I think it's peach canker. I hope more experienced peach growers will chime in. I was told that with canker, nothing much you can do but keep the tree healthy and vigorous so it can recover from this fungal disease. It depends on where the canker is. When possible, you could remove the affected branch. I've heard that some trim off the affected area and spray with fungicide.Never try it. I usually let my trees heal their canker wounds. So far, canker has not killed my peach trees yet. Also, look out for peach borers, too. It's an insect that attacks the base of your tree. Look around the base for oozing jelly-like stuff. In our area, growing peach is a lot more challenging than apple or pear.

Guy: The ooze is the egglaying site of the oriental fruit moth. You may not be able to find larvae now, but wait a while. As the fruit ripens, they will show up around the pit, causing deterioration and rot and rendering the peach useless. The OFM is a persistent insect that can have three or more generations, especially in warmer climates. You omit your location both in your post and ID line, so I can't make a judgment on that. Imidan is effective against OFM, but on a 10-14 day schedule you may not get them all, and the residual effect of the insecticide may be insufficient to be 100% effective. Permethrin is also effective against OFM, and I use it extensively on stone fruits. I do not use Diazinon as a cover spray on tree fruits. If you have only 10% damage, then your spray program has been 90% effective, which is not too bad for this insect in an area where OFM pressures are high. But, depending on where you are located, there may be weeks to go before picking ripe peaches, and every night is another opportunity for the OFM. Some backyard peach growers have taken to installing shoe store try-on footies on their peaches, tying them over the twig or branch the peach grow on. Footies are very effective against OFM and plum curculio as well, and may be left on the fruit until it is fully ripe. There has been quite a bit of discussion of the footie phenomenon in the past on this forum, and you can probably find much of it with a search. Don Yellman, Great Falls, VA

Sometimes this leakage is caused by borers, sometimes it's due to wetness with the high sap pressures of early spring. Hose off the gel and look carefully around the base or where the sap was of the tree. If you do not see borer holes you are in the clear. Just leave the tree alone and it will heal itself up. It's also not a fungus or other disease. I have had this happen several times on young peach and nectarine trees. If it is borers get a insect spray for fruit trees that will protect it you can dig out the borer with a coat hanger if you have them. Your not giving your location so it hard to know your weather...but those trees look great you do need to trim them or thin some peaches in the future to get a bigger peach, It also helps the tree with less stress on the branches. I wish I didn't need to spray my trees and could have what you get...that' s great! Md

I always called Botryosphaeria dothidea blister canker or Botryosphaeria canker, which is a better term as some other fungi are also called blister canker. Gummosis translated is a condition of gumming. ___Osis, is a condition, not a disease, more describing conditions and not cause. And those are all cankers shown in the photo. It looks like that is what this is. When you first said fungal gummosis, well Leucostoma Canker is also a fungal gummosis but would agree this looks more like Botryosphaeria canker. The other fungal cankers look different. http://pubs.ext.vt.edu/450/450-726/450-726.html