A smoke tree issue?
+6
I friend of mine has had a Smoke Tree for several years. It has several trunks and all but one split clear through this spring. Leaving her with only one live trunk (branch), we live in zone 4. Any ideas what happened? 
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Hello Robin,
Did you have the "Beast from the East" visit your area (Very strong winds)?
If I understand this article, the others should be removed. Take a look and see:
https://www.thespruce.com/growing-a-purple-smoke-bush-3269235#common-problems
How old is the smokebush? A number of tree varities become stressed when they have multiple trunks. Look carefully to determine if carpenter ants or similar invaded the trunks. For precise answer, take a good photo /photos and take them to a local Master Gardener or arborist at a local university or nursery.
Hello. Its hard to say without a photo, some thin bark trees split during weather conditions at wintertime. I used tree wrap on my October Glory Maple because of this problem as the bark splitting- cracking was damaging the tree growth and development in a vertical plane above the splitting. Not sure if my situation is similar to yours...
Usually frost or sun scald is the cause
https://tomlinsonbomberger.com/blog/cracks-and-splitting-in-tree-trunks/
Hi Robin: It could be because of freezing. The most common cause for splits in trunks is from frost cracking or sun scald. Sun Scald most often occurs on the south to southwest side of tree trunks on young trees with thin bark. On a warm winter days, the direct sun's heat warms up the surface of the bark. Later that night, these areas rapidly re-freeze. Sometimes, Splits can occur on the trunk of the tree as well as on branches. ... Excessively late growth in the fall stimulated by warm temperatures, high humidity, and high nitrogen levels can increase susceptibility of trees to frost cracking. Some trees simply can't be saved or are not worth saving. If the tree has already been weakened by disease, if the trunk is split, or more than 50 percent of the crown is gone, the tree has lost its survival edge.
I found a discussion regarding this problem, and here's what was said: the way its sprouting from the ground.. its probably all dead above ... and i wouldn't put much stock in a few piddly leaves ...the future holds a new shape and form for your tree ...
either wait and find out what is dead above and remove it ...or cut it all down now ... leaving only the lush low growth ...with no insult to the mature root mass.. it will probably be near as tall as it was prior.. by fall ...reduce the number of suckers... to as many as you want ...i would call it.. bad winter damage it will never look like it used to ... but perhaps.. you can train it into something better ....ken" Hope this helps. Good luck
here is info that may help you out - you could call the extension service in your area or a garden center also to ask their advise and see if they have anything that will help good luck