Are these on grafted root system? At 6ft. the trees are several yrs old. You will need to prune properly--very important to do it correctly and early. I did not let my fruit trees produce fruit for two yrs after I planted them. I wanted the energy going into great root systems. The third year, I had several apples.  By the four yr. I had enough to can and make jelly from..
I planted four peach trees, every yr. they are FULL of beautiful pale pink blossoms and set 100's of green peach shaped fruit BUT because I refuse to spray (peaches are favorites of all kinds of pests and fungi) I have never gotten ONE peach.. I had thought about having my dh pull them up but my honeybees adore them--so they can stay. 
I have plums, peach, blue,black, dew-berries, fig, pear, cherry, apple and muscadine and table grapes and do not spray anything==the peach is the only ones that are not able to handle it! 
This yr. I planted Asian persimmon and pomegranate and I hope they do well without spraying..