Sweet gum tree
Planted 100 sweet gum trees in 2011, about half of them growing up to more than 8' tall. But every year some of them just wouldn't grow "normally". The main stem dried up but new grows popped out from bottom of the stem (Pic. 2, these two pics. showing the same tree. The left picture showing some twigs trimmed away.). There're many new grow twigs around the dried stem like a shrub. My question is would these new grows survive next year? Should I keep taking care of these "shrub" like sweet gum like those healthy ones I trimmed and cut every spring? (Pic. 1 showing healthy ones with a "shrub" like one standing between them.)
Genesee County Michigan
This tree has trouble with temperatures that get below -15 in the winter and we had this happen in late January. It looks like when the stem died back it allowed new shoots to come up below the graft. Often cultivars (unique varieties) are grafted onto to normal root stock, so what comes up below the graft is the common form of the plant. If you can cut out the dead stem and select for the most vigorous shoot you may be able to grow a decent plant. If this continues to happen in very cold winters even to the sprouts growing from below the graft it would not be worth keeping them.