Cascalote tree losing leaves

 I live in the AZ desert and have a Cascalote tree [Caesalpinia
cacalaco] that my local nursery planted.  It's approx. 8 feet tall x 8
feet wide.  It was beautiful when it was planted four months ago, but
the tree is not doing well now.  The leaves are turning yellow, and
leaves are falling off big time.   I'm wondering if I might be over-
watering it (what are the symptoms of over-watering a tree???)   Also,
some of the leaves seem to have little specks of a white crystalline
substance on them -- it kind of looks like rock salt.   Is that a sign
of an insect problem?   Thank you for any information.
-john

 No thoughts or ideas?  Anyone?

 zgraf said:

The only though from way up here in Michigan is, perhaps
to consult the nursery.   They planted it for you.  Did they
offer some sort of guarantee?

Knock a branch over a sheet of white paper and check to see
if any tiny insects can be seen crawling on it.  (A quick Googling
suggests that psyllid infestation is possible in April/May.)

--
Pat in Plymouth MI
    
"So, it was all a dream."
"No dear, this is the dream, you're still in the cell."  
 
email valid but not regularly monitored
  

 
Thanks, Pat.  Appreciate the information.