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Is Tree Pruning Sealer Necessary?

Tree pruning sealer is a liquid used on the bark of a tree to protect it from rotting and insect infestation. This article will help you decide if tree pruning sealer is necessary for your trees. 

The answer to this question depends on many factors, such as type of tree, location, etcetera. For example, if you live in an area where plenty of insects can damage the bark or live near saltwater, then using a sealant would be advisable. 

However, if you don’t think these measures are necessary, then feel free to skip adding the product into your yearly routine.

Tree pruning sealer is a product that many people use to protect their trees from the elements. However, there are other ways you can protect your tree without using this type of product. 

Instead of sealing your tree with sealant, you could try painting it or wrapping it in plastic wrap. These two methods are just as effective at protecting the tree but do not have any lasting effects on the environment or neighbourhood animals that might eat them. 

Tree pruning sealer helps keep your trees healthy and safe by preventing water damage and insects from getting into them – but there’s another way! You can paint or wrap your trees without harming our planet and its inhabitants.

Why Painting on Tree Pruning Sealer Is a Bad Idea

It was common practice to use a pruning sealer when trimming trees for a long time — a seemingly common-sense practice recommended by trained arborists and nursery workers alike. Generations of homeowners grew up believing that painting on an application of pruning sealer on trees limbs/branches was an integral part of “safe” tree pruning.

No longer. Current best practices no longer recommend applying sealants to tree wounds. So let’s talk about why it’s now considered a gardening myth and how yesterday’s tree bandage became today’s bad practice.

What Is A Tree Pruning Sealer?

A tree pruning sealer is a specially designed waterproof product that is applied, or “painted,” onto the exposed cut on a limb or branch after pruning. For many, many years — and still to this day in some cases — people were told by an arborist that tree wound had to be covered with a sealant.

A tree pruning sealer is a bandage of sorts meant to cover the wound. Their packaging claims to aid in healing pruning cuts, minimise sap loss, and protect trees from decay, insects, and fungi.

It was an easy DIY project, the product was (and still is) in stock at all garden and big box stores, so it became ingrained as a habit for homeowners.

While good in theory, scientific research conducted by Alex Shigo of the U.S. Forest Service in the late 1970s explained that pruning cuts should not be painted. Rather, the tree should be left to heal through its own devices after you prune it. 

He emphasised the importance of following proper pruning practices. Let a fresh cut heal naturally instead of covering it with a wound dressing, he urged.

Why Tree Sealant Fell From Grace

Later studies confirmed Shigo’s work. As a result, today’s arborists are trained to consider sealers a bad practice because they make it harder for trees to recover after pruning.

It’s important to understand that trees don’t really heal after they have been damaged. According to the University of Arizona Cooperative Extension, they instead isolate damage through a process called compartmentalisation


Callus tissue develops at the edge of the wound and gradually grows in toward the centre. When trees are pruned correctly, this new growth eventually covers the pruning wounds, protecting the damaged trees.

These sealant products are typically petroleum-based, although some may contain asphalt and trap moisture inside the tree wound, which may encourage more problems instead of preventing them. Some products exist touting natural ingredients such as collagen, pectin, or aloe vera. Unfortunately, there isn’t any scientific proof that they benefit the tree, either.

The petroleum and asphalt-based wound dressings are known to:

  •  seal in moisture and decay;
  •  sometimes serve as a food source for pathogens;
  •  prevent wound wood from forming;
  •  inhibit compartmentalisation;
  •  eventually crack, exposing the tree to pathogens.

They’re no fun for humans, either.

Thanks to their volatile combination of asphalt and solvent, according to the safety data sheet for one popular product, they:

  • Contain gas under pressure and may explode if heated.
  • Cause serious eye irritation.
  • Cause skin irritation.
  • May cause genetic defects.
  • May cause cancer.

Wear skin and eye protection, the label advises, and store it in a cool, well-ventilated place. So after learning those tidbits, it’s a bit easier to see why you should stop using pruning sealer on your trees.

Should You Seal Pruned Limbs At All?

The short answer to this is no! You should not use pruning paint to seal pruned limbs at all. They are better left to undergo natural healing through their own plant defense mechanisms.

