A Phytophthora species was found on blighted foliage of Ipomoea longipedunculata, a morning glory native to the highlands of central Mexico. Based on host range, morphology, allozymes, mitochondrial DNA haplotype and rDNA sequences it is concluded that a new Phytophthora species, P. ipomoeae sp. nov., is the causal agent of leaf blight disease on I. longipedunculata.

We investigated the influence of changes in external phosphorus (P) concentration on the proportion of phosphatase-active structures of the arbuscular mycorrhizal fungus Gigaspora margarita associated with Allium cepa. The P treatment was started when mycorrhizal colonisation had been established, and plant systems were harvested three times after the start of the P treatment. Higher shoot dry weights and P contents were observed in the high-P treated plants at the last harvest. We did not find any change in the proportion of phosphatase-active extraradical mycelium following P treatment. However, the proportion of alkaline phosphatase-active mycelium was positively correlated for extraradical and intraradical mycelium. Also, the proportion of alkaline phosphatase-active arbuscules seemed to increase with the shoot fresh weight, whereas the proportion of acid phosphatase-active arbuscules decreased with higher shoot P concentration and dry weight. We have shown experimentally that the intraradical mycelium of G. margarita, but not the extraradical mycelium, responds metabolically to plant P concentration, and possibly also to external P availability.

Colonisation of Pinus radiata sapwood by sapstain fungi results in a permanent discoloration of the sap and is one of the major problems associated with P. radiata timber production in New Zealand. No fungicides are available that can provide a reliable level of control of sapstain for the extended time period required to export timber. A 4-year survey, commencing in 1996 revealed that the most common species which cause sapstain on radiata wood are Sphaeropsis sapinea (syn. Diplodia pinea), and two species of Ophiostoma (O. floccosum and O. ips). A total of 21 different species that cause sapstain have been identified to date. Two approaches for the control of sapstain are presented in this paper. The first relies on the ability of microorganisms to inhibit the growth of sapstain species. Such an ability has been demonstrated in laboratory trials on wood chips or wood blocks for 116 isolates of the 848 fungal and bacterial isolates initially considered. Six of the most effective isolates were further tested on sawn timber or debarked logs in field trials. Isolates of Trichoderma spp. and Trichothecium roseum were found to control sapstain as well as the standard fungicide treatments. T. harzianum was significantly better in controlling sapstain in the internal tissues of debarked logs than the fungicide. The second approach is based on inhibition of the sapstain causing fungi by secondary metabolites produced by plants or microorganisms. Massoialactone, produced by various fungi including Trichoderma spp., showed good antisapstain activity in laboratory and field trials. Twenty-nine essential oils from different plant species inhibited O. piceae in the laboratory. The most efficient oils were found to contain high levels of oxygenated monoterpenes. Oxygenated alcohol or phenolic monoterpenes proved to be extremely active against sapstain fungi preventing discoloration of sapwood for up to 9 months. A method of control for sapstain based on pine oil derivatives containing some of these compounds is now being developed for commercial use.

Eleven new species of the ascomycete genus Mycosphaerella from Queensland, Australia, are described, illustrated and where necessary compared with closely related members recorded in the same host family. The new species described are: M. cuttsiae, M. cyperi, M. dodonaeae, M. glochidionis, M. khayae, M. melaleucoides, M. morindaeM. platylobii, M. queenslandica, M. wollemiae, and M. xylomeli. With the exception of M. queenslandica, which is found on Dianella, all of the other species occur on host genera indicated by the specific epithet of the fungus. Apart from M. cyperi, the other species are all associated with necrotic leaf spots. Additionally, Sphaerella escalloniae is transferred to Mycosphaerella as M. escalloniae comb. nov., and M. aequatoriensis and M. pericampyli are newly reported from Australia.

