Application of an eco-friendly hydrogen peroxide-based compound peroxyacetic acid (PAA), to leaves of okra and sunflower plants significantly reduced infection with powdery mildew. The maximum percent disease control was recorded with acetic acid (AA) + hydrogen peroxide (H2O2) mixture at 0.2g/l AA + 2.0g/l H2O2 concentration, being 69.28 and 70.07 %, when okra and sunflower plants were sprayed three times, respectively along 2 growing seasons. Decreasing sprayings and mixture concentration reduced percent of powdery mildew control. Accordingly, PAA showed a beneficial role to control powdery mildew of either okra or sunflower plants. Thus, PAA could be recommended for integrated disease management program (IDM) against powdery mildew of okra and sunflower