Q.Azalea Leaf Problem
I am wondering what is causing this leaf rust looking problem on the azaleas I planted last year. It happened last year as well. We planted two of these about 40 feet away from each other and the one has this problem and the other does not, at least to this extent. I thought the two plants did not make the winter but around June we finally saw some leaves starting and now both plants seem to be leafing out good, but this rusty stuff is showing up again. We live in the woods and the soil originally is very much clay but this area has been the garden for decades so the soil is better but still mostly clay and in the pine forest. Thanks for any ideas.
Orange or rust coloring, especially on the undersides, can be caused from rust fungus and is treated with fungicide. Leaves will normally regrow. Other issues could include pests. Look carefully for any signs of pests, which can be treated with neem oil (also doubles as fungicide). Here is more information: https://www.gardeningknowhow.com/plant-problems/disease/learn-about-plant-rust-disease-and-rust-treatment.htm