WSU Tree Fruit Research & Extension Center

Tree Fruit Market Diseases

Saturday, September 23, 2017

WSU-TFREC/Postharvest Information Network/Tree Fruit Market Diseases/corerot



Penicillium, Physalospora, Alternaria and certain other genera

The carpels or seed cavities of apples will often be discolored or overgrown with mold. This condition arises from the growth of various fungi whose entry has been greatly facilitated by calyx tubes that open into the seed cavity or terminate close to it. Such calyx tubes are commonly found in Delicious, Golden Delicious, Wagener, Macoun, Gravenstein, and certain other varieties. Fungi found in discolored or moldy carpels include species of Penicillium, Physalospora, Alternaria, Fusarium, Rhizopus, Coniothyrium, Aspergillus, and Botrytis. In some seasons a substantial number of Delicious apples coming out of storage will be affected, but rotting of the flesh is not common. Open calyx tubes may also permit certain chemical pesticides to penetrate to the carpels and injure them.

Most of the fungi associated with moldy carpels in apples can also produce a fleshy core rot. Penicillium, Physalospora, and Alternaria are the most common causes of decay. Core rot can follow codling moth or lesser appleworm injury, cracking at the calyx end, and moldy carpels. Core rot generally does not cause much loss in storage or on the market.

Core rot, Red Delicious
Core rot, Red Delicious

Core rot, Red Delicious
Core rot, Red Delicious

Core rot
Core rot

Core rot
Core rot

Tree Fruit Research & Extension Center, 1100 N Western Ave, Washington State University, Wenatchee WA 98801, 509-663-8181, Contact Us