Eudarluca caricis, the teleomorph of Sphaerellopsis filum, was found on blackberry rust (Phragmidium violaceum) in south west England and its morphology is described. Cultures derived from ascospores produced pycnidial conidiomata and conidia typical of S. filum, confirming the connection between the meiotic and mitotic stages of the fungus. Microconidia were also found in the cultures derived from ascospores. Conidiomata developed on the majority of uredinial pustules of P. violaceum 10 d after inoculating detached, uredinia-bearing blackberry leaves with the conidia from the cultures derived from ascospores.

A method for the observation of the three-dimensional structure of intact ectomycorrhizal rhizomorphs is described. The method is based on a combination of clearing the material with KOH followed by staining with congo red and subsequent imaging under a laser scanning confocal microscope (LSCM). The images obtained are of a much higher three-dimensional resolution than those obtained previously by use of conventional light microscopical techniques. The structure of highly differentiated and undifferentiated rhizomorphs is described. Applications of the method are briefly discussed.

The PCR technique based upon randomly amplified polymorphic DNA (RAPD) markers using 10-mer oligonucleotide primers was used to investigate the phylogenetic relationships among 33 isolates of Heterobasidion annosum belonging to the intersterility groups F and S. The F isolates originated from Italy, the S isolates from the Italian Alps, northern Europe and North America. The presence or absence of some bands was shown to be population-specific. The North American S group and the European S group differed significantly from each other, but within the latter group there were no significant differences between the Italian S and the northern European S populations, with as much similarity within these populations as between them. More DNA polymorphisms appeared within European F and S groups than in the North American S group. The North American S group appeared to be more closely related to the European S group than to the F group. The isolates of the Italian F population seemed to be most closely related to the Italian S isolates and then, in decreasing order, to the northern European S and North American S isolates. The order of genetic similarity was inversely correlated with the mating frequency in vitro obtained in an earlier study.

Isolates from potato in an isolated garden in North Wales in 1995 consisted of essentially two distinct phenotypes. Phenotypes P1 and P2, of A1 and A2 mating type respectively, had distinctive multi-locus (RG57) and telomeric RFLP fingerprints. In addition, about 6% of isolates forming abundant oospores were self-fertile and showed a combination of both fingerprints. Among a total of 40 single-hyphal-tip and single-sporangial propagations from two self-fertile isolates, 16 were P2 whereas only one propagation was P1; four propagations were still self-fertile and still carried the molecular markers typical of both P1 and P2. Most of the remainder were A1 but otherwise carried both P1 and P2 molecular markers. Uninucleate zoospore lines from two of these were also of A1 mating type but had segregated molecular markers typical of P2; a zoospore line from a third segregated both A2 mating type and markers typical of P2. The original self-fertile isolates appeared to have heterokaryotic hyphae and sporangia with P1 and P2 nuclei and also nuclei of A1 mating type but P2 markers. Tetraploid nuclei within a heterokaryon, resulting from fusion of P1 with P2 nuclei, could have segregated to yield the latter.

Hyphae of Saprolegnia ferax recovered from intracellular acidification with variable degrees of apical vacuolation and migration of cytoplasm out of the apex, prior to apical refilling and resumption of growth. The response was not due to alkalinization, but was generalized to recovery from diverse growth inhibitors including procaine, latrunculin B and the kinase inhibitor 6-dimethylaminopurine. The vacuoles apparently arise from expansion and fusion of apical tubular vacuoles. This process is mediated by microtubules, since their disruption suppresses apical vacuolation. The shape of the vacuoles appears to be F-actin imposed, because their expansion is enhanced by F-actin disruption. The accompanying, often bidirectional, cytoplasmic migrations are independent of tip growth, require F-actin, and probably represent part of a hypothetical generalized cytoplasmic avoidance response.

A new species of Cryptosporiopsis is described. It was isolated frequently from roots of healthy-looking and declining oaks (Quercus robur and Q. petraea). The relationship to C. radicicola, a similar species also occurring on oak roots, is discussed. The new species is separated from C. radicicola by means of morphological and physiological characters, genomic analysis by the PCR-based RAPD technique as well as by the production of metabolites.

