Question
You commented earlier about excessive leaf loss due to water fluctuations, probably too little moisture.  I'm having a similar problem but the tree in question may have been getting too much water due to a sprinkler problem - trunk starting to show green 'moss' nearly 4 ft up.  The tree, normally dense, is now thinning incredibly.  I've corrected the sprinkler breakage and direction of spray to not hit the tree.  Should that save the tree?  Should I worry about the leaf drop?   The tree 10 ft. adjacent is doing fine.  These are nearly 20 yrs. old.  Southern CA, current experiencing 100+ heat and some humidity.

Answer
Hi Annette:

Just as not enough water can be detrimental, too much can be stressful too! If the soil doesn't drain very well, the root/soil environment becomes unsatisfactory.  Extended periods of saturated soil can create an anaerobic condition in which the roots cannot get enough oxygen.  The soil in those areas can develope a "sour" or sewage-like smell.  This condition can lead to root diseases, which in turn can be manifested as leaf drop and eventual tree death if not corrected.  Soils that contain a lot of clay tend to have more problems than those with sand.  In the case of your tree, time is the best answer.  Survival depends on the present condition of the roots and whether or not damage isn't too severe.  It is just a waiting game.  This tree sounds as if it is well established, so this will be in its favor.  Hopefully the leaf drop will be temporary and you will get another flush of leaves.  I would not be too concerned about the "moss" at this point as much as getting the sprinkler issue resolved.

Always be sure to avoid damaging the bark.  It is amazing how much damage is done to trees every year by lawnmowers and stringtrimmers bumping up against the tree and scuffing the bark.  Damaging the bark can lead to serious irreversible problems.

Enjoy your carrotwood.  I use to sell these trees at a nursery in Florida.

Regards
Steve