Linear relationship between incidence and severity of Carrot leaf spot in different carrot genotypes

ABSTRACTUMO

Occurrence of Carrot leaf spot can reduce the yield and compromise the root quality. The objective of this study was to establish the relationship between incidence and severity on the intensity of Carrot leaf spot in different carrot genotypes. The design was in randomized blocks with four replicates and eight treatments, constituted of the genotypes ‘Alvorada calibrada média’; ‘Brasília’, ‘Brazlândia’, ‘Ferracini’, ‘Flakee’, ‘Nantes’, ‘Nantes Express’ and ‘Suprema calibrada média’, in order to promote a disease intensity gradient. The disease intensity was weekly evaluated based on the severity and the incidence. The obtained data were subjected to linear regression analysis. Using the equation of best fit for two seasons and replacing the severity value of 1%, the obtained incidence was 1.09; 1.63; 1.99; 2.16; 1.78; 1.97; 1.92; 1.55% for the genotypes ‘Alvorada calibrada média’, ‘Brasília’, ‘Brazlândia’, ‘Ferracini’, ‘Flakee’, ‘Nantes’, ‘Nantes Express’ and ‘Suprema calibrada média’, respectively. The estimated severity based on the incidence and vice versa allows it to be used for technical assistance in the monitoring of Carrot leaf spot in different carrot genotypes.

Keywords
Daucus carota; Alternaria dauci; disease intensity