by James B. “Jim” Kea
Area Extension Forestry Agent – now retired
Thursday, February 9th, 2006
Stumps have always proven to be an obstacle to man. By nature they are designed to stay put. Natural substances (toxins) slow their decay. Their root structure resists 100 mile per hour winds and the yellow backed diesel caterpillar. Even stump grinders, dynamite, and the old grubbing hoe leave some roots to sprout or produce mushrooms. Fire tends to either char or harden.
Rotting out stumps seems to be the slowest (5 years), least labor intensive, most inexpensive, and yet most effective way to go. The things that do the work (fungi, termites, wood borers, snails, rolly polies, etc.) need moisture, nitrogen and oxygen.
The first step in rotting the stump out is to remove as much as possible with a stump grinder or chain saw. The stump top should be scored with cuts, chops, and drill holes to increase the surface area and pockets to hold moisture.
Fast working fungi can be encouraged by inoculating the stump top with powdered milk as soon after felling as possible. Moisten the top before sprinkling on the powdered milk. Fungi will get some of their nitrogen needs from the wood but still need some to get started. Sprinkle a teaspoon of dry nitrogen containing fertilizer like 8-8-8 or 10-10-10 or add water soluble house plant food to the water used to moisten the stump for the powdered milk. Mushrooms are a sure sign that the fungi are doing their job. Caution, too much fertilizer (salt) will help preserve the stump.
To keep the stump moist, cover with dirt or mulch and water occasionally. As the stump decays and settles, add more dirt and fertilizer (a teaspoon). Too much water will also slow decay by reducing oxygen.
Stumps within 15 feet of the house need to be monitored for termite infestations. Stumps that will be under the house need to be completely removed.
As the stump breaks down, the center heartwood part formed by some trees may be left. It can probably be pulled out without much trouble.
Stopping stump or root sprouts may require treating fresh cut stump tops with a herbicide. Care should be taken since roots may graft with other desirable trees of the same species. Sprouts may have to be chopped off until food reserves in the stump and roots are depleted.
Red cedar and pine stumps may also need a sprinkling of borax to prevent inoculation of the cut stump with annosus root rot. Some sandy soils contain this rot. Rain water will splash the spores on the fresh cut stumps. The fungi will grow down the stump and roots and into other pines or red cedars through root graphs.