Treatment options to strengthen decay cavities or hollows are limited.  Past practices involved removing the decayed wood and filling the cavity with various rigid fillers.

Currently, it is believed that filling cavities may do more harm then good.  In addition, the fill material may not strengthen and support the tree as much as the new growth that develops around the wound.

If a tree has good vitality, it may maintain structural integrity by producing new wood around the injury. Removal of decayed wood from a cavity has little effect. However, if healthy wood tissues are damaged in the attempt to remove the decay, the tree’s ability to control the spread of decay may be reduced.  In most cases, it is better to leave the cavity alone.  If the cavity is large enough to compromise structural strength and there are targets present, the tree may need to be removed or pruned to reduce the size and weight supported by the weak area.

Production of new wood is important to tree stability, so ensuring favorable growing conditions for the tree is an important component of management.  Ensuring good soil health, moisture, and aeration, and applying organic mulch are examples of good management practices to which trees may respond favorably and improve in condition