Performing a cavity surgery used to be much like what a dentist would do to a cavity in a tooth.
OLD SCHOOL METHOD
Decaying wood was TOTALLY removed from the cavity, exposing the GOOD wood of the cavity's inner walls.
Then a sealant was used on this freshly exposed wood.
Then a substance such as concrete or plaster was packed into the cavity as a FILLING. Filling the cavity with these substances has proven to be detrimental, not only to the tree, but also to the saw chain that ultimately has to cut the tree when it becomes victim to storm damage, or death as a result of disease, or even the moisture and bacteria, fungi, and insects that breed and grow between the FILLING and CAVITY WALL.
The current method that is considered to be "PROPER CAVITY SURGERY" by most arborists' today is :
Removal of all undesirable debris from the cavity.
Drying of the interior cavity walls
Sealing the interior walls with a "SPRAY" pruning sealer.
Leaving the freshly cleaned and sealed cavity open.
Removing all undesirable debris is obviously logical. Drying the walls prior to applying the sealer insures the lack of a moisture layer between the sealer and the walls. Using a spray type sealer instead of a tar so that CAKING will not occur. Sealing a cavity interior is purely for cosmetic reasons. Caking of a sealer such as tar or a very thick paintable sealer can result in separation from the cavity wall thus creating another possible moisture layer or insect hide out.
Leaving the cavity open and not filled allows condensation and atmospheric moisture to rapidly dry from the cavity on a continual basis.
If you MUST fill the cavity with something, we suggest an expanding injectable foam that adheres strongly to any surface and solidifies to a firm consistency. Foam fillings can be sculpted and painted to resemble the tree.
RovingArborist™ Tree & Lawn Services