The article Debunking the Myths of Bonsai has been submitted for the Bonsai Vault Article Contest....Good Luck!

Name: #3 - Will Heath
Country: USA
Credits: See References
Category: Non-Fiction
Submission Date: 04/24/2008

Thank you Will for your submission

Another interesting article from the fingers of Will Heath. Keep 'em coming Will, you give us food for thought. This type of article is what makes for good debate here in the VAULT and that is what we are about.


Ash

Yep, good debate.

Thanks.


However, I'm afraid there isn't really a lot to debate, when some of the greatest horticulturists of our time and studies from major universities agree on a subject, you can pretty much bank on the results. One would be hard pressed to offer serious rebuttal on any of these myths backed with sources and studies of the same caliber.

Without controlled experiments and qualified individuals conducting them, the all too common "well it works for me" just isn't quite good enough.

As I mentioned in the article, many people will hang on to these myths, if for no other reason than they have too much at stake, retailers and those who have promoted the myths for example....

Part two and three more myths will be coming soon.



Again, thanks for the kind words, they are much appreciated,


Will

As with all methods, there are exceptions to rules (and myths).

In regards to the "do not seal" debate, I went searching. I've always seen the oak trees sealed locally, even when done by the master gardners. I found out why-there's a disease called "Oak Wilt" that affects oaks and elms. Quote from Minnesota:

"Neither elm nor oak trees should be pruned from April to October. Oak wilt is found throughout Minnesota. "Although 'do not prune in April, May and June,' is a nice jingle, in some years spring comes earlier than we expect," Beckerman says. "It's time to stop pruning when daytime temperatures reach the 50s, and if you have to prune an oak during this period, be sure to apply pruning sealer or wound paint immediately after the wound is created to infection." (Janna Beckerman, plant pathologist with the University of Minnesota Extension Service)
http://www.extension.umn.edu/extensionn ... pprun.html

It could be argued that this is only for up north......but here's Texas:

"Live Oaks, Red Oaks, Water Oaks, and Shumard Oaks should have wounds covered with an approved tree wound product to prevent possible infection from Oak Wilt disease."

http://www.dallascityhall.com/Parks/for ... uning.html

Minnesota says seal when daytime temps reach 50's, Dallas says always seal-because how often are the daytime temps not in the 50's?

This place : http://www.treehelp.com/howto/howto-prune-a-tree.asp
Had another caveat:

..."since most pruning should be done in late fall or winter, insects should not be much of an issue. However, there exist some circumstances when it is preferable to seal the wound with a non-asphalt-based pruning sealer. In particular, you should seal pruning wounds on trees that are susceptible to damaging insect infestation such as birch, oak, and elm trees. Also, if the weather is particularly dry, a pruning sealer will help the tree retain more moisture."

So they reiterate sealing oak and elm, adding in birch. They also point out that sealing helps prevent insect infestation and if the weather is dry helps the tree retain moisture. Where I live, insects abound and lately so does dry weather. If you were to do a lot of pruning on a tree (as we bonsaists can do....) pruning sealer would help stop the tree from drying out due to the loss of large areas of bark/branches.

Another exception: fruit trees. There may not be a lot of fruit trees used in bonsai, but they are there. Whereas the earlier trees should be pruned in winter, apparently apple trees are different:

"Pruning should not be done in the winter since the apple tree might develop a serious disease called "silverleaf" unless the cuts are treated with a top quality wound sealing paste..."
http://www.essortment.com/all/howgrowapplet_rnil.htm

"As a general precaution against silverleaf infection it would be wise to apply dressings to all wound larger than 10 mm in diameter. All wounds on the main stem/ trunk should be treated to prevent the entry of silverleaf which invariably results in more severe silvering than infection in peripheral branches. In the absence of detailed monthly silverleaf susceptibility data for fruit tree cultivars, it is safest to assume that they are susceptible to silverleaf infection throughout the year. Accordingly, all pruning wounds should be treated regardless of the season"
http://www.hortnet.co.nz/publications/s ... asorch.htm

In other words, large wounds should be treated, all wounds on the trunk should be treated, and if you don't have data on monthly susceptibility (i.e. trees not susceptible in May in your county), treat it all year round. Most of us don't have susceptibility tables I'm guessing!

