This looks like sun scald to me. Sunscald is often exacerbated by high temperature and drought

Sunscald symptoms will appear as yellow or white lesions on foliage and/or fruits. The lesions eventually may turn brown and/or shrivel. Note that once damage occurs, other soft rots (e.g. from bacteria) may invade the fruit to cause further damage.

How to control. An extension document from Purdue University states:
"Encouraging healthy foliage by proper positioning in the garden, appropriate fertilization, pruning and pest control can help prevent sunscald on garden plants. Using tents or screens to provide light shade in late afternoon may also help. Moving susceptible perennials and shrubs to more-protected locations, particularly away from the afternoon sun, may be warranted."

http://www.hort.purdue.edu/ext/sunsca...