Fungal decomposers are important contributors to the detritus-based food webs of salt marsh ecosystems. Knowing the composition of salt marsh fungal communities is essential in understanding how detritus processing is affected by changes in community dynamics. Automated ribosomal intergenic spacer analysis (ARISA) was used to examine the composition of fungal communities associated with four temperate salt marsh plants, Spartina alterniflora (short and tall forms), Juncus roemerianus, Distichlis spicata and Sarcocornia perennis. Plant tissues were homogenized and subjected to a particle-filtration protocol that yielded 106 microm particulate fractions, which were used as a source of fungal isolates and fungal DNA. Genera identified from sporulating cultures demonstrated that the 106 microm particles from each host plant were reliable sources of fungal DNA for ARISA. Analysis of ARISA data by principal component analysis (PCA), principal coordinate analysis (PCO) and species diversity comparisons indicated that the fungal communities from the two grasses, S. alterniflora and D. spicata were more similar to each other than they were to the distinct communities associated with J. roemerianus and S. perennis. Principal component analysis also showed no consistent, seasonal pattern in the composition of these fungal communities. Comparisons of ARISA fingerprints from the different fungal communities and those from pure cultures of selected Spartina ascomycetes supported the host/substrate specificity observed for the fungal communities.

Stagonospora blotch of wheat has been difficult to control in the eastern United States. The objectives of this research were to evaluate the effects of field inoculum, seedborne inoculum, and seed treatment and foliar fungicides on Stagonospora blotch development and to develop more effective management strategies. In 1995 and 1996, similar experiments were established in “infested” and “clean” fields using two seed lots of Coker 9543 (“low” and “high” levels of seed infection) and six seed or foliar fungicide treatments. Planting in clean fields, planting seed with a low level of seedborne inoculum, treating seed with difenoconazole or triadimenol + thiram, and applying propiconazole or tebuconazole to the foliage all contributed toward reducing leaf infections by Stagonospora nodorum, severity of leaf and glume blotch, and incidence of S. nodorum in the harvested seed. Propiconazole alone was the least effective treatment. Planting in an infested field tended to negate the beneficial effects of low level of seed infection and fungicide seed treatments. Crop rotations and tillage that allow wheat debris to decompose before the next wheat crop along with difenoconazole or triadimenol seed treatment to reduce seedborne inoculum should be sufficient to avoid serious losses. In fields where wheat is grown every year, tillage and seed treatment would still be helpful, but a foliar fungicide at GS 8 may be necessary for adequate control. Applying an effective fungicide to seed appears to be a more efficient means of reducing seedborne inoculum than does producing seed with low levels of inoculum.

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A marine xylarialean fungus, isolated from roots of Rhizophora (mangrove) in Australia, displays morphology of eight ellipsoidal dark brown ascospores in a cylindrical ascus having a refractive apical apparatus. Each ascospore has a longitudinal germ slit. The fungus grew very slowly and produced dark brown water-soluble pigment(s) on various media. It developed unique, column-shaped, indeterminate synnemata on which needle-shaped conidia were produced. The sexual stage of this fungus was not observed under the laboratory conditions tested. Molecular phylogenetic analyses of the combined sequences of nuclear ribosomal RNA genes and their internal transcribed spacers placed it at a basal position in the clade of Diatrypaceae of the Xylariales with comparatively high statistical support. However the morphological features and phylogenetic position of this organism do not closely resemble any known fungal taxa. Therefore this fungus is proposed to be a representative of a novel taxon and described as Diatrypasimilis australiensis gen. et sp. nov.