Brown Spot On Mango And Fly Insect On Leaves

Question

Please advise how to treat the tree

Answer 1

Likely, they are related. I am unable to see the pest, or damage in question, though, as your photos did not come through.

What I can do, in the meantime, is point you to some articles that will get you started on assessing and correcting the situation:

https://www.gardeningknowhow.com/special/organic/natural-home-pesticides-organic-garden-pest-control.htm

https://www.gardeningknowhow.com/edible/fruits/mango/mango-tree-diseases.htm

https://www.gardeningknowhow.com/edible/fruits/mango/growing-mango-trees.htm

This link will help you to find your local extension service. They can help to ID the pest and disease in question, too!

https://www.gardeningknowhow.com/extension-search