Twenty-nine field isolates of the broad host range pathogen Claviceps purpurea from various host plants and different geographical origin were compared by RAPD analysis. The RAPD patterns obtained showed considerable diversity; it was even possible to discriminate all strains tested with single primers, indicating an unusual high degree of genetic diversity within this species. A parsimony analysis using the PAUP software grouped most strains from specific host plants together, indicating some degree of host specificity in this fungus. Those strains derived from rye seem to be genetically less diverse than those from other host plants. However, the geographic origin also seems to be important.

The RAPD technique was used to distinguish two forms of Melampsora rust on Salix viminalis. Fifteen isolates of the stem-infecting form and 19 of the leaf-infecting form collected from the U.K. were tested with 10 arbitrary primers. All the primers generated polymorphic bands and 46 putative loci were examined. Seven primers gave a total of eight bands specific for the stem-infecting form and four primers produced five bands characteristic of the leaf-infecting form. Cluster analysis using Unweighted Pair-Group Method with Averaging (UPGMA) revealed 62% disagreement between the two forms. The RAPD band patterns of the stem-infecting form isolates were almost identical, while those of the leaf-infecting isolates showed up to 29% variation.

The effects of growth media, temperature, pH and light on the development of four isolates of Coniothyrium minitans (CONIO and CH8 (colony type 3), G4 (colony type 4) and G9 (colony type 5)) were examined. Conidial germination, pycnidial production and hyphal extension rate were initially studied on seven different agar-based growth media at 18–20 °C. Potato-dextrose agar (PDA) and malt extract agar (MEA) consistently gave the greatest conidial germination, pycnidial production and hyphal extension rate for all four isolates. Growth and development on molasses-yeast agar was equivalent to that on PDA and MEA except that hyphal extension rate was slower. Subsequently, the effects of temperature, pH and light on the development of C. minitans were investigated on PDA only. The temperature range of conidial germination and pycnidial production of the four isolates was between 10–25° with the optimum at approximately 20°. Hyphal extension occurred over a greater temperature range, between 4 and 25°, with a maximum extension rate of approximately 3·5 mm d−1 for all isolates occurring between 20–25°. Conidial germination, pycnidial production and hyphal extension occurred over a pH range between 3–8 with optimum values for all growth assessments occurring between pH 4·5 and 5·6. Increasing light period from continuous dark, to 12 h light/12 h dark or continuous light had no effect on conidial germination or extension growth, but significantly increased pycnidial production.

Isolates G4 and G9, previously characterized by sparse production of pycnidia in comparison with CONIO and CH8, consistently exhibited a reduced production of pycnidia on all media, at all temperatures and pH ranges, and all light regimes tested. This demonstrates the stability of this character among these isolates of C. minitans. The significance of these results for improving production of inoculum of this biocontrol agent and in the identification and classification of isolates of C. minitans is discussed.

A total of 500 strains of the thermophilic fungus Thermomyces lanuginosus were screened for their ability to produce proteases. A selected strain, T. lanuginosus P134, showed high enzymatic activity for proteases. The maximal yield of proteases was obtained with 4% casein, 4% glucose and 4% yeast extract in submerged culture. The protease system was shown to contain at least two protease isoenzymes by SDS–PAGE with gels containing gelatin as protease substrate. The effects of inhibitors imply that the two enzymes appear to be serine proteases. The crude proteases of T. lanuginosus P134 displayed unusual properties. The proteases were shown to be one of the most thermostable proteases so far isolated in fungi. The proteases were 100% stable at 50 °C. The half-life at 60 and 70° was approximately 160 min and 60 min, respectively. Temperature optimum of activity was 70°. The crude proteases were stable over a broad pH range (4–11). Optimum pH of activity was at 5·0 and 9·0.

The haustorial morphology of 21 Ravenelia species, two Kernkampella species, and four leguminicolous Uredo and Uraecium species which are probably related to Ravenelia, was investigated by light microscopy. Three different kinds of interaction could be found: (1) species with haustorial complexes comprising dikaryotic haustoria and intracellular hyphae. These species showed strictly intracellular growth of the parasitic mycelium. (2) Species with only dikaryotic haustoria, and (3) species with only intracellular hyphae or monokaryotic haustoria. Complexes of dikaryotic haustoria and intracellular hyphae were found in 17 of the investigated Ravenelia species and three Uredo species. Three Ravenelia species revealed dikaryotic haustoria, and Ravenelia lonchocarpicola had only intracellular hyphae. Complexes of dikaryotic haustoria and intracellular hyphae are probably the prevalent type of parasitic interaction in Ravenelia. The investigated Kernkampella species revealed dikaryotic haustoria.

