Fig. 3

Assessment of latent infection of Plasmopara viticola in leaf residues and asymptomatic leaves based on real-time PCR detection. The molecular disease index (MDI), calculated as the ratio of the amount of P. viticola DNA (ng) to the amount of Vitis vinifera DNA (ng), was used to quantify the levels of latent infection. a, b Different bars and vertical lines show the mean and standard deviation for each MDI of leaf residues, area under the disease progress curve of MDI (AUDPC-MDI) of asymptomatic leaves, and AUDPC of disease index (AUDPC-DI) from nine vineyards in 2018 (a) and ten vineyards in 2019 (b). Each numerical point represents an assessment point for each vineyard. ANOVA with the Kruskal‒Wallis nonparametric test was applied to determine the difference in MDI of leaf residues, AUDPC-MDI of asymptomatic and AUDPC-DI among vineyards. Vertical bars represent the standard errors for the means. The same letter on the graph indicates no significant difference for each vineyard group at P < 0.05