Four years ago we moved and inherited an old Azalea which never looks healthy but it flowers quite well every year. The top of leaves are covered with very fine white specs and they are curled. Next to this we have a Rhodedendron and the leaves on that do look a little yellowy but there are no white specs. Any ideas please.
Certified GKH Gardening Expert
It sounds like both plants could use some fertilizer. A balanced fertilizer or a azalea/rhododendron specific fertilizer will work fine. The azalea sounds like it has aphids or scale. These pests are attracted to plants that are stressed by things like being under-fertilized or onder watered. These pests are both treated the same with a pesticide. I prefer neem oil myself because it is safe for people and pets and also addresses other issues the plant may have. Here is more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm