2.6.1. Effect of Treatments against *Macrophomina phaseolina in Planta*

For the treatments conducted with seedlings grown in non-sterilized soil, significant differences between treatments were observed for their effect on DS (*p* ≤ 0.0001). DS ranged from 21.7 ± 2.1 to 6.4 ± 2.8% for seedlings treated with *Streptomyces* sp. CBQ-EA-2 and Celest® Top 312 FS, respectively, with all treatments showing a significant effect on the disease progress in comparison with the non-treated and inoculated seedlings (positive control; DS = 70.3 ± 3.1%) (Figure 3).

**Figure 3.** Disease severity (%) in *Phaseolus vulgaris* cv. Quivicán seedlings treated with biological or chemical compounds and inoculated with *Macrophomina phaseolina* isolate CCIBP-Mp1 at 35 days growing on non-sterilized or sterilized soil. Each column represents the mean of 40 seedlings per soil and treatment combination. Columns with a common uppercase or lowercase letter do not differ significantly according to Fisher's protected LSD test (*p* = 0.05) for treatments on non-sterilized or sterilized soil, respectively. Vertical bars are the standard errors of the means.

Concerning the treatments conducted with seedlings grown in sterilized soil, significant differences between treatments were also observed for their effect on DS (*p* ≤ 0.0001). In this case, all treatments also resulted in significant effectiveness compared to the positive control (DS = 98.3 ± 0.7%). DS among treated seedlings ranged from 63.6 ± 4.9 to 25.8 ± 2.5 for treatments with *Streptomyces* sp. CBQ-B-8 and *Streptomyces* sp. CBQ-EA-2+ CBQ-B-8, respectively (Figure 3).

The Disease Incidence (DI) was markedly lower in treated seedlings grown in nonsterile soil than those grown in sterile soil. In both cases, not only there were significant differences in DI between treatments, but also significant differences were observed between all the treatments and the positive control (*p* ≤ 0.0001 in all cases), the latter always showing the highest DI values. In all cases, the treatments with *Streptomyces* sp. CBQ-EA-2 + CBQ-B-8, *T. harzianum* A-34, or Celest® Top 312 FS showed the lowest DI values (Figure 4). No

seedling mortality was not observed in any case, except for the positive control grown in sterile soil which presented 100% mortality.

**Figure 4.** Disease incidence (DI, %) in *Phaseolus vulgaris* cv. Quivicán seedlings treated with biological or chemical compounds and inoculated with *Macrophomina phaseolina* isolate CCIBP-Mp1 at 35 days growing on non-sterilized or sterilized soil. Each column represents the mean of 40 seedlings per soil and treatment combination. Columns with a common uppercase or lowercase letter do not differ significantly according to Dunn's multiple comparisons for proportions test (*p* = 0.05) for treatments on non-sterilized or sterilized soil, respectively.
