1. Grasscity.com August contest: Subscribe to our channel on YouTube to be entered to win a PAX 2 Vaporizer! Winner will be announced Sept 1st
    Dismiss Notice

Mycorrhizal Fungi; Myths and Truths

Discussion in 'Organic Growing' started by Microbeman, Jan 11, 2012.

  1. #1 Microbeman, Jan 11, 2012
    Last edited by a moderator: Jan 11, 2012
    I am beginning this thread in an effort to clear up some of the misconceptions which have been circulating concerning mycorrhizal fungi and to point out some facts, pertaining to its usefulness. This is done to the best of my ability and knowledge and as in all things, I can be wrong or there can be information not yet available. I am completely open to correction, input and questions.

    Because this forum deals with the cultivation of Cannabis (hemp), I will refrain from spending a lot of time on mycorrhizal fungi other than endomycorrhizal. Briefly ectomycorrhizal fungi predominantly form associations with certain types of trees. An example of this is truffles which form symbiotic, mutualistic associations with trees such as Hazel Nut, Holly Oak and English Oak. In the ‘ecto’ group there is a sub-group which is referred to as ectendomycorrhizal fungi. It is merely a description for fungi which displays both ecto & endo traits. [outside & inside]

    Typically ectomycorrhizal fungal hyphae surround and encapsulate the roots of the plant they are colonizing and exchange nutrients by proximity, while endomycorrhizal fungal hyphae enter the cells of the roots to exchange nutrients. Fungal hyphae are microscopic strands which grow from fungal spores, hyphal complexes and mushrooms. Many of them combine to create fungal mycelia, visible to the human eye.

    Two sub-groups of endomycorrhizal fungi are Arbuscular Mycorrhizal fungi (the most common and what we are concerned with here) and Ericoid Endomycorrhizal fungi. In the latter there are two additional sub-groups Arbutoid Endomycorrhizal fungi and Monotropoid Endomycorrhizal fungi. There is no current research I know of indicating that these are of value in supporting the growth of cannabis/hemp.

    For those interested in exploring this further here is some excellent information compiled by a student. The biology of mycorrhizas home page

    There is some research indicating that there is another type of fungi which may be mycorrhizal with plants. It is labeled ‘dark septate endophyte(s)’. It is my hypothesis that some of the species of fungi imperfecti grown out of [vermi]compost into compost tea are this type of fungi but that is yet to be researched. [the term ‘fungi imperfecti’ is used in this case to describe species of fungi lacking a (so far discovered) sexual stage and typical fruiting body]

    The word mycorrhiza has been tossed around willy nilly and there has been enough money ass hype spewed to choke a hundred horses. Mycorrhiza is not the fungi. It is the word used to describe the symbiosis or mutualistic association between root and fungi. Mycorrhizae is plural of this. The term to describe the type of fungi itself is mycorrhizal fungi.

    We all know that there is a plethora of products on the market with super attractive labeling and names. Super Ecto Screaming Eagle Myco, is fictional but representative of the crap one is confronted with. In reality if you are serious about getting endomycorrhizal fungi to colonize the roots of your plants you should know that, according to current science of which I am aware, there are only two known endomycorrhizal fungi species which colonize the roots of cannabis/hemp.

    They are Glomus Intraradices and Glomus Mosseae. If you are looking for the maximum potential to colonize roots of this species, your chances go up with the higher spore/propagule count per gram. Unless you have a mix specifically formulated I know of no product which includes only these two fungal species. Because Intraradices has been shown (through studies) to be a relatively easy colonizer of most endo-type plants world wide, it is logical to consider using it as a stand alone mycorrhizal inoculant (if you live in North America), because;
    1/ It is produced in North America
    2/ one can get (in bulk) powder based products at a spore/propagule count of 3200 per gram 1,452,800 per pound or a liquid product at 2,000,000 spores/propagules per gram (available as agricultural products > Increase your yield with MYKE® PRO mycorrhizae ). To get Glomus Mosseae at such densities would be very challenging. [I’m hoping that this will be available in smaller packages in 2012, at least higher than 200 spores/gram]
    Your best bet to get colonization is to apply the spores to the seeds or prepared cutting and/or the roots at planting time. There are apparently some studies showing that it can take up to 6 weeks for the full benefits of infection to be measurable which has led some to conclude that endomycorrhizal fungi is not that useful in the normally fast paced growth 'pattern' of indoor grown cannabis. This is by all means not even close to being 100% factual. I have yet to satisfy myself of this issue one way or the other, having read some studies indicating early infection/colonization. [I will attempt to update the thread later if I learn something relevant to this]

