Answer: Unfortunately it sounds like the plants have become stressed. I suspect it was the extended dry weather combined with cold temperatures that caused the dieback, although poor rooting might have also contributed. At this point the best you can do is wait and see how they begin to grow for the year, and then trim off the dead tips. You may be able to train a side branch from the top to replace the lost leader. Dead wood will not resprout, it will be off color, dry and brittle with no green inside the bark. Take care not to overwater, this plant is very sensitive to overwatering and you could damage the roots if you keep the soil wet. You might also wish to consult with your local county extension to try to make sure there is not a pest or disease problem at work. I'm sorry about your trees.
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