A recent study investigating practices in managing powdery mildew has found that a combination treatment effectively controls the disease while simultaneously improving yield and maintaining nutritional quality. Rodale Institute scientists found that combining ultraviolet light (UV) exposure with an organic fungicide significantly reduced powdery mildew severity and even increased harvestable weight by nearly 45% relative to their untreated plot. The practice also resulted in higher levels of certain amino acid compounds, demonstrating that it’s possible to control diseases organically without sacrificing quality. 

The research team chose to utilize a controlled greenhouse environment to grow lettuce for the study. Prior to transplanting, seedlings were exposed to either UV-B or UV-C light. Further treatment included spraying the plants twice during the season with fungicide or not at all. To compare the treatment groups, disease severity, yield, and nutrient composition, including vitamin C, sugars, minerals, and amino acids, were measured. The results showed that the organic potassium bicarbonate fungicide (called Milstop) effectively suppressed powdery mildew and improved yields. Interestingly, higher amino acid concentrations that are typically linked to resilience and nutritional value in plants were associated with UV-B light exposure specifically. 

The combination of physical and organic-approved fungicide treatments presented in this study highlights the innovative nature of organic farmers and researchers. The results add to a growing body of evidence that suggests organic systems are not only safer but can also produce more nutritious food.