I moved this tree in 2010; and watered it weekly until last summer with a soaker hose. Last summer, I assumed it was established, and started to give it just a light watering about every other day. Our summer here, was very hot and dry, and in August some of the leaves started to look distressed and sun scorched . When I crawled under its branches to reinstall the soaker hose I noticed the split in the bark for the first time. I'm sure this split wasn't there before the year's foliage covered the tree. I returned to giving the tree a good watering, with the soaker hose once a week until the fall rains returned in October. The tree dropped a good third of its leaves early ( they dried up and fell off) and the remainder changed color (color was more muted than normal) and fell off in the fall as they normally do. During the winter I noticed a fair amount of die off, of the smaller branches on the tree, more of them seem to located on the same side of the tree as the split (south side). I've removed the dead branches this week, and the tree is starting to bud. My questions are: 1-Was the split in the trunk caused by stress from a lack of water or could there be another cause? 2- To treat the split; should I trim as much of the dead bark away as I can and let callus tissue grow? 3- Are there any other remedies I should be doing? Edited to correct pictures!