At one time I had three peach trees in my yard - the one tree gave peaches so big you had to use both hands to eat them. Two would make a pie!
I also had a mature apricot tree which gave neither blooms nor fruit for about three years. My neighbor at the time came over and walked around it several times in one direction, and several times in the other direction. She leaned up against the tree, looked at me and said: "It needs iron." She retrieved some nails from her garage and buried them around the base of the trunk. The next year I had apricots like you wouldn't believe! It doesn't seem like summer unless I can have peaches with my cereal in the morning. :)