I had to take up a rotting wooden floor in a shed adjacent to my garage and remove some soil prior to installing a cement foundation. In the digging process several small roots (finger size) were cut and later covered with soil. Within days huge wet mounds appeared at the root site with fermenting mold growing on top of them. The smell was overpowering. I removed the wet soil and found that each root was leaking an unusual amount of fluid. One cluster of roots is leaking a gallon of fluid per day (for 12 days). I think the roots are coming from my neighbor's elm tree; at the cut site the fluid is only running from one end of the cut root. How can I stop the flow so that I can finish my project without mounds of fermenting mold under my new floor.

Is the end that is ‘leaking’ closest to the tree, or the part of the root that was cut off, away from the tree?

Either of two things can be happening. The part that was severed from the tree, farther way, might still be absorbing and transporting fluids from the soil, but of course it can’t get to the tree. It will probably stop soon, as the cells die.

The other possibility is that the tree is pushing fluids back to the roots. This provides the growth hormones and other materials that trigger root growth and metabolism.

The first possibility seems the more likely. I can’t think of anything to stop the fluids. Paint or tar on the cut ends probably won’t stick until the roots are dry, and then there is no need. One option might be to provide some pathway for the fluids to drain, such as a gravel bed. Then replace the floor base and pour concrete over it. The mold will not likely grow beneath a solid surface.

Thank you Russ for your reply. My local nurseryman inspected a portion of the rot and said he thought it was Elm; he said that my neighbor's tree is pushing fluids under my garage to it's injured roots. He also indicated that this might continue for as long as two months. I have had no success with paint, tar etc. because of the volume of fluid leaking from each root. A variation on your idea of creating a pathway for the fluid is to dig each root hole 2 feet deep (like a post hole), fill it with rock up to the roots and then put a concrete cap on top. In this way I won't be digging across my shed area and cutting other roots. The concrete cap will be wider than each hole and hopefully the fluid will simply drain down in the rock and be absorbed in the soil. Your reply has convinced me that this is my only alternative. Thanks again for you help.

Tom Ferrando (aka Shedman)