[Arid_gardener] Question from Home-Hort WWW page

[MTCactiPi@aol.com]

I have a red grapefruit tree planted in my yard in Tucson.  It was planted in the summer of 99'.  I have 8 two gallon an hour emmiters around the tree in the tree's basin.  The tree basin is about 7 feet in diameter.  The tree itself is roughly 6'tall and 4' wide.  I water about twice a week in the summer and once every week to two weeks in the winter.  My question, is my watering schedule approiate? Some of the leaves on the tree are light green, yellow and a couple are even whitish.  I fertilized as directed in Feb, May and August.  Iron was also added during the summer.  What can I do to darken up the leaves and optimize growth?  Thanks for any assistance.