Bitter pit

The affected fruit have dark spots, about ½ cm diameter, which occur on the skin or in the flesh or both.

Fruit that were free of bitter pit at harvest were often severely affected after a short period of storage.

The breakthrough in control came with the discovery in North America that the mineral calcium was low in affected fruit.

[10] However, in the southern hemisphere where highly susceptible fruit had to be harvested early for export to Europe, the problem remained.

[12] Export of susceptible apples from New Zealand was under threat and new methods for controlling bitter pit were investigated.

The vacuum treatment was commercialized in New Zealand for the Cox's Orange Pippin cultivar in 1978, and was used for several years.

It is more difficult to control storage pit in highly susceptible cultivars as field spraying may not be able to apply sufficient calcium to the fruit.