Peach Tree Bark Damage

Question: Hello!  I am desperately in need of some help.  We planted two Reliance peach trees about three years ago but I haven't been able to make them happy.  We've always made sure they are well watered (about 3-5 gallons weekly the first year and 1-2 gallons thereafter) and I feed an organic fruit tree fertilizer at the beginning of each season.  I haven't pruned them yet because I don't know how but I know this is important. I would love to learn how. 

To provide a brief overview, each growing season, the leaves get little brown spots on them and then turn yellow and fall off on what seems like the lower half of the tree along with any fruit.  This year, as usual, the trees started out looking healthy and while the fruit did stay longer, the trees went through the same process of losing their leaves and tiny fruit (only one stayed and grew into a small, juicy peach).  When the tree started dropping leaves, I noticed the trunk looked "chewed" up in spots.  Upon looking closer, there was stuff oozing from these spots (I've since learned this could be a sap for healing?).   

I tried an internet search and also posted to an area Facebook page but I'm still not certain what I'm looking at.  I don't see any holes that might suggest bugs. The attached photos were taken in June and I have since pulled the mulch back at least a foot from the trunk.  Someone suggested the tree may be buried too deep (I later found out I didn't dig the hole wide enough after seeing local community apple trees being buried).  Perhaps, I need to carefully dig up the trees and replant them (they do not have any type of burlap wrapped around them as another person asked).

If anyone might have an idea of what could be wrong with my trees, I would be most grateful. I'd also love to know if there are any pruning classes available to the public.  :)

Thank you kindly for any help!  ~R

responder: Thank you for contacting the Infoline, a service of UNH Cooperative Extension  Replied September 05, 2024, 10:29 AM EDT
response: Hello Rebecca,  Thanks for reaching out to the UNH Extension Infoline.  We do offer pruning classes in the late winter and spring. Keep an eye on the UNH Extension events page which is where we post all of our workshops and classes.  So, it looks to me that your tree is suffering from a canker disease which is fungal in nature and very common for stone fruit trees. While you may not have dug wide enough holes, I would urge you not to dig up the trees at this point because that will add more stress to already stressed trees.  Treatment of canker diseases is not very simple and involves fungicide spraying, cutting out the infected parts, and patience but it can be quite effective.  For a detailed explanation on what you'll need to do, see this resource from Penn State Extension- https://extension.psu.edu/stone-fruit-disease-cytospora-canker I hope this is helpful and please get in touch with any further questions!

responder: The Question Asker Replied September 06, 2024, 9:05 AM EDT
response: Hello - Thank you for your expertise. I have read the PSU Edu. page regarding doing surgery to remove the canker disease. It says the best time to perform this is in May or June. So, is it okay to leave the canker disease to grow until next May. Or, should I address it now (in September).  With winter coming, I wasn't sure if it matters. Also, someone mentioned O need to protect my peach trees in the winter. While I *believe* I have Reliance Peach Trees, I did not get them from a nursery but am going by trust in the individual who sole them to me. At the office chance they sold.me a different variety, would it hurt to protect the tree even if it's a Reliance variety? And how does one actually protect the tree of its okay to do so?  Thanks in advance!!!

responder: Thank you for contacting the Infoline, a service of UNH Cooperative Extension  Replied September 06, 2024, 11:07 AM EDT
response: Hi Rebecca,  At this point in the year I would be afraid that the cuts wouldn't seal up in time for winter, which could lead to more damage. While removing the cankers is time sensitive for the longevity of the tree, I would still probably wait until early summer next year.  For peaches in our climate, the biggest cause for concern is the freeze/thaw cycles that happen in March/April. Cold nights followed by sunny days can cause the bark to crack given the temperature differential. For that reason, we sometimes recommend painting the trunk of the tree with a white latex paint diluted with equal parts paint and water. However, with the canker, I don't think that's the best option for you.  I think it would be best to leave it be, hope for the best this winter and plan to do the surgery during May.