Stop using pruning seal when you cut limbs off your trees. This standard practice is actually harmful to your trees. Pruning seal can trap moisture in tree wounds, inviting rot, pests, and disease. It also disrupts natural healing and compartmentalization processes a tree undergoes after losing a branch. This can lead to long-term health problems for your tree.
Table of Contents
Why You Should Never Use Pruning Seal [5 Reasons]
Whether it’s an old-fashioned tar-based pruning seal, a latex product, or even a “natural” pruning seal made from aloe vera, it does more harm than good to your tree. This may go against everything you’ve been taught, but sources at Washington State University and New Mexico State University agree that you should not applying pruning seal to trees. Here’s why:
Causes Tree Decay
Pruning seal sprayed on a tree wound traps moisture and sap near the wound area. This leads to moist, dead wood that is extremely susceptible to rot. Once rot attacks the area where the pruning seal was applied, it can quickly spread to other parts of the tree.
Prevents Natural Healing
After a branch is removed, a tree naturally forms wound wood in a process called “compartmentalization.” This wound wood is callus tissue that covers the wound and protects from infection, insects, and rot. Proper tree healing often takes the form of a raised circle around the area where the branch was removed. This may look strange, but it’s actually part of the tree’s natural process.
Pruning seal actively prevents the growth of this callus “wound wood,” so the tree never truly heals. It disrupts the tree’s natural ability to bounce back from pruning cuts.
Attracts Disease
Certain pruning seals contain scents and compounds that attract bacteria, fungus, or insects that initially arrive to feed on the wound paint. Once they’ve eaten the pruning seal, the tree has an open, exposed wound that has been prevented from healing. This is a recipe for disaster.
This problem is especially prevalent with natural pruning seal containing collagen and aloe, but can occur with synthetic pruning seal as well. It’s common to see harmful fungus forming near tree wounds painted with tar-based pruning seal.
Risk of Long-Term Harm
Pruning seal can naturally flake off, decay, or crack over time. As it does, it opens up wounds that the tree cannot heal. This makes it easy for insects, bacteria, and fungus to infect the tree. By applying a pruning seal, you are placing a temporary band-aid over a wound that won’t close. It’s only a matter of time before that pruning seal creates a bigger problem than it solves.
Save Money and Protect the Environment
It’s more expensive and more work to buy a pruning seal and apply it than it is to simply prune your tree and let it heal naturally. This alone makes foregoing pruning seal a great idea. You make your tree healthier by doing less work.
In addition, several pruning seals contain petroleum-based products, like tar, which are harmful to the environment. Not to mention, aerosol sprays contain chemicals that are toxic to air, water, and soil. Put money back in your pocket and do the right thing by avoiding pruning paint.
The Only Time You Should Use Pruning Seal
The one time you should use pruning seal is when you are pruning oak trees. This is because Nitidulid Beetles are drawn to the smell of oak sap and these beetles often carry the fungus that causes oak wilt. Oak wilt is a serious tree disease that can kill your oak tree. Use a pruning seal on your oak to seal off the smell of oak sap and keep your tree safe.
How Do You Seal a Tree Branch After Cutting?
The simple answer is, you don’t. After pruning a limb, simply leave the open wound. Over time, the tree will form wound wood growth and seal itself. This natural process is the safest for the tree and will only occur if you don’t use a pruning seal.
How to Prune Trees Naturally
To keep your tree safe without using a pruning seal, there are steps you can take to ensure tree health and reduce the chance of tree disease. These are:
- Clean your pruning tools with rubbing alcohol before pruning each new tree. This prevents any disease from being passed from tree to tree.
- Prune tree branches off close to the trunk, leaving only the branch collar. Do not leave stubs or “coat hooks,” as these are prone to disease.
- Gather and pruned branches, especially dead or diseased ones. This will prevent the disease from spreading to the living tree.
That’s all it takes. As long as you follow these steps, your trees and other plants will remain perfectly safe without a pruning seal.
Should You Seal Cut Tree Limbs?
You should not apply a pruning seal to any tree wounds, including those made when pruning and removing limbs. Using pruning seal has the following negative effects:
- Traps moisture near the wound, inviting decay.
- Stops the tree from healing naturally.
- Invites bacteria and pests that feed on pruning seal and can disease your tree.
- Pruning seal will crack or break down over time, leaving unhealed wounds in your tree, where pests and disease can strike.
- Adds unnecessary cost and labor to your pruning work. Also, some pruning seals are toxic to the environment.
For these reasons, it’s important to stop using pruning seals entirely. Your trees will be healthier and you’ll save yourself from the hassle and mess of applying pruning seal.
