Hi, I need advice on orange disease. Don't know what disease my orange has in the photos? The leaf fall off. How to help him? I changed the clay but the leaf fall off.
Perhaps it's mesophyll collapse: Citrus: Identifying Diseases and Disorders of Leaves and Twigs—UC IPM.
It does not look like mesophyll collapse to me, but it is plausible. To me it looks like some form of bacterial (more likely) or fungal infection based on the pattern, particularly the darker and probably expanding edge if the dying area. I would strongly suggest removing all the infected leaves and disposing of them in the garbage or burning them if you have the facilities. Those types of infections tend to spread... alternatively, look into copper based sprays.
