What causes the leaves on Crepe Myrtles to turn yellow

Question

What causes the leaves on some Crepe Myrtles to turn a yellowish color but rarely fall off?

Answer 1

This sounds like a nutrient deficiency, likely iron chlorosis. Here is more information on chlorosis: https://www.gardeningknowhow.com/plant-problems/environmental/leaf-chlorosis-and-iron.htm

As a precaution, I would fertilize the tree with a general fertilizer too.