Chinese Elm Dead or Dormant?

Hi from Arizona!
I planted 2 24" box chinese elms in April this year. I noticed last month that one of them started to turn yellow, then a week later-completely brown! The other one is still green. I scratched the trunk and I don't see any green. Is this tree dead or did it go dormant really early? The temperatures here are still 85-90 degrees. And if it did die, how? Both trees are in the same watering schedule. Please help- is this normal for this tree? Thank you.

daisyh

 

Is it dry and crispy?

 

Yes. The leaves are brown and dry and crispy.

 

What about the twigs?

 

Yes, the twigs are dry and crispy as well.