With this being a Canadian (Red) chokecherry, you will have suckers. That is a given; and in that respect your nursery man was correct. This problem is being and will continue to be exacerbated by the incorrect planting.
With the height of the top of the cage visible, you have just reached the top of the ball not the root flare.
My concerns are the main root system may have been terminally compromised and, if so, the main tree is living on stored energy and the adventitious root system. If so, removing this system, which is what we would normally suggest, may hasten its demise.
The adventitious root system will continue to live without the main root system and, if the main tree does succumb, you can restructure with what you are left with if a clump tree is satisfactory to you.
A side note: There appears to be webbing in the crotches approx half way up the canopy. If these are eastern tent caterpillars, you should remove the web. The larvae feed on foliage and one or two colonies can completely defoliate a tree. Be sure before removing any dead limbs that they are, in fact, dead and not just defoliated.
There are a couple of new sprouts forming on the trunk which could develop into nice branches so I would leave those for now.
Sylvia
With the height of the top of the cage visible, you have just reached the top of the ball not the root flare.
My concerns are the main root system may have been terminally compromised and, if so, the main tree is living on stored energy and the adventitious root system. If so, removing this system, which is what we would normally suggest, may hasten its demise.
The adventitious root system will continue to live without the main root system and, if the main tree does succumb, you can restructure with what you are left with if a clump tree is satisfactory to you.
A side note: There appears to be webbing in the crotches approx half way up the canopy. If these are eastern tent caterpillars, you should remove the web. The larvae feed on foliage and one or two colonies can completely defoliate a tree. Be sure before removing any dead limbs that they are, in fact, dead and not just defoliated.
There are a couple of new sprouts forming on the trunk which could develop into nice branches so I would leave those for now.
Sylvia