How Do You Seal A Tree Wound

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Written By Janine Clarke

I am Janine Clarke AKA Equipment Girl, a nerdy girl with an unhealthy knowledge about power tools and gardening! You can contact me here.

As all gardeners know, tree pruning is a vital part of gardening and, when done properly, will keep your trees healthy.

Over-pruning can be disastrous, and it’s often touch-and-go as to whether your tree will survive. I dealt with this in another Equipment Girl article (how to fix an over-pruned tree), so be sure to check this out.

Today, I’m focussing on how to treat a tree wound, whether it’s after pruning or as a result of any other kind of damage. While it’s not quite as drastic, cutting branches from a tree is a little bit like removing a limb from a human.

However, unlike we humans, trees have developed an effective defence mechanism over the millennia and are capable of dealing with some pretty severe wounds. Even so, they sometimes need some TLC to get them back to full health.

If you want to do things the right way, giving your trees the best chance to thrive, it really helps to know what’s going on first.

Different Types Of Tree Wounds

Tree wounds are split into three basic categories: branches, roots or trunk.

The actual injuries themselves have hundreds of different causes, including lightning strikes, strong winds, vandalism, animals (deer, in particular), fire, insect infestation, accidental damage from machinery, and pruning.

A tree’s bark is an amazing protective coat provided by Mother Nature and is essential to its survival. Like human skin, it forms a barrier against disease, and any damage to the bark can let in infection and rot.

So, when you prune trees, are you deliberately injuring them? Well, yes, in a way, but when done properly it can be beneficial.

Check out: When Is The Best Time To Prune Trees In The UK

How Do You Seal A Tree Wound

Self Healing?

When we break our skin it is capable of healing itself (within reason!) but trees can’t do this. Instead, special wound wood (or callus tissue) grows around the injury and compartmentalises the area to protect the rest of the tree.

New wood will eventually grow around the damaged area. Some trees also produce powerful chemicals that prevent decay organisms, disease, fungus spores and insects from getting in.

Yes, trees can cope with a lot and can keep going. But sometimes, sadly, the damage is too great and the process of death and decay will begin.

This is why many people believe applying a tree pruning sealer is a good idea, as it covers the area and stops the bad stuff from entering the wounded area.

What Is A Tree Wound Dressing

Tree pruning sealers, also called pruning paint, wound paint, tree wound sealers and tree wound dressings, are basically the same thing, although there are lots of different brands.

These products are liquids that can be sprayed or painted onto a damaged section of the tree, such as pruning cuts and broken branches. The idea is that they seal the area, stopping bacteria, fungus and infection.

What Are They Made Of?

Tree pruning sealers can broadly be split into two types:

Synthetic Tree Wound Sealer

Most of these are petroleum-based products, and some also have a high asphalt content. You can also get latex-based paint and oil-based sealers. All of these claim to reduce sap loss and stop disease and fungi from taking root.

Some of these brands boast that their products can double as a waterproof coating for roof flashings and gutters, which doesn’t seem like the type of thing you’d want to put on your damaged tree!

Natural Ingredients

Rather than an oil-based sealer or petroleum-based solution, you could look for a natural tree pruning sealer containing aloe gel or collagen.

But before you do this, I should add that some of these are also mixed with petroleum by-products and asphalt! Also, questionable as to whether any of the ingredients actually do anything to help the tree wound.

DIY Tree Wound Sealers

Some gardeners make pruning sealer at home, often using aloe gel, and there are many recipes on the web, but use them at your own risk! Not all of these will be suitable, so make sure you research them well before going ahead.

Should You Dress A Tree Wound?

This is an excellent question! In the past, it was common practice to apply pruning paint to tree wounds.

When it was tree trimming time, you got out the pruning shears, lopped off branches and slapped the pruning sealer on. These days, however, almost every tree expert out there will advise against using tree wound sealer.

On balance, it’s best to leave pruning wounds alone. The tree’s own natural defences will handle it, and by applying a pruning sealer you may do more harm than good. Healthy and younger trees especially will heal pretty quickly if left alone.

Why Avoid Using A Pruning Sealer?

You’ve seen what’s in some of these mixtures. Asphalt will absorb heat, potentially damaging sensitive cells that are designed to close wounds. Petrol products contain toxins that will attack the tree’s sensitive vascular system which will waste precious energy fighting this as well as trying to heal.

Also, most tree wound sealer examples out there actually seal in moisture and prevent sunlight from reaching the affected area, providing ideal conditions for fungi and rot!

Exceptions To The Rule

There are times when it might be okay to use a tree wound sealer, and that’s for species like oak and elm or any tree affected by vascular wilts.

Oak wilt and Dutch elm disease are no joke, so it’s sometimes advisable to apply a very thin coating of pruning sealer to prevent damage from these nasty diseases after pruning.

You might also want to apply a latex-based paint or pruning sealer to very large tree wounds where it’s likely that the tree would otherwise die.

Check out: Best Tool For Cutting Hedges

Dealing With Storm-Damaged Trees

Storms and gales are a nightmare, especially when you have tall, mature trees. So, do you apply a wound dressing to the broken branch?

The trouble is, the end still attached to the tree trunk will be jagged and splintered, making it difficult to cover. And sometimes the branch is broken but still attached, so what do you do?

In most cases, it’s impossible to fix a splintered branch. Skilled arborists might be able to fix it, but it takes time. If you are concerned that it will become infected, or you just don’t like how it looks, you could prune back any broken or splintered branches, although many will continue to thrive anyway.

When you do cut the branch back, make sure to avoid going beyond the collar, as this contains the natural chemicals that help the healing process. Remove as much of the damaged wood as you can without taking away any healthy bark or wood.

Check out: Best Tools To Cut Tree Branches

Pruning Trees: A Few Handy Tips

Pruning trees can be beneficial and will keep them healthy, and, if you prune properly, wound dressing is rarely necessary. Fruit trees will yield a better crop on pruned branches, and other species look much healthier for a good trim now and then.

Pruning Tips:

  • Remember the ‘three D’s – only prune branches that are dead, damaged or diseased.
  • Use sharp tools and make clean, angled cuts. While straight cuts leave smaller wounds, they don’t repel moisture and encourage rot.
  • Prune in season – late autumn to early spring, depending on the species.
  • Avoid making cuts flush to the trunk as these can damage the bark.

Check out: Best Tool For Cutting Small Trees

Sealing A Tree Wound: In Summary

We began by asking how you seal a tree wound and the honest answer is: it’s best to avoid it unless you absolutely have to.

Trees have a remarkable ability to look after themselves and will deal with almost anything – although some species are hardier than others! That’s why it’s wise to brush up on your tree knowledge. Get to know what’s in your garden and how to look after it and you’ll get so much more out of your gardening adventures!