Field Evaluation of Nanosulfur to Control Grapevine Powdery Mildew ( Erysiphe necator )

Abstract This field study evaluated nanosulfur to control powdery mildew on mature grapevines (Vitis vinifera cv. Chardonnay) over 56 days (growth stages E-L 32 to E-L 35/36). Three sulfur nanoformulations, uncoated (NS), stearic acid-coated (SA), and polyvinylpyrrolidone-coated (PVP), were applied at 1.47 kg/ha per application, alongside a commercial micronized sulfur (Microthiol Disperss) at 14.7 kg/ha, and a water-only control. The sulfur nanoformulations achieved similar plant protection against powdery mildew to micronized sulfur but at a 10-fold lower rate, demonstrating greater efficiency. While fruit yield and relative chlorophyll levels did not differ from micronized sulfur, nanosulfur treatment influenced grape quality, particularly titratable acidity, grape juice pH, and elemental content. Nanosulfur treatments enhanced oxidative stress responses, particularly catalase activity, indicating a potential role in plant host defense in grapevines. This work contributes to the growing body of evidence demonstrating the efficacy of nanomaterials in the field, not only for plant protection but also for the potential for increasing yield and crop quality in viticulture.