Control of Phacidiopycnis washingtonensis storage rot of apples by hot-water treatments without the ethylene inhibitor 1-MCP

Phacidiopycnis washingtonensis, cause of rubbery rot of apples during long-term storage, was first observed in Denmark in April 2010 on fruits of the 2009 harvest. Hot-water treatments were examined as a possible way to control P. washingtonensis. The effective temperature causing a 50% mortality of infectious spores (conidia) after a 3-min submersion in water was 40.2°C. A significant reduction of rubbery rot was achieved by dipping artificially infected fruit in a water bath at 47-52°C for 3 min. Using naturally infected apples, P. washingtonensis as well as the widespread storage-rot pathogen Neofabraeaperennans were effectively controlled by a post-harvest dip at 50°C for 3 min or by a rinse at 55°C for 20 s, followed by cold storage in controlled-atmosphere conditions. In contrast, a treatment of freshly harvested fruits with 1-methylcyclopropene (1-MCP) instead of hot water failed to control P. washingto nensis.