A fossilised fungal colony is described and illustrated from Dominican amber dating back 15–45 Myr. Many hyphae in the coenocytic mycelium had produced terminal or intercalary protuberances resembling the sporangia of some extant zygomycetes and oomycetes. Other hyphae had produced cylindrical arthroconidia similar to those of Geotrichum and related extant yeasts. Many fossilised diaspores had germinated prior to preservation. The fungus seems to have been a rapidly growing saprophyte, utilising fluid substrates, possibly plant exudate. The palaeoenvironment proposed for the mycelium, namely that of a moist epiphytic or epixylic microhabitat, supports earlier conclusions that the original Dominican amber forest possessed a tropical moist forest biome.

Perenniporiella gen. nov. is segregated from Perenniporia. The new combinations Perenniporiella neofulva and Perenniporiella micropora, and the new species Perenniporiella pendula are proposed. Perenniporia piperis and Perenniporia albida are considered as taxonomic synonyms of P. neofulva. The three species are described and their taxonomic position is discussed. A key to the neotropical Perenniporiella and Perenniporia species with pileate basidiomes is presented.

Five local oak species, Quercus boissieri, Q. calliprinus, Q. cerris, Q. ithaburensis and Q. libani were identified as hosts of Tuber melanosporum, the black truffle of Perigord, following inoculation of roots. Q. cerris and Q. libani developed abundant mycorrhizal roots, similar to the amount found in roots of Q. pubescens, the traditional host of this mycorrhizal fungus. Roots of Q. ilex, Q. hartwissiana and Q. pedunculiflora, introduced species in Israel, were also heavily colonized by the mycorrhizal fungus. Mycorrhized hazel (Corylus avellana) roots, were also obtained by the same inoculation procedure. Recovery of T. melanosporum from roots of inoculated oak was improved when chloramphenicol was added to the isolation medium. Recovery varied between 14 and 54% for C. avellana and Q. calliprinus, respectively. Recovery was highest for the two local species, Q. calliprinus (54%) and Q. boissieri (50%), followed by Q. pubescens (44%) and Q. ilex (41%). Identification of the isolated fungi was conducted using arbitrarily-primed PCR. Identical band patterns were observed among AP-PCR-amplified DNA extracted from an authentic culture of the fungus, ascocarps (truffles) and cultures isolated from roots. In addition, AP-PCR was reliable for differentiating between representative isolates of T. melanosporum, T. magnatum, T. borchii, T. maculatum, T. dryophilum, T. macrosporum and T. uncinatum.

The development of apothecia of Pyrenopeziza brassicae (anamorph Cylindrosporium concentricum) on oilseed rape debris and compost malt agar was observed by scanning electron and light microscopy. On oilseed rape debris, apothecia developed directly beneath the epidermis as small globular structures of dense mycelium, which protruded through the epidermis as they increased in size. The apices of erumpent immature apothecia then developed small ostiolar openings which increased in diameter to expose the hymenia of mature apothecia containing dome-shaped asci interspersed with filiform paraphyses. On compost malt agar, hyphae of one mating type grew towards hyphae of the opposite mating type 3–4 d after inoculation of conidia onto agar surfaces. The subsequent development of apothecia on compost malt agar was similar to that on oilseed rape debris.

A Paraisaria-like fungus isolated from a larva of a cerambycid beetle, Anopolophora oshimana, produced small obovoid conidia from multi-necked conidiogenous cells arising from synnematous conidiophores. In culture, the fungus produced curved Harposporium-like conidia in addition to obovoid conidia. When introduced into nematode-infested cultures, nematodes were infected after ingesting the curved conidia and infection typical of Harposporium, producing curved conidia from globose conidiogenous cells, resulted. Reinfection of beetle larvae by injection of hyphal bodies from pure culture and by contact with conidia from the original host showed pathogenicity to cerambycid larvae.

