Location of the wound above is located on the left side in this picture.

Is that injury on Southwest side tree if is more than likely sun-scald. Canker more likely to be in limb crotches I give tree sometime to heal. In link below you want see any healing like your tree.

Here is a link that might be useful: canker

Yes the spot is located on the south side however I doubt it's sun-scald from this year since it was under a tree wrap.

I guess it could be sun scald from the nursery?

Could this be mechanical injury from the nursery and this is how peach trees heal? If so I would imagine that it would be beneficial to scrape the black edging away to expose the Cambrian layer and promote smooth healing?

You need just give more time to heal up clean off with rag removing more bark will be more injury peachtrees heal slow. Mildew turn black around injury. You use Clorox small amount in water clean with rag are paint brush. Fertilize water so tree grow faster.

It looks like the "knot". It seems that canker or crown rot usually forms around that knot at the base of peach trees. I can see a little goo in mine even (on my peach tree). Ive sprayed copper in the past to keep it at bay but cannot give results as the one on my tree is so small. Try copper or sulfur.

I followed gator_rider2's advice and wiped the black around the injury with diluted clorox bleach.

I plan to wrap the trunk loosely this winter to assist with healing and speed the process.

How many more years will it take to completely compartmentalize this wound?

It may be the wrapping that caused the problem, if you had it wrapped during the growing season.

DONT WRAP IT!! Lol...copper or sulfur if anything. Trust me. Wrapping it will cause more problems. It needs air and something to stop the bacteria from spreading which is where copper and sulfur come in. In all actuality it is very hard to cure what you have there. The standard treatment, if any, is a copper spray or sulfur and pruning.

It could be a cytospora infection. Another more extreme way is to get a really sharp knife and cut underneath it to remove the infected parts. You will see good wood underneath. After treat with copper/sulfur. I dont recommend this method as Ive only seen it done by professionals on branches. But seriously, dont wrap it. But I do not think there is an actually "cure" for what you have (if it is cytospora infection)

Sound familiar?

http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/Pages/LeucostomaCanker.aspx

Cankers that form on the main trunk, branch crotches, scaffold limbs, and older branches are the most conspicuous expression of infection (Figure 5). Dead scaffold limbs comprise a symptom called "flagging" that are recognizable at a great distance from infested orchards. Cankers are elliptical, parallel to the long axis of the stem. Usually the first external symptom of such cankers is the copious production of amber-colored gum. Gum production is a natural host response to irritation, but gum production due to infection by Leucostoma spp. is excessive. As the canker ages, the gum becomes dark brown, and the infected bark dries and cracks open exposing blackened tissue beneath. Leucostoma canker can occur on weakened branches without the production of gum, especially if winter injury precedes infection.

Surgically remove cankers. Cankers should be removed, and (if possible) burned, buried, or moved out of the orchard (Figure 17). Cankers on trunks and large limbs can be removed surgically in mid-summer when trees heal most rapidly. Surgery should be performed in dry weather with a forecast of dry conditions for at least three days. During surgery, remove all diseased bark around the canker and about 4-5 cm (1.5-2 inches) of healthy tissue from the sides and ends, respectively. Disinfest cutting tools between cuts with an alcohol or bleach solution. The resulting wound when finished should have a smooth margin and be slightly rounded above and below to favor rapid wound closure. The practice of covering pruning cuts in spring with a thiram-latex paint mixture provides some degree of protection against fungal infection. Sites of surgery heal best if left uncovered.

I recall seeing this wound when planting the tree and figured it would heal itself. Wrapping the tree did not cause this problem as stated I had seen it before planting.

Like Gator said all the pictures of canker I have seen do not show the active healing which is occurring around the wound. I do not have a lot of experience with Peaches but did not expect that amount of ooze around the wound.

Actually I do recall performing a bench cut on a 2-3 inch nectarine tree leader. This was about 3-4 years ago and also recall seeing a lot of ooze in the wound at the time of healing over those years. Now when I look at that wound I can't even tell it was cut there due to healing.

Therefore my assumption is that peach trees ooze as they heal over time unlike something like a Magnolia which does not ooze as it heals.

I just found one on the bottom of my red baron but I think it might be healing? If they heal? I think the copper is helping because it seems to dry it up a bit and stop the ooze(I hope). Mine is small and mostly black though but seems hard to the touch and more like dead wood. I did notice a few more that looked possibly to be affected. It seems my red baron is prone to them I guess? When the unknown peach tree next to it is virtually free of them? Lets just say summer pruning came a little early (or on time?) this year. It seems as if the dead non oozing cankers(if thats what they are) are all just dead clean wood but a couple of them were actually oozing so I cut the branch a little ways back to good wood with (hopefully)no problems. I think I know now why this red baron was the last on the lot...hehehe So I kinda know what your goin through:-)

Quick Update
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It's been about a month since the above pictures. The tree has almost completely healed over at this point. I can not see any heart wood. I do not believe this was canker but rather physical injury prior to shipping.

Sometimes mother nature will take care of problems.

Maybe it would be helpful to note that trees are not aided when wounds are treated like human or animal wounds. They do not have the same kind of immune system that attacks the pathogen directly- instead they wall it off- creating a chemical barrier between healthy and unhealthy wood. The pathogen then is likely to starve and at any rate can't go beyond the barrier into healthy wood.

You can't automatically assume that cutting to clean green wood is helpful- especially if the walling off process is already complete. Also dressing and wraps generally create a nicer (moister) environment for the trees main enemy- fungus.