A Comprehensive Characterization of Ecological and Epidemiological Factors Driving Perennation of Chasmothecia on Hop ().

Hop powdery mildew, caused by the ascomycete fungus , is a consistent threat to sustainable hop production. The pathogen utilizes two reproductive strategies for overwintering and perennation: (i) asexual vegetative hyphae on dormant buds that emerge the following season as infected shoots; and (ii) sexual ascocarps (chasmothecia), which are discharged during spring rain events. We demonstrate that chasmothecia, in the absence of any asexual growth forms, are a viable overwintering source capable of causing early season infection two to three orders of magnitude greater than that reported for perennation via asexual growth.