This study aimed to evaluate the temporal dynamic of 'Gala' leaf spot under conventional and organic systems of production in edafoclimatic conditions of Santa Catarina plateau. The incidence and severity were quantified biweekly in 100 leaves distributed in four branches of the "Royal Gala" cultivar with 12 replications, generating 16 maps for each system of production. The disease severity was evaluated in accordance with the specific diagrammatic scale. Curves of disease progress were made and the epidemics compared according to: a) the beginning of symptoms appearance (BSA); b) the time to reach the maximum disease intensity and severity (TRMDI and TRMDS); c) the maximum value of disease intensity and severity (Imax and Smax); and d) area under the incidence and severity disease progress curve (AUIPCI and AUSDPC). The incidence and severity data were analyzed by linear regression, adjusted for three empirical models, Logistic, Monomolecular and Gompertz. The 'Royal Gala' cultivar was susceptible to Colletotrichum spp. and the highest disease intensity was observed in the organic than in conventional system of production. The Logistic epidemiological model was the most appropriate to describe the disease progress curve and, there is no significant difference between systems when used only incidence value. The severity progress rate (r) was significantly higher in the organic than in the conventional system of production.
Malus domestica; Colletotrichum; epidemiology
