Powdery mildew (PM) infection of cucurbits is a major problem facing commercial New Zealand growers. Resistance to demethylation inhibitor fungicides is widespread so, there is a demand for new-generation bio-fungicides that can provide durable control alternatives in both conventional and organic systems. A wide range of milk products, plant and animal fats/oils, and natural plant elicitors were tested for their ability to control PM on squash and zucchini plants in a series of four glasshouse trials. The most promising product tested was anhydrous milk fat (AMF), in formulation with an emulsifier (Alanate 191™ or Panodan® AL10), an antioxidant (Grindox 122™) and/or other products (Synertrol Horti oil). These treatments were as effective as commercial fungicides in controlling PM, but there were significant issues with plant health. Future work will focus on reducing concentrations of the active ingredient to produce an effective formulation that is not detrimental to plant health. Soybean oil, coconut fat and olive oil formulations with Panodan® AL10 and Grindox 122™ also gave effective PM control with minimal effect on plant health.

Powdery mildew (PM) is a serious fungal disease of a wide range of horticultural crops and can adversely affect crop yield and quality Anhydrous milk fat (AMF) and soybean oil (SBO) emulsions were evaluated for control of PM (Sphaerotheca pannosa var rosae) on potted rose plants (Rosa L sp Splendid Surprise and Sahara) maintained in a controlled environment Foliage was sprayed weekly with AMF (07 w/v) SBO (2 w/v) fungicide (Supershield 1 v/v) water or left unsprayed PM infection increased to 100 leaf area in water and unsprayed control plants over 6 weeks The fungicide reduced infection to a severity rating of 5 (>40 leaf area infection) The AMF and SBO treatments gave significantly better disease control (P