Hi! We love our hibiscus - affectionately named Bessie. We recently noticed a fungus or mold or pest on her and are wondering what it is and what we should do to help her out. Thank you! She's the only plant I've never accidentally killed and she made the recent move from Michigan to Florida with us! She's a survivor! Thank you for your help and expertise! ps The effected area only seems to be on certain parts of her, and is not on every leaf.
Your hibiscus appears to have a whitefly infestation. It's hard to tell for sure but the flower bud looks covered in whiteflies. It could be aphids and close inspection will reveal the culprit. The bugs' secretions create perfect conditions for sooty mold to develop. Both can be treated or you can prune out infested/infected branches and carefully monitor. https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm