2.1.3. Experiment III: Interaction between Olive Cultivar and Treatments

OSE from plants of cv. Frantoio did not show marked differences in RGI between treatments. A moderate effect on RGI was observed for OSE from treated plants of cv. Arbequina, with RGI slightly increasing for OSE from plants treated with *A. pullulans* and copper phosphite. On the other hand, significant differences in RGI were observed in 'Picual' between the OSE from treated and control plants, as well as between the OSE from plants treated with the different BCAs and chemical products (Figure 3).

ANOVA confirmed that there were no significant differences for EC50 between treated and non-treated plants of cv. Frantoio (*P* = 0.9510). In 'Arbequina', significant differences for EC50 were only observed between the OSE from plants treated with *B. amyloliquefaciens* (EC50 = 13.0 ± 1.57) and copper phosphite (EC50 = 14.2 ± 1.19) compared to that obtained for OSE of the controls. Finally, in 'Picual', the OSE from treated plants showed significantly lower EC50 values than those of the OSE from both negative and positive controls; however, EC50 did not differ significantly between the different products evaluated (Table 3).

**Figure 3.** Effect of olive stem extract (OSE) from healthy olive plants of cvs. Frantoio, Arbequina, and Picual treated by root applications with the most effective compounds from *Experiment II* (*Aureobasidium pullulans*, *Bacillus amyloliquefaciens*, copper phosphite, or potassium phosphite) and from non-treated control plants, both non-inoculated and inoculated with *Verticillium dahliae* isolate V-180 on the relative conidial germination inhibition (RGI) of *V. dahliae* isolate V180. In each graph, data are the means of 240 conidia (six replicates) per combination of olive cultivar and OSE concentration. Vertical bars represent the standard error of the means. \*LSD bars represent the critical values for comparison at *P* = 0.05.


**Table 3.** Effective concentrations of olive stem extract (OSE) from cvs. Frantoio, Arbequina, and Picual and treated with the most effective compounds to inhibit 50% of conidial germination (EC50; μL mL<sup>−</sup>1) of *Verticillium dahliae* isolate V180.

<sup>a</sup> All evaluated treatments were applied by root applications in non-inoculated plants. Control (−): non-treated and non-inoculated plants; Control (+): non-treated and inoculated plants with *V. dahliae* isolate V-180. <sup>b</sup> EC50 of conidial germination was calculated as predicted value of the regression: relative germination inhibition (%) over OSE concentration. Values represent the average of 240 conidia (six replicates) per extract (cultivar) and OSE concentration. Means followed by a common letter do not differ significantly according to Fisher's protected LSD test at *P* = 0.05.
