There is no doubt that mycorrhizae fungi play an important role in plant growth. They help aggregate the soil which in turn provides plant roots with better access to water and oxygen. Their symbiotic relationship with plants helps them access water and nutrients. It is only natural that companies want to sell these fungi to you. Don’t fall for it.
Mycorrhizae Fungi
Mycorrhizal fungi (mycorrhiza) are found in all soil where plants grow. They form large networks of fine filamentous growth throughout the soil. They associate with plant roots; some even burrow into the roots to create an even greater association with plants. About 80% of all plant species form some type of association with these fungi.
Think of mycorrhizal fungi as a vast network of very fine plant roots. They are not plant roots, but they behave in similar ways to plant roots. They burrow into nooks and crannies in the soil and collect water and nutrients for the plants. In return the leaves of plants send sugars to the fungi as food. Given this important association it is natural for one to think that it would be beneficial to add more mycorrhizal fungi to the soil. For a more detailed description of mycorrhizal fungi see Microbe Science for Gardeners.
Arbuscular Mycorrhizal Fungi
There are two basic types: EM and AM.
EM fungi (ectomycorrhiza) form associations with only about 2% of plants, mostly the woody plants like trees and shrubs. Since woody plants make up a large portion of the plant community, they are important to natural ecosystems but they are not usually found in commercial products for the garden.
AM fungi, called arbuscular mycorrhizae (a type of endomycorrhiza), make up the largest group and form bonds with the majority of plants. They provide mostly phosphorus to the plant. These are obligate symbiotic fungi, which means they can not survive for long without a host, although they can produce spores (a types of seed) that can survive until a host root shows up. This is the type found in commercial products.
The fact that they can survive as spores is important because it makes it easier to produce them. Commercial products contain a combination of spores, small fragments of mycelium and small pieces of roots that contain bits of fungi. Together these are called arbuscular fungi propagules and the number is listed on some commercial packaging. For example one product claims to have “60,000 propagules per lb”.
Facts About Mycorrhizae
- Garden soil already contains vast quantities of mycorrhizae, or at least it does if any kind of plants grow in it. Adding more is a waste of money, since they are already in your soil.
- Manufactured mycorrhizae consists of 2 or 3 types of fungi. It turns out that there are hundreds if not thousands of different kinds in your soil and some of these are very specific to certain types of plants. How do you know your plants will benefit from the 2 or 3 types you buy?
- Manufactured mycorrhizae are heat sensitive. If the container is left in a greenhouse, or a transport truck too long, the heat kills the fungi. There is no way for you to know that the product you buy contains active fungi – they could all be dead.
- Manufactured mycorrhizae are of a specific species, almost certainly from an area that is foreign to your soil. It is possible that these foreign species inhibit the growth of your native species. You have no way of knowing but it is never a good idea to import foreign species of any kind into your garden.
There is just no good reason to buy mycorrhizal fungi for your garden.
Special cases
There are some special cases that might warrant the addition of mycorrhizal fungi.
Bare Soil:
Soil that has no plant growth probably has few natural fungi. It would seem that this would be a good case for adding them. The problem is that if the soil is not suitable for plant growth, it is probably not suitable for the growth of mycorrhizae. Adding them will simply result in them dying. If you want to grow plants in this soil you first need to solve the problem in the soil. As plants start to grow, native mycorrhizal fungi will also show up, naturally.
Sterile potting soil:
Sterile potting soil used in containers has no natural fungi. Studies have shown that adding mycorrhizal fungi to this type of environment can have some positive results. Keep in mind that the main value of the fungi is to provide the plants with water and nutrients. In a potted situation, many gardeners over water and over fertilize, negating the benefit of the fungi. If you water and feed your plants regularly, there is little benefit to adding mycorrhizal fungi.
Commercial Inoculants vs Compost
Most commercial products have a dozen or fewer species in the product. Some don’t even list the species. A recent analysis of a compost sample showed that it contains 305 fungal species and 360 bacterial specials.
In a recent review I checked with 5 commercial product manufacturer and asked them for proof that their product worked. You can read about the results in Mycorrhizal Inoculant Investigation – Do They Work?.
The Latest Science About These Fungi
The latest news investigates how tilling affects fungi in soil, and how effective commercial products have been in agriculture. Read all about it in Mycorrhizal Fungi – The Latest Scientific News.
The latest data clearly shows that claims such as “In soil that has recently been tilled/worked, mycorrhizae will be lacking” are not true.
Better Ways to Build Soil Health.