Epichloë spp. (Clavicipitaceae) and their close asexual relatives, Neotyphodium spp., form systemic endophytic associations with Pooideae grasses. Interactions between Lolium and Festuca host grasses and fungal endophytes were examined in studies focusing on leaves of natural associations and also of plants into which the endophyte was introduced by seedling inoculation. Light microscopy as well as fungal isolation was used to locate the position of hyphae, while transmission electron microscopy was used to examine host/fungus interactions at the cellular level. These studies provide support for synchronised plant and endophyte growth. This characteristic pattern of growth was maintained when both Epichloë and Neotyphodium spp. were introduced by seedling inoculation into new host species. Hyphae, with few exceptions, grew rapidly as leaves grew and ceased when leaf growth ceased. This pattern of growth offers an explanation for the characteristic appearance of hyphae in leaf sheaths of host grasses; seldom branched and for all species other than N. occultans, aligned parallel to the leaf axis. Hyphal growth of a second group of endophytic fungi, referred to as p-endophytes, was not regulated in the same way, with growth continuing as leaves aged. This pattern of growth gives rise to high concentrations of branched ramifying hyphae in old leaf sheaths. Although host genotype did not effect the basic pattern of hyphal growth of Epichloë/Neotyphodium endophytes, it strongly influenced the concentration and distribution of hyphae throughout leaves. Examination by TEM revealed no evidence that penetration of hyphae into dense tissue was aided by the secretion of pectic enzymes that loosen the middle lamella connecting host cells. Instead it appeared that penetration occurred by hyphae physically pushing between cells. The absence of enzymatic loosening of the middle lamella during penetration could explain why hyphae of these endophytes apparently do not elicit host defence reactions in natural associations. However, subtle interactions between the hyphae of Epichloë/Neotyphodium and host cells in natural associations were observed.

The effects of different temperatures and pH on the growth and solubilization of insoluble calcium phosphate, cobalt phosphate, manganese phosphate, strontium hydrogen phosphate and zinc phosphate by Rhizoctonia solani on solidified media were assessed. Solubilization of the metal phosphates was monitored by the production of a clear zone around or underneath the fungus. R. solani efficiently solubilized all five metal phosphates except cobalt phosphate when grown on medium at pH 7. Solubilization activity by R. solani decreased with increasing pH on medium containing calcium phosphate but increased on strontium hydrogen phosphate-amended medium. The uptake of metals by the mycelia was unaffected by the pH of the medium or the growth temperature. Small quantities of crystals were produced in the agar when R. solani was grown on calcium phosphate- and strontium hydrogen phosphate-amended media and these were identified as calcium or strontium sulphates respectively: there appeared to be little or no production of insoluble oxalates although a role for oxalate in the overall solubilization process cannot be discounted. These results are discussed in relation to their physiological and environmental significance, and the important roles of fungi in effecting transformations of insoluble metal-containing compounds in the environment.

Cryopreservation of ectomycorrhizal fungi is often difficult, but needed for patent deposits and for enabling experiments on model strains with constant characteristics. In this study we report a protocol for successful cryopreservation of the ectomycorrhizal mushroom Cantharellus cibarius, together with a brief summary of some unsuccessful attempts. A slow freezing rate (0.3°C min−1) of agar cubes carrying the mycelium, and a gentle addition of the cryoprotectants sorbitol and DMSO were important features. This protocol was successfully repeated by ATCC who used it to deposit a patented strain of C. cibarius, and therefore the protocol should also be tested for other ectomycorrhizal basidiomycetes.

The relationship between teleomorphs of Cordyceps spp. and their presumed anamorphs have been investigated by analysis of 5.8S and ITS rDNA sequences. The morphological and sequence data confirm that Paecilomyceshawkesii is the anamorph of Cordyceps gunnii, while Cordyceps hawkesii is a synonym of C. gunnii, and P. gunnii is a synonym of P. hawkesii. The following presumed connections are also confirmed: Beauveria brongniartii is the anamorph of C. brongniartii, Metarhizium anisopliae var. majus is the anamorph of C. brittlebankisoides, Beauveria sobolifera is the anamorph of C. sobolifera, Mariannaea pruinosa is the anamorph of C. pruinosa, Paecilomyces militaris is the anamorph of C. militaris, and Hirsutellasinensis is the anamorph of C. sinensis. The other isolates sequenced are unlikely to be anamorphs of the teleomorphs from which they were isolated because the sequences from the culture and the teleomorph are quite different. 5.8S and ITS sequences provide useful information for establishing anamorph–teleomorph connections and assisting in the delimitation of species within Cordyceps.

