Why are some of the leaves on my citrus tree curling, bubbling, and falling off?
Typically these are the symptoms of a fungal disease commonly known as ‘leaf curl’. Typically you need to catch this early and spray fungicide when the tree is budding. By the time you see the symptoms the damage has already been done and it will be too late to spray. You can spray with pest oil but traditionally you need to start spraying in September.