Yet I can find very little scientific support for any of them, either natural or synthetic.

Why do you think that is? *wink*

For rooting hardwood cuttings and plants that are notoriously difficult to root they can be of some benefit if used properly.

For plants like tomatoes that even develop roots in the air if the humidity is high enough they are not needed nor of any use.

Dave

Dave may be limiting response to the Giberelic Acid compounds on the market but there are many others that have logical merit but limited supporting research to have everyone flock to purchase them. Many of the biological controls like RootShield, Actinovate, Cease, Milstop, Oxidate, Serenade, Sonata have had some success in stimulating plant growth although the successes aren't always repeatable. Products like the Biofungicide discussed in another thread ( as added to ProMIX) is said to colonize the plant roots and aid in nutrient absorption. One expert cited the complex nature of soil interactions as one reason why different trials have widely differing results; sometimes certain of these products may actually have negative results.

I woudn't give up totally on this group of products since they likely hold the future of improved plant performance in environmentally friendly ways. Marrone Bio Innovations has invested heavily in registering biological pesticides with varied modes of action and their products are recommended for tomatoes. Some might not be thought of as root stimulants but indirectly they are since new root growth is often the first part to suffer of the stressed plant.

Good point B - Clonex, Gib acid, NNA and IBA and similar products are what I'm referring to.

I don't normally consider the bio/bacterial additives to be "root stimulants", at least not in the normal sense. And the Milstop, Serenade, Actinovate group all have other primary uses so any root stimulation is a secondary benefit.

Better I should have asked exactly what the OP means by "root stimulants"?

Dave

Things that stimulate root growth. You apply it and you get more and bigger roots.

digdirt is right: tomatoes are rooting fools. They are perhaps the easiest plant on earth to root from cuttings and they grow new roots along the stems when in contact with dirt. Tomato roots are improved by care in watering, not chemicals. Since you would be eating that fruit later, how would you know that you were not eating those chemicals or their metabolites too? They used to say DDT was harmless and how could the chemical companies possibly lie? You are what you eat.

Things that stimulate root growth. You apply it and you get more and bigger roots.

Then you are using it as a catch-all label and unless you have a specific brand or at least a class/type in mind it's not really possible to answer except to say they have minimal or no role in growing tomatoes.

As already said, there are all sorts of things - both synthetics and organics - that may claim to "stimulate roots". The term is commonly used as a label for those things I listed and most commonly used with trees and other hardwood plants, not with tomatoes.

B also covered some of the other commercially used products that may be used with tomatoes as a fungicide or nutrient supplement where some root stimulation may be a secondary benefit.

Dave

The reason for my question was that a tomato grower in France uses a product he feels is a very good root stimulant the use of which gives him more and bigger roots. I believe it is an auxin and the brand name is Osyril.

Osyril (not available in the US AFAIK) is an organic and classed as a systemic auxin protectant/stimulant tested for and to be used in turf grass development where nematodes and other soil borne diseases are common. Per most food horticulture sources, like most systemics, it is not recommended for use in food crops.

If the tomato grower in France chooses to use it on food crops that is his choice, his risk to take.

The problem with auxin stimulant IMO is it is a very fine line between enough and too much. The plant naturally produces them to the necessary level assuming no interference from outside sources such as soil disease or nemeatodes or root exposure to light and heat. Supplementing what the plant produces naturally can easily push the plant into stress and even death. 2-4 D and Agent Orange being prime examples of the way excess auxin production works.

A safer and IMO more effective method of root stimulation if needed in food crops, is the use of mycorrhizae supplements as B mentioned above. They are especially beneficial when growing in containers where the beneficial bacteria is missing, less so with in-ground gardening.

The article linked below may be of interest to you.

Dave

Here is a link that might be useful: The use of root stimulants in gardening

Thank you. I know quite a few tomato growers who are trying to get this product. I will not be one of them. Thanks again.

This paper from Virginia Tech says that the biostimulantes humate and seaweed stimulate growth in turf grass, it probably extrapolates to most plants.

Here is a link that might be useful: Questions and answers about biostimulants

As Dave said:

"The plant naturally produces [auxin] to the necessary level"

Auxin is a plant hormone that (combined with other hormones) triggers different growth developments. Roots, stem, etc.. The plant makes whatever auxin it needs to support this growth much like your body makes whatever hormones it needs. Hormone synthesis is regulated via a negative feedback loop in which there is an ideal level maintained by the plant by turning production on or off depending on the actual need. Continuing to force more hormones into the plants would be akin to an unregulated pituitary in you or I.

