Nick, it sounds as though you have no option but to do some summer pruning, the question is "how much?" We find summer pruning can really reduce tree vigour, so it might be wise to go easy on the weaker trees.
In our environment, summer pruning up until the fruitlets are about 20mm diameter , or summer pruning two or three weeks before maturity (to help fruit colour) doesn't seem to have any adverse effect on fruit size, but summer pruning in mid summer really seems to upset our trees, and fruit size really suffers. We suppose this is due to changing the leaf to fruit ratio, and also suddenly reducing the sugar supply to the roots. A light prune in mid summer probably doesn't hurt, but we find the harder we prune in mid summer, the worse it is.
If the trees are on a dwarfing stock such as M9, you will need to be careful when trying to straighten up the ones leaning over, as they tend to be brittle and have a nasty habit of snapping off at the bud union, or just below ground level. Sometimes on trees leaning over badly, it is better to cut to a strong vertical shoot coming from the original (sloping) leader, and straighten the tree that way by establishing a new, replacement leader. Best done in winter, but maybe you will have to do some now.
Of course, we have a very different environment to yours, so some of what we have said here may not apply.
(Just wondering, what does "scrambling with the tent cats" mean?)
Kalangadoo OrchardOn the “other side” in South Australia
Edited 1 time(s). Last edit at 06/02/2014 02:36PM by Michelle & Chris McColl.