I do not know much but I can tell you we lost one of our peach trees this summer. They are all about same age range and height as your two.

I can't say either, but I know mine does that too.

Gatormom : Thanks for the advise. There are no spots on any of the leaves, and see many new, lighter green leaves coming out now. Since I fertilized with a 4-6-8 generic fertilizer 3 weeks ago, the leaf drop has just about ceased so am optimistic, especially after katkin's comment.
Will look around now for something closer to 8-0-8. I will be spraying my 4 mango trees for fungus in a month, so will include the 2 peach trees as well,...can't hurt.
Thanks again for all the comments.

Good plan.
Wishing you success and a good crop.

I have 5 peach trees and they are all doing the exact same. I think it started after we got 6-8 inches of rain in a day, but they are still growing and have 90% of the leaves healthy.

With mine it seems to happen with too much rain or not enough, exactly what this year has been.

I'm pretty sure your peach trees have a nitrogen and or iron, and or magnesium deficiency, and or nematode problem. My "Florida Prince" has leaf yellowing and falling with no signs of fungus. Found enough info on the internet to narrow it down to 4 things things. LOL
I applied Southern Ag's calcium nitrate, common magnesium sulfate(Epson salt), Sunniland's nematode control, and ironite.
My tree is 3+ years old now and produced over 200 peaches this last season. I was using strips of bicycle inner tube to truss the branches up because it had so many peaches.
I live in citrus county Florida. Very hot and humid here during the summer.. I spray with a solution of neem oil weekly to keep any fungus at bay.
I hope this helps. Im sure it wont hurt anyways. I'll post results in a month or so.