While there may be a point to where this is desirable to the grower, I don't think it's going to make for a very happy plant. Eventually, the added stress is going to cut down production. So, while results may peak at a certain point, its going to eventually decline, and I think that it would be very difficult to tell when enough has become too much until it's already too late.

This post was edited by ZachS on Tue, Mar 18, 14 at 13:21

I would be more apt to agree with a university study than some "Dave" on GW. Nobody says you have to dump the whole bottle on everything, why does it have to be all or nothing. Any extra root mass will only help. According to that paradigm, growers would not use rooting aids at all, even though we know they all do, after all "The plant naturally produces [auxin] to the necessary level" so just let them produce it! Right, tell them that, they do it for a living.
We are growing plants in an artificial environment as it is, you do not think your plot of tomatoes is a part of nature do you? People have been growing things for a long time, it is only now that we have the WWW that you say anything and people will believe you. I need real hard data.

Always free to disagree Frank but relevancy plays a role. So based on the VT study on turf grasses that you linked (corrected link below) how much of each product and how often would you recommend using them on tomato plants?

I note that the article does include the warning that I addressed above

"One should be aware that most of the biostimulants are hormonal in nature and excess applications could be harmful to plants".

I also noted the stress the research gave to using only biostimulants derived from very specific sources. For example:

brown seaweed prepared by alkaline hydrolysis from Norwegian or Nova Scotia waters

Source of such product?

Then there is the whole discussion about the effects of antioxidants and free radicals caused by stress in turf grasses and how these biostimulants might reduce those effects.

Yet when one looks at the studies done by NIH (National Institutes of health) on the effects of stress in broad leaf plants like tomatoes we find very different results - minimal formation of antioxidants and free radicals.

the leaf superoxide anion and hydrogen peroxide concentrations in the transformed tomato plants did not alter much, suggesting a well regulated formation of free radicals suppressing oxidative stress in them.

Effect of water withdrawal on formation of free radical, proline accumulation and activities of antioxidant enzymes in ZAT12-transformed transgenic tomato plants.

So if the antioxidants and free radicals are not affected in tomato plants dosing them with biostimulants, even in safe amounts if known, provides little to no benefit as it would with grass.

That brings me back to your assumption: "it probably extrapolates to most plants." and there is the problem. Grass is unique in the plant world in many respects. It is a monocot - different vascular tissue, different circulatory system, different fibrous-only root system, and no cortex. Tomato plants are dicots - woody stems, ringed vascular tissue with a cortex, reticulated veins, taproots . So one can not accurately extrapolate from tests results on grass to tomato plants.

Hope this helps clarify some things.

"some Dave on GW who for what it is worth, has been in the nursery & landscaping business for more than 50 years"

Here is a link that might be useful: Questions and answers about biostimulants

Maxicrop is hydrolyzed, surely anyone in the nursery business for 50 yrs. should know that.
http://www.maxicrop.co.uk/better-products/
What studies have you done, and why should I believe YOU? Have you published? The NIH link has nothing to do with stimulants, it has to do with genetics. Methinks you just want to obfuscate the original question. And please, spare me, grasses need the same thing as all plants need. I encourage anyone to try seaweed and see how it works for them. The safe amounts are on the label directions.

I am apt to agree with books, journals, papers, and studies on the subject of biology, hormone synthesis, and cell function written and peer reviewed just the same as the VT study. The reason I agreed with Dave is not simply because he is Dave, but because he happens to be correct.

To me, there is one glaring difference between the grass in the study and the plants in our garden.

"Biostimulants have been shown to improve turfgrass... when the turf is subjected to low soil moisture, dollar spot, nontarget pesticide applications, nematode infestation, high soil salinity, high UV light intensity and heat."

This statement, coupled with the fact they used stressed grass as the experimental control, clearly shows that the reason the extra hormone was effective on the grass is because the grass was growing in conditions that either inhibit root growth or kill the roots it has. Basically what this whole study says is that dosing stressed grass with hormones brings it up to snuff with healthy grass, not that it makes healthy grass healthier.

"And please, spare me, grasses need the same thing as all plants need"

True, and as it so happens, they also need pretty much the same things as animals and protists need, though we all get them through various ways.

