Modeling Sclerotinia sclerotiorum disease development in lettuce cultivars: uncovering cultivar-specific disease dynamics through nonlinear growth models

Abstract Temporal disease severity reflects complex biological processes influenced by host–pathogen interactions. This study aimed to model white mold progress in lettuce genotypes inoculated with Sclerotinia sclerotiorum strains. Detached leaves of Crespa, Lisa, and Mimosa genotypes were inoculated with strains collected in Bagé and Cristal, Rio Grande do Sul, Brazil. The experiment followed a completely randomized 3 × 2 factorial design with five replications. Disease severity was assessed from 24 to 168 hours after inoculation. Repeated-measures analysis of variance was performed, and Gompertz, Logistic, and Von Bertalanffy models were fitted using nonlinear least squares, with generalized least squares applied when necessary to address heteroscedasticity and residual autocorrelation. Genotype, strain, and time interactions significantly affected disease progress. Crespa showed lower susceptibility, whereas Lisa and Mimosa inoculated with the Bagé strain exhibited greater severity. Logistic and Gompertz models performed best, effectively characterizing disease dynamics and supporting epidemiological research and disease management strategies.