I have two peach trees that are about 6 years old. This year and last year after the leaves sprouted and grew to full size, they developed holes in them, died, and dropped off. This has happened to about 80% of the mature leaf canopy. In their second or third year, I had a problem with leaf curl which I treated and I don't see signs of that any more. This seems to be something different. The trees get about 6-8 hours of direct sun in the morning until early afternoon. They are planted in a side yard in soil that is a mix of topsoil and clay (like most of this area). Can you tell me what is going on with my poor trees. They seem to be struggling.