Assessment of Silicon, Sulfur, and a Surfactant for Managing Grapevine Powdery Mildew in Georgia, 2025

This study investigated the efficacy of a foliar-applied silicon product, Sil-Matrix, either alone or combined with sulfur (Microthiol Disperss) and/or a surfactant (Silwet L-77) for managing grapevine powdery mildew (PM). The trial was conducted on 16-year-old ‘Chardonnay’ vines at the University of Georgia's Blairsville Research and Education Center. Despite unusually high rainfall that substantially delayed disease onset, PM severity was assessed. Results indicated that sulfur and silicon plus surfactant treatments significantly reduced disease severity, 45.4 and 53.6% respectively, while silicon alone was not statistically different from the untreated control. These findings suggest that while silicon may provide positive physiological benefits, it may not have standalone or consistent efficacy against PM under southeastern U.S. vineyard conditions.