A: The first thing that stood out to me with this question I received is that, even without a known diagnosis, the homeowner’s first instinct was to use a pesticide. There are so many steps to take first before chemical treatment is considered.
If the issue is thought to be an insect or a disease, do some research. Look at a garden book, talk with a gardener, share a picture on a garden blog, or call your local county extension office. I put “Google it” behind all of these others for good reason. Search engines are known for their quantity of results, not necessarily quality. In the Internet’s results, look for articles that link back to websites ending in “.edu”. More than likely, these come from a university’s Cooperative Extension site or publication and are reliably science-based. Take those findings one step further- use the information from an extension that is your state’s or a neighboring state’s. What Penn State posts about hibiscus is not going to match the recommendations by the University of Florida.
All of that being said, I asked for more information about this photograph. I learned that the yard is fenced in and that the new leaves go partially missing or are completely gone (not falling off onto the ground). My thought is that something is eating the leaves, be it a rabbit or a deer. Deer can still jump fences if they really want to! My recommendation is to put a cage around the tree while it is young and monitor it.