Another update. I've found out that the trees are doyenne du comice and
bon chretien. Apparently neither of these is self fertile. This might
explain why I haven't seen any flowers. How do I get them to flower?
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No - it would only explain why any flowers you may have don't set fruit.
I have several books on pruning, they all say that no fruit should be
allowed to develope as it take strength away from the tree, so even if
you had any it is best to remove them. Best wait until winter then
prune to shape the tree as you wish. A weak branch should be pruned
harder than a strong one, if you wish them to develope equally, sounds
odd but it is so.

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