Silicon Supplementation — via Fertigation and Foliar Sprays — Enhances Zucchini Resilience Against Powdery Mildew

Zucchini plants are prone to powdery mildew, a fungal disease that can hamper plant growth and yield. This study investigated whether silicon supplementation, applied via fertigation or foliar sprays, could enhance plant resilience and reduce powdery mildew disease severity. Two independent greenhouse experiments were conducted, testing six treatments that varied in both silicon (Si) concentration and application method. The most pronounced effect was observed when fertigation with 1.5 mmol/L Si was combined with weekly foliar spraying (12.5–25 g/L Fertigro Sil), resulting in the lowest disease severity. Microscopic analysis further revealed significantly thicker cell walls in silicon-treated plants, suggesting a mechanical defense mechanism that may hinder fungal penetration. These findings highlight the potential of silicon as a sus-tainable and effective component in integrated crop management strategies for zuc-chini cultivation.