Foliar Feeding - Myth?

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After the recent debate on wound sealants, King Kong is determined to debate another myth I mentioned in my article, "Debunking the Myths of Bonsai" which is folair feeding.

I'll just cut to the chase and start the discussion with a direct quote on the subject from my article:

"Foliar feeding at first glance seems almost romantic; the thought of delivering nutrients directly to the foliage instead of though the soil, roots, and up the trunk to the foliage seems idea. The soluble fertilizer companies, seeing possibilities of increased sales, since foliar feeding uses far more of their product than traditional feeding practices, are quick to tout such claims as immediate results, prolong bloom times, increased pest and disease resistance, and even increased crop yields.

The problem is that most of these claims are based on some research done by Michigan State University in the 1950's in which, by the use of raidolabeled nutrients, it was determined that the leaf is a very efficient organ for absorption. The amounts absorbed were actually very low but the efficiency was high, leading to false claims that foliar feeding was many times more effective than soil applications.

Linda Chalker-Scott, an Extension Horticulturist and Associate Professor at the Puyallup Research and Extension Center of Washington State University, clarifies this in her article, "The Myth of Foliar Feeding."

"Obviously, materials applied directly to a leaf are more likely to enter the leaf in large quantity than the same materials applied to soil. Leaching, chemical reactions, microbial activity, etc. can decrease what actually reaches the roots and is taken up into the plant. But material applied to the leaf do not necessarily travel throughout the entire plant as effectively as they do through root uptake. The often remain in the same or adjoining tissues but travel no further. This is especially true of those elements recognized as "immobile" within plant tissues (apart from root uptake and xylem transport)."

Linda goes on to state that the nutrients plants need the most of are the very ones that cannot be absorbed in large enough quantities by the leaf to do any good, such as nitrogen, phosphorus, and potassium. She also specifically states some facts based on research that may surprise many bonsaists, such as:

Tree and shrub species differ dramatically in their ability to absorb foliar fertilizers.
Micronutrients are the only minerals that can be effectively applied by foliar feeding and too much of these can damage or kill a plant.
Foliar spraying is only a temporary solution to the larger problem of soil nutrient availability.
Any benefit from foliar spraying of landscape trees or shrubs is minor considering the cost and labor required.
The common myth of foliar feeding is based on misreading and/or misinterpreting research done over 40 years ago. Since that time it has been shown that foliar feeding is ineffective in almost every aspect promoted by the companies that sell products designed for the practice. In fact, foliar feeding has been shown to work the best only in the case of soil with low nutrient availability, in other words, when a plant has no other option for nutrients. As bonsaists, our soil would never reach the level needed for foliar feeding to do any good.

Bonsai need nitrogen, phosphorus, and potassium the most, as do any other plants and these nutrients are the very ones that foliar feeding is the worst at providing.

It is my personal opinion that any success by bonsaists using foliar feeding can be directly attributed to the mixture running off onto the soil, not through absorption through the leaves. The common practice of watering from above and dosing the foliage puts the nutrients into the soil, even though the bonsaist believes they are foliar feeding."



I, as always, would welcome rebuttal that is based on at least the same quality references, sources, and research as presented. As always, I would love being proved wrong as much as I love being proved right, either way, our knowledge and understanding of the subject is increased. No matter the outcome of these debates, we all win.



Will
 

greerhw

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Will, A simple question if you don't mind. If plants don't recieve nutrients from folair feeding, why are they able to absorb herbicides like Roundup.

Harry
 

ghues

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Will, A simple question if you don't mind. If plants don't recieve nutrients from folair feeding, why are they able to absorb herbicides like Roundup.

Harry

Not the total answer but........"It is absorbed through foliage (through the stomata I would assume)and translocated to growing points. Because of this mode of action, it is only effective on actively growing plants"
gman
 
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In fact, foliar feeding has been shown to work the best only in the case of soil with low nutrient availability, in other words, when a plant has no other option for nutrients. As bonsaists, our soil would never reach the level needed for foliar feeding to do any good.