Liquid media with differing carbon concentrations and carbon-to-nitrogen ratios were tested for production of desiccation tolerant blastospores of Paecilomyces fumosoroseus. While all media tested supported sporulation in submerged culture, high blastospore concentrations (5·8 × 108 spores ml−1) were produced in media containing 80 g glucose l−1 and 13·2 g Casamino acids l−1 (MS medium) and a significantly higher percentage (79%) of these blastospores survived air drying. Media containing glucose concentrations greater than 20 g l−1 and Casamino acid concentrations between 13·2 and 40 g l−1 supported maximal production of desiccation tolerant blastospores. All 23 isolates of P. fumosoroseus grown in MS media produced high concentrations of desiccation tolerant blastospores. When stored at 4 °C, more than 60% of the lyophilized blastospores produced in MS medium were still viable after 7 months storage while less than 25% of the air-dried blastospores survived after 90 d storage. Standard whitefly bioassays were performed to compare air-dried blastospores of P. fumosoroseus ARSEF 4491 with solid substrate-produced conidia of Beauveria bassiana ARSEF 252. Air-dried blastospores of P. fumosoroseus gave LD50S of 60 and 113 blastospores mm−3 for the silverleaf whitefly (Bemisia argentifolii) in two separate bioassays with potency ratios (LD50 B. bassiana/LD50 P. fumosoroseus) of 3·9 and 3·8, respectively. These results have demonstrated that high concentrations of blastospores of P. fumosoroseus can be rapidly produced in liquid culture, remain viable following drying, and infect and kill silverleaf whitefly.

Delortia, represented by the type, D. palmicola, is redescribed from fresh decaying palm material collected in north Queensland, Australia. Two new species, D. tumidoapicis and D. aquatica, collected from wood submerged in a freshwater stream, also in north Queensland are described. The three species are illustrated with light micrographs and line diagrams and discussed in relation to each other.

Spatial characteristics of Suillus variegatus populations, including the size, distribution and number of genets, were measured in four naturally regenerated stands of Scots pine, Pinus sylvestris in Sweden that were more than 100 years old. In the oldest forest, a continuous tree-layer had been present at least since the last forest fire in 1647. Genets were identified based on somatic incompatibility reactions performed on mycelial cultures from sporocarps. In total, 38 genets were identified from 120 tested sporocarps. The maximal extension of a genet, as reflected by its outermost sporocarps, was 27 m in the oldest stand and ranged between 10 and 17 m in the other stands. On average, genet size was 20 m in the oldest stand and 10 m in the other stands. Other genets were not found within the domains of established genets. The closest detected distance between genets was 1·5 m, and the average distance was 4 m. The number of genets ranged between 56 and 74 ha−1 at the studied sites. Possible reasons for the high degree of resemblance in characteristics in old forests between S. variegatus, the dominant bolete in mature forests, and S. bovinus when present, more a characteristic for younger forests and only scarcely occurring in older forests, are discussed.

Three species of fungi endoparasitic in nematodes were obtained in pure culture for the first time. The fungi belong to Harposporium and Verticillium. Morphology of the fungi on corn meal agar was studied and infectivity proving Koch's postulates was achieved for each species. The infection method for Harposporium cycloides was shown to be by spore ingestion. Whilst all species were found to produce infection conidia in pure culture, both species of Harposporium produced accessory conidia and, in H. lilliputanum, arthroconidia were also formed.

An examination of microscopic and macroscopic vegetative reactions between paired isolated of Rhizoctonia solani AG-8 revealed that pairs of isolates that give a C2 anastomosis reaction at the microscopic level always gives a ’tuft’ reaction at the macroscopic level. Similarly, any pair that gives a C3 anastomosis reaction at the microscopic level always gives a ’merge’ reaction at the macroscopic level. Thus, macroscopic vegetative (’tuft type’) reactions can be used to predict the microscopic (anastomosis) reaction (and vice versa) between paired isolate of AG-8. This pattern also seems to apply to paired isolates of AG-3, AG-7 and AG-10 but not the other AGs of R. solani. The C2 anastomosis reaction is always observed when two isolates from different zymogram groups of R. solani AG-8 are paired. When isolates from within any of the five zymogram groups comprising AG-8 are paired, either a C2 or a C3 anastomosis reaction will result. Many field isolates of AG-8, when paired, give a C3 anastomosis reaction. We propose that a group of field isolates of R. solani that give a C3 anastomosis reaction be designated a ’vegetatively compatible population’ (VCP).

