PT - JOURNAL ARTICLE AU - McDaniel, Alexa L. AU - Schrader, M. Jacob AU - Amogi, Basavaraj R. AU - Khot, Lav R. AU - Moyer, Michelle M. TI - Ozonated Water Spray Does Not Suppress Grapevine Powdery Mildew or Grape Mealybug AID - 10.5344/ajev.2023.23062 DP - 2024 Jan 01 TA - American Journal of Enology and Viticulture PG - 0750002 VI - 75 IP - 1 4099 - http://www.ajevonline.org/content/75/1/0750002.short 4100 - http://www.ajevonline.org/content/75/1/0750002.full SO - Am J Enol Vitic.2024 Jan 01; 75 AB - Background and goals Ozone (O3) is a powerful oxidizer. When dissolved in water, O3 offers a direct, residue-free application to potentially control unwanted pests. Ozonated water spray (OWS) has been shown to suppress powdery mildew growth in greenhouse settings and cause insect mortality under in vitro conditions. Our goal was to evaluate the ability of OWS in lab and field settings to manage two main pests in eastern Washington vineyards: grapevine powdery mildew (Erysiphe necator) and grape mealybug (Pseudococcus maritimus).Methods and key findings The potential curative effects of ozonated water on nascent E. necator colonies and its lethal effects on P. maritimus nymphs were evaluated using O3 concentrations of 1 or 7 mg/L, delivered through a laboratory OWS system. These studies were coupled with field evaluations using a commercial OWS retrofit system to manage E. necator prebloom and P. maritimus as a delayed-dormant treatment. Our lab studies against E. necator confirmed that OWS was not effective at reducing colony formation. Due to low disease pressure years during the study, we cannot confirm the field efficacy of OWS applied prebloom. Laboratory-scale OWS was inconsistent at increasing P. maritimus nymph mortality. OWS field evaluations for P. maritimus management did not reduce the nymph population.Conclusions and significance Current OWS systems are not an effective tool for E. necator and P. maritimus management when applied at the O3 concentrations that current commercial units can generate.