Plus, why would you want to put a product on your tree that can also be used to seal and waterproof rain gutters, roof flashings, wooden planters, the underside of a lawnmower deck, or even small sections of asphalt driveways? If something claims to be effective for these other outdoor uses, don’t put it on a living tree. In my opinion, it’s better to leave the tree be so it can “fix” itself.

Instead of sealing pruning wounds, it’s better to implement prevention. For example, you can minimise problems that may stem from pruning by following these tips.

  • Properly sterilise all pruning tools with a 70% isopropyl alcohol solution before and after using them. That applies regardless of the time of year you are pruning or the type of tree you are working on.
  • Control the spread of disease by properly disposing of all problematic limbs/branches after pruning. Use only use disease-free mulches or compost.
  • Make clean, smooth cuts making sure not to leave stubs but keep the branch collar intact.
  • Prune trees at the proper time, preferably in the spring when they are still dormant and haven’t started forming leaves. This makes them less susceptible to infestations or infections.

The Exception: Oak Trees

Inbout 24 states, from the Middle Eastern states south through Texas, oak trees can suffer from oak wilt. The damage done can be both devastating and irreversible. The fungus that causes the disease spreads from tree to tree, carried by Nitidulid beetles attracted to the smell of the tree’s sap. 

The insects will then move to another tree, laden with oak wilt fungus spores, and spread the disease. So quickly covering any pruned branches will cover that fresh-sap smell before the beetles come a-running.

“Most forms of paint work equally well, and there is no need for specialised rubberised or petroleum sealants,” says Texas A&M’s Flocke. He’s stationed in Austin, Texas, where oak tree wilt is such a concern that pruning oaks are discouraged from February through June. “The wound paint is only necessary for the first two to four days after the cut has been made,” Flocke says, “so there is no need to reapply paint or to go out and paint old wounds.”

How To Remove Pruning Sealer

I’m sure you’re now asking yourself if using a pruning sealer has caused irreparable damage to your trees. You may also wonder if you should consider removing it. Unfortunately, this isn’t so easy to answer, and surprisingly there isn’t much discussion about it online.

I recommend if your trees’ pruning cuts had a sealer applied to them, remove it if possible. Unfortunately, due to the chemical composition of the sealer, you can’t simply peel it off and throw it away.

The best way to remove the pruning sealer would be to make a new pruning cut on the branch. Remove the paint, and create a new, open wound. A new pruning cut wouldn’t need to be made much below the old one. Perhaps a quarter to a half of an inch is good if there’s enough wood to do that. Make sure it’s a clean, straight cut and your tools are sterilised.

Is Tree Pruning Sealer Necessary?

You have decided to straighten up the yard a bit by pruning trees and shrubs.  You have all your gear gathered, and you are ready to go.  Then you have a thought. . .

Is tree pruning sealer necessary?  No, today’s latest research has shown that by applying a sealer after you prune a plant can actually provide a great protective place for insects and disease.  As well as impeding the healing process altogether.

The late Dr. Alex Shigo of the U.S. Forest Service Laboratory in Durham resulted in a huge shift in thinking by arborists and foresters.  From how to properly trim a branch to whether using pruning sealer was positive or negative. 

After all his research, it was determined that using a pruning sealer was not beneficial to the healing process of the plant and, in fact, usually would have the opposite effect.  But there are exceptions to every rule.

How Does a Tree Heal Itself?

Unlike animals that heal themselves, the tree actually don’t heal themselves.  But rather “grow over” the wound or cut area.  This growth encapsulates the cut or wound and isolates it from the rest of the good healthy wood.

If you look at a tree that was either pruned or injured a few years ago, you will notice that you can still see the old cut, but the tree is growing over the top with new growth.

The natural process of the tree is for the sap to cover the area to protect the tree from insects and rot temporarily.  Then it will start the process of growing wood over the cut like a callus to permanently seal off that area and continue to grow for many years to come.

If the tree suffered storm or wind damage, then you may need to make a cleaner cut to make it easier for the tree to cover over the area.  Just remember to make your cut just before the “collar” next to the trunk or if you are cutting off part of a damaged branch, then make your cut just before a fork or branch on the limb.

If you leave a stub, the tree will take much longer to grow over the area. This is because the stub will have to completely rot and fall off in order for the tree to grow over it.  This process can take years, and you will have to look at the ugly stub during this time.

