<i>Verticillium</i> Wilt of the Hop <i>(Humulus Lupulus)</i>

Abstract

An account is given of the methods used to determine the relative pathogenicity of isolates of Verticillium albo‐atrum from fluctuating and from progressive outbreaks of the wilt disease of hops. Isolates from fluctuating outbreaks were less pathogenic to young hop plants than those from progressive outbreaks, and it is suggested that this is the main cause of the differences in symptom incidence and intensity between the two types of outbreak in the field.