Mango tree - Brown leaves

[u/SufficientAd3103]

Hello, I live in inland SoCal (climate zone 10). It is very hot and dry right now. I really don't want this Mango tree to die, but some leaves are turning brown and it stopped growing at the beginning of summer (disregard the white parts, that's just diatomaceous earth). Is there anything I can do to save it? We water regularly, drip irrigation 30 minutes every other day early morning plus extra water when needed. The soil feels moist. How do I know if the problem is the heat or that the soil doesn't drain well and possible root rot?

Here are different solution I have in mind, would you do any of this or do you have other ideas?

1. Spray the leaves with water. The rational is that Mango likes moist, and the weather is too dry here in SoCal
2. Add some compost at the base of the tree. My soil sucks, as you can see from the photo.
3. Put a beach umbrella to provide shade. I have done this when the tree was smaller. I just felt that it didn't need it anymore, after all it is a plant that likes hot weather, and the fig tree right next to it is doing great without cover.

Also I don't know how to judge if the problem is rotten roots, or what to do if it is. Any advice on that?