Does any of you who have been growing a lot of fruit trees for a long time use or have ever used mycorrhizal inoculants when planting your trees? Is there any evidence that it makes enough difference to be worth the extra expense when planting trees in healthy natural topsoil with plenty of organic material already present? Local nurseries around here are constantly pushing the stuff whenever people buy trees or shrubs. And usually, the directions on the bags of these products say use the whole $20 bag for one tree or bush which has always triggered my scam alarms. It’s just hard to imagine it adding anything that isn’t already in the soil or that a natural soil could sustain in the quantities that warrant so much inoculum. If it does add a new species of fungi, I can’t think of a reason why the amounts the directions call for would be needed given that it’s fungi spores or mycelium mixed in a dried medium. Most fungi I have experience with will overrun any substrate in a matter of days with just a swab of inoculum provided the right amount of nutrients and moisture are present. But that’s just intuition from a guy with a MS specializing in plant ecology. What are your experiences and practices? Is there any real evidence of it making a real difference for you with newly planted trees in an orchard? And does it make a big enough difference for any of you commercial growers to mess with it?
I’ve found that it helps with transplant shock and rooting young plants so I’ve always used it after i found out about it.
I’ve killed multiple Ruby supreme Guava trees in the past and they seem to respond better overall when i started using mycorrhizae powders during repots.
Fig roots as well seem to respond better to them in my experience and this one is easy to test when you’re rooting things 
Interesting. Do you use it in the recommended quantities, or do you add just a little bit? I can see it being super important in a potting soil or rooting medium that’s been through a sterilization process to kill plant and seed pathogens.
I just dump a bunch on or whatever i feel necessary lol. I stopped listening to the packages on those things once i realized i didn’t need to be so strict on when it comes to mycorrhizae.
I always advise others to plant it in ground with it is well since in my experience, things have always done better with it overall. I understand that the native soil contains other microbes and stuff but i feel it gives them a headstart when you use it during planting because the soil doesn’t always contain just helpful creatures but creatures that may also eat at the plant as well. Just my opinion is all
I used it for a couple years but didn’t notice any difference. I think if your soil is well-populated already it might not matter much.
In my case about the only new trees I ever add are new plum strains which I graft onto suckers coming from the same orchard. In my case it’s hard to imagine that the mycorrhizal inoculum in a bag being better for a plum tree growing in my orchard than what’s already on the roots of plum trees already growing in the orchard. Thanks
I think that’s right. If you’re going to spend any money on soil stuff I would spend it on milky spore or predatory nematodes or something
Marcus,
I use it and think it makes a big difference if you mulch your trees out to the drip line with a bed of woodchips. I simply make my own by piling up a pile of woodchips with as much fresh chip ramial wood as possible, then I innoculate it with natural native micorrhizae that I obtain from local sources. The type you want Arbuscular can typically be found around mature fruit trees in your neighborhood that have a woodchip mulch that’s been in place for several years. You simply use that to innoculate your new chip bed. Each year you need to add chips as they get consumed to feed your trees.
To get started without paying a fortune for starter, these articles helped me understand what I needed to do.
Dennis
Kent, Wa
Google: how do vesicules relate to mychorizal funji
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/vesicular-arbuscular-mycorrhiza
Ectomycorrhiza
The formation of ectomycorrhizae is linked to accumulation of an organic litter layer in soils.
In the following study the conclusions below hyperlink:
Conclusions:
- Beech and Spruce humus give the greatest rates of Arbuscular mychorrizal formation.
- Arbuscular mycorrhizae (AM) are the most common type of endomycorrhizal (EM) fungi, whose hyphae extend into the cell membrane of the cortex root cells and form vesicles. These vesicles are structures that help the plant-fungi association exchange water and nutrients.
- What is the role of vesicles in mycorrhiza?
The hyphae of VAM penetrate the roots of host plants, form specialized structures within arbuscles and sometimes vesicles. Arbuscles are considered to be where transfer of nutrients (to the host) and carbon (to the fungus) takes place and vesicles to be organs of storage.
This article by University of Oklahoma list plants that benefit from types of mycorrhiza: https://extension.okstate.edu/fact-sheets/mycorrhizal-fungi.html#:~:text=Arbuscular%20mycorrhizae%20(AM)%20are%20the,association%20exchange%20water%20and%20nutrients.
How to make your own mycorrhizal fungi: How to make your own mycorrhizal fungi
If you know anywhere that there is grass just dig up a few swaths of grass and shake and rinse out the dirt from the roots in a bucket etc… replace the grass clump… then inoculate whatever you think is devoid of myco with the dirt and liquid from the root dirts.
If your walkways or planting areas are lush with thick grasses you probably dont need to add any…
If you add any…be careful. (im not sure anyone really knows but it makes sense).
ive read that compost is just as rich in it than the store bought stuff. just sprinkle some in your planting hole and you’re good. also soil duff under old trees is also rich in them and very good to inoculate bagged soil. if using decent native soil there’s no need as they are already at capacity in there.
I have been listening and re-listening to a lot of podcast episodes at work this past week.
