Epidemiology and control of strawberry powdery mildew: a review

Abstract

Strawberry powdery mildew, caused by Podosphaera aphanis, is an economically important disease for strawberry production. Typical symptoms are white mycelium on all aerial parts of affected plants, with young host tissues being the most susceptible. The pathogen overwinters on infected leaves, either as mycelium or chasmothecia, although the quantitative role of chasmothecia in epidemics are not fully understood. In spring, under favourable conditions, the fungus sporulates, disseminating conidia and causing polycyclic infections. The disease is mainly controlled using synthetic fungicides, but there is increasing interest in sustainable alternatives, including microbial biocontrol agents (e.g., Ampelomyces quisqualis, Bacillus spp., Trichoderma spp.) and substances of plant or animal origin (e.g., Equisetum arvense, orange oil, chitosan, whey). Physical methods, (e.g. UV-C, ozone) are also promising alternatives to fungicides. All of these strategies should be combined with appropriate agronomic practices (e.g., overhead irrigation, canopy management) to create unfavourable environments for the pathogen. However, agronomic practices have never been assessed for P. aphanis. Disease forecasting models and DSSs, though available, are underutilized due to their complexity and lack of validation across locations. This review presents the current state of knowledge on P. aphanis the available methods for control of strawberry powdery mildew, and highlights knowledge gaps relating to this host/pathogen relationship.