Mycorrhizae, bacteria, and modern bonsai substrate

[One First Matter All]

Hi all,

Let me preface this post by acknowledging that I know almost nothing about soil chemistry, and what I do know I learned this afternoon from the Internet, which is always right. In short, you'll want to fact-check what I'm about to say.

As I journey into the world of bonsai, I have noticed two things that appear irreconcilable. Maybe you can help. First, modern substrate contains little or no organic material. Got it. Second, the best way to protect a tree from diseases and pests is to encourage the growth of mycorrhizal fungus and good bacteria. Hm? Perhaps I've missed something, but my limited research suggests you can't have it both ways. Inorganic substrate (i.e., pumice, DE, lava, etc.) cannot support the growth of "good" bacteria or mycorrhizal fungus, both of which require organic material to thrive. Sure, they might grow in limited quantities, but nothing like they could in organic soil mixtures.

If that's right, then . . .

(1) Those worried about harsh pesticides/fungicides that destroy substrate (e.g. copper fungicides) need not worry, since the substrate is more or less sterile anyway. Of course, you can (and should) still worry about what those harsh chemicals do to you and the environment more broadly.
(2) Organic fertilizers that rely on the presence of good bacteria to release N/P/K in tree-drinkable form will not perform as well as chemical fertilizers in which N/P/K appears in a form immediately useable by the tree.

But is that right? And, if so, what advantage does modern substrate provide, other than the fact that it prevents newbies like myself from overwatering? It seems as though modern substrate invites the use of a lot more pesticides/fungicides because it prevents the growth of "good" fungus and bacteria that would otherwise serve as a natural protectant for the tree, no? Somewhere there's an analogy to be made with modern body-building and the use of steroids, but I'm not sure where.

Anyway, thanks for reading. If anyone has any input or can direct me to another post explaining matters in more detail, I'd love to hear or see it. I do not have a background in science, so it wouldn't surprise me to learn that I got it all wrong.

Chris

 

[wireme]

Hi all,

Let me preface this post by acknowledging that I know almost nothing about soil chemistry, and what I do know I learned this afternoon from the Internet, which is always right. In short, you'll want to fact-check what I'm about to say.

As I journey into the world of bonsai, I have noticed two things that appear irreconcilable. Maybe you can help. First, modern substrate contains little or no organic material. Got it. Second, the best way to protect a tree from diseases and pests is to encourage the growth of mycorrhizal fungus and good bacteria. Hm? Perhaps I've missed something, but my limited research suggests you can't have it both ways. Inorganic substrate (i.e., pumice, DE, lava, etc.) cannot support the growth of "good" bacteria or mycorrhizal fungus, both of which require organic material to thrive. Sure, they might grow in limited quantities, but nothing like they could in organic soil mixtures.

If that's right, then . . .

(1) Those worried about harsh pesticides/fungicides that destroy substrate (e.g. copper fungicides) need not worry, since the substrate is more or less sterile anyway. Of course, you can (and should) still worry about what those harsh chemicals do to you and the environment more broadly.
(2) Organic fertilizers that rely on the presence of good bacteria to release N/P/K in tree-drinkable form will not perform as well as chemical fertilizers in which N/P/K appears in a form immediately useable by the tree.

But is that right? And, if so, what advantage does modern substrate provide, other than the fact that it prevents newbies like myself from overwatering? It seems as though modern substrate invites the use of a lot more pesticides/fungicides because it prevents the growth of "good" fungus and bacteria that would otherwise serve as a natural protectant for the tree, no? Somewhere there's an analogy to be made with modern body-building and the use of steroids, but I'm not sure where.

Anyway, thanks for reading. If anyone has any input or can direct me to another post explaining matters in more detail, I'd love to hear or see it. I do not have a background in science, so it wouldn't surprise me to learn that I got it all wrong.

Chris

Mycorrhizal fungi get what they need to grow from the plant, it’s symbiotic. They do just fine in coarse inorganic substrates as long as there is also some kind of plant roots growing there. Bacterial populations can explode very quickly, an organic feed will have them multiplying away like mad in a modern substrate.