10 Easy Soil Testing Methods For Measuring Soil Health
Preventing a Nitrogen Deficiency in Soil – How to Manage Nitrogen Levels
Soil Bacteria – The Myth of Identification & Management
10 Fertilizer Myths That Will Save You Money
Bonsai planting media is often completely inorganic. Why not use one of these AMF? OK, then, which? At what concentration? How do I know if the AMF remains viable? Hmmm. Come to think of it, the plant serves as it’s own innoculant.
I took the AMF out of my shopping cart.
I have used mycorrhizal fungi in my pot. Can I use Calcium Nitrate in my pot or will it kill/inhibit my mycorrhizal fungi in the pot?
Too much of anything will kill fungi. Both calcium and nitrate are nutrients needed by fungi.
Very interesting discussion on all sides. Your point though is that these fungi are unnecessary as additives as they are already present in garden soil. Most of my plants never touch soil of any kind. I grow orchids, which here in Northern California are generally grown in bark chips, with sometimes the addition of coir, perlite and maybe charcoal, and for the warm growers, maybe some sphagnum as well. So I think I’ll give the mycorrhizal fungi a try on a few plants and see if I notice any difference.
I assume you are growing epiphytic orchids and I don’t believe they associate with mycorrhizal fungi, although they have a fungus they do associate with. You would have to buy the right kind of fungus.
Have you looked into the mycorrhiza research at A&M? Those guys don’t mess around. Their findings are interesting. In general, would like to see more references and links to studies in this article… behttps://www.sciencedaily.com/releases/2004/06/040621073636.htm
That is not a published study – and the description lacks details.
They have published a study in the Journal of the American Society for Horticultural Science: https://aggie-horticulture.tamu.edu/Faculty/davies/research/abstracts/pdfs/2005-130-JASHS.pdf
This is a completely artificial environment. Plants were grown in sterilized soil-less mix.
That tells us nothing about how these additives would perform in a real field soil condition, where the soil is already populated with mycorrhizal fungi.
We don’t doubt the value of fungi – only that adding them to garden soil is pointless, because they are already there.
“You have no way of knowing but it is never a good idea to import foreign species of any kind into your garden.”
Please list the potatoes, tomatoes, cabbage, rape, etc indigenous to Canada.
Even if *you* may only grow native species, which is doubtful, I’m positive others are not. Hence the benefits of introducing non native mycorrhizae that have been found to companion with those non native yet traditional garden vegetables. 🤦♂️
Once a fungi is in the soil – you can not get rid of it. If potatoes escape into natural area – they are easy to control.
What is your point?
There is huge evidence! The solution is you must add an auxin such as Super Thrive. If auxins and cytokinin’s are not applied after the implementation of mycorrhizae spores, you are wasting your money and time. This is how the world record fruits and vegetables are made.
1) So where is this “huge evidence”? You did not find one reference to post?
2) Super Thrive is a fertilizer, not an auxin.
They tend to use it in the Arizona desert where there was next to no plants to begin with !
But is there any evidence it works?
This has been a useful read as I try to learn about the potential effectiveness of commercial innoculant for dryland ecosystem restoration. Though I can’t weigh in on the body of literature on this topic, I have to say, to those frantically criticizing the author’s scientific literacy: The onus is on –you all– to demonstrate that you are not attack dogs of myco-innoculant companies. Reading through many of your comments was absurd.
When I propagated rose cuttings last August, those dipped in mychorrizal fungi powder developed roots much sooner than the untreated cuttings. The same with clematis. To me it’s a good enough evidence.
1) mychorrizal fungi connect with a plants root in a symbiotic relationship. A cutting has no roots and so they can not connect to the plant or help the plant make roots.
2) Did you do some controls? Lets see the data for that. Without controls, you can’t reach the conclusion you have reached.
Robert are you sure you understand what controls are? It seems simple, but Ted clearly said he compared the positive results against untreated cuttings (controls). It was treated vs. untreated control. He absolutely can make conclusion he made. If you have a special condition you think could have fooled him, and should have been controlled for, then you should have said what it was. His test was simple but conclusive. Casting vague shade at his clear results is beneath you.
You’re making a lot of assumptions.
Ted made a very casual statement but provided no evidence of how he did the comparison. To that I replied “Did you do some controls? Lets see the data for that. Without controls, you can’t reach the conclusion you have reached.”
That seems fair. Ted make some claims that are not supported by current science and i explained why, and so he can show us his data and explain how he did the controls. Until You see that – you can’t assume the controls were done correctly. Making a statement like ” His test was simple but conclusive” is clearly not correct without much more information. I stand by my earlier conclusion.
