There are numerous instances where pruning is necessary to promote a tree’s health, provide clearance for sidewalks/roads, reduce hazards to people and property, and train and shape a young tree. Pruning cuts also create potential entry points for insect and disease organisms. Many people feel the need to apply wound dressings or tree sealants following pruning.
What is a tree pruning sealant, sometimes called pruning paint?
Most often, these products are petroleum-based, but some even contain asphalt. Alternatively, there are natural tree sealants with ingredients like collagen and aloe gel. These products often claim to ‘aid in the healing of pruning cuts or ‘minimize sap loss.’
So, should you use pruning sealants after pruning your trees and shrubs. No, you should not.
The use of these sealants is not based on science and has been shown time and again to inhibit the natural healing of pruning wounds. Simply put, pruning sealants make it harder for your tree to heal.
Pruning sealants may also trap moisture in the tree, which can encourage wood decay or fungi.
After pruning, trees grow new wood, which covers the pruning wound, and prevents the invasion of diseases or damaging insects.
Well placed pruning cuts, made to maximize the tree’s natural ability to close its wound and defend itself from infection, are the best way to promote closing of the wound.
When pruning, make clean, smooth cuts. Do not leave branch stubs. Leave a small collar of wood at the base of the branch. The branch collar is a slightly swollen area where the branch attaches to the trunk. Cutting the limb flush with the trunk will leave a larger area to callus over and a greater chance of decay organisms entering the wound. (see image at left)
When removing larger branches use the “three-cut” method. Start by making a slight undercut well above the location of the final cut. The second cut should be on the top of the branch above the undercut. This cut removes the weight of the branch and prevents bark stripping. The final cut should be made outside the branch collar. (see image at left)
Trees and shrubs have natural resistance mechanisms to fight insect attack or disease. Pruning sealants are unnecessary. Covering wounds with traditional sealants inhibits sealing of the wound by new wood growth and interferes with internal chemical and physical processes that wall off decay.
Just say “no” to pruning sealants.
University of Florida:
University of Washington: https://s3.wp.wsu.edu/uploads/sites/403/2015/03/wound-sealer.pdf