Peach Tree Leaves Turning Yellow and Dropping
Trees are about 4 years old. I live in Denver, CO. Natural soil is high clay content, but I planted with lots of compost and peat mixed in.
Certified GKH Gardening Expert
There are many reasons that this could happen. I would look to make sure that it is getting enough water and, if you have not fertilized, I would go ahead and do this (after the plant has been well watered).
This article will have some other suggestions on what it could be: