i had a hugh tree of heaven in my yard. I had it cut down by a tree trimming co. Unfortunatley they did not know the proper procedure to follow after the cutting, NO HERBICIDES. A month later after the cutting i saw growth on the stump, so I had the stump grinded. I applied NO herbicides because i did not know that is really the only way to kill the tree of heaven. Is there any way I can dig down to the root system to inject herbicides directly into the roots?