抄録
Effect was investigated of spraying electrolyzed strong acid water (ESAW) obtained by electrolysis of a NaCl dilute (ca. 50mg L-1) water solution on the incidence of downy mildew (Pseudoperonospora cubensis Rostowzew) in cucumber (Cucumis sativus L, cv. Naoyoshi) grown in a plastic house. pH, free effective chlorine concentration and oxidation-reduction potential of the ESAW were 2.8, 32 ppm and 1 120 mV, respectively. Different amounts of either the ESAW (0.25, 0.5 or 1 L plant-1) or well water (0.5 L plant-1) were sprayed onto the leaves once every third or, fourth day. The incidence of downy mildew was controlled almost perfectly for the experimental period of 17 d by spraying the ESAW, regardless of the amount sprayed, while the symptom of downy mildew was observed on day 10 with well water and on day 13 with non-treated control. On day 17, the incidence was significantly reduced by spraying the ESAW (0 or 2%) as compared to both well water (48%) and non-treated control (32%) . However, spraying the ESAW caused a leaf burn-like physiological disorder in some leaves after day 7, regardless of the amount sprayed. The results indicate that ESAW can be a viable alternative to some fungicides to control several crop diseases, or it can at least be effective in reducing fungicide use ; however, there remains the problem of eliminating the leaf burn-like physiological disorder.
