I have a peach tree that produces good peaches on half of the tree and on the other half they stay green Why?

Question

I have a peach tree that produces good peaches on half of the tree and on the other half they stay green Why?

Answer 1

Perhaps the side with peaches that don't ripen is in the shade.  Peaches ripen fairly late in the summer and if one side has fruit that ripens more slowly due to shade, it may not  have time for the fruit to ripen before the onset of cold weather.

Answer 2

orientation to the sun,shade...