Correct, however the same is also true in a soil with good fertility but the plant itself is severely compromised in its ability to absorb water and nutrients such as right after collection.
 

greerhw

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Not the total answer but........"It is absorbed through foliage (through the stomata I would assume)and translocated to growing points. Because of this mode of action, it is only effective on actively growing plants"
gman

Sorry gman, I'm still confused.

Harry
 

Smoke

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Will, A simple question if you don't mind. If plants don't recieve nutrients from folair feeding, why are they able to absorb herbicides like Roundup.

Harry


Sorry Harry, I already tried that in the virgin discussion some where else. I was told by Mr. Heath that we mix poisen in lethal doses. Thats the difference. Of course we all know that a lethal dose of fertilizer would do the same thing. How about dissolving some ammonium sulfate 21-0-0 full strength and spraying the leaves with that in summer and pray like hell Mr. Heath is right. Hey it's just fertilizer!

I am enjoying reading round two of all the de-Bates though.
 

Smoke

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All of these discussions about myths have large grey areas that make them very impossible to just throw a blanket over the topic and consider it debunked.

If one bonsai branch was saved from the application of cutpaste, in my book I could not reasonably dismiss its entire use. Walter Pall has written that on occasion he has used foliar feeding to nurse back plants with weak roots. So have I, in fack California Junipers are fairly incapable of either taking up water or fertilizer thru their roots untill they have been established in a pot for a year. You want to green up a pale hinoki cypress before a show? dissolve one teaspoon epsom salts in a gallon of water and foliar the week before. (many plants enjoy the boost of magnesium) You will be surprised.

So if plants can take up nutrients thru their leaves, then how can you say a myth is debunked. Is it the best way to feed a plant, probably no.
Is root feeding the only way, no. You could foliar feed. You just can't dismiss it.

KK started a thread on another forum about a finished bonsai in a show placing the same as a near copy of the same tree. KK feels the award should go to the tree that was started by seed. Implying that somehow a tree started from seed is somehow worth more than a tree either collected, layered, struck from cutting or otherwise. I don't think so.

The same could be said for the myth of the single front. While I agree a tree seen better from multiple sides may be more favorable, I don't perscribe to the notion that a tree very much desireable from one view is diminished by being viewable from one view. Some do though. I look at that as a very narrow view of bonsai in the big picture.

Ok carry on
 

greerhw

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Much like you Al, I tend to do what seems to work for me, I'm not prone to believing everything I read. I don't wish to cast any doubt on Mr. Gores much heralded fiction movie for which he won an Oscar, but I have now read that Global warming actually started in 1850. It must have been caused by methane gas from all the Bison.

Harry
 

Smoke

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Much like you Al, I tend to do what seems to work for me, I'm not prone to believing everything I read. I don't wish to cast any doubt on Mr. Gores much heralded fiction movie for which he won an Oscar, but I have now read that Global warming actually started in 1850. It must have been caused by methane gas from all the Bison.

Harry

I am sure that Mr Gore's home has contributed it's fair share.;)
 

Ang3lfir3

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WH you accidently missed a portion of the original article... so i wanted to make sure you had it here.

Original Myth Article said:
Based on every single professional horticulturist statements on the subject that I could find, as well as studies from major universities, there is no other logical conclusion other than foliar feeding is ineffective, a waste of time, a waste of resources, and all claims to its validity are false.

The truth is that foliar feeding offers no advantages at all to the bonsaist.


