I have a first year peach tree, bought from Costco in Bremerton Washington. It has been planted for 3 weeks now and has been doing great, with many peaches and full leaves. Then, in 2 days time, almost all of the leaves have fallen off. The fruit is still intact and seems to be doing well, but I know it is not normal for the leaves to just fall off like they that. I have no sign of pests that I can tell. I have not set up a watering system yet, as here is Washington, it has rained almost every day for the past 3 weeks. I sprayed last week with Garden Safe brand Neem Oil Concentrate but I am 95% peach tree illiterate and have no clue what it is or what to do about it. I have uploaded photos to show what the leaves and the tree look like. Notice that most of the leaves are still completely green. Others have a rust color on them. No rusty lumps though. Also, the tree looks pretty healthy to me, with no visible spots or cankers. The season now is mid May in the state of Washington.
Green Leaves Falling Off My Peach Tree.
Certified GKH Gardening Expert
This looks like a Bacterial spot on the leaves.
This is a difficult disease to control and most home gardeners look for resistant varieties to grow.
You can check with your County Extension Office for a list of such fruit trees for your area.
These links have more information.