Survey of Moldy Core Incidence in Germplasm from the Three U.S. Apple Breeding Programs

Abstract

Moldy core, mainly caused by Alternariaspp., in apples has been studied in a limited number of cultivars, and susceptibility is attributed to open sinuses and calyxes in the fruit. In three US apple breeding programs, a diverse germplasm collection was characterized for core opening, calyx opening, and moldy core incidence at several time points during storage. Ten cultivars showed signs of moldy core, all had open cores while only three had open calyxes. Fruit with either an open core or an open calyx increased the likelihood of moldy core incidence. Two susceptible cultivars, 'Gingergold' and 'Pinova', also had progeny with high incidence of moldy core. A separate project screened 707 seedlings with diverse parentage in the Washington State University breeding program for core opening, calyx opening, sinus opening and moldy core incidence. Only four of the seedlings had open sinuses, and all failed to develop moldy core. The cultivar survey information presented here may be useful to other breeders, horticulturists, and pathologists interested in determining the heritability for moldy core susceptibility.