Also i wanted to include the complete Subtitle of the article by Linda Chalker-Scott... just so everyone who didn't read it can be clear on its actual complete title and purpose. The complete title of the article being The Myth of Foliar Feeding - "Fertilizers sprayed on the leaves of trees and shrubs are more effective than soil applications." actually let me just link to the article.... http://www.puyallup.wsu.edu/~Linda Chalker-Scott/Horticultural Myths_files/Myths/Foliar feeding.pdf

I also wanted to ask for an explanation as to what specific bonsai myth you are targeting? Your original article doesn't specify exactly what you were debunking in terms of bonsai. If you were trying to debunk the bonsai "myth" that foliar feeding is useful in some ways in bonsai (which I presume your statement "all claims to its validity are false" is suggesting) then I believe you chose the wrong article to backup your claims. Linda Chalker-Scott's article states specificly that macronutrients can and are taken up by the foliage.. which in cases such as the one stated by Al (Smoke) as well as for trees after collection (tho i personally suggest not feeding freshly collected trees) would make foliar feeding of some (however small) benefit to the plant.

I was also interested to see that environment and cuticle size (which you fail to mention at all in your argument) play an important role in the uptake of nutrients from the foliage. She suggests that "Plants in a protected situation (like a greenhouse) have thinner and more porous cuticles than plants in the field and take up foliar sprays more readily" . I would offer that bonsai culture is certainly not "in the field" and that many persons do care for and keep tropicals in a more moderate greenhouse environment. Therefore, its not possible to state that foliar feeding is "useless" as this article it self has shown that it can be useful, however in the context of the article is showed little use for landscape material which already was established and had to it the available macro and micro nutrients necessary for survival.

In conclusion it seems apparent that it has been proven that:

1) both macro and micro nutrients can be delivered by foliar feeding.
2) delivery of macro nutrients via foliar feeding is less effective than soil application (the point of the Dr. Chalker-Scott's article)
3) foliar feeding as an addition to soil application may be useful in moderate environments.
4) foliar feeding would be preferable when a plant had no other means of receiving nutrients.


just my 0.02
 

greerhw

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I attempt to use as much common sense as possible when trying to address anything to do with my little trees. When I see a healthy RMJ surviving in a crag on a granite mountain with no organic soil worth a crap, I assume it must be getting some benefit from it's foliage. The rain water has to run off quickly. In the summer when there is no rain, the only conclusion I can come to is it's getting enough moisture through the folliage from the morning dews. If someone has a better idea, please prove me wrong.

Harry
 
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Will, A simple question if you don't mind. If plants don't recieve nutrients from folair feeding, why are they able to absorb herbicides like Roundup.

Harry

Old question Harry. Different chemicals and properities is the short answer. Think of this, mercury can be asorbed by human skin and poison us, so how come we can't rub food on our skin instead of eating it?

See the point?


Will
 
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I do believe in foliar feeding. Especially the yamadori trees with less roots gain from it.
Even spruce do benefit from certain products. Also a gift of magnesium to buxus has great results.
A lot of study’s and essay’s of leading agricultural university’s in Europe (Wageningen UR (Holland) and Leuven Belgium) describe the benefit of foliar feeding.
They published several study’s of the effects of it on tree’s ,scrubs and vegetables like spinach and cauliflower.
If you like you can search for the articles on the huge portals of these university’s.
Most of them are published in English. One tricky thing: because of the commercial benefits of these articles you must have acces to the library. Acces is only allowed if you are allied to them.
 
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WH you accidently missed a portion of the original article... so i wanted to make sure you had it here.

Thank you, the full artice is linked to above also.




Also i wanted to include the complete Subtitle of the article by Linda Chalker-Scott... just so everyone who didn't read it can be clear on its actual complete title and purpose. The complete title of the article being The Myth of Foliar Feeding - "Fertilizers sprayed on the leaves of trees and shrubs are more effective than soil applications." actually let me just link to the article.... http://www.puyallup.wsu.edu/~Linda Chalker-Scott/Horticultural Myths_files/Myths/Foliar feeding.pdf

.... Linda Chalker-Scott's article states specificly that macronutrients can and are taken up by the foliage.. which in cases such as the one stated by Al (Smoke) as well as for trees after collection (tho i personally suggest not feeding freshly collected trees) would make foliar feeding of some (however small) benefit to the plant.
Small is the key word above, so small in fact that except in certain cases, it is a waste as simple normal soil feeding is much more effective, so why bother?