Generally speaking the good microbes like aerobic conditions and pathogens grow more in anaerobic conditions so modern substrate is in that way suitable to select the good microbes as well, many pathogens will die very quickly when expose to 02 rich conditions.

Throw in some chunky high carbon material if you’re worried about it, occasional feeding with carbs...

 

[One First Matter All]

Thanks for helping clarify.

While we're at it, can you confirm/disconfirm that mycorrhizae dislike phosphorous, and, thus, any fertilizer with a high "P" content should be avoided? The Internet told me that, as well.

 

[One First Matter All]

My comment about phosphorus actually came from Jeff Lowenfels' book, Teaming with Fungi--not the Internet at large. In the book, he writes:

"The amount of phosphorus or nitrogen in the soil greatly affects the germination and formation of arbuscular mycorrhizal fungi. With too much of either nutrient in the soil, mycorrhizal spores are less likely to germinate and mycorrhizae growth is hindered. To compensate for the unavailability of phosphorus, many farmers saturate soil with synthetic chemical phosphate fertilizers, because once all the soil exchange sites are full of phosphorus ions, any excess nutrients will be more readily available to the plants. This practice results in a huge excess of phosphorus in the soil, which inhibits mycorrhizae from forming, and it can take decades for phosphorus levels to reduce to the point where the arbuscular mycorrhizae can thrive again."

I have not seen this point made elsewhere. Anyone?

 

[fredman]

Thanks for helping clarify.

While we're at it, can you confirm/disconfirm that mycorrhizae dislike phosphorous, and, thus, any fertilizer with a high "P" content should be avoided? The Internet told me that, as well.

My kinda thread...love it. Thanks for putting it up.
Yes, from all my research the most important i've gathered, is to much N and P will either damage or kill microbes and mycorrhizae.

 

[One First Matter All]

Thanks to you both for the replies.

Not to be a rabble-rouser, but . . . If modern substrate (1) allows for the growth of "good" fungus and bacteria that (2) does not like too much N or P, then why do so many people (including prominent bonsai artists on this site) recommend a 20/20/20 fertilizer applied at moderately to insanely high rates? Do practitioners of this variety simply not care about the rhizosphere and accept the fact that they will be forced to resort to a full arsenal of fungicides/pesticides when the tree invariably gets sick from the lack of mycorrhizal protection?

 

[KillerButts]

Wet lava rock is a perfect example, on a mature substrate with lava rock you would find it home to many aerobic bacteria.

 

[fredman]

Thanks to you both for the replies.

Not to be a rabble-rouser, but . . . If modern substrate (1) allows for the growth of "good" fungus and bacteria that (2) does not like too much N or P, then why do so many people (including prominent bonsai artists on this site) recommend a 20/20/20 fertilizer applied at moderately to insanely high rates? Do practitioners of this variety simply not care about the rhizosphere and accept the fact that they will be forced to resort to a full arsenal of fungicides/pesticides when the tree invariably gets sick from the lack of mycorrhizal protection?

I don't know much about chemical fertilize...don't want to really.
I remember I once read....plants generally "feeds" at a 3:1:2 ratio. That sits well with me when chemical fertilizer is combined with organic ones.

 

[KillerButts]

Thanks to you both for the replies.

Not to be a rabble-rouser, but . . . If modern substrate (1) allows for the growth of "good" fungus and bacteria that (2) does not like too much N or P, then why do so many people (including prominent bonsai artists on this site) recommend a 20/20/20 fertilizer applied at moderately to insanely high rates? Do practitioners of this variety simply not care about the rhizosphere and accept the fact that they will be forced to resort to a full arsenal of fungicides/pesticides when the tree invariably gets sick from the lack of mycorrhizal protection?

