if you want to inhibit growth then prune in summer if you want to encourage growth prune late winter. but wait till fruit sets before pruning

Cowboys right about the affect on vigor but I pretty much prune all the time- been pruning every working hour since Jan 3 and started spraying oil a few days ago although I didn't finish all my clients yet. Did some pruning of one of my trees today. I don't agree that you need to wait to assure a good crop- what's removed elsewhere has very little affect on another part of the tree- just don't remove any pencils around fruiting buds.

I agree with Mark and Hman. Prune when the knife is sharp. I know that's a primitive old proverb, but I haven't noticed any deleterious effects from it. I think folks up north can get into trouble pruning too late in the season, but our winters here have been mild enough that its not been a problem.

As you live in coastal California the rainy season is over and I would not worry about fireblight. All the buds removed now will cause more energy to the remaining buds and fruit. The added sunlight will help next years flower buds to set. I can not think of any reason not to prune now. Al

A more accurate claim is that when the tree has energy in reserve pruning results in regrowth, when a tree is trying to send energy into reserve pruning results in less regrowth.
But pruning always nets less growth than if it had never been pruned (even though it may not seem like it).

I would wait to prune. More flowers are a bigger billboard to attract more insects and provide more pollen. But I wouldn't wait until after harvest.
Take some shears along when you thin the fruit.

Actually I believe that old hort nugget is somewhat inaccurate. Mature peaches have been shown to grow ultimately larger when pruned harder and any spurry growth removed from apples and pears will result in greater vegetative vigor and a larger tree than otherwise at end of season. What you say is true of sexually immature trees but all bets are off once a tree puts energy into fruit.

Harvestman, '...just don't remove any pencils from around fruiting buds.' Its the first time I've heard the 'little pencils' reference. Why not, are these next year's fruiting buds?
Thanks for your comments.

On many varieties the best fruit comes from buds on the smaller to moderately vigorous shoots their second year. The shoots also feed the spurs dirctly beneath them making apples bigger and sweeter. It's a delicate choreography leaving the right amount of annual wood so that it isn't excessively shady which makes pruning apples difficult.

Sometimes if you wait for trees to bud out before you prune you can learn a lot just by seeing where the flower buds are.

Thanks, your writing is instructive to me. Since the trees are budding now, I'll be more observant. The spurs on some apple trees and the swollen fruiting segments on the Northern Spy are easier to spot than wherever the Baldwin decides blossom. That tree is still a mystery to me.