Someone asked me the other day if it is too late to prune apple trees now that the trees are leafing out and getting ready to bloom. Perhaps I answered too quickly when I said that it was too late. Yes, it is too late to do the vigorous pruning you would do in the dormant season but light pruning can continue throughout the summer.
More detailed pruning information has come my way via local grower Mark Wessel. He has a friend who is a professional orchardist in the NY area. The advise from Alan Haigh is as follows:
Water sprouts can be wiped out any time and for the most part you can prune any season if you understand what you want and how trees respond.
Too much pruning before mid-summer and even after can have an adverse affect on the quality of the fruit. Summer pruning can also improve the quality of fruit by getting light where you need it – when it hurts is when you make fruit watery as foliage can steer water and N away from the fruit to some degree as it ripens increasing the concentrations of sugar in the fruit.
I will add his comments on pruning peaches, plums and cherries in another post.