Wound sealant: helpful or harmful?

[Antidemagogue]

I think every bonsai source I have read makes the case for using wound sealant on pruning wounds. However, I recently read two sources that argued that it is of no benefit to use wound sealant. A paper written by Shigo and Shortle (Journal of Arboriculture, 1983) (http://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=1923&Type=2) and a short polemic, if you will, written by Chalker-Scott (https://s3.wp.wsu.edu/uploads/sites/403/2015/03/wound-sealer.pdf) claim wound sealant provides no benefit (this latter article seems unconvincing; it is filled with many claims that lack support, but I wanted to post it since it makes the claim).

Does anyone know of any studies that support the use of wound sealant, or any studies that do not support the use of wound sealant? And can anyone speak to their own experience, both with sealant in general and with specific types of sealant?

 

[0soyoung]

When the cambium is exposed, it will subsequently desiccate. Promptly covering the exposed cambium with anything that is an effective moisture barrier for 10 to 15 days, until a new epidermis is formed, will prevent desiccation and death of cambium cells.

With a branch stub, the ring of exposed cambium will tend to die back under the bark until it has built up a new epidermis. Then it begins regrowing, some cells becoming phloem (inner bark), but most xylem (wood) - the same process by which tree stems thicken which will proceed toward 'healing' the wound. On the scale of forest trees, the temporary die back is insignificant. In the scale of bonsai, every bit of die back is more time lost waiting for the wound to 'heal' in order to produce a quality work.

When bark is stripped from the wood, there are residual cambium cells left on the exposed wood (xylem initials). These can be a problem in making air layers as these cells will, in common practices, be promptly covered in a damp medium (e.g. sphagnum) that prevents desiccation of those exposed, residual cells which then regrow the phloem and bark that was removed. For an air layer this affects bridging and failure of the layer. Often the practice is to vigorously scrub/scrape the exposed wood so the air layer girdle won't be bridged by regrowth from those residual cambium cells. Easier and possibly more effective, is to simply let the exposed wood stand in open air for 24 hours - all the xylem initials will have desiccated and be dead.

I posted the thread 'The Bark Is Back' as my version of a conclusive study that moisture barriers ('sealants') have a beneficial effect if

1. applied promptly over over cambium that has been exposed
2. remains in place for 10 to 15 days.

Anyone will be able to reproduce my test and verify what I've said for themselves, IMHO though the test I presented did not include another similarly treated stem with no moisture barrier covering.

 

[Adair M]

These and other studies are presented as “proof” that wound sealants are worthless.

Yet, these studies are based upon landscape or timber production trees.

With bonsai, aesthetics are very important. We want the wound to “heal” quickly, yet minimize the scarring. These studies don’t go into that.

Azalea are VERY prone to dieback if they’re not sealed immediately! Sappy trees, it’s not as important.

So, in regards to studies by arborist, I would simply ignore them. Instead, I would follow what the most accomplished bonsai Masters do: seal the cuts.

 

[papymandarin]

same as adair said, existing studies have been made in a context irrelevant with bonsai, My opinion is that there is no sanitary reasons to use it (as those studies show and contrary to popular belief in bonsai), but it is useful for aesthetics reasons: we want quick, complete AND nice flat healed scars, and there cut paste is useful

 

[Wires_Guy_wires]

I found that parafilm works for me. It helps callus breathe and prevents moisture lock in. On my junipers this allowed 0.5cm strips of lost bark to be re-established.
It acts like a pliable second layer of skin, whereas wound sealant would act as an (in most cases) immovable scab.
It doesn't look pretty, but it leaves no marks and no residue, there's no need for brushing it off and just a few cm's of the stuff could wrap half the tree.
So I'm all for seals, just not most of the sealants out there. But it's a personal preference, there are advantages on the paste-sealer side as well.

 

[hemmy]

Does anyone know of any studies that support the use of wound sealant

Here is a popular article that references some. I have not read the referenced articles.

https://www.treerot.com/wp.../04/Arborist-News-Callus-and-woundwood_Luley.pdf


“It is generally accepted that wound dressings are not
needed and generally do not increase wound sealing or
decrease decay, possibly because of their inhibitory effect
on callus and woundwood formation. However, some
studies have shown that Shellac® and Lac Balsam® can
increase initial wound closure on some species depending
on the time of the year they are applied (Marshall 1931;
Hudler and Jensen-Tracy 2002). McDougall and Blanchette
(1996) showed that polyethylene plastic wrap increased
callus and reduced dieback around wounds when applied
right after wounding on certain tree species. This effect
may have been due to the enhancement of conditions,
such as high humidity, which apparently foster callus
development along the edge of wounds (Hartig 1894).”

McDougall, D.N., and R.A. Blanchette. 1996. Polyethylene plastic wrap for tree wounds: A promoter of wound closure on fresh wounds. Journal of Arboriculture
22:206–210.

Hudler, G.W. 1984. Wound healing in bark of woody plants. Journal of Arboriculture 10:241–245.

