Preliminary study on the efficacy of ozonated water in the control of grapevine diseases and its influence on the plant microbial diversity

Environmental contamination and biodiversity loss associated with the use of conventional phytosanitary products in crops has driven the search for sustainable alternatives. Ozone is a powerful disinfectant with proven applications in the agri-food chain. In recent years, water ozonation systems have been developed for agricultural sprayers, yet research on their effectiveness remains limited. This study evaluated the viability of ozonated water (OW) for grapevine disease control and its impact on plant microbiota. Six application strategies were tested in two vineyards of the ‘Albariño’ cultivar, assessing disease severity and microbial communities in leaf and berries. Disease incidence was generally low, except for downy mildew, which was prevalent. Consequently, the efficacy of OW was only assessed against this disease. While conventional treatments effectively controlled downy mildew, OW treatments failed, resulting in significant yield losses. Microbial analysis allowed to identify 400 fungal and 270 bacterial genera. Overall, plants treated with conventional products exhibited lower microbial abundance, highlighting the detrimental impact of chemical products on biodiversity. In conclusion, although OW is beneficial for the microbial communities compared to conventional products, it is not recommended for controlling downy mildew in regions with high disease pressure.