Carl, I’m wondering why you’d wait until now to prune? Keep in mind the balance of nutrients in your tree; it stored what it had received the previous growing season within its roots. When it sends those nutrients back up to begin new growth, removing that growth will rob the tree of those nutrients. As they establish new shoots and foliage, they will of course begin collecting additional nutrients, unless they’re snipped off.

If you had removed the waterspouts ‘last summer’ (straight up shoots off the uppermost branches), they’d not be shading the canopy or fruit. If they are, I’d remove them. Additional thinning can of course be done, but it will remove fruit and energy collecting material. A balance seems to take place regarding fruit; remove some and those remaining become larger… That would likely be the case now.

The most successful ‘Summer pruning’ I’ve witnessed was done at harvest. A longtime HOS member would take her hand pruners up the ladder, and after picking the apples within reach, she’d prune the same. I’ve never been so ambitious! But it does keep the ladder-work to a minimum, and while it’s still leafed out, allows the cuts to instantly seal & heal.

If you’re pruning ‘now’ to reduce the trees vigor … I suspect it will. Removing large limbs would definitely deplete its nutrient storage and collecting ability. I doubt it would have much of an effect on the current crop… though if enough material is removed to starve any portion of the roots, it would likely reduce next year’s ability to produce fruit …if not survive.

I like to 'see' what I’m doing, so generally wait till the leave fall before my annual pruning. I’ll remove waterspouts if they’re within reach during the summer, but have noticed ‘enough’ material appears to peel away from the base that I’d rather make a more ‘surgical cut’ when dormant than leave an open wound on a humid summer day. The only research I’ve seen regarding the loss of nutrients described ‘those produced within a waterspout’ stay within the waterspout. I’d assumed they fed the fruit and foliage… not so. So removing those shoots can be beneficial any time of year – and using a nice hand-pruning device would likely be better than tearing or ‘popping’ them off as many of us do…

So, I’ve no definitive answer to your rather technical question, only my opinion " title="Wink" />