The effect of acibenzolar S-metil ester (ASM, Bion®), potassium phosfite (Hortifós PK®) and of a foliar fertilizer (Nutex Axcell®) was assessed on the spore germination and mycelial growth of Phoma costarricensis. The effect of these products on severity of Phoma leaf spot was also assessed on coffee seedlings. The percentage of conidial germination of P. costarricensis was not affected by doses of phosfite and ASM, but reductions on the mycelial growth of the fungus were detected. The area under the disease progress curve (AUDPC) and the disease severity were lower in all treatments compared to the inoculated control. There was a reduction of 50.9% on disease severity in plants treated with the standard fungicide tebuconazole. Low values for severity and AUDPC were observed when plants were treated with ASM 0.1 g/L; phosfite 2.5 mL/L; phosfite 5.0 mL/L and the fertilizer Nutex Axcell® at 4.0 mL/L, which differed from other treatments.O patógeno Phoma costarricensis Echandi infecta várias partes da planta de cafeeiro (5), causando a doença conhecida como mancha de Phoma, que pode ter um potencial de dano elevado sob condições ambientais propícias. Almeida & Matiello (2) quantificaram perdas de 15% a 43% da produção no Sul de Minas Gerais, em regiões favoráveis à doença com temperatura em torno de 20°C e umidade relativa superior a 80%.Alguns trabalhos já foram conduzidos visando verificar o efeito de fungicidas de diferentes princípios ativos e publicados em anais de congressos realizados no Brasil, contando com aproximadamente 17 produtos registrados para o controle da mancha de Phoma em cafeeiro, sendo 13 princípios ativos distribuídos em 11 grupos químicos (1). Entretanto, diante do novo paradigma ecológico da agricultura sustentável é necessário buscar alternativas para os fungicidas no controle de patógenos, com menor custo para o ambiente e segurança para o consumidor. Barguil et al. (3) verificaram redução de 35% na severidade da mancha de Phoma em mudas de cafeeiro pulverizadas com extratos de folha de cafeeiro ou produtos a base de biomassa cítrica (Ecolife® e Agromil®). Da mesma maneira, produtos disponíveis no mercado como indutores de resistência e fertilizantes podem propiciar a redução da severidade neste e em outros patossistemas (10).Portanto, objetivou-se estudar o efeito dos produtos acibenzolar S-metil ester (ASM, Bion®, Syngenta Proteção de Cultivos Ltda), fosfito de potássio (Hortifós PK®, Agrichem do Brasil Ltda) e de um fertilizante foliar a base de boro, cobre, enxofre, manganês e zinco (Growmaster Axcell®, Intercuf Ind. & Com. Ltda) na germinação dos conídios e no crescimento micelial de P. costarricensis e na severidade da mancha de Phoma em cafeeiro.Foi utilizado um isolado de P. costarricensis obtido de cafeeiros na região de Lavras -MG. Para obter o inóculo, as folhas infectadas foram lavadas em água corrente, desinfestadas com hipoclorito de sódio 2% e deixadas em câmara úmida por 24 horas para esporulação. Os conídios foram transferidos para placas de Petri contendo meio b...
Phoma leaf spot, caused by Phoma costarricensis poses a serious threat to coffee (Coffea arabica) production, especially in the highlands of the state of Minas Gerais, Brazil. Extracts of citric biomass, coffee berry husks and coffee leaves severely affected by rust caused by Hemileia vastatrix, were evaluated against P. costarricensis. In an in vitro assay, aqueous extracts of rusted leaves and berry husks plus the commercial extracts based on citric biomass named Ecolife® and Agromil® were tested at various dilutions on the mycelial growth inhibition of P. costarricensis. In vivo, coffee seedlings maintained in glasshouse, were sprayed with these extracts seven days before inoculation of P. costarricensis. Only extracts from citric biomass had inhibitory effects on the fungus. In vivo, Ecolife® (5 ml/l), Agromil® (5 g/l) and the aqueous extract of rusted coffee leaves (dilution 1:6) reduced Phoma leaf spot. Both, Ecolife® and the extract of rusted coffee leaves were significantly more effective in reducing the area under the lesion progress curve when applied at lower doses, indicating a possible effect on the induction of resistance.
Anthracnose is one of the most important diseases of lima bean in Brazil. Previously, the disease was attributed exclusively to Colletotrichum truncatum. Therefore, this work aimed to characterize the diversity, prevalence, and virulence of Colletotrichum spp. associated with anthracnose in lima bean in Brazil. Here, we report the species C. truncatum, C. brevisporum, C. lobatum, C. plurivorum, and C. musicola in association with anthracnose of lima bean. All species were pathogenic to lima bean. In addition, several strains were found that represent novel lineages, presented here as Colletotrichum lineages 1 to 5. C. truncatum is the prevailing species and more virulent than all other species studied.
