I have an approximately 4 ft tall baby nectarine tree. Some, but not all, of the fruits, have large areas of missing skin, and deeply damaged dark interior sections.
I live in zone 9b in Northern California.
What could be the problem?
This is a guess until we have more information, ID of the thrip for example? Do you have any blooms left? This article tells you how to find the insects (they are tiny). A little specimen microscope and or a camera with micro capabilities.