Navegando por Autor "Saraiva, Rodrigo M."
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Item Biocontrol of gray mold in tomato plants by Clonostachys rosea(Tropical Plant Pathology, 2015-04) Borges, Álefe V.; Saraiva, Rodrigo M.; Maffia, Luiz A.Greenhouse conditions are favorable to the growth of Botrytis cinerea, and an increase in the occurrence of gray mold caused by this pathogen is therefore expected. Biocontrol using microbial antagonists is one of the approaches to control the pathogen. In previous experiments, Clonostachys rosea isolates suppressed B. cinerea in tomato leaves, but it was not evaluated in wounds caused during pruning, where the pathogen predominantly infects. Here, the efficacy of four C. rosea isolates to control B. cinerea in wounded tomato stems was evaluated. Influence of the following factors on the antagonist’s efficiency were evaluated: i) application time of C. rosea respectively to time for B. cinerea inoculum deposition, ii) conidial concentration of C. rosea, and iii) application of individual isolates versus isolate mixture. Results indicated that the four C. rosea isolates are effective in controlling gray mold, and that they may be applied either individually or as a mixture. The biocontrol efficiency of C. rosea was higher when it was applied 1 day before or simultaneously with the pathogen inoculation at a concentration of 106 conidia/mL- 1, reaching 100 % in stem segments and more than 90 % in whole plants. The antagonist has potential to be used in greenhouse tomato, especially in an integrated management context.Item Isolation and selection of Hemileia vastatrix antagonists(European Journal of Plant Pathology, 2014-04-21) Haddad, Fernando; Saraiva, Rodrigo M.; Mizubuti, Eduardo S. G.; Romeiro, Reginaldo S.; Maffia, Luiz A.Organic coffee growing is rapidly increasing in Brazil, and many diseases, especially coffee leaf rust (Hemileia vastatrix), are threatening its production. This study is a first step towards a biocontrol program for coffee rust on organically grown plants. In three organic coffee farms in the state of Minas Gerais, 393 microbial strains including 154 bacterial and 239 fungal strains were isolated from leaves, leaf debris, and soil samples, and in 6 month-old coffee plants, 17 of these isolates reduced both the infection frequency (IF) and the number of H. vastatrix urediniospores produced per leaf (UPL) by more than 70 %. The isolates were identified as eight bacteria isolates, seven Bacillus spp. and one Pseudomonas sp., and nine fungal isolates, four Fusarium spp., two Penicillium spp., one Aspergillus sp., one Acremonium sp. and one Cladosporium sp. Each fungal and bacterial isolate was applied 0, 4, 8, 12 or 16 days before and 0, 4, 8, 12 or 16 days after H. vastatrix inoculation, and the efficiency in reducing both IF and UPL was evaluated. The efficiency was higher and lasted longer when the bacterial isolates were applied before H. vastatrix inoculation. Six Bacillus (B10, B25, B143, B157, B171, B175), two Fusarium (F205, F281), and one Pseudomonas (B286) isolates are potentially efficient as biocontrol agents of H. vastatrix and will be tested using field experiments.