We have a fairly new tree (around 4 years old) in the front yard. It grew
pretty fast and was approaching the 20-ft level. A few nights ago, a gust of
wind snapped off the top six feet of the tree. The rest of the tree looks
fine, but still needs pruning of the lower branches. A nursery told me to
point a branch near the break to vertical so it would become the central
leader after applying a thin coating of prune sealer to the break. I have a
bungee cord holding the new leader in place pointing straight up and have
applied the sealer.

1. How long do I need to keep this branch tied up?
2. Can / Should I still prune the lower branches this winter? They are
really obnoxious and would they hinder the healing up top?

Thanks
m