Apple

Calcium deficiency causes bitter pit on  apple surface and brown corky areas in the flesh. Bitter pit is a common problem that shows up in apples just before harvest or, more frequently, after a period of cold storage. It appears as small, dark, bruise-like spots or depressions which tend to be concentrated towards the calyx end of the fruit. The tissue beneath these spots typically becomes hard and corky, and, needless to say, these apples can't be sold as fresh fruits in the market.