Postharvest Fruit Rots in Apples Caused by Botrytis cinerea, Phacidiopycnis washingtonensis, and Sphaeropsis pyriputrescens

After harvest, apple fruit may be stored in cold storage for several months or up to 12 months in controlled-atmosphere (low O2 and high CO2) storage prior to packing. Packed fruit may also be held in cold storage for an extended period of time before shipping to the market, depending on the market needs. Postharvest fruit rot diseases can be a limiting factor for storage of apples. Gray mold caused by Botrytis cinerea is a common postharvest disease of apples worldwide (12). Sphaeropsis rot caused by the fungus Sphaeropsis pyriputrescens and speck rot caused by the fungus Phacidiopycnis washingtonensis are two recently reported postharvest fruit rot diseases of apples in the United States (6,16,17,18). Symptoms of these three diseases can appear on infected fruit as early as within three months in cold storage after harvest, but most decays that originate from infections of the stem and calyx of fruit develop after an extended period of time in storage. In a recent survey of postharvest diseases of apples conducted on cultivars Red Delicious, Fuji, and Golden Delicious in Washington State, gray mold and Sphaeropsis rot account for 28% and 17% of the total decay, respectively (7). Speck rot occurred sporadically in Washington State during the survey from 2003 to 2005 (6). However, both Sphaeropsis rot and speck rot can cause significant economic losses of apple fruit during storage. For example, instances with up to 24% losses resulting from Sphaeropsis rot or speck rot have been observed on Red Delicious apples during storage (Figs. 1 and 2).