Figure 2.
Effect of leaf treatments on grapevine downy mildew severity under greenhouse conditions. Plants were left untreated (UNT), or treated daily with water (H2O), nutrient broth (NB) or laminarin (LAM) three times before Plasmopara viticola inoculation. Disease severity was assessed as percentage of abaxial leaf area covered by P. viticola sporulation 7 days after inoculation. The F-test revealed differences between the experiments (P = 0.046) and each experiment was analyzed separately. Mean severity and standard error values of 12 replicates (plants) are presented for each treatment and experiment. Different uppercase and lowercase letters indicate significant differences among treatments according to Fisher's test (α = 0.05) in experiment 1 (solid bars) and experiment 2 (striped bars), respectively.