#1) A dormant oil spray will suffocate any insect eggs laid in the bark of a fruit tree, especially effective around the last frost.
It needs to be applied prior to any 'bud break' of new leaf growth.
I believe that you can use the neem oil as the dormant oil spray.
#2 Regarding lack of fruit set, I suggest an 'off-the-wall' suggestion; sometimes trees don't bear fruit (seed/ plant replacement) or flowers due to "complacency".
Make the fruit trees less complacent, by beating the trunk at different locations 3 or 4 times with a baseball bat to make it less complacent,
and thus placing mild stress on the tree.
Some times this makes the tree less complacent, and ready to set replacements (fruit/seeds) through fruiting.
I know, this sounds weird, but it has worked before; a friend in Ohio had a campisis radicans( trumpet vine) for 10 years in the same location,with no flowering,
but after assaulting the plant with a bat, that spring it resulted in bountiful flowers and seed production.
The alternative and less combative method is to inject/ dig phosphorous within the tree 'drip line", thus feeding what nutrients may be in short supply to the tree.
#3 When pruning a tree, never remove more than 1/3 of the plant growth, or you may 'shock' it too severely.
Thanks much appreciated.
I hear you. Truth is, I am way too lazy to prune back too hard! I have only ever used neem. I just never remember to get it on the apple trees early enough. But now the deer have devoured the one apple, so it’s a new one in this spring. Different variety probably. And I do need to add blueberries to our yard.