Cucurbit Downy Mildew (Pseudoperonospora cubensis)

Abstract Downy mildew of cucurbits, caused by Pseudoperonospora cubensis, is a globally significant disease with major impact on cucurbit production. The pathogen induces sudden and widespread foliar epidemics that lead to considerable yield losses, particularly in cucumber and melon crops. This review outlines the taxonomy, biology, host specificity, distribution, life cycle, and epidemiological characteristics of the pathogen. There are two main races, one that infects cucumbers and melons, and one that infects pumpkins and squash. This disease can spread via air, water, and on agricultural equipment and human hands. In this review, special emphasis is given on host-pathogen interactions between P. cubensis and its economically important cucurbit hosts (Cucumis sativus, Cucumis melo, Cucurbita momordica, Cucurbita maxima, and Citrullus lanatus); pathogenic variability in P. cubensis at the species, genus, population levels and differentiation of races. This review serves to summarize the current status of this major pathogen and most important topics for future research and international collaboration.