Species of the anamorph genus Phoma are commonly isolated from a wide range of ecological niches. They are notoriously difficult to identify due to the paucity of morphological features and the plasticity of these when cultivated on agar media. Species linked to Phoma section Peyronellaea are typified by the production of dictyochlamydospores and thus have additional characters to use in taxon delineation. However, the taxonomy of this section is still not fully understood. Furthermore the production of such chlamydospores also is known in some other sections of Phoma. DNA sequences were generated from three loci, namely ITS, actin, and btubulin, to clarify the phylogeny of Phoma taxa that produce dictyochlamydospores. Results were unable to support section Peyronellaea as a taxonomic entity. Dictyochlamydospore formation appears to be a feature that developed, or was lost, many times during the evolution of Phoma. Furthermore, based on the multigene analyses, five new Phoma species could be delineated while a further five required taxonomic revision to be consistent with the genetic variation observed.

In order to study the species composition of endophytes from wheat healthy plants in Buenos Aires Province (Argentina) and to determine their infection frequencies from leaves, stems, glumes and grains, wheat plants were collected from five cultivars at five growth stages from crop emergence to harvest. A total of 1,750 plant segments (leaves, stems, glumes and grains) were processed from the five wheat cultivars at five growth stages, and 722 isolates of endophytic fungi recovered were identified as 30 fungal genera. Alternaria alternata, Cladosporium herbarum, Epicoccum nigrum, Cryptococcus sp., Rhodotorula rubra, Penicillium sp. and Fusarium graminearum were the fungi that showed the highest colonization frequency (CF%) in all the tissues and organs analysed. The number of taxa isolated was greater in the leaves than those in the other organs analysed.

tion of the influence of N supply on the disease severity have been studied with contrasting results (Johnston et Nitrogen fertilization is required for achieving high yields in wheat al., 1979;Howard et al., 1994; Leitch and Jenkins, 1995; (Triticum aestivum L.), but N may enhance the development of leaf Lovell and Royle, 1999). Simó n et al. (1998) found that blotch (Septoria tritici Roberge in Desmaz., teleomorph Mycosphaerella graminicola (Fuckel) J. Schrö t. in Cohn). The present study in conducive conditions, N fertilization increases the was undertaken to investigate how Septoria leaf blotch affects yield, severity of Septoria leaf blotch and discussed the effect yield components, and test weight (TW) of different cultivars under of different factors affecting the influence of N supply. different N supplies. Field experiments with six cultivars were carried Most of previous papers studying the influence of N out in a split-split plot design during 1996 and 1997. Inoculation treaton the expression of disease concerned the expansion ments were the main plots, N fertilization levels were the subplots, of the necrotic area or pycnidial coverage on foliage. and cultivars were the sub-subplots. Thousand-kernel weight (TKW) Few studies include the incidence of this agronomic was higher and TW lower in 1996 than in 1997. Interaction year ϫ practice on yield and yield component losses. Leitch inoculation was not significant for any trait; year ϫ fertilization was and Jenkins (1995) observed that control of Septoria significant for yield and EPM 2 , and year ϫ cultivar was significant leaf blotch increased yield, with the magnitude of this for all traits except TKW. The separated analysis for each year indicated that additional N increased yield, EPM 2 , and KPE, but not effect greater at the higher rate of N applied. Johnston TKW or TW. Inoculation with S. tritici reduced yield and KPE, in et al. (1979) found a greater increase in yield in fertilized both years and TKW, TW, and EPM 2 in 1996. Differences between conditions compared with nonfertilized conditions when cultivars occurred for all traits except EPM 2 in 1996. The percentage fungicides were applied in only one of two years. reduction in yield, yield components, and TW due to the inoculation If the increase in the severity of the disease under N was similar in fertilized and nonfertilized conditions, despite the infertilization causes a reduction in yield and yield compocrease in the area under disease progress curve (AUDPC) values by nents, higher amounts of fungicides would be necessary N fertilization in 1996. Cultivar differences in tolerance is suggested.under high-N input systems. The aim of this work was to evaluate the influence of an early artificial infection of S. tritici on the yield, yield components, and TW 1974

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