    The foregoing is not intended to imply that there are only two types of fungi which will ever associate with cannabis. Far from it. There are many species of mycorrhizal fungi, yet unidentified and as usual scientists are only scraping the surface in the research in this area. There may well be fungal species growing in the field behind your house which are indigenous endomycorrhizal fungi (or dark septate endophytes or…?) which may associate with cannabis/hemp just fine. What I have outlined is simply your most logical route to success if you are going to buy the spores.

    The following is a post by Eco I copied from the other thread which nicely outlines the mycorrhizal species available on the market. I’ve included the post which appeared prior to his as well for cohesiveness.

    Thankfully there are people like David Doudes who have outlined for growers methods of producing one’s own local mycorrhizal spores/propagules. Here are some links and attached PDF.

    Cultivating diversity underground for better yields above



    Another consideration if one is contemplating purchasing one of the myco-mixes on the market, is if it contains Trichoderma spores. Because Trichoderma is so much cheaper, the spore count for it in these mixes usually eclipses all the other organisms put together. Unlike endomycorrhizal fungi, Trichoderma requires no root contact to sprout and grow. In addition to this, its favorite food is…..wait for it…..wait for it….other fungi! So you guess what happens if you inoculate your roots with a mix that contains 10,000 spores per gram of Trichoderma and 100 spores per gram total of other fungal species which are slow to sprout.

    In my opinion, in most cases, "Yummy" says the Trichoderma as it gobbles down the few sprouting mycorrhizal spores. But, you say, "I get such incredible results when I use ‘Super Ecto Screaming Eagle Myco’. So there!"

    Well ya, Trichoderma is a great root/plant protector and there have been studies indicating that it enhances nutrient uptake. Remember the studies indicating it might take a long time for endomycorrhizal to effectively colonize roots? Maybe if you are doing a fast vegetation then kicking into flower Trichoderma is your answer. Maybe it is all that is working effectively in your Screaming Eagle stuff. Maybe it is incredibly cheap to buy elsewhere.

    The screaming Eagle people will tell you; Look! Trichoderma is ubiquitous in the soil and grows naturally in conjunction with mycorrhizal spores all over the world. At 10,000 to 100? Freeze dried? Hello.

    Am I trying to discourage you from attempting to colonize your cannabis roots with endomycorrhizal fungi? Totally no. I even believe I had success at this by inoculating cuttings and roots as previously mentioned but by also keeping my soil alive and undisturbed (mostly) in between crops. In this way the hyphae and spores remaining in the soil were/are there waiting for the new fresh roots. There are some who now are using companion planting or living mulch, like clover to keep live roots going in the soil at all times. Just be sure you select a plant which is mycorrhizal with the same species of fungi. Not only does this support mycorrhizal networks but keeps the microbial population buzzing along. I wish I had thought of it for my indoor plantation (long gone). I do realize this is not practical for all growers, as it calls for a fairly large volume of soil to preserve it as a living entity.

    In reality it appears there are 2 to 5 labs and multiple middlemen wearing lab coats in this world getting extremely rich off everyone’s ignorance over the microbial craze. Wanna spot a phony? If they say they have a product with bennies, microherd or beneficial microorganisms or soluble mycorrhizae, chances are 99% they are full of it.
    If they cannot describe the function of the microbes they are selling or cannot explain how nutrients are cycled, even rudimentarily, walk away (or run).

