In apples, such disorders include cork spot, bitter pit, Jonathan spot, water core, internal breakdown, and storage scald. Cork spot occurs during the growing season, and is characterized by localized green to brown sunken spots on the fruit or in the flesh. The spots in the flesh, which may or may not develop just under the skin, are brown, corky, dead tissue, and are more prominent toward the calyx half of the apple. The spots in the flesh have a bitter taste. Under severe conditions, fruit cracking can occur.
Bitter pit develops late in the growing season or in storage.
It is very similar to cork spot, but the areas of brown, corky, dead tissue are confined to areas just under the skin. Jonathan spot occurs late in the growing season or in storage. It is characterized as small, brown to black spots on the skin that may or may not be sunken. Water core occurs before harvest, and is characterized as translucent, water-soaked areas in the flesh. These water-soaked areas commonly develop near the core, but in severe cases, can radiate out to the skin.