I bought 2 Saturn Peach Trees. I planted both of them in my back yard in Salem, Oregon. The only difference in planting them was that I used a bit more fertilizer on one of them as compared to the other. Anyhow, the tree that was planted with less fertilizer is doing great while the one that I put a little more fertilizer on is not doing well. The leaves on the one that isn't doing so well have faded to a light green with purplish spots on a few of the leaves while the other tree is nice and green throughout. I did over-water them in the beginning (2-3x/day x 10 minutes now I do every-other day for about 30 minutes) but that doesn't really explain why one is doing good and the other isn't. Is it maybe, because I used too much fertilizer? Do you think that this is a result of over-watering?
Have you tested the ph of the soil?
I would start with learning the ph of your soil.
These links will refresh you on care requirements, watering and fertilizer application.