    I probably should have referenced stuff as I went along but since I’m not getting grades for this I’ll just lump a bunch of attachments for those of you interested in exploring this fascinating subject in depth. I may hafto do this bit by bit over time.
    I’ve at least attached the list of (some) plants which associate with mycorrhizal fungi and Doude’s instructions to begin.

    [OR maybe not. Daddyo it would not attach the two PDF documents  On-farm Production and Utilization of AM Fungus Inoculum.pdf and Mycorrhizal Plant-List-11-08.pdf which I posted on the other threads. I don't know how to move these. Can you do it?]

    I should also mention in case it is not readily apparent that endomycorrhizal spores do not sprout and grow in compost tea, as a lot of people seem to believe.
    Dro Smoe likes this.
  2. Thank you so much for this MM!!
  3. #3 WeeDroid, Jan 11, 2012
    Last edited by a moderator: Jan 11, 2012
    :D !Awesome! :D

    I'll be doing this. My cover crop, atm, will be White Clover and Pensacola Bahia Grass. Both will be established in my beds, before I plant any cannabis. I'm hoping I can just use 4 foot dual tube fluorescent lights on them, otherwise my electric bill is going to be out of control, getting them up before my cannabis crop and between crops.

    I'll document my results in the organic grow journal forum here. Don't expect it until spring though.

    I'm also adding old cannabis roots from previous grows to my compost piles, in hope some myco fungal inoculation can occur.
  4. Thanks, MM. I tried to rep you up, but the clunky controls won't let me. Anyway, much appreciated. This is a subject I'm really ignorant on, so your post is helpful in organizing my thoughts......MIW
  5. thanks MM! didnt know that about the trichoderma.

    you can take a guess at who isnt ever buying plant success products again. (this guy) :smoke:

  6. #6 LumperDawgz2, Jan 11, 2012
    Last edited by a moderator: Jan 11, 2012

    I've seen posts of yours over the years and you've cited Dr. Rober Linderman so you know some of his work in this area though that wasn't his only area of study - he headed up a staff of 16 Phd, post-Phd and Phd candidates at Oregon State (Go Beavers!)

    Dr. Robert Linderman graduated from UC Berkeley in 1968 with a Phd in Botany. 5 years later he arrived at the Agriculture Research Station (ARS) at Oregon State University. The ARS programs were set up decades ago to help state universities and colleges with the heavy lifting as far as hardcore research. Almost all of these stations are agriculture based. The one that Dr. Linderman headed for 35 years was centered on horticulture, i.e. to help growers earn more money and reduce costs using better methods.

    Dr. Linderman retired 3 years ago and the last 20 years of his career was centered on horticulture and what role endomycorrhizal fungi could play. He was the one who first published research that showed the degradation of several microbe colonies from Phosphoric acid and later showed that even uber levels of elemental Phosphorus can have negative effects.

    He's the guy the others often quote without giving credit. There is a web page listing his major work spanning 40 years and many of them are available to download (PDF files).

    Most of us probably won't be happy with most of his work if fertilizers and 'special stuff' is at the center of the garden paradigm.

    Don't shoot the messenger!


  7. Just real happy to see you posting here MM. Cheers!
  8. Lots of research to be done yet. Makes me want to be a scientist. :)
  9. thanks LD.

    i've always known chemical fertilizers harm fragile fungi microbes. i will look up some of his research & use it as a reference next time some (add expletive here) tries to argue with me differently on the sick plants & problems section, saying that the chemicals dont harm them.

  10. #10 LumperDawgz2, Jan 11, 2012
    Last edited by a moderator: Jan 11, 2012
    Can I explain why the Trichoderma spores were added to the original product one last time?

    When Mycorrhizal Applications ventured into the horticulture deal he faced a couple of realities. Well - several actually.

