Powdery mildew (PM), caused by Erysiphe spp., is a common fungal disease that affects lettuce and other leafy crops, particularly in greenhouse environments. This study investigates an integrated pest management (IPM) approach combining ultraviolet (UV) light exposure and OMRI-certified fungicides to control powdery mildew in organic lettuce production. The research was conducted in a greenhouse setting, focusing on the effects of UV light on fungal growth and the efficacy of an OMRI-certified fungicide in reducing powdery mildew incidence. The results showed that UV light exposure significantly reduced powdery mildew development, while the fungicide provided additional control. The combination of both methods led to a marked reduction in disease severity and improved plant health compared to untreated controls. This study highlights the potential for using UV light exposure in conjunction with organic fungicides as an effective and environmentally sustainable method for managing powdery mildew in greenhouse organic lettuce production.