I know it's an old thread, but I came across it and felt I could add something for other people wondering the same thing. Wow, so ok, this thread is... very interesting? Went from somewhat helpful to nursery bashing lol. There are four ways to control vigor/ size in a tree: Precocity, spacing, dwarfing rootstocks, and pruning out large branches. You can plant them 2ft apart in the row and 8ft alleys as a spindle if you want, or 20 ft apart as an open vase if you want (hint: the spindle is going to yield more than the vase per acre). The biggest thing to maximizing yields is maximizing bearing surface and light interception per acre. I use dual-leader UFO (upright fruiting offshoot) training for everything now. UFO was originally developed for spur-fruiting species (apples, plums, pears, cherries), but it can be modified to work with tip and year-old-growth bearing species (some apples, peaches, apricots). You just have to space out your uprights more and allow for limited lateral branching. For peaches, I plant trees 8 feet apart in row, with 7ft alleys (I use a TYM 234 tractor). I plant the trees at roughly a 45 degree angle. I allow the uprights on the primary leader to grow (keep terminal bud upright), and select one below the bottom cordon to train as the second leader. I then remove the other buds below the bottom wire. By the end of 1st leaf, you should have both leaders tied to the wire, and mostly filled the space between trees, you've pruned off the pendant shoots, and you should have some fruiting wood for next year. In the winter, tip back the fruit sticks and eliminate damaged/crowded wood. second leaf- limited fruiting possible, focus on establishing your uprights roughly every 10 inches (6 inches for spur bearing species) and finish filling in the space. Eliminate pendant wood, shoots sticking outside of the vertical plane, and any uprights beyond your "permanent" ones in late summer, after any harvest (limited regrowth that way). Next year's fruiting wood is now on the upright shoots. Tip back the fruit sticks and eliminate damaged/crowded fruiting wood. Third Leaf- should definitely get fruit, goal is to get your upright shoots to the top wire (which for a should be roughly 75% of your alley width, IMO). Same kind of pruning as previous years. At some point, your laterals are going to start to grow together, at that point, you need to do renewal pruning in the winter back to a bud near the upright. Once your uprights get to about 1.25x your alley width, head the uprights back to on bud above the top wire (otherwise you'll shade the bottom of the next row). As uprights approach 3/4 to 1 inch diameter at the base, take the largest one every year down to one bud above the leader (unlike apples and cherries, peaches don't regenerate as readily, so you need to give it the best chance). All renewal type pruning should be done before budbreak, to encourage vigorous regrowth.

Rayrose, I'm engaging in discussion- not trying to suggest your advice is bad. This is a forum for more than just simple advice and a lot of people are interested in why and not just proscribed directions from "experts". These experts often contradict each other but if you have a sense of the reasoning and research behind advice you can better learn how to deal with problems from a point of actual understanding. I think that's how you get good at most anything. I believe the reason sealants are no longer recommended is that they've generally been found not useful, at best, in research. If you have research to counter this, please forward it- I'd much rather stand corrected than remain ignorant. Many horticultural traditions are found wanting when put to actual trial. Don't you find it interesting that Cornell recommends pruning peach trees when they are in growth to help prevent gummosis, while your experts suggest pruning during peak dormancy? It may be based on weather conditions but I suspect one or the other side is wrong and I'm very curious to know which.

Have to disagree with gardengal, Cut the tree now and it's wide open for the fungus or insects to invade a weakened tree. Wrong wrong wrong, that's old time thinking when they painted trees etc. Cut it after a good frost, the longer into the winter, the better. In addition you want to trim the tree, you want air to circulate within the central area of the tree to ward off fungus. You also don't want to take too much off the tree during winter trimming otherwise you will get lots of leaves etc with little fruit in the next growing season, however in your case it looks like you need more structure within yor tree to support the heavy fruit. Below is from the North Carolina Coooperative Extension: Dormant pruning vs Summer Pruning Trees respond very differently to dormant and summer pruning. Dormant pruning is an invigorating process. During the fall, energy is stored primarily in the trunk and root system to support the top portion of the tree. If a large portion of the tree is removed during the winter, while the tree is dormant, the tree's energy reserve is unchanged. In the spring, the tree responds by producing many new vigorous, upright shoots, called water sprouts, which shade the tree and inhibit proper development. Heavy dormant pruning also promotes excessive vegetative vigor, which uses much of the tree's energy, leaving little for fruit growth and development. Historically, much of the vigorous, upright vegetative growth has been removed during the dormant season; heavy dormant pruning results in a yearly cycle with excessive vegetative growth and little or no fruit production. Timing of dormant pruning is critical. Pruning should begin as late in the winter as possible to avoid winter injury. Apple and pecan trees should be pruned first, followed by cherry, peach, and plum trees. A good rule to follow is to prune the latest blooming trees first and the earliest blooming last. Another factor to consider is tree age. Within a particular fruit type, the oldest trees should be pruned first. Younger trees are more prone to winter injury from early pruning. Summer pruning eliminates an energy or foodproducing portion of the tree and results in reduced tree growth. Pruning can begin as soon as the buds start to grow, but it is generally started after vegetative growth is several inches long. For most purposes, summer pruning should be limited to removing the upright and vigorous current season's growth; only thinning cuts should be used. To minimize the potential for winter injury, summer pruning should not be done after the end of July.

Late winter is thenorm because of risk of dieback in hot seasons. You might try taking off little shoots on the offending branch ,now ,to let in some light. I wouldn't risk big cuts right now. Readers digest Illustrated Guide to gardening has a good article on peach pruning. Also, call your local county ag fellow and ask him if it would be detrimental to cut now being all you want to accomplish is getting rid of a bad branch.