An injury to the trunk of your tree does not mean all is lost. There are many ways for a tree trunk to develop a wound-- such as from scratching or feeding of an animal, blunt force trauma that tears the bark, or from a branch being torn from the tree. When a tree suffers a wound it works to seal it, as opposed to healing it. It grows specialized callus material that eventually covers the wound and creates a barrier that doesn't allow disease or decay to spread into the undamaged parts of the tree. The following tips can provide you with knowledge to help the tree through this phase of the recovery process.
Tip #1: Clean up the edges
Clean bark edges are able to begin the sealing over process more readily than ragged edges. Take a sharp, clean knife and trim the ragged edges of bark. The goal is to turn the hole in the bark to an oval shape that is narrow on the top and bottom and wider in the middle. It doesn't have to be perfect since you want to avoid cutting into the living bark. Just trim away the loose dead bark from the edges of the hole, taking care not to cut into the wood beneath.
Tip #2: Skip the paint
You may have heard of or seen tree paint or wound dressing. These substances range from a white paint to a dark tar-like substance. They supposedly seal the wound to keep disease organisms out. As a general rule, they do the opposite. Covering a tree wound with any kind of dressing can trap moisture, which makes fungal growth and rot more likely. Trees are biologically equipped to seal over their wounds without the help of any type of paint-on dressing.
Tip #3: Consider some irrigation
Many people don't water their lawn trees specifically. Instead, they depend upon irrigation of nearby grassy areas to provide enough water and usually this is fine. The exception is when a tree is in recovery from a major bark wound. It's a good idea to increase tree-specific irrigation during any extended dry periods, since otherwise the tree may not be able to focus on sealing the wound if it is suffering from drought stress. A once-weekly, deep watering is sufficient until the rains or cooler temperatures return.
If you have further questions about helping your tree recover, talk to a tree services company like the one represented at http://www.schulhofftlc.com.