Poplar Tree Roots
How do you kill the roots of a poplar tree that was cut down about a month ago in which the stump is still there? The roots are growing fine and sending up shoots.
Certified GKH Gardening Expert
Cut into the roots and paint the fresh cut with undiluted Round-Up. The fresh cut will cause the plant to pull the Round-Up into its system and will kill it. You may need to repeat 2-3 times if the roots grow deep, but it will work.
Perhaps this article may be of some help: https://www.gardeningknowhow.com/ornamental/trees/tgen/how-to-kill-a-tree-killing-trees-in-your-garden.htm