The causal agent of a patch disease of buffalo grass (syn. St Augustine grass) is determined and described as a new species, Gaeumannomyces wongoonoo sp. nov. Glasshouse experiments have shown that it is pathogenic to buffalo grass (cultivar ST 1191) but not to maize or wheat. The pathogen is different to the varieties of G. graminis in having shorter ascospores (36–75 μm) and producing numerous perithecia readily on malt extract and potato dextrose agars. The disease is named ‘wongoonoo patch’ to distinguish it from take-all patch of turf grasses caused by G. graminis.

The aerodynamic diameter, da, of conidia produced in vivo and in vitro by the entomopathogenic fungus Erynia neoaphidis were estimated using an impaction method. The estimated values of da for conidia produced in vivo were smaller than those produced in vitro: in vivo the values of da for primary and secondary conidia were between 16 and 18 μm (equivalent fall speed, Vs, 0·8–1·0 cm s−1); for in vitro produced conidia da values were between 28 and 31 μm (Vs, 2·4–3 cm s−1). For conidia produced by field collected cadavers the value of da, was estimated to be similar to that for conidia produced in vivo in the laboratory. The aerodynamic diameter of primary conidia of Conidiobolus obscurus (strain X39) and Zoophthora radicans (strain NW250) produced in vivo were also measured using the same method. The values of da for these two species were 45 and 17 μm (Vs, 6·2 and 0·9 cm s−1) respectively. Implications for dispersal of E. neoaphidis are discussed. The physical diameters of the test spores were measured microscopically and compared with the aerodynamic diameters.

Thirty 3–4 yr-old twigs were collected at each of three sampling dates between May 1995 and May 1996 from each of ten approximately 120 yr-old European beech trees in the Tuscan-Emilian Apennines to examine the bark for the presence of endophytic fungi. Five trees with low crown transparency ([les ]5%) and five trees with high crown transparency ([ges ]25%) were compared. Almost all of the 900 examined bark samples were colonized by endophytic fungi. More than 30% of the twigs appeared to host three or more fungal species. Forty-four endophyte species were detected. An Aposphaeria and a Cryptosporiopsis species, Botryosphaeria quercuum, Discula umbrinella and Neohendersonia kickxii occurred most frequently in all of the three samplings and seemed to play a dominant role as endophytes in beech bark. Significant differences in endophyte assemblages between trees with low and trees with high crown transparency could be detected only with respect to the Aposphaeria species. The colonization of tissues by this fungus, possibly a weak pathogen, was predominant on trees with high crown transparency.

Four day/night temperature regimes (11/6, 14/9, 17/12, 20/15 °C), three photoperiods (0, 12, 24 h d−1), and four continuous temperature regimes (10, 13, 16, 19 °) were evaluated for their effects on growth, sporulation, and conidia discharge of two isolates of Valdensinia heterodoxa, a foliar pathogen of salal (Gaultheria shallon). All temperature regimes supported mycelial growth; however, growth rates were faster at higher temperatures. Sporulation and conidia discharge in both isolates was generally highest at 17/12 ° (day/night) or 16 ° constant compared with other temperature regimes. Photoperiods of 12 and 24 h d−1 resulted in faster growth and significantly greater sporulation and discharge compared with a continuous dark treatment. The study shows that temperature and light conditions have a moderate effect on mycelial growth but are crucial for sporulation of V. heterodoxa. Possible implications for the use of V. heterodoxa as a potential biological control agent for salal are discussed.

Two new thermotolerant species of Thielavia were isolated from Easter Island and India, after treating soil samples with 65% (v/v) ethyl alcohol: T. intermedia sp. nov. characterized by large, obovate, dark brown ascospores with a terminal germ pore; and T. arxii sp. nov. distinguished by the large, ellipsoidal to fusiform, brown ascospores with a prominent, lateral to medial germ pore. A phylogenetic study of the ITS-5.8S rDNA sequences of 18 species of Thielavia and Melanocarpus thermophilus was performed. This analysis revealed that T. intermedia could be the ancestor of the remaining species and that all the species tested were genetically closely related.

Five fungal isolates, tentatively identified as belonging to Thysanophora, were re-examined to confirm their generic placement. DNA sequences from multiple loci were determined and compared to homologous sequences from other fungi. The Thysanophora-like isolates belong in the genus Penicillium on the basis of phylogenetic analysis of their gene sequences. Because these isolates have unique phylogenetic positions within Penicillium and have unique phenotypes we describe them as the new species P. boreae, P. subarcticum and P. canariense spp. nov. In addition, P. pullum sp. nov. is described for NRRL 721, which served as the typical isolate of P. fuscum in the monographic studies of Raper & Thom and Ramirez; however, the name P. fuscum has been applied and neotypified using a different specimen and NRRL 721 is markedly different phylogenetically from the neotype of P. fuscum.

