Reducing Watering to soon?

In the fall I start scaling back the automatic watering of the Bonsai trees.  Any additional needed watering I would do by hand.  We recently had a stretch of cool fall weather so I dropped the watering to once every 3 days.  

That in it self is not the problem.  The problem occurred because I went on a 3-day trip and forgot about the change.  Two trees were affected and only one of the two appear to be damaged.

What is surprising it that it happened on two well established Hackberry trees.  Below are two pictures of the most effected tree.  The silver gray of the leaves because they dried out.  I first thought it had died buy scratching the bark reveals green substructure.  So at leas it did not die.  

I am hopping to see buds develop in the few weeks.  I'll provided an update later regardless of what happens.

[Photo] Damaged Hackberry tree

[Photo] Closeup of the dehydrated leaved.