The other reason for no fertiliser or especially no fresh manure, is
that the new tender roots would be burnt by the chemicals.

Check out T slot planting of bare rooted trees, not however applicable
to fruit trees.
http://www.gb-online.co.uk/t_slot.html


The reason for no manure/compost/fertiliser is to encourage the tree to
go and find those things itself. i.e. if it can't get enough
water/nutrients, then it will grow longer roots - if you provide
everything it needs, the roots wont grow long. So presumably you wait
a couple of years and can then feed it happily...