Black spots & yellowing of leaves on my hibiscus plant
What do I use to stop the leaves from dying of black spot?
Certified GKH Gardening Expert
A hibiscus with black or brown spots on the undersides of leaves is likely suffering from an infestation of black scale insects or a leaf spot disease.
Because they don't move around, scale may not initially be recognizable as an insect and may be mistaken for a disease. Black scale insects secrete a sticky honeydew which attracts a black sooty mold.
Prune heavily infested branches. Prune also to allow more air and light into the canopy as this can help kill young scale insects, who are sensitive to heat and light.
Bacterial and fungal leaf spot can cause black or brown spots on both the upper and lower sides of leaves. Though unattractive, these spots rarely cause serious harm to the plant and often go away when the weather warms up. To expedite the process, remove heavily infected leaves and branches. Sweep up any fallen leaves. Leaf spot diseases are encouraged by wet conditions, so avoid overhead irrigation and water in the morning so that splashed leaves have time to dry out before nightfall.