The difference in monocots and eudicots is significant, not in what they need, but how they work.

Since we are on the topic of plant hormones, Ill bring up herbicides. 2, 4-D is an herbicide that is effective for killing broadleaf plants, but it will not kill monocots. 2, 4-D is auxin based. The reason it kills dandelions and not crabgrass? Because monocots have the ability to inactivate the synthetic hormone in the poison. Eudicots cannot, and thus wither and die as a result of a hormone overdose (Reece et al, 2011).

I am not using it as an example because I think that's what will happen if you use a natural auxin supplement, but because it demonstrates a key difference in how these two clades of plants respond to different stimuli, despite all of them having the same needs.

Maxicrop is hydrolyzed, surely anyone in the nursery business for 50 yrs. should know that.

Ahh, Maxifort. I figured you must have a particular product in mind. Yep, it's a good fertilizer if one prefers to use only organics. But we are talking about biostimulants not fertilizers. The distinction between the two classes was made early on in the discussion.

What studies have you done, and why should I believe YOU? Have you published?

Published? Not a one. Years of personal comparative studies? Many. If publication is your primary criteria for belief then by all means feel free to follow the published claims of the manufacturers.

I'm not asking you or anyone to believe me. What I am asking is that before you make up your mind you first learn the basics -

how different plants work (in this case grass vs. tomato plants,

how biostimulants and fertilizers work or don't work and the effects the two different things have on different plants,

the different types of biostimulants and how they differ from fertilizers.

It also helps to understand how manufacturers buff up their advertising and inaccurately use labels to sell their products but that is a whole other issue.

The NIH link has nothing to do with stimulants, it has to do with genetics. Methinks you just want to obfuscate the original question.

Yes it is about genetics - the genetics of tomato plants and how they work very differently than the genetics of grass (in your linked study) do.

Dave

If you do happen to use a root stimulant, the possibility also exists that the plant will decide to put all its growth into the roots, and none into fruiting.

i can tell you that one place i do learn from is the Marijuana growers.

They tend to want to get the very biggest and fastest growing plants, and will do a tremendous amount of work, experimentation, reading, and expense to get to their destination.

root stimulant marijuana
https://www.google.com/search?q=root+stimulant+marijuana

I just purchased some crab fertilizer.
supposedly it has Chitin (from the shells)
this is also present in insect Frass.

Chitin+roots+tomato
https://www.google.com/search?q=Chitin+roots+tomato

excellent for root rot, which i have problems here in New Orleans, it can rain for 3 days straight.

ALSO...
[Disease resistance signal transfer between roots of different tomato plants through common arbuscular mycorrhiza networks].
http://www.ncbi.nlm.nih.gov/pubmed/22919820

Here is a link that might be useful: Chitin+roots+tomato

always be careful to keep plant supplements in right ratio and portion...i am considering a product called ...nitron a-35 available at www.gardeniq.com...expensive but a bottle last a long time and keeps forever....volcanic rock dust is a great way to grow healthy plants ...the indian

nitron is a surfactant, you can just use baby shampoo for the same effect and much cheaper.

Agree with Frank. NitronA35 is nothing more than a surfactant

compounds that lower the surface tension between two liquids or between a liquid and a solid

covered with lots of expensive hype. While they don't list the actual ingredients (it's a secret formula) there is much web speculation that it is nothing more than a combo of yucca extract, some soapwort (herb) infusion, and maybe some beer by-products or amino acids. In other words cheap ingredients sold for a high price. Like most of these "secret ingredient" mixtures it has its advocates and its scoffers.

But there are many cheap, readily available surfactants: baby shampoo, yucca extract (health food stores), any natural soap, beer, fabric softeners, etc.

And please do keep in mind that there are negative side effects to the use of any surfactant, primarily for aquatic life forms from any run-off, but also for beneficial soil dwelling organisms.

Due some research into surfactants as a whole before deciding to use one.

Dave

Regarding the OP's question: Would the motivation be for the growing of a more vigorous tomato plant that can eventually deliver more nutrition in the fruiting phase?

If so, I would be grateful if someone could address the following:

Regarding stimulating the plant to grow with more vigor using essentially a single plant drug (natural or not) - to increase overall yield of seeds per plant or for that matter size of flesh, is this hypothesis demonstrated with any single clear example agent for any flowering plant at all?

If so, what's an example?