Best way to handle only partly dead river birch
Heritage River birch trees seem to sprout fairly easily in my area.
I have a single trunked Heritage birch planted early last fall. At the time it had been stressed enough for the top canopy to be leafless with one long lower branch about 5 feet up the trunk that did have some leaves.
I planted the tree in an area where it can access moisture and soil saturation from runoff of my nextdoor neighbor's lot.
This spring the tree has produced water suckers that are full of leaves and which are growing all up and down the previously clean trunk. Above, all this green up, there are no leaves at all that have grown on the branches of the canopy which starts above all that new growth I just described.
The top branches in the canopy are definately dead, dry, and brittle the lowest branch which was the only one to leaf last year is still a little flexibe and definately not brittle yet.
I planted the tree hoping to get its roots established enough for them to send up some root srouts that would take on the roll of becoming the tree's main trunks.
Question: When should I cut of the dead canopy and upper trunk from which, previously, those dead branches had grown? Also, am I correct in my expectation of this tree's potential to survive and confidence in its ability to overcome its challanges enough to develop into a healthy and well structured tree?