A Pathotype Classification for Mycosphaerella pinodes

Genetic variation of Mycosphaerella pinodes in the pathogenesis of Pisum sativum is described for the first time. On a particular host line, isolates varied from those producing a few necrotic flecks to those causing large lesions on stems or leaves. Based on reactions of nine differential host lines, 45 isolates from a wide range of geographical locations could be classed, by stem symptoms, into 9 groups or, by leaf symptoms, into 16 groups.