Just Googled it. It sure does! I guess that's what it must be. Thanks a bunch! ^_^

It's hard to say for certain from just a picture. I will say that frequent shallow watering will cause the absorbing roots to stay near the surface leaving them susceptible to drying out when the watering schedule is changed or temps increase. Based on the fact that Mesquites, in general, can survive on the natural amount of rainfall that occurs in the desert these trees were given more water than they 'needed'. Is root rot possible? Yes. Could the roots have been stressed when you changed the irrigation? Possibly. The trees could also be planted too deeply. The link I included is a fantastic website for irrigation advice. Here is a link that might be useful: Irrigation guidelines

What are your temps like in Albuquerque this time of year? It might still be on the cool side. I can't tell you for sure, but I think it was in the upper 60s/low to mid 70s before my Prosopis juliflora leafed out completely. My Prosopis pubescens (screwbean) is a bit behind and hasn't fully leafed out yet.

The fact both trees are a bit slow ought to be a clue. You've got transplants and it takes at least a full growing season for these things to establish. While we were moist this winter, did you water? Mulch? Even the xeric plants need some help. Also remember new plants are putting energy in establishing a root system (thankfully) so may be slow. And as just mentioned above, mesquites are slow.....and if in a cold area, can die (but not this winter). When in doubt about any woody plant do two tests: 1. Feel the limbs. On the side away from the sun, it should be cooler than air temp indicating water movement. If its air temp, chances are it's gone. 2. Flexibility......bend some stems, branchlets, etc. If flexible, not brittle, there's still hope. I'm in a cold pocket near the river, my fragrant ash, vitex and desert willows are just leafing out.