To summarize, what I've dug up (pun intended) says that if you raise Oak, Elm, Birch, or fruit bonsai.....seal with a good sealing paste to prevent diseases and insects. If you prune large areas on trees, seal. Unless it's a pine or ficus or other species that makes its own would sealant that is!
Good qulaity sealing paste is a whole different debate (right Joanie?) and not using substitute seems to be supported by the evidence.

Another time to use sealing paste is when dealing with grafting......but that's a whole post by itself!

So given the evidence, I wouldn't say that wound sealing is a complete myth. As with many techniques, there are times and species to use it on.


Susan in Florida

From the article:

"Wound Paints and Sealants - While most horticultural books recommend the use of paints or sealants on tree wounds, Dr. Shigo's research shows that such treatments have no long-term value. Provided pruning is done properly by cutting as closely as possible to the branch collar, there is no need to paint wounds regardless of their size."

It is very difficult to argue with Dr. Shigo's research and he debunked the sealant myth years ago, yet it still persists.

References to using sealants are based on information from decades ago, most serious aborists today do not use such on any species, however the consumer has been conditioned so many arborist spray the cut with black paint, just for appearances.

I'm am sorry to say Susan, that sealants serve no useful purpose at all, with the exception of making the person using them feel good. But, by all means, continue using them, the retailers will be happy at least.



Will

Will, I enjoyed this article. However with any scientific opinion there always is always room for debate

I have to throughly agree with your points on vitamin B1 and the products that incorporate it, and the companies that extol the virtues of the product. I have done, as some others, a side by side comparison using B1 on plants with and without it and agree with your conclusions in your article.

However, the other two subjects I would debate:

Foliar feeding I believe works as I have witnessed a benefit by doing so...if properly done. Graham Potter's article here explains this technique. It also cites research by Dr. H.B. Tukey , Head of Michigan State University's Department of Horticulture,and S.H. Wittwer that flies in the face of Linda Chalker-Scott's opinion. So I do believe that there is room for debate on this topic.

The approach you took on cut paste is hard to argue with, but you are trying to debunk Bonsai Myths not debunk myths of trees grown in the wild. You are comparing apples to oranges by applying research done for field grown trees and applying it to trees in container culture.

Cut paste/wound sealant alone if for no other reason in bonsai application will help in retention of the trees moisture loss after pruning. A maple pruned in late fall without cut paste will suffer from die back due to winters harsh environment due to drying of the tissue that is exposed from the cut. Something that, if you grow maples, you can observe. Junipers that have been carved will suffer the same effects. This especially bad since they have a trait to draw back from the wound as they heal. Then there are exceptionally large wounds that we create from hard pruning. We all know that a callous won't form over rotting wood, so wound sealant, be it cut paste or epoxy is applied to give a hard rot free surface for the callous to form over a long period of time on a substantially large wound.

The techniques used for pruning as cited in your references for speedy healing of wild trees is not the approach we take in bonsai. To cut right after the collar of a branch would definitely not lend itself to a graceful art form. Something I'm sure that Dr. Shigo's and Diane Relf didn't take into account for. In fact you even quote Dr. Shigo "Provided pruning is done properly by cutting as closely as possible to the branch collar, there is no need to paint wounds regardless of their size." In our applied practice this is not the case we cut out the collar or are pruning farther down the branch.

Cut paste / wound sealant in bonsai culture started out I'm sure with a single intension in mind such as I stated above. I'm sure as you alluded to in your article, manufactures came up with other benefits that may or may not be actually true.

No one to my knowledge with academic credentials has done scientific research and published papers on bonsai as a specific subject. Reaching out to a close cousin (trees in the wild), while useful information, is a shaky basis for debunking bonsai myths (IMO).

Thanks for the article Will, as always you made me think and reread articles that I had long forgot.

Personally, I rarely use sealants on my plants. Why? I raise tropicals not woody plants or fruiting ones or oaks or any other species vulnerable to fungus and blights. I wasn’t talking about what I use personally, just giving exceptions to the “sealants not needed” statements-no retailer will benefit from me.

