Evaluation of linear relationships between incidence and severity of Cercospora leaf spot in different beet genotypes

Leandro Luiz Marcuzzo Bruno Tabarelli Scheidt Tatiana da Silva Duarte About the authors

ABSTRACT

Occurrence of Cercospora leaf spot can reduce the yield and compromise the root quality in beets. The aim of this study was to evaluate the relationship between incidence and severity on the intensity of Cercospora leaf spot in different beet genotypes. Two experiments were conducted in Epagri, an experimental station located in Ituporanga, Santa Catarina State, Brazil. Experimental design was in randomized blocks with four replicates and seven treatments constituted of the genotypes All Green, Boro, Cabernet, Early Wonder, Modana, Itapuã and Stays Gree in order to generate a disease intensity gradient. Disease severity and incidence were weekly evaluated. The obtained data underwent linear regression analysis. Using the equation of best fit for two crop seasons and replacing the severity value of 1%, the obtained incidence was 5.8, 5.6, 5.3, 6.0, 6.0, 6.3 and 5.9% for the genotypes All Green, Boro, Cabernet, Early Wonder, Modana, Itapuã and Stays Green, respectively. Severity estimated based on incidence or vice versa can be used in breeding programs and technical assistance to quantify the reaction of different beet genotypes to Cercospora leaf spot.

Keywords
Beta vulgaris ssp. vulgaris; Cercospora beticola; disease intensity

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