Answer: What you describe is gummosis and is common on apricot, peach and cherry trees. It is usually caused by a fungus (Cytospora), but the oozing can also be a sign of boring insects. While an insecticide might control the insects, it will do nothing to treat the fungal disease so be sure to carefully inspect your tree before proceeding with treatment. Here is some background information:
The fungus enters through wounds caused by winter injury, pruning cuts, insect punctures or mechanical injuries. The infected bark tissue exudes gum. The tissue dries out and breaks away as it is killed.
The fungus over winters in live bark at the edge of a canker. Cankered areas may or may not be surrounded by a roll of callus. Cankers enlarge yearly until the limb or trunk is completely girdled. Gum production is almost always associated with cankers.
The fungus becomes active in the spring as the tree becomes active. Tree growth may callus off the infection. However, as tree growth slows, the fungus invasion may move beyond the callus barrier.
This disease can be confused with damage caused by the Peach Tree Borer (aka Peach Crown Borer). As this insect feeds in the base of the tree a gum is produced. Damage caused by this insect, however, usually does not extend above a foot from the ground. The ooze resulting from the feeding activity of this insect is not the clear amber ooze produced by Cytospora; it contains frass from the feeding activity of the insect.
If you are dealing with Cytospora rather than borers, a fungicide will sometimes help. I suggest you contact your local Cooperative Extension for current control measures.
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