All 39 marine species described so far from Spartina spp. are listed. Anthostomella torosa sp. nov. is described from culms of Juncus roemerianus in North Carolina, and A. spissitecta sp. nov. is described from leaf sheaths of saltmarsh Spartina alterniflora in the USA (Connecticut, Florida, North Carolina, Rhode Island) and from S. densiflora in Argentina (Buenos Aires). Both species occur close to the rhizome and are classified as obligate marine fungi. The new species are compared with similar taxa, and a table comprises characteristics of the nine known aquatic Anthostomella species.

We report an investigation into the relationship between Aspergillus nidulans mutations sltA1 and agaA50, conferring salt sensitivity and arginase deficiency, respectively, and the ability of spores to swell and commence germination. Spores from both mutant strains exhibited uncontrolled swelling at pH 5.5 in the presence of arginine as the nitrogen source. The controlled swelling of spores from a salt tolerant strain under these conditions was disrupted by the Na+/H+ exchange inhibitor amiloride. Swelling in the presence of amiloride was associated with an elevation in the concentration of arginine within the spores of each strain tested. The possible consequences of alterations in the arginine economy of the spore for colony establishment in osmotically challenged habitats are discussed.

A synopsis of the subgenus of lichenicolous fungi Lichenogramma is presented. It comprises eight species of Lichenostigma with oval to elongate ascomata connected to superficial strands of vegetative hyphae. Five of them are described here as new: Lichenostigma diploiciae (on Diploicia subcanescens); L. epipolina (on Diplotomma epipolium); L. gracilis (on Acarospora fuscata); L. rouxii (on Squamarina spp.); and L. subradians (on Acarospora spp., mainly subgen. Acarospora). The concept of the genus Lichenostigma is enlarged to accommodate also species with submuriform ascospores. A key to all the species of the subgenus is provided.

The objective of this study was to assess the influence of clay minerals on the morphology of mycelial pellets produced under submerged conditions as a prelude to the development of biomineral sorbents for toxic metals. The macro- and microscopic morphology of fungal pellets of melanin-containing microfungi Cladosporium cladosporioides, C. herbarum and Humicola grisea grown in liquid clay-containing medium was studied using scanning electron microscopy. It was found that the inclusion of clay minerals (bentonite, palygorskite and kaolinite) in the liquid medium influenced size, shape and structure of the mycelial pellets produced. In general, a reduction of pellet size, an increase in the length of surface hyphae of the pellets (except for H. grisea), and a reduction in exopolymer production were observed with increasing clay mineral concentrations up to 5% (w/v). For C. herbarum, an increasing concentration of bentonite changed the normal pelleted growth form to diffuse star-like growth, which was also observed for C. cladosporioides in the presence of kaolinite. The presence of bentonite and kaolinite in the medium for H. grisea and palygorskyte for C. cladosporioides led to the formation of numerous bulbous hyphae in pellets. However, bentonite decreased such bulbous growth in C. herbarum compared to control pellets which grew as bulbous mycelium. The dynamics of C. cladosporioides growth and pellet formation in the presence of bentonite (0·5% (w/v)) was investigated. It was found that the clay particles were involved in the formation of pellet structure at all stages of fungal growth. The porosity of a growing pellet (evaluated as the ratio of surface hyphae length to pellet radius) increased during early growth (17–24 h) and then decreased up to the stationary phase. A general model of the structure of a fungal pellet grown in clay-containing medium is proposed. The pellets consist of three main layers: a central core, with densely packed mycelium aggregated with solid clay minerals or a matrix of clay/polysaccharides; a middle layer with looser mycelium mixed with clay mineral flakes; and an outer, or ‘hairy’ zone, with loose hyphae surrounded by clay mineral flakes. The relevance of these studies to fungal growth and morphology, and to the development of biomineral sorbents for metal removal is discussed.

Notes on the nomenclature and taxonomy of British species recorded in the genus Tazzetta, and in its synonym Pustularia, are presented. The new combination T. scotica is proposed, with a neotype designated. Four species are recognised as British, and a key for their identification provided.