Spraying efficacy of distilled water (DW), acidic electrolyzed oxidizing water (AEOW), or alkalic electrolyzed reducing water (AERW) alone and successive spraying of AEOW followed by AERW or vice versa on controlling powdery mildew infection (PMI) with suppressing visible physiological disorder on cucumber (Cucumis sativus) leaves (Experiment I) and the seedlings leaves (Experiment II) were investigated. The severity of PMI and visible physiological disorder on the leaves sprayed with the AERW followed by AEOW were suppressed at the last observation day compared to the solitary spraying of AEOW. The visible physiological disorder on the seedlings leaves caused by the spraying of AEOW can be suppressed by the successive spraying of AEOW followed by AERW without suppression of leaf area and dry weight of aerial parts. At the seedling stage, successive spraying of AEOW followed by AERW is recommended for controlling PMI and avoiding physiological disorder without suppression of seedling growth.