toxin, dothistromin, was transformed with the pAN7-1 plasmid containing the Escherichia coli hygromycin B phosphotransferase gene (hph). The frequency of hygromycin resistant transformants was 9–48 μg−1 DNA. Southern blot analysis indicated that a single copy of the vector DNA had integrated into the genome in at least six of the eight transformants tested and that the site of integration was different in each case. All transformants analysed were mitotically stable through several subcultures without selective pressure.

Didymium subreticulosporum, a rare species from Valencia, is described and illustrated by SEM and LM photographs, and compared to related species.

The ability of an unidentified mycobiont from Pisonia grandis mycorrhizas to utilize organic nitrogen and phosphorus sources was determined in axenic liquid cultures. The fungus utilized inorganic phosphate and both freely- and poorly-soluble salts of inositol hexaphosphate as sole phosphorus sources. With the exception of uric acid which did not support growth, the yield of the mycobiont on all organic nitrogen sources tested was significantly greater than the yield on either NH4+ or NO3−. It is suggested that the major ecological role of the Pisonia mycobiont in stands of P. grandis on coral cays may be rapid absorption of allantoin and urea produced during degradation of uric acid by the soil microflora. This may be important in retaining nitrogen in the soil[ratio ]plant system prior to loss from the coral cay by further degradation, volatilization and/or leaching.

Twenty-six fungi associated with leaf spots of palms in north Queensland have been identified, including 12 ascomycetes, one basidiomycete and 13 deuteromycetes. Eight were identified as species new to science. A new species of Pseudospiropes is described and descriptions of two unnamed species of Glomerella are also given.

Penicillium nodositatum induces the formation of nodules on the roots of Alnus. The analysis of RFLPs in the PCR-amplified ITS1-5·8S-ITS2 ribosomal sequence demonstrates that all the nodule-inducing strains isolated belong to a homogeneous taxon, P. nodositatum, distinct from other morphologically close species of Penicillium. A gene tree inferred from the ITS1-5·8S-ITS2 PCR/RFLP data shows that the P. nodositatum sequence clusters with those of Penicillium species belonging to subgenus Biverticillium. RAPDs generated using four 10-mer primers, allowed us to identify four distinct groups of strains in a sample of 28 strains of P. nodositatum collected in 10 different geographic sites. Only one group was found in each sampled site. No link could be established between RAPD-based groups and the geographic origin of the strains. However, our results suggest a possible link between these groups and Alnus species and/or habitats associated with each of the four French Alnus species.

On water agar, hyphae of many fungi are attracted to viable pollen grains of Pinus nigra. Hyphae of 41 of 157 species tested could penetrate the pollen grains, ramify within the interior and consume the contents. It is proposed that pollen serves as a supplementary seasonal source of nutrients, particularly nitrogen, for litter- and wood-decaying members of the Basidiomycota.

A new ascomycete, Iodosphaeria polygoni sp. nov., is described and illustrated from Taiwan. It is compared with the other known species of Iodosphaeria. A key to species is also given.

The teleomorph of Phoma medicaginis var. pinodella is reported for the first time. A single isolate, collected from infected plant material in Australia, produced asci and ascospores in culture. The anamorph was identified as Phoma medicaginis var. pinodella on the basis of axenic colony morphology, symptoms on the foliage of a susceptible pea line and characteristic hybridization banding patterns observed during RFLP analysis. The ascospores and asci, although similar in morphology to those produced by Mycosphaerella pinodes, were considerably larger. Therefore, the binomial assignment of the teleomorph remains open to speculation. The potential impact on disease dissemination and effectiveness of control measures against P. medicaginis var. pinodella are discussed.

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.

Two nematode-parasitic isolates of Harposporium are reported to form synanamorphs attributable to the Hirsutella. One is attributedto Harposporium anguillulae, the second is described as a new species, H. cerberi. H. cerberi also produced an arthroconidial synanamorph. In infection studies of nematodes, conidia typical of Harposporium proved to be capable of killing bacterial feeding nematodes (Rhabditis sp.) when ingested. Infective conidia of H. cerberi were located posterior to the oesophageal bulb, while those of H. anguillulae lodged above it. Hirsutella conidia were not observed to be infective or adhesive, and none of the spore forms was capable of infecting either of two species of stylet-bearing nematodes (Aphelenchus sp. and Meloidogyne hapla).