I was also interested to see that environment and cuticle size (which you fail to mention at all in your argument) play an important role in the uptake of nutrients from the foliage. She suggests that "Plants in a protected situation (like a greenhouse) have thinner and more porous cuticles than plants in the field and take up foliar sprays more readily" . I would offer that bonsai culture is certainly not "in the field" and that many persons do care for and keep tropicals in a more moderate greenhouse environment. Therefore, its not possible to state that foliar feeding is "useless" as this article it self has shown that it can be useful, however in the context of the article is showed little use for landscape material which already was established and had to it the available macro and micro nutrients necessary for survival.
Actually most bonsai grown are not grown in greenhouses and most bonsaists do not let their soil substrate reach the point of low nutrient levels that would make foliar feeding useful, however these levels may be reached in the field when all nutrients have been expended can can not be repalced, even then foliar feeding is a short term fix.

In conclusion it seems apparent that it has been proven that:

1) both macro and micro nutrients can be delivered by foliar feeding.
No arguement, but not in levels that can out perform simple soil feeding.
2) delivery of macro nutrients via foliar feeding is less effective than soil application (the point of the Dr. Chalker-Scott's article)
Exactly.
3) foliar feeding as an addition to soil application may be useful in moderate environments.
Maybe? Maybe not!
4) foliar feeding would be preferable when a plant had no other means of receiving nutrients.
Certainly does not sound like bonsai culivation, does it?

later this evemning I will post other studies to confirm my premise in the article.


Will
 

greerhw

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Will, I understand you point, but there have been many scientific studys done on plants in general, but none I know of know of on bonsai. Plants react differently in different situations, lab tests,field studys and so on. I will continue my home grown methods until someone studys little trees in pots and there are proven results that bonsai react the same as plants in the ground. I'm just hardheaded that way. My Doctor says if I take a aspirin a day I will live longer, how does he know that.

Harry
 

Ang3lfir3

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Small is the key word above, so small in fact that except in certain cases, it is a waste as simple normal soil feeding is much more effective, so why bother?
I certainly don't suggest replacing soil application with foliar... but you had stated previously that "all claims to its validity are false." which simply can't be true since it is a valid method of fertilization when not other option exists.... it may not be effective but effective and valid are not necessarily 1:1.

Foliar feeding of micronutrients may be more effective when it comes to temporary health care issues in trees. Long term they may not be as effective but in the short term they may provide the needed nutrients faster. As Al also mentioned show prepping a tree, which is really a special case for bonsaists, you can see that foliar feed may be more effective for such scenarios when looking to rectify a foliar deficiency.

Ang3lFir3 said:
I was also interested to see that environment and cuticle size (which you fail to mention at all in your argument) play an important role in the uptake of nutrients from the foliage. She suggests that "Plants in a protected situation (like a greenhouse) have thinner and more porous cuticles than plants in the field and take up foliar sprays more readily" . I would offer that bonsai culture is certainly not "in the field" and that many persons do care for and keep tropicals in a more moderate greenhouse environment. Therefore, its not possible to state that foliar feeding is "useless" as this article it self has shown that it can be useful, however in the context of the article it showed little use for landscape material which already was established and had to it the available macro and micro nutrients necessary for survival.
Actually most bonsai grown are not grown in greenhouses and most bonsaists do not let their soil substrate reach the point of low nutrient levels that would make foliar feeding useful, however these levels may be reached in the field when all nutrients have been expended can can not be repalced, even then foliar feeding is a short term fix.

I didn't say that most bonsai were grown in greenhouses, please read more carefully. The portion of my response you quoted simply comments on my interest that the effectiveness of foliar feeding plant material grown in a more moderate environment was higher than that of for example yard trees. It also suggests that supplementing soil applications of macro/micro nutrients with foliar sprays may offer an additional method of supply food to tropical specimens being grown in greenhouses or similar environments.

