*2.3. Biocontrol Activity of KOF112 against Downy Mildew in Grapevine*

Because KOF112 inoculum contained 10% soybean casein digest (SCD) medium, 10% SCD medium was used as a control in the assay for biocontrol activity of KOF112. A large number of *P. viticola* white symptoms were observed on the untreated disks and the disks treated with SCD, whereas growth of symptoms on the disks treated with KOF112 was apparently inhibited (Figure 5A). In particular, 1 × <sup>10</sup><sup>8</sup> cfu/mL KOF112 completely controlled *P. viticola* symptoms. Disease severity was significantly reduced by KOF112 compared with control or SCD treatment (Figure 5B). The inhibitory effect of KOF112 on *P. viticola* infection was dose-dependent. No symptoms were observed on the disks treated with 1 × 108 cfu/mL KOF112, whereas a large number of white symptoms were visible on the disks treated with 1 × 105 cfu/mL KOF112. *Agrobacterium* sp. isolate CHB3 exhibited no inhibitory effect on downy mildew.

**Figure 5.** Suppression of grape downy mildew by KOF112. (**A**) Representative symptoms of grape downy mildew on leaf disks treated with KOF112 (1 <sup>×</sup> <sup>10</sup>8, 1 <sup>×</sup> 107, 1 <sup>×</sup> 106 or 1 <sup>×</sup> 105 cfu/mL) or *Agrobacterium* sp. isolate CHB3 (1 <sup>×</sup> <sup>10</sup><sup>8</sup> cfu/mL). Bar, 1 cm. (**B**) Disease severity was evaluated as described in Materials and Methods. Crosses (×) indicate means of two independent experiments with five leaf disks. \* *p* < 0.05 compared with control and SCD. Control, untreated. SCD, treated with 10% SCD. *Agro*, treated with *Agrobacterium* sp. isolate CHB3 used as control isolate with no antifungal activity.
