You shouldn't spray until you know what you're shooting at.

Then, too, only a few damaged leaves should be ignored.

So how many leaves are affected?

Do you have deer?? The deer tend to ignore 99% of my tropical plants that go out for the growing season. But hibiscus frequently appears on lists of plants that deer love to eat. I only learned this after they ate my plants (flowers, leaves, stems,..)

buddyzzz,
Are the leaves turning yellow and dropping all along the entire length of stems and then the stems also turn yellow? This is what's happening to one of my hibiscus and now whatever it is seems to have spread to a nearby hibiscus. The whole stem drops its leaves and eventually turns yellow. Then it spreads to another stem on same plant. I think it must be bacterial, fungal or viral. I'll see if I can post a picture on here somewhere.