Should You Use Wound Paste on Pruning Cuts?
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The Verdict: Busted. Wound sealers do not help trees heal and can actually trap moisture and pathogens under the seal.
Why People Believe This
It makes intuitive sense. When you cut yourself, you put on a bandage. When you prune a tree, you seal the wound. Tree wound paint and pruning paste have been sold at garden centers for decades, and arborists used to apply them routinely. The shiny black coating looks like you are doing something protective. It feels responsible and thorough.
What the Research Says
Research from the USDA Forest Service, led by Dr. Alex Shigo, conclusively demonstrated that trees do not "heal" wounds the way animals do. Instead, they compartmentalize damage by growing new wood around and over the wound. Wound sealants interfere with this natural process. UC ANR's guidelines for home orchards state plainly: "Do not apply wound dressing or tree seal to pruning cuts."
Studies at UC Davis found that pruning paints can trap moisture against the cut surface, creating ideal conditions for fungal pathogens. In some cases, treated cuts showed more decay than untreated ones. The one narrow exception noted by UC IPM is in areas with severe oak wilt or specific canker diseases, where immediate sealing may reduce insect vectoring of the pathogen. But for routine pruning of fruit trees, ornamentals, and roses in Santa Cruz County, wound paste does more harm than good.
What to Do Instead
Make clean pruning cuts with sharp, sanitized tools and let the tree handle the rest. Cut just outside the branch collar (the slightly swollen ring where the branch meets the trunk) at the correct angle, and the tree's natural compartmentalization process will seal the wound on its own. Prune deciduous fruit trees during winter dormancy when disease pressure is lowest. Sanitize your tools with a 10% bleach solution or 70% isopropyl alcohol between trees, especially if you suspect disease.
This week: Clean and sharpen your pruning shears, and toss any cans of wound paste you have in the garage.
For more on caring for your fruit trees, check out our free Fruit Tree Care Guide at Your Garden Toolkit.
Frequently Asked Questions
Should I seal pruning cuts with wound paste?
No. Research from the USDA Forest Service showed trees do not heal wounds the way animals do; they compartmentalize damage by growing new wood over it. UC ANR's home orchard guidelines state plainly not to apply wound dressing or tree seal to pruning cuts.
Can wound sealer actually harm my tree?
Yes. Studies at UC Davis found pruning paints can trap moisture against the cut surface, creating ideal conditions for fungal pathogens, and in some cases treated cuts showed more decay than untreated ones.
Is there any time sealing a cut makes sense?
One narrow exception noted by UC IPM is in areas with severe oak wilt or specific canker diseases, where immediate sealing may reduce insect spread of the pathogen. For routine pruning of fruit trees, ornamentals, and roses in Santa Cruz County, it does more harm than good.
What should I do instead of using wound paste?
Make clean cuts with sharp, sanitized tools just outside the branch collar and let the tree compartmentalize the wound itself. Prune deciduous fruit trees during winter dormancy and sanitize tools between trees with a 10% bleach solution or 70% isopropyl alcohol.
