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Tree Pruning

Painting on Tree Pruning Sealer is a Bad Idea – Know Why

It was common to use a sealant when trimming trees till recently, and was even recommended by professional landscapers and expert arborists alike. However, today we are learning that painting on a tree pruning sealer is a bad idea

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Most homeowners still believe that painting over a pruning sealer on trees is necessary to keep the tree safe. In contrast, expert landscapers today recommend against painting over pruning sealer. Let’s take a quick look at why is it not recommended to paint over a pruning sealer.

What is a Tree Pruning Sealer?

Pruning Sealer

A tree pruning sealer is a waterproof product that can be painted onto an exposed cut on a tree limb or branch, from pruning. For years, and even today, arborists were of the opinion that painting over a pruning sealer helps to prevent disease, damage and decay to the “wound” from pruning. 

Think of a pruning sealer as a bandage for trees and was meant to cover the fresh cut after pruning. The way pruning sealers works is by:

  • Helping to heal the cuts developed from pruning trees
  • Minimizing loss of essential tree sap 
  • Protecting tree from insect, fungi and decay

It used to be done as a DIY project by most homeowners and you can still find the product gracing the shelves of your local garden supply stores. However, a scientific research carried out by Alex Shigo of the U.S. Forest Service in the 1970s found that pruning cuts should not be painted over. Instead, the tree should be left to heal on its own, after pruning. His findings emphasized the importance of using correct pruning techniques. In this, he urges to let a fresh pruning cut heal naturally instead of covering it with a pruning sealer and painting over it.

Why is Tree Pruning Sealant not necessary?

Additional studies have confirmed the findings/suggestions made by Alex Shigo. Today, arborists are trained to avoid using sealers as they make it harder for the tree to recover after pruning. It is important to know that trees don’t essentially heal after suffering damage instead they isolate the damaged part through compartmentalization

You may notice callous tissue developing at the edge of the pruning cut which gradually grows to cover the center. When you prune trees using the correct method, the callous growth tends to gradually cover and seal off the pruning wounds naturally. This helps to protect the rest of the tree by preventing decay or damage from spreading all over it. 

Tree pruning sealers are usually petroleum-based products and some even contain asphalt. These work to trap moisture within the tree wound. This ends up causing more problems than solving. 

Tree pruning sealers work to:

  • Seal in moisture, causing decay
  • Serves as food source for pathogens
  • Prevent wound wood from forming
  • Prevents compartmentalization 
  • Can gradually crack and expose the tree to pathogens

How does Tree Pruning Sealer affect Human Health?

Tree sealants are not safe for humans. These products usually contain a combination of solvent and asphalt, including some substances that are considered hazardous by OSHA

As per the safety data sheet for these products, tree pruning sealers have risks too, such as:

  • Containing gas under pressure which may explode if heated
  • Can cause serious eye irritation 
  • Can cause skin irritation 
  • May cause cancer
  • May cause genetic defects 

The labels on these products clearly advise users to wear protection, such as eye-wear and skin protection (gloves and masks) when using the sealant. After knowing this, it is easier to understand why you should avoid using tree sealant after pruning a tree in your yard or garden. 

Should Pruned Tree Limbs be sealed?

Pruning

No, you should not use pruning sealant or paint to seal a pruned tree limb in any situation. It is better to let nature takes it course and the tree to heal itself naturally, using compartmentalization process. Apart from this, it doesn’t make sense to use a product on a living tree, which is also used to seal and waterproof rain gutters, wooden planters, roof flashings and undersides of lawn mowers and asphalt driveways. 

Instead of sealing the wound on a pruned tree, prevention is highly recommended. You can reduce problems that may arise from pruning a tree by following the tips listed below:

  • Use a 70% isopropyl alcohol solution to properly sterilize all pruning tools before and after using them, regardless of the type of tree or the season.
  • Prevent the spread of tree disease by properly disposing of all damaged limbs or branches after pruning and use only disease-free compost or mulch. 
  • Ensure to make smooth, clean cuts and not leave stubs but make sure to keep the branch-collar intact. 
  • Make sure to prune trees at the recommended time of the year, which is usually in spring as the trees are in the dormant stage. This has less risk of infection and infestation. 

How to remove Pruning Sealer?

Now that you know the dangers of using the product, you must be wondering how to remove pruning sealer that you have already unknowingly applied. 

Expert landscapers at Eden recommend removing any pruning sealer from tree as soon as possible. As the sealer is made from different chemicals it is not possible to simply peel it away. However, an efficient way to get rid of pruning sealer from a tree is by:

  • Making a new pruning cut
  • Removing the pain and
  • Creating a new open wound 

Make sure that the new pruning cut is just below the old one. You can make a new pruning cut around half an inch below the old one. Make a clean, straight cut with sterilized tools to ensure optimal natural healing of the new cut. This way, you will trigger the tree’s compartmentalization process and initiate the natural healing process. 

Conclusion

Tree pruning sealer is not only harmful for the tree but also poses health risks to humans and animals too. If you have already applied tree sealant after pruning, you can get rid of it by making a new, fresh pruning cut right below the old one and letting the tree’s natural healing process work its wonders. For more details and helpful tips, you can call expert landscapers, such as Eden.

Enjoy a beautifully manicured lawn with our timely yard work services that care for your yard according to the season. Call us today!

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