    The first one was that there was no friggin' way that a large nursery would screw with 2 or more products when batching out their potting soil mixes. It wasn't even clear, initially, what spores would be best for the myriad of perennial cultivars grown in this industry. That's where the real money is - growing annuals is for the newbies who'll either figure how to switch gears or they go broke.

    Then again a commercial nursery will have to take on contracts for some annual plants - what to do, what to do?? Simple - create a product with both! Bingo.

    Not so fast - about that time Coir arrived on the scene with their list of promises, hopes, dreams, schemes, etc. but a big selling point was that Coir had high(er) levels of Trichoderma spores than did Peat or Sphagnum Peat. Not my claim - that's the claim by the commercial Coir brokers.

    Hmmmm.......yet another 'what to do' moment. This was really easy - add the Trichoderma spores to the endo/ecto mix and now you could have the same levels of Trichoderma spores whether you used Coir or Peat - pretty simple, eh?

    Problem was that besides this mongrel mix, Phosphoric acid is at the heart & soul of nursery stock growers. You would have a better chance at getting Microbeman to give up compost and worm castings than you would removing the bags of Phosphoric acid from these guys.

    That's how Dr. Linderman's initial studies came about - to determine why things weren't working out as planned down on the farm (nursery).

  11. Microbeman,

    Thanks for taking the time to publish this valuable information and links on mycorrhizal fungi. There is so much misinformation surrounding this topic, that I believe this thread will help set the record straight.

    I'm going to stick this thread to keep the information up on top.Here's the links to the pdf that you asked about.



    Thanks again for this valuable contribution,


  12. HEAR! HEAR!
  13. #13 Senseimilla, Jan 12, 2012
    Last edited by a moderator: Jan 12, 2012
    Forgive me if this was answered above and I missed it, but I once read that too much N & P in the soil will kill the fungi or prevent it from doing what it's supposed to do. If I remember right it was somewhere around 1 or 2 N, can't remember for P but wasn't much either -- is this true or made up??? If it is true, what are the level of N-P-K we should stay under???

    I see a mention above of P being the issue, but I still don't see where it says what levels are too much... help?
  14. it doesnt matter what level they set on the bottle.

    ANY chemical based fertilizer harms beneficial microbial life in your soil. the first to go would be the fungi. than the bacteria, i believe.

  15. Salt fertilizers can harm microherds. This is more of an issue for indoor container grows than it is for outdoor grows. However, given the scale of commercial agriculture, large swaths of land can be rendered near sterile due to excess salts.

    In addition, from what I have read, high levels of available phosphorus can hinder a fungal spore from breaking dormancy when near a root. However there doesn't seem to be a problem with insoluble forms of P or with organic or natural fertilizers (SRP, manures, humates, fish, kelp, etc).

    It is readily available phosphorus derived from soluble (liquid) or fast release fertilizers that contribute to this situation.
  16. Who said anything about chemical fertilizers??? I was referring more to higher phosphorous bat guano powders or amendments. Would those harm the fungal system? For example Sunleaves Indonesian Bat Guano is 0.5-13-0.2
  17. #17 WeeDroid, Jan 12, 2012
    Last edited by a moderator: Jan 12, 2012
    Reread my post and stop getting your knickers in a twist. ;) You asked about N and P, you didn't specify what form.
  18. 'ello guvna', I think I've lost me knickees.

    Anyway, I'm still not sure what the answer to the question is -- is a higher P guano (between 4 & 13 P) that is either slow or fast release going to damage the fungal system. What about the higher N guanos? What is the highest N-P-K I should consider using without risking adversely affecting it?
  19. i wouldnt add any guano directly to the plant. it should be composted first.

    BUT, if it is composted & properly used, i dont believe guano would affect the mycos.

    dont worry about the NPK ratio & how it affects the microorganisms. as long as things are composted (or how you set out your soil mixes to "cook" for a month), you shouldnt have any problems.

  20. Bat guanos don't need to be composted.

Share This Page