FIGURE 4.

Effects of the less efficient pure volatile organic compounds (VOCs) against downy mildew. Grapevine leaf disks were treated with water (control), 1,3‐octadiene (A), α‐farnesene (B) or cadinene (C) at 5, 20 and 50 mg L⁻¹ in air volume and downy mildew severity was assessed at 6 days post‐inoculation. Five replicates (dishes with five disks each) were assessed for each treatment and the experiment was carried out twice. For each assay, the Kruskal‐Wallis test indicated no significant differences between the two experimental repetitions (P > 0.05) and data from the two experiments were pooled. The pooled mean and standard error values of 10 replicates from the two experiments are presented for each treatment. Different letters indicate significant differences among treatments according to the Kruskal‐Wallis test (P ≤ 0.05)