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Question from Cynthia, Holladay, UT (received 5/15/20) -
I live in Holladay, Utah. I just found that my recently transplanted peach tree (two years ago) is leaking sap badly in several spots. I've read about the borer pest but is that likely the cause this early in the year? We replanted this tree in my yard from an orchard In American Fork that was going to be cut down for development into housing.
Answer from Gabrielle Harden, USU Forestry Extension Educator (sent (5/18/20) -
Cynthia,
It appears your peach tree has gummosis - prolific oozing of sap. Many stone fruit trees are sensitive to injury, and this can result in sap leaking from the trunk in the spring. This can be caused by different biotic (living) and abiotic (nonliving) factors - Chemicals, insects, disease, growing conditions, or wounding damage.
To help identify which factor is contributing to the gummosis, it is best to rule out the most destructive first. Insects will leave exit holes and frass (similar to sawdust, but very finely ground). If insects are causing the gummosis, the exit holes and frass will be visible beneath the sap. I can not see any in the photos, but I suggest you do an up close inspection to ensure that insects are not to blame here. (If you see something but you're unsure, send a photo)
If you've treated the area around the trunk with a chemical herbicide, this could have made the gummosis worse, as it is easily absorbed through the trunk. It is also important to consider how the tree is being watered. If you have a sprinkler system that is putting water on the trunk, this can lead to damage and eventually gummosis. Make sure the tree is only being watered around the base.
Pathogens can also be to blame. When a tree is stressed from any of the previous reasons, they are more susceptible to disease infection. Fungal gummosis causes blisters and raised lenticels - which cause cankers. The areas around the canker then ooze an amber-colored sap in the spring. Because I am unable to see any evidence of insect damage (again - get a closer look - you will be able to see better in person than I can in a photo), I suspect this tree is infected with the fungus Cytospora.
This fact sheet briefly describes the various pests of peach trees.
I would also recommend a quick Google search of peach tree cankers.
Unfortunately, once insects or pathogens get into a tree, there is little that can be done.
I hope this helps.