Are brand new leaves light green (or no new leaves for a while)? If so, I believe that's a pretty severe nitrogen deficiency. For a short term fix you can give it some nitrogen fertilizer, and for a longer lasting fix, start putting composted material (especially manure) around the tree every fall and spring (try to keep it off the trunk though). Also might be worthwhile to add some time released fertilizer to it every season..

Thanks iAndy! This tree has had no leaf growth until recently and that was after I fed it miracle grow liquifeed in desperation a couple weeks ago. What's spooky though is that I fed this tree with AZ's best slow release granules and mulched it with worm castings in early September yet it's still nitrogen deficient. I'll probably just add the manure this spring- hopefully that does the trick.

Here's the new growth

Chelated iron should help. I sometimes make a 'cocktail' of Ironite and Super Thrive, it perks them right up. Ironite will stain the container red that you use for mixing the cocktail. Google iron chelate for some info. Good luck.

I agree with the suggestion of chelated iron, that's classic mineral deficiency you've got going there.

Check out http://cals.arizona.edu/pubs/crops/az1007/contents.html for good diagnostic pics and info.

Just like a broken record, I recommend adding zinc. Almost always low in our alkaline soils.