Currently, it is getting half a gallon of water every other day.

===>>> does it need that much.. that often ... are you guessing.. or inserting your finger and finding out.. it its actually near drying in between heavy watering ...

how long has it been in the pot.. and that media... such wears out ... and can be a reason... it needs so much water ...

so.. i am thinking a water management problem.. is stressing the plant... and once you have a stressed plant .. all kinds of things can overlay that basic issue ... but if you solve those.. w/o addressing such .. you dont end up winning ...

i cant recall offhand.. what forum used to carry a heavy load of A questions ... fruit.. houseplant.. or tropical fruit ... you might want to peruse around them ...

ken

There is an avocado forum on Garden Web. You will get help there. http://www.gardenweb.com/forums/avocado-growers
My avocados are in ground. Our soil is well drained. The trees are on 2 gallon emitters for 45 minutes every other day. I have one in a pot. It's a sacrificial tree. It will serve as budwood to graft onto a 6 year old seedling. It gets the same water schedule as those in ground, but it's pot is HUGE and it's outside in full sun. Very healthy.
I haven't seen a problem like yours, but those in that forum may help you.

thank you suzi! I'll try the avocado forum!