My older azalea bushes (19 yrs) have a yellowish/rust color on the top.
Azaela Bushes Have a Yellowish/Rust Color on the Top
Certified GKH Gardening Expert
Your azalea may be suffering from rust disease. This article will help you with your rust problem: https://www.gardeningknowhow.com/plant-problems/disease/learn-about-plant-rust-disease-and-rust-treatment.htm
it's not the branches they are fine, the leaves are the problem with yellow and rust color on top and black spores on the backs of them the new leaves are a nice bright shiny green as they should be, but there are not many new leaves
do you think it is missing a nuetrient of some sort?