Black Soot on Camellia

Question

There is black soot like matter covering leaves of camellia tree.

Answer 1

It has sooty mold, which is a symptom of a pest infestation, usually aphids. Treat the plant with neem oil. This will help with the pests and the sooty mold. Here is more information:
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm
https://www.gardeningknowhow.com/plant-problems/pests/homemade-aphid-control-a-natural-way-to-kill-aphids.htm