A wound on a tree trunk is usually no reason for major concern. Trees can acquire a minor wound from many sources—mechanical damage from lawn equipment, animal scratching or gnawing, or from storms and wind. Healthy trees usually recover, and the bark slowly calluses over the wound site. The following treatment guide can help you ensure that the wound heals properly and that no further problems occur.
Clean up the wound
Tree wounds don't necessarily heal. Instead, the tree creates a collar of tissue around the damage that prevents any type of infection from spreading from the damaged area into the rest of the tree. Cleaning up a wound site helps the tree better form this callus-like collar.
Begin by cleanly cutting away any remaining branch stub, if applicable, so that the wound is flush to the trunk. If the bark is badly torn, use a clean knife to smooth the ragged edges. Avoid right-angle cuts, as these can collect moisture.
Skip the sealants
Tree wound dressings or paints can cause more harm than good. Part of a tree's defense is to allow the exposed wood to dry out. Dressings trap moisture against the wound, and this can lead to fungal growth and disease. These fungal diseases can spread throughout the tree.
The only time a dressing is necessary is if the damage is to a large diameter cane on a rose bush. These cane wounds are attractive to certain types of solitary bees, which will burrow into the plant if a dressing isn't applied to keep them out. Otherwise, skip the dressing or sealant.
Monitor the wound
There is very little care necessary once the wound is cleaned up. You will want to monitor the wound for a year or two. Watch for signs of disease or insect problems, such as weeping sap, fungal growth, or the formation of cankers. Cankers may look like wet open wounds, or they may form raised galls of balled-up sap. Increased insect activity on the damaged area may also indicate a problem. Cracks aren't necessarily a problem if they are small, as these are a side effect of the drying-out process that trees use to compartmentalize the wound.
If you suspect that diseases or pests are plaguing the wound, call in a tree service to have the issue properly diagnosed. Then you can begin an insecticide or fungicide treatment to help alleviate the problem before it progresses too far.
