Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Mycobiota of the weed Tradescantia fluminensis in its native range in Brazil with particular reference to classical biological control(Australasian Plant Pathology, 2016-02) Macedo, D. M.; Pereira, O. L.; Hora Júnior, B. T.; Weir, B. S.; Barreto, R. W.Tradescantia fluminensis [Commelinaceae] (common name wandering Jew or trad), is a native Brazilian herbaceous plant, which has been introduced to be used as an ornamental in many warm areas of the world. In New Zealand and other countries it has become an aggressive invader of natural ecosystems, causing serious environmental disturbances and threatening biodiversity. Surveys of pathogen and insect natural enemies of T. fluminensis were conducted over several years in Brazil to identify potential candidates for use as classical biological control agents in New Zealand. The surveys found seven pathogenic fungi associated with T. fluminensis and related Tradescantia species: Cercospora apii (leaf spot), Rhizoctonia solani (leaf blight), Sclerotium rolfsii (crown rot) and Uromyces commelinae (rust), and three novel species described in this paper: Ceratobasidium tradescantiae sp. nov. (web blight), Colletotrichum riograndense sp. nov. (anthracnose) and Kordyana brasiliensis sp. nov. (white smut-like disease). Observations of damage in the field and expected host-range suggest that K. brasiliensis and U. commelinae have the highest potential for use as classical biological control agents.Item Colletotrichum dracaenophilum causes anthracnose on Dracaena braunii in Brazil(Australasian Plant Disease Notes, 2016-12) Macedo, D. M.; Barreto, R. W.Dracaena braunii (lucky bamboo) is a plant of West Africa widely used as an ornamental. Recently individuals bearing anthracnose symptoms were found in Viçosa (state of Minas Gerais, Brazil). Morphology was typical of Colletotrichum dracaenophilum and sequence analyses indicated a high homology to the internal transcribed spacer region and Beta tubulin with the ex-type sequences of this species. This is the first record in Brazil.Item Alternaria cichorii in Brazil on Cichorium spp. seeds and cultivated and weedy hosts(Journal of Phytopathology, 2008-08) Barreto, R. W.; Santin, A. M.; Vieira, B. S.Alternaria cichorii was recorded for the first time in Brazil causing leaf spots on endive (Cichorium endivia) in 2003 based on material collected at Catalão, state of Goiás, in 2001. In 2005, A. cichorii was found causing severe leaf‐spotting in an escarole (C. endivia) plantation in Viçosa, state of Minas Gerais and shortly afterwards also in Viçosa, but at a different location, in the weed hosts common sowthistle (Sonchus oleraceus) and spiny sowthistle (Sonchus asper). A description of A. cichorii based on specimens collected in Viçosa is provided herein. The natural occurrence of A. cichorii on weed hosts in Viçosa indicates that it has already become naturalized in Brazil surviving on non‐cultivated composites, complicating disease management. Pathogenicity tests, complementary to those already published, were performed to better elucidate the range of potential alternative hosts in the Asteraceae of this fungus. This involved inoculation of one isolate of A. cichorii obtained from cichory and one obtained from common sowthistle on selected species and cultivars of 10 tribes in the Asteraceae, but concentrated in the Lactuceae. All species included in the test were shown to be susceptible to at least one of the isolates. A high incidence of leaf spot or blight resulted from inoculation of most individuals. All plants of six test species were killed after inoculation with one of the isolates of A. cichorii. Several of the test species have not been previously recorded as hosts for A. cichorii. Surprisingly, the known host‐range for this fungus is restricted to only few members of the Asteraceae (Acroptilon repens, C. endivia, C. intybus, Carthamus tinctorius and Lactuca sativa). Our results indicate that A. cichorii has a wide host range within the Asteraceae and that other cultivated or non‐cultivated members of this family may serve as inoculum reservoirs for this fungus in the absence of cichory, endive or escarole. An attempt to verify if contaminated seeds might be the original source for such geographically distant occurrences of A. cichorii in Brazil was made. Analysis of 24 samples of cichory and endive seeds obtained from dealers in five different Brazilian states showed that 25% of these samples carried A. cichorii with an incidence varying from 0.6% to 13.75%. Such a result highlights the vulnerable situation in Brazil for avoiding introduction of exotic seed‐carried vegetable pathogens. It is known that a very significant proportion of vegetable seeds marketed in Brazil are imported and seed inspection for pathogens is not performed regularly for such material imported for commerce. It is probable that contaminated cichory, endive and escarole seeds served as a vehicle for introduction of this fungus in Brazil and that the fungus has then become naturalized in many vegetable growing areas and is now surviving on other Asteraceae in the absence of cultivated hosts.Item