Resistance to Sclerotium cepivorum in Allium and other genera

Stimulatory and non-stimulatory species of Allium and four other members of the Liliaceae were susceptible to infection by germinating sclerotia of Sclerotium cepivorum in unsterile soil. Plants belonging to other families were not infected in soil even when germinating sclerotia were in contact with their roots. Under aseptic conditions S. cepivorum infected plant species not closely related to Allium , particularly when large amounts of inoculum were used. Infection was slight in the presence of germinating sclerotia. It is suggested that within the genus Allium and a few related genera resistance results from the lack of ability to stimulate germination of sclerotia. Non- Allium plants also lack this ability but in addition possess tissue resistance to S. cepivorum.