Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Passalora gochnatiicola sp. nov. on Gochnatia amplexifolia from Serra do Cipó, MG, Brazil(Acta Botanica Brasilica, 2006-01) Pereira, Olinto Liparini; Barreto, Robert Weingart; Braun, UweThe leaf-spotting hyphomycete Passalora gochnatiicola sp. nov., collected on Gochnatia amplexifolia (Gardner) Cabrera (Asteraceae: Mutisieae) in the 'campos rupestres' of Serra do Cipó (Minas Gerais State, Brazil), is described, illustrated, discussed and compared with allied species.Item Reavaliação taxonômica de Colletotrichum guaranicola Albuq. agente causal da antracnose do guaranazeiro(Acta Amazonica, 2004) Bentes, Jânia Lília da Silva; Barreto, Robert WeingartFoi realizada uma reavaliação morfológica de estruturas reprodutivas e de infecção do agente causal da antracnose do guaranazeiro (Paullinia cupana var. sorbilis), visando confirmar a identidade do patógeno. Os resultados reforçam o reconhecimento da espécie Colletotrichum guaranicola Albuq., como um novo taxon dentro do gênero Colletotrichum.Item Sphaceloma poinsettiae as a potential biological control agent for wild poinsettia (Euphorbia heterophylla)(Biological Control, 2004-07) Nechet, Kátia de Lima; Barreto, Robert Weingart; Mizubuti, Eduardo S. G.Sphaceloma poinsettiae, a scab-causing fungus that attacks wild poinsettia (Euphorbia heterophylla) was evaluated as a mycoherbicide. Plants representing nine different E. heterophylla accessions were tested and variable resistance levels to 10 different isolates of S. poinsettiae were observed. One isolate was selected based on its high aggressiveness; it caused scab that led to stem-girdling in the majority of plants belonging to most wild poinsettia accessions. Plants inoculated with conidial suspension developed low disease severity; suspensions of mycelial fragments caused higher disease severity. Viability of mycelium declined rapidly either in storage under room temperature or at 4 °C. After 25 days, 60% of mycelial fragments kept in distilled water at 4 °C or in 35% sterile sucrose solution germinated. Cultures of S. poinsettiae were capable of growing at temperatures ranging from 10 to 30 °C (maximum growth at 25 °C) whereas the mycelial fragments germinated at 20–30 °C. The highest mycelial yield occurred in potato-dextrose broth after culturing for 12 days at 168 rpm at room temperature. A host-range test involving 37 plant species in addition to wild poinsettia indicated that S. poinsettiae is highly specific to E. heterophylla. The viability of S. poinsettiae as a mycoherbicide depends on the development of suitable mass production, formulation, and inoculum preservation methods. On several occasions, this fungus has been observed to cause devastating epidemics in the field on this host; therefore, it should be considered a potential biocontrol agent of wild poinsettia.Item Nimbya alternantherae a potential biocontrol agent for alligatorweed, Alternanthera philoxeroides(BioControl, 2007-04) Pomella, Alan William Vilela; Barreto, Robert Weingart; Charudattan, RaghavanAlligatorweed, (Alternanthera philoxeroides (Mart.) Griseb.), an aquatic and wetland plant native to South America, is an aggressive weed in many parts of the world. Its ability to compete with other native plants and to impede waterways has made it a serious threat to aquatic ecosystems. Although biological control with insects has been fairly successful in aquatic habitats, there is a need for additional agents to manage the weed in upland sites. Accordingly, in a survey in Brazil in 1997 a fungus, Nimbya (=Alternaria) alternantherae (Holcomb and Antonopoulus) Simmons and Alcorn, was discovered and confirmed to be highly damaging to alligatorweed. Studies were conducted to determine the potential of this fungus for controlling this weed. Several isolates from Brazil, USA, and Puerto Rico were compared and no differences in virulence were observed, although a lower dew requirement was demonstrated for the Brazilian isolates. Conidia were more effective than mycelial suspension, and inoculum concentrations of 1×105 and 1×106 conidia per ml provided significant levels of control of the weed in greenhouse and field experiments, respectively. In a host-range study, N. alternantherae infected 6 plant species from a total of 42 species belonging to 23 families. N. alternantherae has the potential to be an effective mycoherbicide for alligatorweed.Item The mycobiota of the weed Mikania micrantha in southern Brazil with particular reference to fungal pathogens for biological control(Mycological Research, 1995-03) Barreto, Robert Weingart; Evans, Harry CharlesA survey of the fungi associated with the tropical weed Mikania micrantha was conducted during 1988 and 1989 in part of its native range in southern Brazil. Sampling was concentrated mainly in the state of Rio de Janeiro, covering 70 sites in different climatic or ecological zones. Nine species were identified, including the recently described downy mildew species Basidiophora montana and the previously undescribed Mycosphaerella mikania-micranthae sp. nov. with its anamorph Septoria mikania-micranthae. Asperisporium mikaniae comb. nov., Asperisporium mikaniigena comb. nov., Pseudocercospora plunketii comb. nov., and Cercospora mikaniacola are new records for Brazil. Field observations indicate that Basidiophora montana has potential as a classical biological control agent of the weed in Old World subtropical or montane climates, whilst Mycosphaerella mikania-micranthae and the microcyclic rust Puccinia spegazzinii appear to be equally damaging to the host but to have a wider climatic range and thus are highly promising agents for introduction throughout the Palaeotropics.Item Cercosporoid hyphomycetes associated with Tibouchina herbacea (Melastomataceae) in Brazil(Mycological Progress, 2014-08) Parreira, Douglas Ferreira; Silva, Meiriele da; Pereira, Olinto Liparini; Soares, Dartanha José; Barreto, Robert WeingartA survey of fungal pathogens associated with cane tibouchina, Tibouchina herbacea (Melastomataceae), was conducted in the neotropics, concentrated in south and southeastern Brazil and aimed at finding potential biological control agents for this herbaceous invasive weed for introduction into Hawaii. Numerous fungal species were found, including five cercosporoid fungi. Four new taxa are described and illustrated here: Passalora tibouchinae, Pseudocercospora subsynnematosa, Pseudocercospora tibouchina-herbaceae and Pseudocercospora tibouchinicola. A phylogenetic analysis of the ITS and TEF-1α regions of the three new species of Pseudocercospora was conducted and confirmed their separation as distinct taxa as indicated by morphological and cultural features. Additionally, Cercospora apii is reported for the first time on T. herbacea. Among the species of fungi described in this study, two appear particularly promising for use in a biological control program because they were found to cause severe disease on T. herbacea: Passalora tibouchinae and Pseudocercospora subsynnematosa. Additional tests, including host-specificity screening, will be required in order to confirm this potential.Item Petal spotting of hydrangea flowers caused by Corynespora cassiicola: old pathogen — new disease(Mycologist, 2000-02-03) Leite, R. S.; Barreto, Robert WeingartDiseased hydrangeas (Hydrangea macrophylla) were found growing in gardens of highland localities of the states of Rio de Janeiro and Minas Gerais (Brazil). Distinct multiple purple spots in flowers that gave an unsightly chicken-poxed (varicella-like) appearance to the inflorescences were found along with leaf necrosis. The severity of the disease seriously impairs the ornamental value of this highly popular garden plant. The fungus Corynespora cassiicola was found associated with leaf and flower lesions. Brush inoculation of leaves with conidia obtained from a flower isolate resulted in the formation of leaf spots identical to the ones observed in the field. Although this fungus is known to be a pathogen of hydrangea foliage this is the first time the fungus is recognised to cause a flower disease on this host. The flower disease, here called petal spotting of hydrangea, and the fungus involved are described and illustrated.Item First record of Pyricularia grisea causing leaf blight of Costus spiralis in Brazil(Australasian Plant Disease Notes, 2011-12) Santana, Eduardo A.; Guatimosim, Eduardo; Fuga, Cicero A. G.; Glienke, Chirlei; Barreto, Robert WeingartA leaf blight was observed on Costus spiralis in an experimental area in the campus of the Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil. Morphology and ITS sequences placed the fungus associated with the disease in Pyricularia grisea. Pathogenicity was demonstrated. This is the first record of P. grisea on Costus spiralis worldwide.Item Mycobiota of the weed Conyza canadensis (Asteraceae) in Brazil(Fungal Biology, 2016-06-21) Duarte, Lidiane Leal; Santos, Fabiana Maria Coutinho; Barreto, Robert WeingartConyza canadensis is a noxious and notably problematic weed in Brazil whose control is greatly challenging due to the appearance, in the last years, of herbicide resistant populations. An investigation regarding the associated pathogenic fungi of this plant was conducted in Brazil aimed at starting a biological control program to help mitigate its economic impact. Ten fungal species were yielded and described: two ascomycetes (Leptosphaerulina conyzicola sp. nov. and Wentiomyces melioloides), five hyphomycete asexual morphs (Alternaria tenuissima, Cercospora conyzicola sp. nov., Cercosporella virgaureae, and Fusarium fujikuroi), two coelomycete asexual morphs (Phoma conyzaphthora sp. nov., Septoria erigerontis), one rust fungus (Aecidium conyzicola sp. nov.), and one oomycete (Basidiophora entospora). Four among the fungi that were collected represent new taxa, and the others represented either new host-records of known fungal species or new geographic records or both, except for C. virgaureae that had already been recorded on C. canadensis in Brazil. None of the discovered species have any potential to be used as a mycoherbicide or to be introduced somewhere else, nevertheless, the knowledge about this mycobiota will help guide the selection of potential biocontrol agents to be introduced in Brazil.Item Bipolaris marantae sp. nov., a novel Helminthosporoid specis causing foliage blight of the garden plant Maranta leuconeura in Brazil(Mycobiology, 2017-06-23) Lourenço, Carla Cristina Gomes; Alves, Janaina Lana; Guatimosim, Eduardo; Colman, Adans; Barreto, Robert WeingartA severe leaf spot, turning to foliage blight, was observed on leaves of Maranta leuconeura growing in a garden in Brazil (state of Rio de Janeiro) in 2015. A dematiaceous hyphomycete bearing a morphology typical of a helminthosporoid fungi was regularly found in association with diseased tissues. The fungus was isolated and pathogenicity was demonstrated through the completion of Koch's postulates. A morphology and molecular analysis led to the conclusion that the fungus belonged to the genus Bipolaris, which is characterized by having fusiform conidia, externally thickened and truncate hila and a bipolar pattern of germination. Additionally, homology of internal transcribed spacer and GAPDH sequences with sequences of other Bipolaris species, confirmed its generic placement. A phylogenetic study also indicated clearly that the fungus on M. leuconeura is phylogenetically distinct from related species of this genus, leading to the proposal of the new species Bipolaris marantae.