fruitless mulberry tree

Question

The leaves are turning lime green with the veins showing. I thought maybe they needed
iron.

Answer 1

This is more likely watering needs.

Fruitless Mulberry do need watering regularly.

They can suffer from cotton root rot, borers and vascular diseases.

https://www.ehow.com/info_8587965_mulberry-leaves-turn-yellow-drop.html