Sorry you didn't get a reply earlier.
Has the cherry's leaves been eaten up more -- definitely something's eating them.
If it is not significantly progressed, I wouldn't worry about it too much -- it can handle it. But if the tree is being defoliate at a rapid pace, you'll need to take action.
Three possibilities are slugs, caterpillars, and/or beetles.
This time of the year, Japanese beetles are a good possibility.
If the weeping branches are touching the ground, slugs can make their way up, but they feed mostly at night, so go out in the dusk or twilight, or on a rainy day, or take a flashlight and inspect.
You may also come across night feeding caterpillars.
Check also for tent caterpillar nest somewhere on the tree.
Once you ID the culprit, you'll be ale to take appropriate action. Even though this is an ornamental, treating a tree means extensive/significant spread, so it would be best to consider your options wisely according to level of toxicity, environmental and personal safety, etc.
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