Fig. 2

Quantification of Plasmopara viticola in soil, leaf residues, and asymptomatic leaves collected from commercial vineyards in 2 consecutive years using multiplex real-time PCR assay. a, b Box plots showing the number of P. viticola oospores in soil and leaf residues and the area under the disease progress curve of P. viticola DNA in asymptomatic leaves from nine vineyards in 2018 (a) and ten vineyards in 2019 (b) prior to the appearance of visible symptoms of downy mildew. The boxplot corresponds to the numerical changes at five sampling points in each vineyard in 2018 (a) and 2019 (b). The thick line in the boxes is the median. The lowest value in each box represents the minimum detected value, and the top part of each box represents the maximum detected value. ANOVA with the Kruskal‒Wallis nonparametric test was applied to determine the difference in the number of P. viticola oospores and AUDPC-P. viticola DNA among vineyards. The same letter on the graph indicates no significant difference for each vineyard group at P < 0.05