Answer: When pruning is done, it should be completed before early June. By mid-June to early July, flower buds for the next season are beginning to form in most crabapples. Pruning after July will reduce floral display and fruiting for the following year. Since you've had such cool spring weather you may be able to prune the branch out now without encouraging water sprouts. Or, wait until the tree is dormant this coming winter and remove the branch in question.
Best wishes with your landscape!
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