Control of sooty blotch and black rot of apple through removal of fruit mummies

Several popular apple cultivars retain their aborted fruits as mummies on the tree. In laboratory conditions, overwintered fruit mummies collected from a Northern German apple orchard under organic management released inoculum, which caused black rot due to Diplodia seriata and sooty blotch due to Peltaster cerophilus on ripe apples. In a field trial conducted over four years in another organic orchard, the manual removal of fruit mummies in winter and again in late June of each year significantly reduced the incidence of both these diseases. However, fruit mummy removal did not significantly affect the development of storage rots due to Neofabraea alba and N. perennans. The potential, limitations and costs of this phytosanitary measure are discussed in the context of organic apple production.