Last week I planted some potted apples, peaches and plums, 2 - 5 gallon. I made no effort to separate the roots which were pretty well bunched up.
Should I dig them up and separate/spread the roots? Also I used no fertilizer.
Some will say yes.
I planted a apple some years back, terrible root bound but left it like that just to see, it did reassuringly well.
Some roots will take off from it ...shouldn't be a problem.
Dig them up and spread the roots. If nothing else you will feel better and it probably will help the trees establish. You are right on the fertilizer. Wait and apply some after the trees start to grow. That's much safer for the roots.
I wouldnt worry.
I planted some kind of tree. I dont know what it is called but it had been in a 10 gal pot for almost 20 years. When I took it out the roots were literally coiled like a spring the same size as the pot and I could stretch them out like 50 feet! They just snapped back into a 2' coil! I planted it just as is without even a pruning. 2 years later and the tree is just fine.
I will admit that if you want better and quicker root development to spread them before planting but if its already planted I would not waste the effort on shocking the tree. At least now you will know how a tree will grow when the roots are not spread before planting. Not much different.