Browsing by Author "Mostert, L."

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    Genera of phytopathogenic fungi : GOPHY 2
    (Elsevier, 2019) Marin-Felix, Y.; Hern andez-Restrepo, M.; Wingfield, M. J.; Akulov, A.; Carnegie, A. J.; Cheewangkoon, R.; Gramaje, D.; Groenewald, J. Z.; Guarnaccia, V.; Halleen, F.; Lombard, L.; Luangsa-ard, J.; Marincowitz, S.; Moslemi, A.; Mostert, L.; Quaedvlieg, W.; Schumacher, R. K.; Spies, C. F. J.; Thangavel, R.; Taylor, P. W. J.; Wilson, A. M.; Wingfield, B. D.; Wood, A. R.; Crous, P. W.
    This paper represents the second contribution in the Genera of Phytopathogenic Fungi (GOPHY) series. The series provides morphological descriptions and information regarding the pathology, distribution, hosts and disease symptoms for the treated genera. In addition, primary and secondary DNA barcodes for the currently accepted species are included. This second paper in the GOPHY series treats 20 genera of phytopathogenic fungi and their relatives including: Allantophomopsiella, Apoharknessia, Cylindrocladiella, Diaporthe, Dichotomophthora, Gaeumannomyces, Harknessia, Huntiella, Macgarvieomyces, Metulocladosporiella, Microdochium, Oculimacula, Paraphoma, Phaeoacremonium, Phyllosticta, Proxypiricularia, Pyricularia, Stenocarpella, Utrechtiana and Wojnowiciella. This study includes the new genus Pyriculariomyces, 20 new species, five new combinations, and six typifications for older names.
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    Genetic diversity among isolates of Phaeomoniella chlamydospora on grapevines
    (2006) Mostert, L.; Abeln, E. C. A.; Halleen, F.; Crous, P. W.
    Phaeomoniella chlamydospora is one of the main causal agents of Petri disease and esca of grapevines. Although it is known to have a coelomycete synanamorph, no teleomorph has thus far been reported for P. chlamydospora, and its disease cycle remains largely unknown. The present study compared the genetic diversity of P. chlamydospora isolates from different grapevine-growing countries using amplified fragment length polymorphisms. Sixty-three isolates from South Africa and 25 from grapevine regions in Australia, France, Iran, Italy, New Zealand, Slovenia and the USA were studied. Two primer combinations were used producing 138 scorable markers, of which 33% were polymorphic. An unweighted paired group method of arithmetic averages analysis showed a high similarity (≥94.5%) among the different isolates. The overall low level of genetic variation confirmed asexual reproduction to be dominant in the field. Different genotypes were found among isolates of P. chlamydospora within the same grapevine, suggesting multiple infections from different inoculum sources. Isolates from different production areas and countries had a high percentage of similarity and clustered together, indicating the absence of genotype-geographic structure. The presence of the same genotype in different vineyards and production areas suggests that long-range dispersal through aerial inoculum or infected plant material play an important role in genotype distribution. © Australasian Plant Pathology Society 2006.
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    In vitro screening of fungicides against phomopsis viticola and diaporthe perjuncta
    (South African Society for Enology and Viticulture, 2000) Mostert, L.; Denman, S.; Crous, P. W.
    Phomopsis viticola is the cause of Phomopsis cane and leaf spot disease of grapevines, while Diaporthe perjuncta is associated with bud mortality. The efficacy of nine fungicides (azoxystrobin, flusilazole, folpet, fosetyl-Al + mancozeb, kresoxim-methyl, mancozeb, penconazole, spiroxamine and trifloxystrobin) against isolates of P. viticola and D. perjuncta was determined in vitro using the mycelial growth test. Additionally, azoxystrobin, folpet, kresoxim-methyl, mancozeb, propineb and trifloxystrobin were tested for their ability to inhibit spore germination in vitro. Ten isolates of P. viticola and three of D. perjuncta were used in the mycelium inhibition tests, and five isolates of P. viticola in the spore germination tests. The effective concentration at which mycelial growth was inhibited by 50% and at which 50% of the spores (EC50 value) were inhibited from germinating was calculated for each isolate/fungicide combination. In the mycelium growth test flusilazole, penconazole and trifloxystrobin gave better inhibition at lower concentrations than folpet and fosetyl-Al + mancozeb. No significant differences in the mean ECso values were detected among azoxystrobin, flusilazole, kresoxim-methyl, penconazole, spiroxamine and trifloxystrobin. There were also no significant differences among the mean EC50 values of azoxystrobin, kresoximmethyl and mancozeb. Flusilazole and penconazole inhibited mycelial growth at the lowest mean EC50 values obtained. Kresoxim-methyl and trifloxystrobin inhibited spore germination at lower concentrations than folpet or mancozeb. Folpet required the highest concentration to inhibit 50% germination and was significantly different from mancozeb and propineb. There were also no significant differences among the mean EC50 values of mancozeb, propineb and azoxystrobin. The mean EC50 values of the strobilurin fungicides were not significantly different from one another. These results indicate that the strobilurin fungicides inhibited mycelial growth and spore germination of P. viticola. Trials need to be conducted to verify these findings under field conditions.
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    Phylogeny and taxonomy of the scab and spot anthracnose fungus Elsinoe (Myriangiales, Dothideomycetes)
    (Elsevier, 2017) Fan, X. L.; Barreto, R. W.; Groenewald, J. Z.; Bezerra, J. D. P.; Pereira, O. L.; Cheewangkoon, R.; Mostert, L.; Tian, C. M.; Crous, P. W.
    Species of Elsinoe are phytopathogens causing scab and spot anthracnose on many plants, including some economically important crops such as avocado, citrus, grapevines, and ornamentals such as poinsettias, field crops and woody hosts. Disease symptoms are often easily recognisable, and referred to as signaturebearing diseases, for the cork-like appearance of older infected tissues with scab-like appearance. In some Elsinoe-host associations the resulting symptoms are better described as spot anthracnose. Additionally the infected plants may also show mild to severe distortions of infected organs. Isolation of Elsinoe in pure culture can be very challenging and examination of specimens collected in the field is often frustrating because of the lack of fertile structures. Current criteria for species recognition and host specificity in Elsinoe are unclear due to overlapping morphological characteristics, and the lack of molecular and pathogenicity data. In the present study we revised the taxonomy of Elsinoe based on DNA sequence and morphological data derived from 119 isolates, representing 67 host genera from 17 countries, including 64 ex-type cultures. Combined analyses of ITS, LSU, rpb2 and TEF1-α DNA sequence data were used to reconstruct the backbone phylogeny of the genus Elsinoe. Based on the single nomenclature for fungi, 26 new combinations are proposed in Elsinoe for species that were originally described in Sphaceloma. A total of 13 species are epitypified with notes on their taxonomy and phylogeny. A further eight new species are introduced, leading to a total of 75 Elsinoe species supported by molecular data in the present study. For the most part species of Elsinoe appear to be host specific, although the majority of the species treated are known only from a few isolates, and further collections and pathogenicity studies will be required to reconfirm this conclusion.