Question
I have a hedge of crimson bottlebrush and some of them die.  I have replanted and some and they tend to last only a couple of years.  They leaves are yellow/green on some and others are healthy.  I live in the CA desert and have an ongoing irrigation.  I am not here in the summer so I don't know when they are affected but dead when I return.  A dead bush can be right next to a healthy one that is being watered by the same sprinkler.  I have not fertilized them.  Thanks

Answer
Hi Ginger, Without seeing them, hard to tell.  But since you said you are not there is the summer, it's probably a water/root disease/drainage issue.  The water needs of two identical, side by side plants are not the same.  Sun, wind, leaf count, root development, limb placement can all significantly affect the needs of the plants and the pattern of water they get.  There is no substitution for checking each plant.
They could be getting too much or too little water, the result is the same.  Jim