Recently I read the following:
For August apple tree care.
Apple - Optional - Summer pruning - If you started last month, finish the job this month. You prune stems back to the first set of leaves. Be sure the shoot has turned woody where you are going to cut it, so that a fruiting spur will form at that point.
I had had never heard the suggestion to wait until the shoot turned “woody” before pruning for spur formation.
At this time of the year I am getting a good deal of new shoots appearing and, where I want fruit spurs, I have been snipping them off after the basal cluster ( 3-5 leaves) .
I am wondering if I am being too snip-happy and should wait some.
There is this: http://www.soilzone.com/Library/Crops/Deciduous%20Fruit/Phenology/Flower%20initiation%20and%20development.pdf
It seems like there is an idea that a critical node number is required for spur formation. (Nodes are the stem section between two leaves). So I wonder if snipping the shoots off early might forever doom them to a state of vegetative growth. It also sort of depends on variety… some are super-precocious partial tip-bearers and others not so much. Zestar is one of those varieties for me. It put on flower buds on 1st year shoots last year without formation of spurs.
That is really interesting and opens gateway for further searches.
Would it be worth experimenting by pruning back the woody shoots on half of a tree to the first set of leaves, performing more typical pruning on the other half of the tree, and comparing? It seems like if enough people did this some sort of conclusion could be reached.