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Macrophomina is a genus belonging to Botryosphaeriaceae that comprises well-known necrotrophic pathogens related to hundreds of plant hosts around the world. Historically, M. phaseolina is the causal agent of charcoal rot in several crops, mainly in tropical and subtropical areas around the world. However, after a recent genetic diversity study using morphological and molecular approaches, which resulted in the epitypification of M. phaseolina, and the description of a new Macrophomina species associated with charcoal rot disease, the hypothesis that other cryptic species could be present under the name M. phaseolina was raised. Previous studies in Brazil revealed a high genetic diversity and different levels of aggressiveness of M. phaseolina isolates associated with charcoal rot in oilseed crops. Thus, the aim of the present study was, through phylogenetic and morphological studies, to determine if isolates of Macrophomina obtained from different oilseed crops represent a single species or distinct taxa. Based on the results obtained, it was possible to identify three different Macrophomina species: M. phaseolina, M. pseudophaseolina and a new phylogenetic species, M. euphorbiicola. This is first report of M. pseudophaseolina in Brazil causing charcoal rot on Arachis hypogaea, Gossypium hirsutum and Ricinus communis and associated with seed decay of Jatropha curcas. In addition, a novel species described in the present study, M. euphorbiicola, is reported as the etiological agent of the charcoal rot on R. communis and Jatropha gossypifolia. Made available in DSpace on 2020-01-14T00:42:45Z (GMT). No. of bitstreams: 1 Bayesiananalysesoffivegeneregions.pdf: 1730069 bytes, checksum: f5baea4698af5fb640afa9eea7f15fb9 (MD5) Previous issue date: 2019

This study aimed to determine the sensitivity of 61 Botryotinia ricini isolates to the fungicides fluazinam and thiophanate-methyl. The isolates were originated from Goiás (n = 3), Maranhão (n = 3), Mato Grosso (n = 12), Minas Gerais (n = 1), Paraíba (n = 8), Rio Grande do Sul (n = 19) and São Paulo (n = 15) states. Mycelial discs (6 mm) removed from 5-day-old colonies were transferred to Petri dishes containing potato dextrose agar (PDA) amended with different concentrations of the fungicides. Two perpendicular measurements of the radial growth were taken and used to calculate the percentage of mycelial growth inhibition (PMGI) for each treatment (isolate × fungicide × concentration) in relation to the control. PMGI were used to obtain the effective concentration that inhibits 50 and 95% of the mycelial growth (EC50 and EC95) by means of linear regression. For fluazinam, the EC50 and EC95 (mean ± SD) were 0.1738 ± 0.0802 μg/mL and 0.7938 ± 0.1254 μg/mL, while for thiophanatemethyl, the EC50 and EC95 were 0.3487 ± 0.0963 μg/mL and 1.1325 ± 0.2063 μg/mL, respectively. Both fungicides have high intrinsic toxicity to B. ricini but fluazinam was a more potent growth inhibitor compared to thiophanate-methyl. Made available in DSpace on 2020-01-15T00:37:08Z (GMT). No. of bitstreams: 1 SensitivityoffieldisolatesofBotryotinia.pdf: 466894 bytes, checksum: 4463d38f33c92b1098c874884a526ce0 (MD5) Previous issue date: 2019