This stuff has already killed my jasmine plant and now is starting on my gardenia and hibiscus. I can't tell if it's mealworms or white mold.
White Fuzzy Stuff on Plants
Certified GKH Gardening Expert
This could be Mealybugs, fungus, Powdery Mildew or a few other issues.
Treat the plants with Neem Oil.
This works as both an insecticide and fungicide.
I have a listed a few links for you with more information.