Product formulation is crucial to the success of lipid-based bio-fungicides
Powdery mildew is a major cause of damage to squash plants. Anhydrous milk fat (AMF) or soybean oil (SBO) may be effective at treating this disease but these active ingredients must be mixed with an emulsifier to enable even distribution and suspension of fat globules, and an antioxidant to prevent rancidity. The overall formulation may affect disease control efficacy, leaf health and product stability. The effect of different emulsifiers and antioxidants on emulsion stability, odour and shelf-life of AMF and SBO bio-fungicides was tested in laboratory assays, and on powdery mildew disease control efficacy and leaf health on glasshouse-grown squash plants. Both AMF and SBO formulations including a polyglycerol ester emulsifier (Grindsted® PGE 20 Veg) resulted in the best emulsion stability, disease control and leaf health. None of the antioxidants tested significantly affected on disease control efficacy in AMF formulations, but SBO formulations containing vitamin E as the antioxidant provided the best disease control efficacy and emulsion stability.