Post-harvest basal rot of coconut fruits in the State of Ceará, BrazilA new post-harvest disease of coconut (Cocos nucifera) was recently detected in fruits exported to European countries. The main symptoms are the blacking and cracking of basal parts of the fruits. Water oozing may occurs as the infection progresses. The fungus
II Identificação e variabilidade genética de isolados de ABSTRACT Anthracnose affects inflorescences quality of ornamentals tropical plants and the fungi specie Colletotrichum gloeosporioides has been related with this disease based only on morphology. Therefore, the objectives of this research was to identify Colletotrichum isolates collected on anthurium (Anthurium andraeanum), torch ginger (Etlingera elatior) and heliconia (Heliconia spp.) plants by means of morphology and polymerase chain reaction (PCR) and also verify the genetic variability using arbitrary-primed PCR (AP-PCR). All isolates were identified as INTRODUÇÃOA floricultura tropical é uma atividade em ascensão no Brasil, uma vez que as flores tropicais apresentam características, tais como durabilidade, beleza e diversidade de cores e formatos, que propiciam grande aceitação pelo mercado consumidor e elevado potencial de crescimento no mercado nacional e internacional (LOGES et al., 2005).As condições predominantes de temperatura e umidade relativa são bastante favoráveis para o cultivo das diversas espécies de plantas tropicais durante o ano todo na região Nordeste do Brasil (WARUMBY et al., 2004). Essas condições também propiciam a ocorrência de doenças fúngicas, as quais I
Senna macranthera is a common tropical tree native to South-and Northeastern Brazil. In July 2006, symptoms of chlorotic spots in the young leaves and mild mosaic in the old leaves were observed in S. macranthera trees at Viçosa, State of Minas Gerais, Brazil. Electron microscopy examination of leaf dip preparations from the young leaves revealed the presence of flexuous rods. Viral RNA was extracted from purified virion preparations and used as a template for the RT-PCR-based cloning of viral genomic fragments. Two fragments (0.9 kb and 2.0 kb in length) were cloned. Sequence analysis of the 0.9 kb fragment indicated that it corresponded to the NIb coding region of a potyvirus, with nucleotide (nt) identity level of 72% for Pepper mottle virus (PepMoV) and Peru tomato mosaic virus (PTV), while analysis of the 2.0 kb fragment indicated that it corresponded to the putative replicase ORF, which displayed 74% nt identity with the ORF1 (replicase) of Garlic virus A (GarV-A). Based on molecular analysis and the isolates' host range, it is concluded that the viral fragments represent new viruses, for which we propose the names Senna virus Y (genus Potyvirus, family Potyviridae) and Senna virus X (unassigned genus, order Tymovirales). Key words: Senna virus X, Senna virus Y, molecular characterization. RESUMO Sequências genômicas parciais de um Potyvírus e um vírus da ordem Tymovirales encontrados em Senna macranthera no BrasilSenna macranthera é uma árvore tropical nativa do Sudeste e Nordeste brasileiro. Em julho de 2006, sintomas de manchas cloróticas nas folhas jovens e de mosaico leve nas folhas mais velhas foram observados em plantas de S. macranthera em Viçosa, Estado de Minas Gerais, Brasil. A observação de preparações "leaf-dip" em microscópio eletrônico de transmissão revelou a presença de partículas alongado-flexuosas. O RNA viral foi extraído de vírions purificados e utilizado como molde para RT-PCR e clonagem de fragmentos do genoma viral. Dois fragmentos (0,9 kb e 2,0 kb de tamanho) foram clonados. A análise da sequência do fragmento de 0,9 kb indicou que este corresponde à região codificadora da proteína NIb de um potyvírus, com 72% de identidade de nucleotídeos com o Pepper mottle virus (PepMoV) e Peru tomato mosaic virus (PTV), enquanto a análise do fragmento de 2,0 kb indicou que este corresponde à ORF que codifica a possível replicase de um vírus classificado na recém-estabelecida ordem Tymovirales, com 74% de identidade de nucleotídeos com o Garlic virus A (GarV-A). Com base na análise molecular e na gama de hospedeiros, conclui-se que os fragmentos virais clonados representam novas espécies, para as quais sugerem-se os nomes Senna virus Y (gênero Potyvirus, família Potyviridae) e Senna virus X (ordem Tymovirales, gênero não definido). Palavras-chave: Senna virus X, Senna virus Y, caracterização molecular.
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