Prune them now to maintain the height you want. Then prune more in winter if needed. There are many ways to do this. But if excess height and overly vigorous growth are issues, prune some now. If those aren't issues then it can all be done in winter. Summer pruning is more dwarfing than winter.

The most important thing is that you do it at some point.

The worms in fruit in CA are likely OFM but could be peach twig borer. In either case go to UC Davis for advice.

Here is a link that might be useful: UC Davis OFM

Winter pruning is for structure, remove dead branches, branches growing inward or rubbing, and branches growing straight up (water spouts). Open center up if growing an open centered tree.

I agree with Drew. Perhaps another way to think about the Summer vs. Winter thing for a home grower is heading vs. thinning.

If size control is important to you, you want to do your heading cuts (i.e., shortening branches) in the Summer. Once after fruit is harvested and, if needed, again in late Summer.

In the dormant season (Winter) you mainly thin. Clear out dead wood, open up the structure, reduce the number of smaller branchlets that can result from Summer heading cuts so you don't end up with a thicket. If you head branches back in the dormant season the tree will respond with vigorous growth in Spring, i.e., you will be working against size control. So try to confine Winter pruning to thinning cuts (i.e., remove branches or branchlets completely).

I'm trying to keep the trees at about 6' and somewhat confined within rows so I'll do both. Thanks guys, you're awesome!

Sandra

I side with Fruitnut. You can prune for structure winter of summer although winter is more traditional. The main difference is that once fruit is gone trees use all harvested energy from the sun to make new wood, including roots. Summer pruning reduces this harvest of energy, which can be a good or a bad thing depending on how much you want a tree to grow.

If a tree doesn't have more than enough vigor or has yet to fill its space you'd want to keep summer pruning to a minimum (water sprouts), but a vigorous tree is probably safe to do a complete prune after harvest.

Last year I completely pruned all my mature peach trees immediately after harvest and can recommend this approach once trees have assumed required space.

Of course, pruning methods are a matter of opinion and there is always a risk in any advice you follow. Someone posted here that in Israel peaches are aggressively pruned after harvest and all fruit is grown from new wood generated after this pruning. I guess that is proof that there are many ways to manage a fruit tree (partly depending on the climate).

Thanks for reminding me that I have a bunch of Summer pruning to do. :)

Here is a link that might be useful: Backyard Orchard Culture