Biological Control of Grapevine Powdery Mildew Disease by Using Brevibacillus brevis Strain CP-1

Erysiphe necator Schw., which causes powdery mildew on grapevines (Vitis vinifera L.) in various growing regions around the world, stands out as one of the most common and destructive obligate fungal pathogens affecting grapevines. Chemical fungicides have typically provided adequate control of most foliar fungal pathogens. However, fungicide resistance problems, concerns regarding pesticide residues, and the revocation of registration of certain widely used fungicides have led to increased activity in the development of biocontrol agents against foliar fungal pathogens. In this study, three different concentrations (500, 750, and 1000 ml/100 L water) of the bioagent Brevibacillus brevis CP‑1 bacterial formulation (107 CFU/mL) were used, in addition to a single concentration (100 ml/100 L water) of Regalia (Reynoutria spp. extract 224.6 g/L) as a comparative control application under field conditions. As a result of this study, it was observed that the 1000 ml/L dose of the tested CP‑1 bioagent bacterial strain was 91.68% effective in the control of vineyard powdery mildew, while this rate was 92.29% in the comparative control application. Furthermore, CP‑1 bacteria demonstrated positive activity in terms of cellulase and amylase. The activity of these enzymes suggests that they may help degrade the plant cell walls, thereby facilitating the penetration of the bacteria into the plant tissue and enhancing their efficacy in controlling powdery mildew.