Wound paints and dressings claim to prevent rot and help trees heal from pruning wounds, but research suggests that they actually do more harm than good. When you cut off a tree limb, or the bark gets damaged, the tree never actually “heals.” Instead, it compartmentalizes the wounded area with a special type of calloused wood – like a scar – that keeps out bacteria and helps the rest of the tree recover.
Painting wound with wound paint or dressing can:
- Prevent the tree from forming calloused wood, which can keep the tree weaker.
- Seal in water, bacteria, fungi, and decay.
- Attract disease causing organisms that feed on the wound paint.
- Interfere with a natural recovery process that nature has taken eons to perfect!
To help keep your trees healthy when pruning:
- Prune in late winter while trees are dormant.
- Sterilize pruning shears and saws between cuts with rubbing alcohol or hydrogen peroxide.
- Target specific risks by treating wounds with an organic fungicide or insecticide.
- Make careful, clean pruning cuts just outside the branch collar, where the tree can most quickly heal.
There are a few devastating diseases, such as oak wilt, that are introduced through insects feeding off pruning cuts, then spread from tree to tree via the roots. Wound paint can reduce (but not eliminate) the risk of these infections, so some tree experts feel that the downside of wound paint is better than the risk of spreading this disease throughout a neighborhood.
Check to see if diseases are a problem in your area. If they are, follow the guidelines from your local extension service regarding the use of wound paint when pruning. In general, however, only use wound paint when absolutely necessary to prevent specific diseases.
- The Myth of Wound Dressings (Washington State University)
- Should I Paint or Otherwise Treat Pruning Cuts? (extension.org)
- Wound Dressings (Shigo and Shortle, Journal of Arboriculture, 1983)
- Proper Pruning to Prevent Oak Wilt Infection (Texas Forest Service)
- When to Trim Trees and Shrubs