Large sclerotia of Sclerotium cepivorum.
Sclerotia of A. cepivorum much larger than typical infective sclerotia were common on naturally infected onions at Pukekohe, New Zealand, during one season but were rare in the next. They could not be recovered from soil one year after their most common occurrence. Similar large sclerotia were formed in culture on autoclaved wheat grains. It is suggested that they are a vestige of the apothecial stage of the ancestors of S. cepivorum.