Some of the members here have extreme grow seasons. They want to get the most in the plant can handle in the time allowed when growing out. Much of it in it’s traditional application was washed in and little stayed as it just washed out. Now some people with more stable grow seasons have backed off with the use of teabags and less npk. In Indiana I think it’s safe to say you should use teabags.

 

[penumbra]

Jeff Lowenfels' book, Teaming with Fungi

So what did you think of the book and did you read the 2 others in the series>

 

[One First Matter All]

Some of the members here have extreme grow seasons. They want to get the most in the plant can handle in the time allowed when growing out. Much of it in it’s traditional application was washed in and little stayed as it just washed out. Now some people with more stable grow seasons have backed off with the use of teabags and less npk. In Indiana I think it’s safe to say you should use teabags.

That makes sense--thanks for the clarification.

 

[One First Matter All]

So what did you think of the book and did you read the 2 others in the series>

I only skimmed the one book while on the hunt for info about encouraging mycorrhizae growth in bonsai. From what I read, the book seemed helpful, certainly for a novice like me. The academic in me wanted more citations--a lot more. I tend to be skeptical of information that does not cite directly to an empirical study. I imagine he intentionally omitted such citations to make it more user-friendly.

 

[One First Matter All]

For those interested, I did come across this study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6587947/), which, among other things, discusses how certain fungicides might adversely impact mycorrhizae.

Unexpectedly, at least for me, the study found that copper fungicide does not damage myc as much as one might think, while neem oil can/does:

In re copper fungicide:
"However, when Cu‐based products were applied to the soil, root colonization was not affected or was only moderately affected (Table S1).53, 54 Thus, the use of Cu‐based plant protection products appears to be compatible with AMF [arbuscular mycorrhizal fungi] due to the strategies evolved by AMF for Cu‐contaminated environments. Nevertheless, AMF can reduce the negative effects exhibited by Cu toxicity on the host plant. However, the compatibility of AMF with Cu is dose‐dependent, and Cu accumulation in soils remains an environmental issue that needs to be addressed."

In re neem oil:
"Azadirachtin [i.e., neem oil] is a triterpenoid produced by species of the tree Azadirachta spp., and it functions as a feeding deterrent and growth disruptor for many insects. This product selectively inhibits the AM fungus C. etunicatum and causes a significant shift in the AMF community in the field."

 

[fredman]

I only skimmed the one book while on the hunt for info about encouraging mycorrhizae growth in bonsai. From what I read, the book seemed helpful, certainly for a novice like me. The academic in me wanted more citations--a lot more. I tend to be skeptical of information that does not cite directly to an empirical study. I imagine he intentionally omitted such citations to make it more user-friendly.

Yes he intentionally wrote the books targeting the layman gardener. To get the full understanding of the soil biology all 3 books should be read.

I enjoyed the first two tremendously. It surely opened my eyes about how complex things is down there. The nutrient one went way over my head.
Dr Elaine Ingham had a huge hand in providing him with information.

 

[cmeg1]

to much N and P will either damage or kill microbes and mycorrhizae.

We probably talked about this before,but I learned that plants will actually fend of the myco for fear off anpathogen if the phospherous in the substrate is available.If it needs broken down to usable formfrom say a Rock Phosphaye organic form then the plant roots will actually invite the myco to grow on the roots and around.It probably is acurate and has something to do with actual certain compounds or aminos produced in each incidense.That goves rise to another reaction of say certain ions being triggers or certain charges.I would not doubt this a bit really.The plany will kicke the myco out if it is getting what it needs(phospherous).
I’m sticking to the assumption from what I have learned that myco is totally essential in organic fertilization.
There is alot to be said about NOT OVER FERTILIZING AT CERTAIN TIMES that has many outcomes and also FERTILIZING ENOUGH AT CERTAIN TIMES that has also alot of outcomes.
Organics can be an very easy approach to fertilizing and would be fun to maintain.I like the idea of good ph water pouring over cakes on the soil.I wohls peobably auppliment with humic and fulvic acids with amino acids regularly( essentially all the bio-stimulants) to maintain a proper microelement base in the media.

