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Primavera do Leste, Brazil

Pezenti L.F.,Instituto Agronomico do Parana IAPAR | Barbosa J.,Instituto Agronomico do Parana IAPAR | Vieira M.A.,Instituto Agronomico do Parana IAPAR | Marangoni M.S.,Instituto Agronomico do Parana IAPAR | And 4 more authors.
Tropical Plant Pathology | Year: 2013

There is a lack of information about the level of resistance of cotton genotypes to a wider range of Ramularia areola isolates occurring across the cotton growing areas of Brazil. For this purpose, firstly it is necessary to know the existence or not of genotypic and phenotypic variability among the R. areola isolates from different geographical origins. The objective of the present investigation was to verify the existence of phenotypic variability among 23 R. areola isolates collected from six cotton growing states of Brazil. Two resistant genotypes, FMT 02102996 and CNPA BA 2003-2059, and the susceptible genotype FMT 701 were individually inoculated with 23 R. areola isolates under glasshouse conditions and the severity of infection was evaluated 30 days after inoculation. Genotypes CNPA BA 2003-2059 and FMT 02102996 were susceptible to three isolates and resistant to the rest of the isolates. Genotype FMT 701 was susceptible to all the isolates except the isolates 22.3 and 42.7. Results indicate the existence of variability among R. areola isolates and that the three genotypes are useful in distinguishing phenotypic variability within isolates of this pathogen. © by the Brazilian Phytopathological Society.

Galbieri R.,Instituto Mato Grossense do Algodao IMA | Cia E.,Brazilian National Council for Scientific and Technological Development | De Morello C.L.,Embrapa Algodao Nucleo do Cerrado | Fanan S.,Instituto Mato Grossense do Algodao IMA | And 2 more authors.
Summa Phytopathologica | Year: 2015

Ramularia blight, caused by Ramularia areola, is one of the most important diseases affecting cotton crop in Brazil. For its effective control, 5-9 fungicide applications on susceptible cultivars are necessary. The aim of the present study was to evaluate, in vitro and in vivo, the sporulation potential of R. areola isolates from different Brazilian regions at distinct temperatures. Spore production was assessed in the laboratory and under green house conditions by using leaves from plants of eight cotton cultivars. The in vitro results indicated that the potential of spore production was dependent on temperature. Maximum sporulation of the fungus occurred at 17°C for isolates from São Paulo State and 23°C for isolates from Goiás and Mato Grosso States. In the in vivo study, there was a variation in spore production according to the cultivar and the isolate. Most isolates showed to be highly aggressive on cultivars FM966 LL and DELTAOPAL. The obtained results suggest a more rational use of fungicides and cultivars with decreased fungal sporulation and can form the basis for further studies of the pathogenic variability of this fungus in cotton crops in Brazil. This is the first report on the sporulation potential of Brazilian R. areola isolates. © 2015, Universidade Estadual Paulista (UNESP). All rights reserved.

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