Fig. 3

Effect of volatile organic compounds (VOCs) from the aerial part of hoary stock collected at pre- or post-blooming on the development of grape downy mildew on leaf discs in the first (2020) and second (2021) years. a, b Disease index. c, d Inhibition rate. Means are separated or compared in three ways: (1) Effects of VOCs from post-blooming flowers, which are marked by lower-case letters a–e; (2) Effects of VOCs from pre-blooming flowers, which are marked by lower-case letters a’–f’; and (3) Comparisons between pre- and post-blooming flowers, which are indicated by an asterisk. Within each group, different letters indicate significant differences of the measurements (Tukey’s post hoc ANOVA; P < 0.05). Asterisks indicate statistically a significant difference between two data points (independent-samples t test; P < 0.05). Bars represent standard errors (SEs)