First record of Cercospora pistiae causing leaf spot of water lettuce ( Pistia stratioites ) in Brazil, with particular reference to weed biocontrol(Mycopathologia, 1998-11) Barreto, R. W.; Evans, H. C.; Hanada, R. E.Pistia stratioites , the water lettuce, is an important pantropical aquatic weed. It has been the target of successful classical biocontrol programmes utilizing an insect natural enemy collected in Brazil and introduced into Australia, Papua New Guinea and South Africa. Little attention was given to the fungal pathogens associated with this weed as potential biocontrol agents. An 11-month field survey in the state of Rio de Janeiro involving repeated visits to 12 sites, and a 2-month survey in the Amazonas Basin (Amazonas state) in Brazil, yielded only one pathogenic fungus on P. stratioites. This was identified as Cercospora pistiae. No previous record of this species has been made in Brazil nor in the New World. The fungus is described and its taxonomy and biocontrol potential discussed herein. C. pistiae is a damaging pathogen of water lettuce. Its distribution was restricted to two interconnected sites in Rio de Janeiro. A literature and herbaria survey yielded few fungi associated to water lettuce (8 species), probably reflecting a lack of adequate collection in the centre of origin of the plant.Item First record of Bremia lactucae infecting Sonchus oleraceus and Sonchus asper in Brazil and its infectivity to lettuce(Journal of Phytopathology, 2006-02) Vieira, B. S.; Barreto, R. W.Bremia lactucae is recorded for the first time causing downy mildew on common sowthistle (Sonchus oleraceus) and spiny sowthistle (Sonchus asper) in Brazil. The disease and etiological agent are described. Pathogencity of sporangia obtained from S. oleraceus was tested on 12 species belonging to the Asteraceae, already recorded in the literature as hosts of B. lactucae, and four commonly cultivated varieties of lettuce. All four cultivars of lettuce, S. oleraceus and S. asper showed symptoms of the disease and sporulation of the pathogen 5 days after inoculation. It has been observed that the disease occurs on Sonchus spp. throughout the year in Vic ̧osa (state of Minas Gerais), being more common on these two hosts than on lettuce. Both weeds are very common invaders of vegetable growing areas in Brazil. This indicates that those two hosts for the fungus may be important inoculum reservoirs for disease occurring in lettuce, highlighting the need for control of these weeds as part of the pro- cedures aimed at controlling this disease. These results are also in agreement with the views that B. lactucae is split into host-specific infraspecific taxa. Lettuce and sowthistles are regarded as closely related, belonging to the same subfamily and tribe in the Asteraceae (Subfamily Cichorioideae: Tribe Lactuceae).Item Mycobiota of the weed Cyperus rotundus in the state of Rio de Janeiro, with an elucidation of its associated Puccinia complex(Mycological Research, 1995-04) Barreto, R. W.; Evans, H. C.A survey of the fungi associated with the pantropical weed Cyperus rotundus was conducted during 1988 and 1989 in part of its exotic range in southern Brazil. The sampling activity was concentrated in the state of Rio de Janeiro, covering 70 sites located in different climatic or ecological zones. Five species were identified as members of the pathogenic mycobiota: Cercospora caricis, Cintractia limitata, Dactylaria higginsii, Duosporium cyperi and Puccinia canaliculata. All are reported here for the first time in Brazil and Duosporium cyperi is a new record from Cyperus rotundus. The complex of six rust species belonging to Puccinia which have been described from C. rotundus was critically re-examined and three of these, Puccinia conclusa, P. cypericola and P. philippinensis are considered to be synonyms of P. canaliculata. The implications for biological control of C. rotundus are discussed.Item Novel fungi from an ancient niche: lachnoid and chalara-like fungi on ferns(Mycological Progress, 2016-10-08) Guatimosim, E.; Schwartsburd, P. B.; Crous, P. W.; Barreto, R. W.A survey was conducted in Brazil to collect fungi on ferns. Based on morphology and inferred phylogeny from DNA sequences of two loci, namely the internal transcribed spacer (ITS) regions and the large subunit nuclear ribosomal RNA gene (LSU), several species belonging to chalara-like genera and lachnoid fungi were recognized. Eighteen fungal isolates, collected from five host species, representing 10 different localities were studied. Three novel genera (Lachnopsis, Scolecolachnum and Zymochalara), and six novel species (Bloxamia cyatheicola, Lachnopsis catarinensis, Lachnopsis dicksoniae, Scolecolachnum pteridii, Zymochalara lygodii and Zymochalara cyatheae) are introduced. Furthermore, two new combinations (Erioscyphella euterpes and Erioscyphella lushanensis) are proposed. Two novel taxa (Lachnopsis catarinensis and Lachnopsis dicksoniae) may be included in the list of potentially endangered fungal species in Brazil, if proven to be restricted to their tree-fern host, Dicksonia sellowiana, which is included in the official list of endangered plant species in Brazil.