When trees are wounded, either intentionally through pruning or accidentally, it sets off a natural process of protection within the tree. Externally, the tree grows new wood and bark around the wounded area to form a callus. Internally, the tree initiates a process to prevent decay. Some gardeners try to help along the natural processes by applying a tree wound dressing. Are there any real benefits of wound dressing on trees though?
What is Wound Dressing?
Wound dressings are petroleum-based products used to cover freshly cut or damaged wood. The intent is to prevent disease and decay of organisms and insects from infesting the wound. Studies (as far back as the 1970s) show that the disadvantages far outweigh the benefits of a wound dressing.
Wound dressings prevent the tree from forming calluses, which is its natural method of dealing with injuries. In addition, moisture often gets beneath the dressing, and sealed in moisture leads to decay. As a result, using dressing on tree wounds often does more harm than good.
Is it OK to Put Wound Dressing on Trees?
In most cases, the answer is no. Wound dressings such as tar, asphalt, paint, or any other petroleum solvents should not be used on trees. If you want to apply a wound dressing for aesthetic purposes, spray on a very thin coating of an aerosol wound dressing. Keep in mind that this is only for appearances. It doesn’t help the tree.
Good pruning practices are a much better plan to help trees heal. Make clean cuts flush with the trunk of the tree when removing large branches. Straight cuts leave smaller wounds than angled cuts, and smaller wounds are more likely to callus over promptly. Cut broken limbs with ragged ends below the point of injury.
Tree trunks often sustain damage during lawn maintenance. Direct the discharge from lawn mowers away from tree trunks and keep a little distance between string trimmers and trees.
One circumstance where a wound dressing may help is in regions where oak wilt is a serious problem. Avoid pruning during spring and summer. If you must cut during this time, apply a wound dressing that contains fungicide and insecticide.