To say that sealants “serve no purpose at all” is a broad statement, and we all know how broad statements work with Mother Nature. To clarify, they don’t. I described several scenarios where a sealant would serve a purpose, cited several sources… so sealants do have a purpose in certain cases. Would I seal a pine? No……..conifers make their own. Ditto for ficus. I have used sealants on splits on my Portulacaria after repair to keep the area moist and give it time to heal over itself. The areas I didn’t seal dried out and stayed split, the ones I did you can’t see the split 6 months later.

Dr. Shigo has been dead a couple of years and the course of disease progressions can change quickly. For example, four years ago there were not huge problems with pine beetle borers in my area. An ailing tree with them was quickly removed. Fast forward through a few hurricanes, and now there are lots of borers. We are told to just leave the affected tree alone, otherwise the borers will just move to another healthy tree. Let them eat the already dying tree and slow their progress to the next tree until an effective large scale treatment can be found. So advice from 2 years ago may be outdated given current conditions.
I see no research by Dr. Shigo on Oak Wilt or Silverleaf diseases either…… so his advice wouldn’t necessarily apply to those species or disease situations.

As my esteemed collegue pointed out, Dr. Shigo’s research was on full sized trees freely growing in the ground. We deal with trees trapped in pots….. different conditions, different approaches. His point is the tree has the resources to heal itself. Ok, here’s one thing to think about. If you cut a one inch branch off a 20 foot tall tree, you’ve removed a miniscule percent of the plant. Easy for the plant to grow over the wound usings very few resources, right? Cut a one inch branch or two or three off a 20 inch tall tree and you’ve removed a substantial part of the plant. Now there’s a large (percentage wise) wound on the tree, as compared to a full sized tree. The inch tall tree may need some help keeping the area moist for or free of fungus while it recovers. It’s like comparing the treatment you give for a splinter to the treatment you give for a 1x2 impalement.

One or two insects on a full sized tree will cause very little damage and may not warrant treatment. One or two insects on a mame, doing the same amount of damage, could easily kill the tree and definetly warrant treatment. A one inch area of fungus infestation on a full sized tree wouldn’t be noticeable-on a one inch trunk it’d be glaring. An arborist deals with full sized trees…….we’re bonsaists, we deal with smaller versions. What holds true for big trees may not hold true for small, and until the research is done using actual bonsai trees the research is advice rather than rule.

Tachigi wrote:
The approach you took on cut paste is hard to argue with, but you are trying to debunk Bonsai Myths not debunk myths of trees grown in the wild. You are comparing apples to oranges by applying research done for field grown trees and applying it to trees in container culture.

There is absolutely no difference in the way a tree grows or responds to injury based on if it is in the ground or in a container.

I personally see nothing "shaky" about comparing how trees deal with wounds in nature (lighting, wind, snow, animals, etc) and how they respond to pruning at the collar or by bonsaists attempting to mimic the damage caused by natural forces. Trees do not know the difference and have no care what-so-ever if it was a rock slide or a nice clean, new pair of concave cutters or jinning pliers that did the damage, the response is exactly the same.

Again The Wikipedia tells us "Dr, Alex Shigo is widely considered the father of modern arboriculture. He developed many of the principles that have become central to arboriculture, and his work served as a foundation for much of the research following it." And that "Dr. Shigo's discoveries went against many arboricultural conventions that existed prior to his research. Many techniques that were staples of arboriculture for hundreds or even thousands of years were shown to be unnecessary or harmful. It took many years, but Shigo's conclusions have been confirmed by other researchers, and a wealth of discoveries are now built upon his initial work. Current ANSI standards for tree pruning reflect his recommendations."

I respect the right for each person to use whatever methods or potions they choose, but personally, when cut paste is labeled worthless by a mind such as Dr. Shigo (dead or not), I think I'll base my actions on his research. At least until someone equally qualified convinces me otherwise.

Until then, I'll continue not wasting my money on cut paste and I should state that I have seen no ill effects, in fact I have seen no difference at all. I will also leave the debate to the sources and studies I have referenced in the article, those sources are far more qualified than I am.



Cheers,


Will