What is the best material to put in the cavity of a tree?

Answer: Best not to fill the cavity
Explanation: It’s usually best not to fill a tree cavity. Concrete and synthetic foams do not stop decay, and they can trap moisture or hide ongoing damage. In addition, filling a cavity can make future trimming or removal more difficult. The better option is to have the tree inspected and determine whether it needs pruning, monitoring, treatment, or removal.

Answer: Best not to fill the cavity
Explanation: If you can cut behind the cavity if possible if not leave it

Answer: Best not to fill the cavity
Explanation: Grind it down

Answer: Best not to fill the cavity
Explanation: The recommended method for patching a tree hole is to use a thin metal flap or screening covered with plaster over the tree hole. This will prevent animals and water from entering the hole and create a surface that the bark and outer living layers can eventually grow back over.

Answer: Best not to fill the cavity
Explanation: The tree adjusts itself to compensate for the cavity

Answer: Best not to fill the cavity
Explanation: don't bother

Answer: Not sure
Explanation: Certainly there will be varying opinions. See the certified people for shade trees.

Answer: Best not to fill the cavity
Explanation: just not the thing to do

Answer: Synthetic foams
Explanation: a saw can still cut it if needs to