 

[One First Matter All]

We probably talked about this before,but I learned that plants will actually fend of the myco for fear off anpathogen if the phospherous in the substrate is available.If it needs broken down to usable formfrom say a Rock Phosphaye organic form then the plant roots will actually invite the myco to grow on the roots and around.It probably is acurate and has something to do with actual certain compounds or aminos produced in each incidense.That goves rise to another reaction of say certain ions being triggers or certain charges.I would not doubt this a bit really.The plany will kicke the myco out if it is getting what it needs(phospherous).

That makes sense to me. Yet, I still see so many folks advocating for chemical fertilizer, saying any ol' fertilizer will do; go for what's cheapest, etc. But if the phosphorus is made immediately available to the tree through an artificial, chemical fertilizer, then it seems as though, as you say, the symbiotic relationship between the tree and the myc. will be broken. In short, the tree won't need the myc. because it's already getting what it wants directly from the chemical fertilizer, which would be all well and good if the myc. didn't also provide an immune boost to the tree. By contrast, an organic fertilizer requires the tree to outsource the work of preparing the phosphorus to the myc. (from "Teaming with Fungi": "Studies indicate that organic fertilizers are generally compatible with mycorrhizae, whereas phosphorus-rich inorganic fertilizers can inhibit mycorrhizal growth").

 

[Deep Sea Diver]

Interesting thread....

Here’s copy of a post today about an Azalea not thriving.... thought it might apply...

Hi @Harunobu et al...!

Sorry about your azalea growing slowly. It looks a bit healthier. Thought these ideas might help provide food for thought!... or reinvent the wheel...!

So I've got this hypothesis forming in my mind on why certain Ericaceous plants fail to flourish at first, then get better, or die off entirely, especially when planted in non organic soil, like kanuma, kitty litter, pumice and lava etc, despite some "container soil" being included in with the roots. Some important background data.

• First, the Azaleas are prominent members of the Ericaceous Family (Heather, Heath, Huckleberry, Rhody) all plants with rely upon creating and maintaining a continuous Ericoid Mycorrhizal Fungi = EMR interface with mainly with Helotiales(ascomycetes) fungi.
• In forming the interface each surface rootlet cell is separately colonized from the soil by fungal hyphae which invade by penetrating the cell wall and grow inside, with the plant cell membrane folding back around the hyphae.
• The enzymes of the ericoid mycorrhizal fungi acquire nitrogen and phosphorus etc for their plant hosts by breaking down organic residues of plants and animals in the peaty soils and....
• The Ericoid plants provide the fungi with sugars from photosynthesis. The fungi partnership enables plants to acquire mineral nutrients from insoluble organic residues.
• This symbiosis with the hair root lasts only a few weeks until the roots thicken on other outside.
• New interfaces are formed with new cells as the roots grow.
• A widespread population of suitable soil fungi is essential to maintain the continual root recolonization, which is a key feature of ERM.

In short, as the root grows, the EMR interfaced root cells turn woody, ending the symbiosis in that plant cell. However, as new cells form, the ever present fungi in healthy Ericaceous soil continually create new interfaces... Keeping both the azalea and the fungi happy!

So say you take a healthy azalea, cut the roots down and clean them off a bit.... and maybe severely cut back its solar panels? Then you plant the azalea in a new, non Ericaceous soil. For example kanuma, or some other non organic mix - kitty litter - pumice and lava etc (with the bit of container soil on the azalea's roots).

The first thing that happens is that the remaining root tips, (Which could be/or not be adversely impacted depending on the nature of its growth and the cutback - bottom & edges), are handling the whole load of the nutrient uptake for the plant, have to get nutrients to keep the plant photosynthesizing. The rootlets first hope is to keep getting a healthy supply of fungi to their roots keep up the EMR interface.

Yet, the entire population of fungi in the soil has been somewhat diminished by the whole process. Even that's not so bad.... after all, there are lots of fungi in a teaspoon of soil. However, the azalea is being put into a non organic soil that has minimal nutrition for the fungi at best.

