Well, you need to fertilize regularly, 3 to 4 applications from February through about September in your area. Be sure you apply the fertilizer at the drip line (edge of the canopy) and not at the trunk. Water your tree well, apply the fertilizer, then water in. Sprinklers should not be hitting your tree at all, you should have your tree on micro-sprinklers pointed out away from the trunk, and spraying out at the drip line. Prune out any dead wood from inside the tree (this is not unusual for older citrus to develop dead wood inside the canopy), and prune very lightly for shape. If the tree is getting too tall, drop crotch prune your tree to bring down the height (Google drop crotch pruning, and you'll see how it's done, or call a GOOD tree trimming specialist and ask them to drop crotch prune your tree to bring down the height). Painting the trunk with a 1/2 strength flat white latex house paint in your area is a good idea, due to your intense sun.

Patty S.

Here is a link that might be useful: Citrus in AZ