How To Prevent Oak Wilt When Pruning


There is an exception to every rule, and with pruning sealers, it is no different.  The oak species of trees ( genus Quercus ) heals in the same way as all other trees, but a disease is spread from insects landing on fresh open cuts – Oak Wilt.

Oak wilt is spread by 2 methods:

  • Method 1 – Oak wilt, which is a fungus, spreads in the ground through the root system of oak trees.
  • Method 2 – Oak wilt is spread by sap beetles that fly from tree to tree with fungus.  These beetles are attracted to the sap of freshly cut or injured oak trees.

If you can just protect the fresh-cut for 7 – 10 days, the oak tree itself will have had a chance to heal itself so that it can defend the area.

You can also contact your local Agricultural Extension Service to see if Oak Wilt is even an issue in your area.  Simply Google the term “Agricultural Extension Service”, and a list of the closest ones will appear.

Most are tied to a local University and have free information because they are funded through land grants.

Immediately after pruning a member of the oak family, you should seal the area. Now, this brings us back to pruning sealers.

What Do You Put On a Tree Wound?

If you are pruning oak trees, you should use a pruning sealer immediately after pruning.  Several products can be used to seal the area.  Keep in mind that the sealer really only has to last about 10 days.  It is just long enough for the oak tree to heal itself and not have the fresh sap that the beetles are looking for.

Asphalt Sealers – Asphalt sealers are what most people remember seeing from when they were a child.  It is an oil-based sealer that looks and smells like road tar.  While this stuff will seal the wound long enough to prevent the sap from running out of the tree, which attracts the sap beetles, it does not help the tree because it is an oil-based product, and do you think that helps a wound heal?

Latex Sealers – Today, we have alternatives to the old school oil-based sealers.  Latex sealers can accomplish the goal of the sealing the sap and repelling the insects until the oak tree has healed itself.

Organic Natural Tree Sealers – are another option to consider.  Remember, the goal is the be able to seal the fresh cut area for at least 10 days. There are several products today that fit the bill.

Homemade Tree Pruning Sealers – I’m sure if you Google homemade pruning sealers, you will see many different recipes and applications, but there are no tests that can confirm that they work well, so you are applying at your our risk.  If it provides the tree with the complete seal for the timeframe needed, it will probably prevent the attraction of the sap beetles that spread the Oak Wilt disease.

Household Paints as sealers – In a pinch, this can be used, but it is not recommended.  The issue is that paints are not designed for live wood healing and will not allow the tree’s natural process to occur properly.

Pruning Sealer Alternatives – Which Have Proven To Be Better

Studies by many Universities, Agricultural Extension Services, and Forestry Services have proven that it is far better to prune the correct way rather than worrying about what sealer to use or whether to use any at all.

If you prune using proper techniques, it will allow the tree or shrub actually to heal faster. Thus, providing the best situation for the natural ability of the sap to do its job to keep out pests.  And for the plant to grow over the exposed area as quickly as possible.

You will want to make the cut for tree limbs that you prune at the trunk right before the “collar” that comes off the trunk and starts the limb.

If you are pruning a branch tip, you will want to make your cut right by a fork or other branch at a slight angle so that water doesn’t sit.

For shrubs, you will want to make your cuts close to a fork in the stem.  Or, if it has multiple stems coming up from the ground, you will want to make the cut as close to the ground as possible with a slight angle ( up to 45 degrees) so that water doesn’t sit on the cut end.

Related  Questions

What Do You Put On a Tree Wound? Nothing.  Make sure that the wound area is clean from debris and has a clean edge, promoting faster healing by the tree.  Depending on how ripped or tore the bark is around the wounded area, you might have to take a sharp knife or saw to make a clean edge around the wounded area.  Sealers are not necessary at all.  Let the tree do its thing naturally.

Does cutting off dead branches help a tree?  Yes, it takes time for a limb to naturally rot enough to fall off the tree and during that time, you are inviting disease and rot to get into the tree’s healthy tissue. By making a nice clean cut, you will help the tree to grow over the area faster.

Do branches grow back after pruning? No, the branch will not grow back if properly pruned.  The tree will grow over the cut area to seal it off from diseases and rot. If it is not properly pruned, then it is slightly possible to sprout new growth by the cut area.

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