The fatty acid composition of pea roots with and without the root pathogen Aphanomyces euteiches was studied using whole cell fatty acids (WCFA), phospholipid fatty acids (PLFA) and neutral lipid fatty acids (NLFA). Initial screening for A. euteiches markers using WCFA analysis showed that the fatty acids 14[ratio ]1ω9, 14[ratio ]0, 20[ratio ]4 and 20[ratio ]5 were specific to roots infected with A. euteiches. The amounts of these fatty acids correlated positively with the percentage of the root system containing A. euteiches oospores, suggesting that they could be useful indicators of A. euteiches root-infection levels. Analysis of the composition of phospholipid fatty acids (PLFA) and neutral lipid fatty acids (NLFA) of pea roots with and without A. euteiches showed similar specificity as found with WCFA analysis. PLFAs and NLFAs specific to roots inoculated with A. euteiches were also present in mycelium from pure culture of A. euteiches. The PLFAs 14[ratio ]0, 20[ratio ]4 and 20[ratio ]5 were used to estimate biomass of A. euteiches and the NLFAs 14[ratio ]1ω9, 14[ratio ]0, 20[ratio ]4 and 20[ratio ]5 were used as indicators of energy reserves of the pathogen. The possible use of specific fatty acids to study growth and development of A. euteiches in pea roots is discussed.

Intraradical vesicles of Glomus intraradices were isolated, entrapped in alginate beads, and stored at 4 °C for periods from 2–74 months. The beads were used to inoculate leeks grown under standard conditions for 6 wk, then development of root colonization by G. intraradices was recorded. Colonization of leeks was high (mean >50% in length) and did not vary markedly until five years of storage. After six years of storage, the inoculum proved infective and viable.

Basidiomes of a Pisolithus species were collected from a ca 2500 m2 Australian sclerophyll forest site during 1997 and 1999 and of a second Pisolithus species from a further ca 150 m2 site during 1999. Inter-simple sequence repeat (ISSR) PCR was conducted on DNA extracted from each basidiome using the primers 5′BDB(ACA)5, 5′DDB(CCA)5 and 5′DHB(CGA)5. Thirty-seven genotypes of Pisolithus species I were detected at the North Wilberforce site, with eight genotypes present during both 1997 and 1999. All other genotypes were observed during only one year. Mapping genotype distribution according to location of basidiome collection at the site suggested that most genotypes were present as small (< 2·0 m2) below-ground mycelial genets, however several larger (> 4·0 m2) genets (including one ca 120 m2 genet) were also present. All Pisolithus species II basidiomes at the North Turramurra site were of a common genotype, suggesting the presence of a single large (ca 69 m2) below-ground mycelial genet of this taxon at the site. Both Pisolithus species thus appear to produce large long-lived soil-borne mycelia, but establishment of large genets may be restricted under some circumstances.

The aim of the present paper is to investigate if Mycocalicium subtile as presently circumscribed is a morphologically highly variable species, or in fact represents two or more cryptic species, and further to investigate the status of M. minutellum. The morphological variation of 19 specimens of Mycocalicium subtile from five continents was investigated and the ITS1-5.8S-ITS2 region of their rDNA sequenced. Sequences from closely related taxa, 4 specimens of M. albonigrum, 2 of Mycocalicium sp., and Chaenothecopsis nana were also included. For comparison the corresponding sequence of M. victoriae and C. pusilla were also determined. We used the sequence of Monascus purpureus as the outgroup for the analysis. The sequences were used for phylogenetic inference using parsimony and distance methods. All the specimens assigned to M. subtile with the exception of two, form a well-supported monophyletic group. Those two specimens represent a morphologically cryptic, but genetically distinctive taxon. The infraspecific clades of M. subtile in the molecular phylogeny did not correspond to geographical origin. Only a weak correlation with geographical origin was found in the morphological analysis. The molecular analysis supports the suggestion that Mycocalicium minutellum is a taxonomic synonym of M. subtile.

