Hi, 

We can see borer holes at the bottom. It is likely from peachtree borer or lesser peach tree borer  which tend to seek out stressed trees. 

Unfortunately at this time there isn't a cure or solution to get them to leave and save the tree. Any recommendations on the link provided are for fruiting cherry trees and the cost of the pesticides is not warranted for homeowners with ornamental cherry trees.

You can keep the tree watered in times of drought (right now) and watch for signs of die back in the upper branches. If the tree is a safety hazard, we would recommend getting an arborist to evaluate and prune or remove as needed. You can find an arborist in your area by searching at https://www.treesaregood.org/findanarborist. 

Emily

Plants cannot heal in the way that people do, and sap ooze (gummosis) is not part of the healing process; its function is mainly to try to smother or push-out a borer or pathogen. However, gummosis can also occur simply due to environmental stress, a phenomenon quite common in cherries and their relatives. It's also possible two or more conditions are overlapping, where borers and general stress, or borers plus an infection like canker, are affecting the tree at the same time. Borers generally attack trees that are stressed or wounded, even if indications of that stress aren't evident at the time an infestation begins. Stress can come from one-time or recurring drought or under-watering, root zone flooding or over-watering, being planted too deep, and root loss from construction, utility digging, etc. The trunk's lack of a visible root flare in this instance suggests that it was planted too deeply and/or over-mulched. (The linked pages provide more information.)

Removing the sap as it congeals on the surface doesn't accomplish much, other than perhaps making it easier to assess if it's building up again or slowing in production afterwards. By cutting into the bark or wood in an attempt to reach borers, the benefit might be being able to kill some of them, but the cost will be greater injury to the wood and vital sap-conducting tissues, which lie just under the bark. Every wound takes time to seal-over, and risks invasion by wood decay organisms (fungi, etc.) in the meantime. Not all borers feed in this cambium layer; some tunnel into heartwood, which is naturally already dead wood. (The more serious borers are in cambium, though, and that's when we would expect to see more gummosis as a result.)

Peachtree Borer, a typical pest of cherry (though not the only possibility), could be discouraged from establishing a new generation by treating the bark with an insecticide yearly, around the time adult moths of this species are active. There is only one generation per year: adult moths lay eggs on top of the bark; larvae hatch and bore into the wood; the larvae pupate just under the bark; and adult moths emerge from those pupae to find mates and begin another cycle. Late June to early July is when the adult moth's emergence peaks in Maryland, on average. Hotter years might see a shift to a week or so earlier than in cooler years.

Larvae cannot lay eggs, and the moths do not lay eggs under the bark or in sap. Orchard managers use mating pheromone traps to determine when moths are flying and active, so they know when to apply bark sprays to kill hatching eggs or discourage egg-laying. Such pesticides are not borer-specific and could harm any other insects coming into contact with the spray residues, which is one reason we do not encourage their use outside of farm settings. They also don't address the reason why borers may be drawn to a particular tree in the first place, which is usually stress or injury.

Miri

You're welcome!