Billy at Permaculture P.I.M.P.cast says he’s been testing any and all mycorrhizal compost/inoculation products he can find locally and claims everything able to be sourced is pretty poor quality from a store. The hypothesis is that the high heat composting process required for product sale kills most of the good stuff and pretty much just leaves nematodes and minimal fungi in the mix. He apparently does make a compost/mycorrhizal product in NC he plans to test to neutralize some potential toxicity challenges they are facing after Hurricane Helene.
The guys at Propaganda by the Seed up in Maine corroborate what @steveb4 mentioned about grabbing material as a start from established plantings.
In an episode I listened to today, might have been the one on ground nuts, they did discuss how plants produce sugars as they photosynthesize and a portion of those sugars can be pumped by the roots into the soil to feed the fungi, which in turn provide other nutrients to the tree.
Most of this is a review for many but I hope it helps.
In this discussion mycorrhizal fungi should be distinguished from saprophytic fungi. The former is what the title is about, and the latter are a side issue. Saprophytic fungi are universally present in soil and abundant in compost and rotting woodchips. They are certainly beneficial to the orchard ecosystem, but I suspect that they don’t need enhancement to do their job, as long as there is sufficient raw organic matter present.
Each mycorrhizal fungus is specific to one or a few species of trees. For an inoculant to be useful for a fruit tree, it has to be appropriate for that tree. I don’t use them; so, I don’t know if the product labels state what type or types of trees they are intended for. This is the most important item to check. I suspect that they are mixtures of several fungi and would probably work with pomes and stone fruits, but may not help with some of the unusual tree types that are discussed here.
YMMV… be careful what you rob from Peter to pay Paul. Sometimes nature knows what its doing and best to leave it alone.
I have observed all kinds of strange things in my woodchip mulches… some may be good some may be bad… im sure there are alot of things that are beneficial and some that are not so much. Alot of unknowns.
I see lots of posts on the social medias these past weeks of folks dragging in hundreds and hundreds of bags of leaves from their towns…where folks have raked their yards or urban cleanups. Hard to know how much good and how much bad stuff you are bringing in… most of those leaves have spores, fungis, bacterias, eggs etc…
Im not so sure that putting microbes and fungis and bacterias that break down organic matter into compost. and leaves and fallen wood into compost are a good thing to put in a hole or bagged soil… maybe?
I have been using this stuff ( a few handfuls) in all my plantings… with great results so far… maybe the boost of myco and the biofungicides help… which must mean that there are bad fungis.
Or maybe i dont need it at all. Tough call.
Like everything else in nature, the answer is: It Depends.
The property I own has Zero dirt, so I’m stuck with purchasing potting soil for my containers. If you’ve purchased (organic) potting soil (recently?) you know that it isn’t soil at all, it is a bag of chopped sticks. So yes, any fungus at all is beneficial to break down the Crap In The Bag to help it become actual soil. Is Mycorrhizal fungi the best, or even good, at soil building? My college degree is Environmental Science - a cross between a Biologist and Ecologist - and I can’t answer my own question.
Given your background you likely know that the way dirt was invented to begin with was by the action of lichens, which are a cross between algae and fungus. So unless your orchard dirt is/was poisoned by pesticides or some chemical, or subjected to years of mono culture, likely the dirt has all the micro-life it needs to sustain your trees.
During especially wet spells my container garden occasionally gets mushrooms of various types, are any of them from the mycorrhizal fungi supposedly in the fertilizers I buy?
Who knows, who cares, fungus improves the crappy “potting soil” I have to buy, and doesn’t (that I’ve seen) have any negative consequences for my crops.
IMO, save your money, use commercial fungi sparingly, nurture your orchard with with yard waste / compost, cows, chickens, turkeys, whatever.
they guy i watch on youtube says that you only need a handful to inoculate like 4cu. ft of soil. i just dig up some of my decomposed wood chips from under my bigger trees and mix that in. compost is even better as its still got a little food in there. throw in some bone and bloodmeal and they will quickly spread throughout the soil. i also like the bx promix but i find i can create my own inoculated soil for about 1/4 the cost of the promix. i mix everything in a kiddie pool. my compost piles are all under my big spruces so they are naturally inoculated from the trees and in turn nourish them. only drawback is i have to cut roots occasionally that invade my compost piles.
You can cut powdered inoculant with brown rice flour to inoculate multiple trees. The increased phosphorous uptake from mycorrhizal fungus occurs mostly when the soil is deficient in P. There is very little benefit if the soil contains adequate P. It is known to make the roots more resistant to disease. It is easy enough to cultivate your own fungus in a compost bin, once the heat has gone down. It takes 3-4 weeks after inoculation to get a healthy colony. You don’t want to disturb the soil during that time.
bone meal is high in P plus adds some N and calcium. fish bone meal also adds some micros.
I just though about this now for the first time, but can anyone ELI5 what exactly a biofungicide is in this context? Maybe I am missing what that word means, but it sounds like it means it uses biology to kill fungi, which in turn sounds counter-productive to the task of improving mycorrhizal fungi… I’m likely missing something.
(explain it like I’m 5 [years old])
I had to look it up so I figured others would as well.
(it’s a reddit thing)