posted 7 years ago
I get a lot of that with my stone fruit trees. It may just be evidence of a very healthy tree, putting off too much sap because the tree is producing so well. Is there actual evidence of borers?
Trees produce sugars as a result of photosynthesis. (You already know this, but bear with me). When they fruit, much of those sugars are given to the production of big ripe peaches, pluots, apples . . . whatever. But 60% of those sugars are actually transferred down into the root zone of the tree where they are either stored or secreted out into the soil in the form of root exudates. Basically, the tree is feeding sugars to the microbial life that surrounds the roots. Bacteria and fungi feed on those sugars, and in turn, provide minerals and other nutrients to the tree. It's a symbiotic relationship, as fungi are unable to produce sugars themselves.
As the tree senses winter coming and the old tired leaves begin to shut down and fall off, the tree begins to pull as much of that sugar-filled sap down into the core of the roots. This food source gets the tree through the winter, and when it breaks dormancy in the spring, all that wonderful sap gets pulled upward toward the branches where it will be needed to support a flush of blossoms and new growth.
Right now, as the tree is preparing for winter, there is an excess amount of sap/sugar/food. Your tree is literally leaking—it's squeezing out through the phloem and out through fissures in the bark. Your tree isn't quite ready to pull it all down into the roots, but it's not needed to produce a bunch of fat fruit or put out a bunch of new leafy growth. My hunch is that those blobs or sap are evidence of good things happening, not insect damage. But I'm not there to take a good look at it, so don't take my word for it. Pluots, apriums, apricots . . . they all tend to kick off a lot of excess sap when they are growing in ideal conditions (lots or water, lots of sunlight, healthy soil).
Before you start spraying, make sure that there actually are borers. No reason to treat something that isn't a problem.
"The rule of no realm is mine. But all worthy things that are in peril as the world now stands, these are my care. And for my part, I shall not wholly fail in my task if anything that passes through this night can still grow fairer or bear fruit and flower again in days to come. For I too am a steward. Did you not know?" Gandolf