Mandevilla plant

Question

Underside of the leaves have become a rusty orange color! However, the plant does have blooms! What could be the problem with the leaves?

Bonnie

Answer 1

This is Rust Fungus and can appear when conditions are damp combined with lack of air circulation.
This article will help you.

https://www.gardeningknowhow.com/plant-problems/disease/learn-about-plant-rust-disease-and-rust-treatment.htm