gardenia bushes

Question

My gardenia bushes have a black film on the leaves. I can wipe it off with my fingers. What causes this and how do I get rid of it?

Answer 1

This is sooty mold. It happens when the plant gets a pest infestation. I would recommend using neem oil, as this will get rid of the sooty mold fungus and kill the pests. Here is some articles that will help you:
https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm