SFN reduces downy mildew disease. A, Plants were treated with water (control), WP, or a WP formulation of SFN (450 µm). Twenty-four hours later, we spray-inoculated plants with a suspension of Hpa conidiospores (5 × 10⁴ spores per mL of water). B, Conidiospores (5 × 10⁴ spores per mL) were suspended in water (control), WP, or a WP formulation of SFN (450 µm). Spore suspensions were mixed and used for spray inoculation of plants. In A and B, inoculated plants were kept at high humidity in short day. After 7 d, we determined the number of spores released by Hpa. Data were analyzed by one-way ANOVA followed by posthoc Student’s t test. Different letters denote statistically significant differences with 95% confidence. Data presented are means ± sd. A, n > 7; B, n > 14.