No arguement, but not in levels that can out perform simple soil feeding.
I never suggested it would outperform soil feeding and I don't believe it has ever been suggested as such in bonsai circles. Please cite references of such remarks.

Certainly does not sound like bonsai culivation, does it?
I never said it did. Tho as Al has mentioned some plants can have a truly rough time surviving after collection. Any possibly supplemental boosts would be beneficial.
 

greerhw

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one more thing........

Nature has it's rules, but sometimes the rules can be bent. You can have a pond full of female koi and one will have the ability to change it's sex to male and fertilize the eggs after a spawn. Viruses mutate all the time to survive, so what makes us think that plants can't adapt to different situations to survive. Maybe someone with a few seedlings would agree to conduct an experment. Take two Identical plants and only feed one throught the roots, cover the soil on the other one and only feed it through the foliage. Not scientific by any stretch of the imagination, but might prove to be interesting.

Harry
 

Ang3lfir3

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My Doctor says if I take a aspirin a day I will live longer, how does he know that.

Harry
Aspirin has been shown to be preventative (meaning helpful in lowering risk) of everything from heart attack to cancer. Lots of work goes into those studies, I promise. take your 81mg of aspirin and be happy about it!
 

greerhw

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Aspirin has been shown to be preventative (meaning helpful in lowering risk) of everything from heart attack to cancer. Lots of work goes into those studies, I promise. take your 81mg of aspirin and be happy about it!

Study results from aspirin companies. I read the paper one day that enough caffeine will kill me. Two weeks later I read where caffeine is good for me. But I will admit I like the one about red wine.

Harry
 
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Will, I understand you point, but there have been many scientific studys done on plants in general, but none I know of know of on bonsai. Plants react differently in different situations, lab tests,field studys and so on. I will continue my home grown methods until someone studys little trees in pots and there are proven results that bonsai react the same as plants in the ground. I'm just hardheaded that way. My Doctor says if I take a aspirin a day I will live longer, how does he know that.

Harry


It is your right to do what you wish, there are no bonsai police that will arrest you for watering with horse pee, if you wished to.

As to your comments above, plants are plants, in the field, in a container, on a mountain side, in a forest, or growing in cracks of sidewalks. They all have the same genetic makeup, they all respond in the same manner for survival (same species react the same way). They do not grow or react differently, they do not magically acquire new response mechanisms simply because they are suddenly called a bonsai or moved to a container. Their responses to damage, to conditions, or to the environment do not change. Their way of feeding, healing, growing, or otherwise does not change just because they are in a pot. Plants in a container absorb nutrients exactly the same way as they do in nature, nothing is different.

The only difference is that bonsai typically will incur more damage (pruning constantly, root pruning, defoliation, etc) but the responses to the damage is exactly the same as in nature. The growth is also slower due to restricted roots.

This is why it is wise to use the vast resource of valuable information gleaned by horticulturist, arborists, researches, and scientist that is out there. These studies based on documented research and experiments performed by trained professionals offer a wealth of information and knowledge that has never been duplicated in the bonsai community. I can't imagine why anyone would ignore such information and insist on finding out the hard way. Isn't bonsai a slow enough art form as it is?

Imagine going to your doctor and finding out you had a heart problem and then learning that there is a wealth of studies out there, backed by experimentation that shows your heart problem can be corrected without surgery. But.....your doctor's been doing open heart surgery for years and will not even consider any other option.

I don't know about you, but I'd be getting a second opinion.


That is all these studies do for us, offer us the advantage of decades of serious research so that we can a) see what has been discovered, b) weigh it against our own personal experiences and knowledge, and c) adjust our thinking and practices to incorporate new ideas in order to advance our own bonsai knowledge.

Of course, we can always go under the knife anyhow....blindly trusting surgery, after all it has worked on millions of people before.....
 
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