Serviceberry tree near Tree of Heaven to be killed.
I have two small serviceberry trees arriving soon. I'd like to put one on the corner of the property where there is currently a Tree of Heaven. I plan to try to kill the Tree of Heaven by herbicide applied to slashes in the bark in July. Could the herbicide that gets carried into the roots harm the serviceberry tree which will have been growing for about 7 weeks about 4 feet from the trunk of the Tree of Heaven? Before I can safely remove the entire Tree of Heaven, can I prune it heavily to reduce the amount that it shades the serviceberry tree without triggering sucker growth? I removed a lot of branches from it before I learned more about it with no apparent bad result. I'm in zone 5 in Wisconsin.