Nine isolates of Peronosclerospora sorghi from maize, sorghum and wild sorghum were sampled from Zimbabwe, Zambia, Rwanda, Mozambique and Kenya. They were compared for variation in conidium and conidiophore morphology, temperature requirements for sporulation, germination and germ-tube growth and for pathogenicity on different sorghum and maize cultivars. Although there were significant differences in isolate morphology, all conformed to the known range for P. sorghi. Mean conidial length×width ranged from 21–23 μm×16·9–19·2 μm, and mean conidiophore length (basal cell-branching) ranged from 116·3–135·6 μm. All isolates sporulated in the range 14–26 °C (optimal at 16–23°), although one isolate from maize from Umbeluzi in Mozambique had a broader optimal range for sporulation (12–25°). Conidia of all isolates germinated between 10° and 34°. Germ-tube response to temperature was similar for all isolates (10–34°). The isolates varied in their pathogenicity towards sorghum cultivars, with an isolate from Rwanda being pathogenic to more sorghum differentials than any other. Cluster analysis of isolates based on host reaction indicated five groups at the 85% similarity level. The existence of pathogenic variability has ramifications for the breeding of sorghum for resistance to downy mildew in Africa.

The new generic name Lecanostictopsis is introduced with three species, L. kamatii (type species), L. syzygii and L. noumeaensis sp. nov., all of which are associated with leaf lesions on species of Syzygium. The genus is compared and contrasted with Lecanosticta, Stigmina and similar genera. The position of Cercostigmina is discussed in relation to Pseudocercospora and Cercoseptoria. Cercostigmina syzygii sp. nov. associated with leaf lesions on S. cordatum is described, and compared and contrasted with Stenella marasasii on the same host substratum. Pseudocercospora syzygiicola sp. nov. is described from leaf lesions on S. cordatum from South Africa, while Pseudocercospora syzygiorum sp. nov. from S. cumini and Passalora syzygii from S. cumini and S. jambos are described from India.

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.

Many plant pathogenic foliicolous fungi recorded on Proteaceae hosts in South Africa are reminiscent of members of the Mycosphaerellaceae and their anamorphs. However, these fungi are often unusual and specific to the Proteaceae, and have proved difficult to classify in the past. To address this issue, a phylogenetic analysis of the ITS-1, 5.8S and ITS-2 DNA sequence data was performed to determine relationships between members of the Mycosphaerellaceae and some taxa apparently unique to the Proteaceae. Results from this study have confirmed Batcheloromyces to be affiliated to the Mycosphaerellaceae. Within Mycosphaerella, Batcheloromyces was also shown to be distinct from Stigmina, which clustered separately from Pseudocercospora. The separation between Mycosphaerella and Teratosphaeria (anamorph Trimmatostroma) was shown to be artificial, which was further supported by several Trimmatostroma species clustering within Mycosphaerella. From these data it is concluded that Teratosphaeria should be reduced to synonymy under Mycosphaerella, and that Trimmatostroma represents yet another additional anamorph of Mycosphaerella.

Chlorotic leaf distortion (CLD) is an unusual disorder of sweet potato caused by a morphologically unique strain of Fusarium lateritium. This study compared 15 isolates of F. lateritium from sweet potato with nine isolates from other hosts for genetic diversity by RAPD analysis and RFLP analysis of the intergenic spacer region and the ITS region of the rDNA. In RAPD analysis, 12 of the sweet potato isolates clustered very closely, nine with similarity of >0·99, and three additional isolates at a similarity of >0·86. This group comprised two pathotypes and included isolates from U.S.A., South America, Asia and Africa. The remaining isolates, comprising three from sweet potato and all isolates from other hosts, showed little similarity with the cluster of sweet potato isolates. RFLP analysis produced similar results, with the 12 isolates that were clustered in RAPD analysis and one additional sweet potato isolate clustered at >0·80 similarity. These data suggest that the sweet potato CLD pathogen is relatively homogeneous and genetically distinct from other strains of F. lateritium. There was relatively little similarity among isolates of F. lateritium from other hosts.