My camellia has a powdery black deposit on some of its leaves. It also appears to drop its flowers too readily. It is a mature plant, about 20 years old, and otherwise appears to be happy. Can you advise please?
Camellia Black Leaf Deposit
Certified GKH Gardening Expert
This is called sooty mold, which more often than not is brought about by some type of pest, like aphid or mealybug. I would recommend neem oil. We have found it to be very effective against these kinds of pests and will also help treat the sooty mold. These articles will explain more: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm, https://www.gardeningknowhow.com/ornamental/flowers/camellia/sooty-mold-on-camellia.htm