 

[Paulpash]

Try both - observe - come to your own conclusions if you are still unsure.

 

[milehigh_7]

One of the most epic wars ever to be on this site was me asking the same question years ago. LOL! My take is that it depends on the a few factors.
1) Species
2) Finished look you are shooting for (personal preferences)
3) Time of year you are pruning
4) Are you sure it's clean under the seal? (You don't want fungus sealed in with moisture or your tree will quickly rot.)

 

[bonsai-ben]

Maitland eh? Come visit. I'm 15 minutes from you. I'll gladly show you a few dozen trees in various stages of wound healing using different products from the sticky gum paste in toothpaste tubes, concrete, durhams rock hard water putty, and duct sealant. It's a big garden, walk fast it'll take you 2 hours, about 225 trees or so. Hit me up if you're bored!

 

[Mike Hennigan]

Those studies are basically irrelevant to bonsai. They’re not worried about timber trees or landscape trees having scars.

 

[milehigh_7]

Those studies are basically irrelevant to bonsai. They’re not worried about timber trees or landscape trees having scars.

Many bonsai pros are not worried about that either. @grouper52 am i correct in my memory that Dan Robinson does not seal? That's why on my list I include the look one is going for in their trees... Bougs are another that will die back if unsealed when chopped.

 

[arreaux]

I've been using water based acrylic artist paints and have been able to match close to the bark colors.
I apply it mostly on larger cuts and or branch removals.
The paint dries to pliable cover and I prefer it over the tree sealants out there.

 

[Mike Hennigan]

Many bonsai pros are not worried about that either. @grouper52 am i correct in my memory that Dan Robinson does not seal? That's why on my list I include the look one is going for in their trees... Bougs are another that will die back if unsealed when chopped.

Is Dan Robinson known for his scarless maples? No, not particularly. I’m not arguing for or against scars, just saying I think we’ve all figured out that if we want to heal a wound more efficiently, cut paste of some kind is in order. I love scars where they are wanted!!!

 

[KiwiPlantGuy]

Hi all,
Can someone explain the sealant some have described as Builders Putty?, or Duct Seal??
I have a hole in the middle of my Ulmus parviflora I am trying to make a broom out of, but don’t want the wood to rot etc.
I have been using PVA wood glue for chops etc, and it seals well ?
Charles

 

[Adair M]

Duct seal, aka “electrical putty” is a soft putty that will keep water out. But it’s soft so a growing callous can expand and eventually cover over the wound.

It’s a cheaper version of the putty sold in little tubs with Japanese writing all over it!

 

[bonsai-ben]

I went to a garden a few days ago, "I stopped using cut paste on Ficuses" and that's why all the branches were scarred and not healing. Food for thought! All mine are healing wonderfully with Durhams Rock Hard Water Putty + Duct Sealant

 

[River's Edge]

I think every bonsai source I have read makes the case for using wound sealant on pruning wounds. However, I recently read two sources that argued that it is of no benefit to use wound sealant. A paper written by Shigo and Shortle (Journal of Arboriculture, 1983) (http://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=1923&Type=2) and a short polemic, if you will, written by Chalker-Scott (https://s3.wp.wsu.edu/uploads/sites/403/2015/03/wound-sealer.pdf) claim wound sealant provides no benefit (this latter article seems unconvincing; it is filled with many claims that lack support, but I wanted to post it since it makes the claim).

Does anyone know of any studies that support the use of wound sealant, or any studies that do not support the use of wound sealant? And can anyone speak to their own experience, both with sealant in general and with specific types of sealant?

For Bonsai purposes i have tried both approaches and a number of products. For deciduous i prefer a liquid sealer that allows the callus to form over the sealant. The key seems to be to use it sparingly with a thin rather than thick cover. Maples will form a very thick callus if a thicker covering is used. For conifers i prefer cutpaste and have used the Japanese product, plus local putties, they work well. The cutpaste versions also work on deciduous. Cutpaste requires re-application and checking to ensure it does not dry out and pull away from the edges.
If you wish to heal over scars for aesthetics then use some form of sealant or cut paste. If you are after a damaged look then it is not needed. My two favorite products are in the first picture and available from " kaneshin" and also from several online sources in North America. The second picture is available from " Michaels the craft Store" cheaper substitute cutpaste, soften with a bit of mineral oil. The last picture is a liquid sealant that contains fungicide which i find helpful on deciduous. I obtained it from the vendor area in the BIB show. Just some suggestions for those who may be looking. These products work!

 

[Tieball]

Sealant...Helpful. And I base that decision for me on my personal experience for my climate and growing conditions. Sealant out of a tube usually.

 

[River's Edge]

Sealant...Helpful. And I base that decision for me on my personal experience for my climate and growing conditions. Sealant out of a tube usually.

The wax products have been very effective for grafting purposes, i like your chances.

 

[Tieball]

The wax products have been very effective for grafting purposes, i like your chances.

My plan is to experiment with both paraffin wax and soy wax and see what I think about results.