Crepe myrtle root obstructing water flow.

Asked February 17, 2019, 7:06 AM EST

I have a row of 8 large healthy crepe myrtles. It runs parallel to a driveway. The row is off the edge of the driveway, about 2 feet. Rain water runs down between the trees and the concrete driveway 2 foot shallow valley. My problem is over the years one of the shallow roots is now growing under the driveway and damming up the flow of water. It root is around a diameter of 2 and 1/2 inch to 3 inches. My thought is the cut the root as close as possible to the tree and again as close as possible o the concrete. Would I then use some form of stump killer on the root? Would I use the type the you have to drill a hole in the stump to apply it? I do not want to hurt the tree, but I will really need to kill that root so that it will not cause any further damage. Please help. Sd

Ellis County Texas

1 Response

If I understand correctly, there is a root from a crape myrtle that is running under the driveway and has caused some up-heaving resulting in some water damming effect.
You also provide some possible solutions.
Here is what I would ask you to consider:
1. You can cut the root. Severing the root from the tree/plant would hopefully stop any additional root growth. However, some crape myrtle have a suckering habit.
2. If you sever the roots and create a clear separation between the plant and the wayward root, you could use the root (some herbicide) on the root part. HOWEVER, this is assuming that the extended root is not connected (grafted) to other roots from the plant. If there is root grafting, there is the possible that a root killer could hurt trees that are connected to that root.
3. The up-heaving of the concrete is unlikely to subside even if you killed the root. However, it should not get worse.

Alternatives to consider, a root barrier metal or tough plastics that can be inserted between the tree and driveway (yes, for install the roots will need to be severed from the plant. This will also help prevent future encroachment of roots.