The basic hydrolysis parameters, i.e. molecular weight of substrate, reaction time, pH, temperature, and enzyme and substrate concentration, were standardized to maximize sugar yield from dextran. Thus, a 74% conversion of 4% dextran to sugar syrup was reached in 12 h using 6 dextranase units g−1 hydrolysed substrate. The high concentrations of sucrose in the reaction medium did not affect the hydrolysis efficiency nor the activity of Penicillium notatum dextranase. Action patterns of dextranase from P. notatum on dextran were investigated. Analysis of the dextran hydrolysis end products indicated that P. notatum dextranase was a typical endo-enzyme, and isomaltose and isomaltotriose were identified as the primary final products of dextran hydrolysis.

Previous studies with a monoclonal antibody (designated UB7) raised against isolated haustorial complexes formed by the pea powdery mildew fungus Erysiphe pisi showed that it recognized an abundant glycoprotein found in cell walls and plasma membranes of haustoria and the surface mycelium. In this paper, Western blotting and phase-partitioning in the detergent Triton X-114 have been used to show that the plasma membrane antigens recognized by UB7 comprise a 62 kDa integral glycoprotein and a set of integral membrane glycoproteins of lower molecular weight. A 59 kDa glycoprotein recognized by UB7 has been extracted from the fungus using aqueous buffer, and the evidence suggests that this represents the cell wall form of the antigen. Binding of UB7 is abolished by pre-treatment of glycoproteins with peptide-N-glycosidase, but is retained after endo-F treatment. This suggests that the epitope to which UB7 binds is the innermost N-acetylglucosamine residue of N-linked carbohydrate side chains of glycoproteins, possibly substituted with one or more sugars. When tested for cross-reactivity with other fungi, UB7 bound to some, but not all, of those examined, and recognized different sets of glycoproteins compared with those detected in E. pisi. However, UB7 did not bind to any higher plants nor to any animal glycoproteins tested. This antibody thus identifies a carbohydrate epitope restricted to glycoproteins in a subset of the fungi.

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.

Lepteutypa hexagonalis sp. nov. is described from a dead trunk of Pinanga sp. (Palmae) collected in an Ecuadorean rainforest. Ascomata are deeply immersed with a distinct ostiolum, asci are cylindrical with a J+ subapical ring, and ascospores are brown, 4-celled, and hexagonal or heptagonal in transverse section.

Isolates of Verticillium fungicola, collected over a period of 45 yr from various geographical sites, were analysed for their responses to four fungicides (benomyl, thiabendazole, chlorothalonil and diethofencarb), and for colony morphology, virulence and DNA polymorphisms. Three different colony morphologies were observed for this population of isolates including fluffy, dense and appressed. The majority of isolates had the appressed colony morphology. Most isolates exhibited high levels of virulence. The appearance in this population of both benomyl and thiabendazole resistance was correlated with the introduction of benomyl for use on mushrooms. Eighty-eight percent of the isolates were cross-resistant between benomyl and thiabendazole and 80% exhibited negatively correlated cross-resistance between benomyl and diethofencarb. Seventy percent of the isolates exhibited negatively correlated cross-resistance between thiabendazole and diethofencarb. The level of resistance to chlorothalonil was relatively high even prior to its introduction and overall the response to this fungicide appears to have varied little over the last 45 yr. DNA polymorphisms, as detected by randomly amplified polymorphic DNA (RAPD) analysis, divided the isolates into four groupings. Limited correlations could be drawn between RAPD groupings, fungicide response and geographical origin. All recently collected isolates (1993–5) were extremely similar in their response to the four fungicides and had appressed colony morphology, high virulence and were members of RAPD group four. The lack of variation in the recent isolates as compared to the older isolates indicates that the V. fungicola population may be becoming more homogeneous.

Botrytis cinerea is known as a β-(1-3)(1-6)-D-glucan-overproducer with an exceptionally high degree of β-(1-6)-branches in the glucan. To localize and characterize the glucan synthase, the incorporation of [14C]glucose, activated by uridyl diphosphate and incubated with mycelial extracts, into ethanol-precipitable material was studied. Whereas crude extracts were found to produce α- and β-glucans, a pure β-(1-3)-D-glucan was formed by the membrane fraction. This was monitored by the complete cleavage into glucose with a purified β-(1-3)-glucanase and by the detection of laminaribiose, a β-(1-3)-linked dimer of glucose, in incomplete digestions. Degradation products with β-(1-6)-linkages, e.g. gentiobiose, which is found after degradation of the native polymer, were not detectable. β-(1-3)-glucan synthase activity was optimal at 22 °C and pH 7·2 with a Km of 0·8 mM and a Vmax of 0·24 mU mg−1 protein. GTP (Ka = 4·2 μM), cellobiose, BSA and EGTA enhanced the reaction whereas UDP (Ki = 0·45 mM) and Ca2+ inhibited it.

This listing covers the period July 1, 1996 through to July 31, 1996. Citations are arranged in groups which roughly correspond with the British Mycological Society's Special Interest Committees.