I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
It may be due to a root circling the base of the trunk and strangling it. Dig down six inches around the base and look for such a root. If you find one cut it and remove it. Otherwise try giving it moist soil conditions for a while to get it growing more rapidly. Fertilize the entire area beneath the branch spread with a cup of lawn fertilizer per 25 square feet of surface area.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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