Control of powdery mildew (<i>Podosphaera leucotricha</i>) on apple seedlings using anhydrous milk fat and soybean oil emulsions

Abstract

Powdery mildew (PM) is one of the most serious global diseases of apples roses cucurbits grapes and cereals The potential of anhydrous milk fat (AMF) and soybean oil (SBO) formulations to control apple PM (caused by Podosphaera leucotricha) on the apple cultivar Royal Gala was investigated Potted seedlings in a glasshouse were left unsprayed or subjected to weekly sprays of AMF SBO fungicide (sulphur as Kumulus DF) or water During 67 weeks of treatment the AMF and SBO formulations significantly reduced PM to <12 infection of the leaf area compared with 100 in unsprayed and water control plants There were no significant differences in PM control between AMF and the fungicide treatment but SBO gave disease control equal to or exceeding the fungicide After two experiments plant height weight and stem girth were significantly higher in plants treated with natural product formulations and the fungicide treatment than those in the unsprayed and water treatments