I just got this Peach tree and haven't planted it yet. In the week I've had it, the leaves have started to brown off and flake away. I bought it at Costco, so it was indoors, but it seemed healthy there. Since I've brought it home and put it on my patio, waiting to prepare the spot to plant it, I've seen the leaves change. It had some pest damage at the store (some holes in the leaves), but they were dying off like they are now. It is a little cool where I'm at (60 in evenings maybe), and can be very windy on the patio where I sat it (I had to tie it to railing to keep it from blowing over).
San Mateo County California
Thank you for your question. Staff at your own county Extension office will be more familiar with these trees and their problems than are we. I suggest you contact them directly through this webpage: http://cesanmateo.ucanr.edu/About/Contact/ Good luck!