Hyalorhinocladiella and Sporothrix are two common mycelial anamorphs of Ophiostoma that are difficult to distinguish from each other. Sporothrix spp. differ visibly from Hyalorhinocladiella by the presence of denticles on the conidiogenous cells. Graphium and Sporothrix are often synanamorphs of the same Ophiostoma species and the aim of this study was to determine whether a relationship exists between sympodial conidium development in Sporothrix and annellidic development in Graphium. Conidium development was examined in Sporothrix schenckii, Ophiostoma nigrocarpum and Ophiostoma piceae. Using fluorescence microscopy, as well as scanning and transmission electron microscopy, distinct denticles were observed on the conidiogenous cells in Sporothrix spp. In some cases, these conidiogenous cells were reduced, giving them a Hyalorhinocladiella-like appearance. Results of this study suggest that a continuum in patterns of conidium development exists between Sporothrix, Hyalorhinocladiella and Graphium. The linear extent, and the angle of the proliferation stage with reference to the long axis of the conidiogenous cell, appear to determine the form of conidium development.

DNA fingerprinting with a set of synthetic oligonucleotides complementary to simple repetitive sequences was used to develop molecular markers for Ascochyta rabiei, the most important fungal pathogen of chickpea (Cicer arietinum). Two compatible mating type isolates (MatI and MatII) from the U.S. Pacific Northwest with the same low level of aggressivity were compared to highly virulent isolates from the Mediterranean region and Pakistan to find suitable mating partners for the production of a mapping population. After Hinf I or Taq I restriction, electrophoresis and in-gel hybridization with ten different simple repetitive oligonucleotides, all tested single-spored isolates exhibited unique fingerprint patterns. The analysis revealed that the two U.S. mating types share a considerable amount of genetic variability. A total of 77 polymorphic marker bands were detected. A higher number of polymorphic bands (up to 104) was observed between these isolates and those from different geographical regions. The isolates from the Mediterranean region and Pakistan shared a lower degree (between 80 and 90 bands) of detectable genetic diversity. These data permit selection of highly virulent crossing partners for the different mating types with a high degree of detectable polymorphism.

A sexual cross was performed to prove the Mendelian segregation of fingerprint bands for future linkage analysis. Additionally, the fingerprint data based on 268 informative characters combined with phenetic and phylogenetic algorithms allow determination of the genetic identity, relatedness and diversity of the different isolates. To confirm the phylogenetic data, two outgroupers Ascochyta fabae and Ascochyta pisi, were included. Results indicate that A. pisi is more closely related to A. rabiei than A. fabae.

A species of Wuestneia occurring on stems of eucalypts is described as Wuestneia epispora. The new species is distinguished by its large 4- to 8-spored asci and ascospores with firm, thick gelatinous sheaths. Two different anamorphs, Harknessia sp. and an unnamed hyaline, non-appendaged conidial species were associated with this fungus. Both anamorphs have microconidial synanamorphs. A new combination, Wuestneia karvarrae, is proposed for Cryptosporella karvarrae.

The morphology of gametangia was examined in 43 pairs of isolates (mating types A1×A2; 11 A1 and 24 A2 isolates; five isozyme/electrophoretic types) of Phytophthora cinnamomi. An amphigynous antheridium always formed with each oogonium. However, in 41 of the crosses a proportion (39 had 0·2–10% and two had >30%) of oogonia also consistently had single or multiple paragynous antheridia. Single or multiple paragynous antheridia formed concurrently with amphigynous ones during the period of gametangial production in paired colonies. Where there were multiple paragynous antheridia associated with an oogonium, sometimes additional antheridia formed after fertilization or even after oospores were visible. Developmental studies showed that when meiosis in amphigynous and paragynous antheridia was simultaneous, fertilization tubes developed synchronously from both. However, cytological examination indicated that either a nucleus from an amphigynous or a paragynous antheridium fertilized the oosphere. Observations of paragynous and amphigynous, and amphigynous-only associations suggested that fertilization from either type of antheridium only occurred when meiosis in the oogonium was nearly synchronous with that of the antheridium. Asynchronous meiosis between oogonia and antheridia may contribute to failed fertilization and aborted oospore development. This appears to be the first description of paragynous antheridia in P. cinnamomi and the second observation of oogonia with both paragynous and amphigynous antheridia in a heterothallic Phytophthora species. Moreover, the development of both paragynous and amphigynous antheridia with an oogonium is rare in Phytophthora, as is the development of multiple antheridia. Antheridial variation is a characteristic to be taken into account in isolate identification. Nuclei from paragynous antheridia appear able to fertilize oospheres and therefore, have a role in sexual reproduction.

Two intracellular β-glucosidases, designated P-I and P-II, were found in Aspergillus nidulans. While both enzymes were subject to carbon catabolite repression, they exhibited different degrees of repression. P-I biosynthesis was repressed only by a strongly repressing carbon source such as glucose. By contrast, P-II biosynthesis was repressed by even weakly repressing carbon sources such as acetate or lactose. Repression of both was relieved in the creAd mutant strain, except for the strong repression of P-II biosynthesis which was still repressed by glucose. Thus P-II biosynthesis seems to be more sensitive to carbon catabolite repression than P-I.