This is my avocado tree and some of its leaves are turning brown. Some of the branches are also turning brown and the whole branch eventually falls off.

Any idea what is going on? I'm assuming its leaf burn but I have no way of knowing.



[/img]

looks like salt damage but the whole branch dropping off could be setting root rot.

Assuming its one or the other, what would be the treatment for both?

For salt adjust your water with sulfuric acid at around 45ppm or add gypsum to your soils and leach out.
If its a root rot issue, depending on the amount of damage, adjust your irrigation schedule if there's allot of damage it may be to extensive to save. If its in the ground and small enough you could remove and replace to a drained location or amend the location where it's at, if it's in a container adjust the mix to a better drained mix.
In a container you can remove the tree and trim the dead/rotted roots off, also trim the foliage to allow whats left of the root system to recover and replant... you can also do the same thing if it's in the ground but depending on the size of the tree to root system might be to big and you'd cause to much damage to recover the tree

Its in a pot. I planted it before I knew anything about trees and found this forum. I believe its in regular potting soil. Would they do well in CHC like citrus or is there another mix I should try? I do have cactus and palm mix that I was going to use for my citrus before I got CHC.

I don't use CHC so I can't say if that's better or not, if it's in a container have you checked to see if it's root bound?
Avocado's are LARGE trees you'll do better if it's in the ground. Being confined to a container it might just have a number of trace elements that are lacking for good foliage growth.