Question

Pistache Tree  

Pistache Tree   Additional photos of Pistache tree from 8/5/12

Answer
Anthony:
From your additional photos, I do see additional cracks in the bark with discolored wood beneath.  The damage may be more extensive than the previous photos. Damage to the bark and cambium will inhibit food transport from the leaves.  I would expect to see leaf yellowing and possible wilt as conditions progress.  You may wish to consider replacement at some point, especially if long term survival is desirable.

Mulching is good for trees when applied properly.  It should be no more than 3" deep and best to pull it back away from the trunk a bit.  Avoid the "mulch volcanoes" that we see often where the mulch is piled up against the trunk. This condition is a good hiding place for insects.

Regards
Steve