*2.1. Morphological and Molecular Identification*

The amplicon of the CARA17 strain obtained during PCR analysis produced a fragment of 669 bp. The sequence of this amplicon analyzed in GenBank (Acc. n. ON548415) resulted in having a similarity of 100% with *Streptomyces albidoflavus* group.

The ITS sequence of the *Plectosphaerella* strain analyzed in GenBank by the BLAST tool resulted in having a similarity of 100% with the reference strain of *Plectosphaerella ramiseptata* (CBS 131861; Acc. n. JQ246953).

#### *2.2. Inhibitory Activity against Fungal Pathogens in Dual Cultures*

According to Shapiro–Wilk tests, the data followed normal distributions for all CARA17 exposition times (14, 21 and 28 days), with W values of 0.77, 0.79 and 0.78 (*p* < 0.05), respectively. The Levene tests showed that the homogeneity of variance was also significant for all three CARA17 exposition times (F = 3.65/3.64/4.19; *p* < 0.05).

One-way ANOVA demonstrated that significant differences in inhibitory activity (IA) by the CARA17 strain against fungal pathogens were observed. The IAs played by the CARA17 strain in dual cultures with fungal pathogens is reported in Table 1. It is possible to observe that the percentage values of IA decreased from 14 at 28 days after inoculation with CARA17 on a medium. In general, the *Streptomyces* strain was able to inhibit the mycelial growth of all fungal pathogens tested with variable percentage values of IA. *Sclerotina sclerotiorum* was the most sensible to antagonistic activity played by the CARA17 strain, as the IAs recorded were 100% at 14, 21 and 28 days after its inoculation. *Athelia rolfsii* resulted in being the least inhibited by the CARA17 strain at all inoculation times. The remaining fungal soil-borne pathogens, *V. dahliae*, *F. oxysporum* and *P. ramiseptata*, resulted in being well controlled with percentage values of IA, such as 71.30% (*V. dahliae*), 82.73% (*P. ramiseptata*) and 84.71% (*F. oxysporum*) after 28 days of inoculation (Table 1; Figure 1).


**Table 1.** Inhibition activity percentage (IA) by CARA17 strain against mycelial growth of soil-borne pathogens in vitro (dual cultures).

<sup>a</sup> Exposition of fungal strains vs. CARA17 grown on medium at different colony ages; <sup>b</sup> Data followed by different capital letters within the column are significantly different (Fisher's tests; *p* < 0.01); <sup>c</sup> Minimum and maximum values detected (five observations).

**Figure 1.** Phytotoxicity/pathogenicity assays carried out on young leaf cotyledones of cucumber (**a**), and inhibition activity played by CARA17 strain against *Athelia rolfsii* (**b**), *Fusarium oxysporum* (**c**), *Plectosphaerella ramiseptata* (**d**), *Sclerotinia sclerotiorum* (**e**), and *Verticillium dahliae* (**f**) after 28 days of exposition of fungal pathogens vs. CARA17 strain grown on medium.