I have used extreme gardening Mycorrhizae on 5 of my 40 clones from the same strain, those 5 out performed the other 35 hands down. It works 100%, Just make sure you purchase the endo myko since the ecto has no benefits on veggies, fruits, flowers or herbs.Also be sure it is single species and contains at least 300 propagules per gram.I am not trying to sell the product but it does work for sure with organic soil not sure how it would work with synthetics.
1) what is synthetic soil?
2) the number of propagules should not matter since they will grow and populate.
3) even if you measured results to verify it worked in your situation, it does not mean it works everywhere.
1. Synthetic soils are artificial, without natural dirt. Usually have a base of peat or coir, drainage components like perlite or pumice, and sometimes (but not always) organic components like compost, castings, and organic fertilizers.
2. The number does matter. You overestimating their propagation speed.
3. Maybe not “everywhere”, but most places. This is settled science. Every farmer that uses it is a hardcore scientist measuring with the most accurate tool: $$$ from amount of yield. Almost ALL real farmers now know the yield benefit in $ for everything they put on the field. They’re not guessing idiots falling prey to marketing like you assume. Those guys don’t last long. The benefits are specifically measured in yield $ by professional growers and farmers everywhere. They’re really not as dumb as you imagine.
“Every farmer that uses it is a hardcore scientist” – that is not even close to being true.
If there is so much evidence that mycorrhizal fungi work in farming, why is it that you have not provided a single link to a scientific study supporting your claim?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3115185/
This study from over ten years ago shows that concentration matters.
OK – but it does not show that inoculants work in the field?
I am not a scientist, and I respect science. I’ve spent 30+ years planting trees at all various stages of growth as part of reforestation efforts (did some work with the nursery end of things), and I am very familiar with soil ecology from the experts that I’ve heard speak at workshops. Never used any form of powdered spores on any of the trees I have planted, so no experience with the product itself. I’ve seen gardening shows advertising these powdered spores, with sponsored gardeners touting the benefits on their programs, so I always reserve skepticism because these individuals are given the product to use (and hopefully convince their viewers that they *need* this product), and as non-scientists, can they really validate the product’s viability and necessity? They are making viewers fear that their soil does not contain *enough* of the mycorrhizae. So just as we test our soil’s pH to determine what will grow best (or how to amend the soil appropriately), it doesn’t make much sense for the average gardener to blindly use a product that they do not really know if it is necessary. Now, for large commercial growing applications, I could see where this is likely ideal since anything that increases quality of a product also has an economic benefit. For the backyard gardening enthusiast, it’s up to the amount of money that they wish to spend on their seasonal endeavors. I for one, neither professionally nor on my property, have ever used the product. The thought has never crossed my mind until I saw it being advertised. I don’t intend to try it as I’ve never experienced issues, but I suppose if you are struggling with trees, shrubs, and other plants on your property, it’s worth a shot.
In response to, reduced fungal activity due to tilling pr any disruption of soil, again what is being grown? If you are fighting a short season and if you are trying to get the fastest turnaround for profit from food crops etc, then yes, undoubtedly you would want to innoculate. Years ago I designed and a low tech mushroom endeavor that had the capacity for 2000lbs of gourmet mushrooms weekly. What I learned pretty early on is that a lot can go wrong on myceliums path to fruiting or sporing out, and in a sterile lab it is a very weak body. I would not reccomend using specific strains of mycelium added for innoculants as this is too narrow of a spectrum. When taken away from the natural network environment you get disproportioned information and health along the mycelial network. If the mycelium was produced within the local area, using methods able to incorporate local soil information, then you would be more in the ballpark of seeing the higher end of benefits that these fungi can provide.
Undoubtedly these fungi will grow better plants when mycorhiza are present vs sterile soil, I dont think anyone here is negating that fact. In the real world we have a serious issue though with disrupting this information highway and regardless of whether you have a 2% or 200% increase in yeild, it is not just the health of the plant to consider. Big agriculture is destroying this network, and we can see this from the bee decline. Look into Paul Staments research on this topic, check out what he had to say on this when he received his advanced medical award. The closer you can mimic nature the more benefits we will get, and from many things we have yet to discover.
Too long of reply, apologies.
Sum up,
Growing fruit products, yes inoculate your plants and trees etc to make faster production and healthier products… if your killing your soil. Or stop killing your soil. (When I mean soil I mean both seeding soil and bed soil)
If your in the flower or aesthetic agriculture business, really not as much of a concern, I dont imagine you would till a field to grow flower bulbs. Fungi will incorporate over time from spores in the air.