This organic-less mix dilemma could and in my opinion likely will, put the entire plant at risk for lack of nutrition... slowing new root growth, nutrient uptake, thus impeding the rate of photosynthesis until somehow the population of fungi can find a way to thrive again. Or not... and the plant dies

....Or the plant can get a replacement for the Nitrogen, Phosphorus, Potassium and micronutients from an outside source...

So here's the kicker. It is often said not to fertilize plants that have been newly potted (and repotted).

I don't think that should be the case for Ericaceous plants. I'm thinking it will stunt the growth of the plant worse that originally intended. The whole idea is to bootstrap the pot's ecological system back into gear. Get the EMR Interface healthy.

So what do you do? Feed it a weak solution of Miracle Grow for acid loving plants.... good for the plant not good for the EMR interface. Put cottonseed/blood meal chunks on it - much better, but its a slow release fertilizer that takes time to get things moving. Too slow for the system in this moment in time.

So my thought is to feed a weak, maybe 1/4 or 1/2 strength, organic liquid fertilizer like Alaskan Fish fertilizer right away and at regular weekly intervals, slowly increasing the strength over a period of time, depending on the plants growth rate. In other words, provide ingredients to build up the entire microbiome in the media.... while also providing both the azalea and the fungi nutrients.

Say for two or three months or so .... adding in whatever you choose for slow release from the get go.

Later, once the systems back into balance again and the pots microbiome is intact, you should be able to use most any kind of liquid fertilizers that supply the ammonium form of nitrogen, like MiracleGro.... since the media has now changed and built up a thriving microbe metropolis. Or alternate with the liquid organic fertilizer.

Last thought. Re potting an existing bonsai is a slightly different story.... then you might follow the old master's advice and include some of the old soil in the new potting soil.... and organic weak liquid fertilizer.

Hope you had as much fun reading this as I did writing it! Any thoughts?
Cheers
DSD sends

 

[Firstflush]

I’m a pretty serious veggie grower and am newer to bonsai. You mention^^ not feeding after major major work.
I have seen awesome recovery rates with transplants and repotting with the Grow More Seaweed Extract. I’m not involved with the company in any way. It has all the micro, macro, growth hormones, aminos Etc....the plant needs. It’s cold pressed and the NPK are all under 1.

Also, anybody think the race car soil can be taken down just one notch. How about 20 percent organic...as in very good compost. Would definitely aid in keeping the rhizosphere foundation solid in confined container conditions.

 

[TN_Jim]

I very much applaud your inquiries. This is a fascinating matter. However, I wish it was more species specific, and possibly bonsai specific, even if broad.

Yes, there is good science being done, much needed research into the field of mycology and associations with woody plants, as well as bacterial associations. It is often amplifying what some prominent ecologists have eluded to for some time, and now on a microscopic and microbial level...look into findings of the human gut biome alone...;however, there is a broad brush being put to the canvas here.

This assertion(s) is not to pick a side or devils advocate, but it seems that combining bonsai (common bonsai container grown practices) with true peer reviewed research that is often subject to a vast array of methodology in practice (not bonsai), and often ag-related, it seems unfortunately difficult to find a hill to die on or raise a definitive flag.

When species and even plant families are pooled into such a discussion it is beyond muddy or vague....

To be transparent, true science only has the goal of answering a question and never an agenda. The agenda will be formed by the public after the basis and results of true science is agreed upon and translated. So my point is to ask for a more concise hypothesis and inquiry.

For example, I believe I have 70 some odd trees of varying development that are established, accounting for maybe 12 different plant families. I have no pines. There are no two really exactly alike -different ages, containers, substrates, light, etc.

Having different biological demands, I have gotten to the point of adjusting soils, light, and especially watering that this year I have applied almost no chemicals (insect/fungal) to any -wooly aphids on 3, fungal on 2. I have applied both synthetic (limited because I had it) and organic fertilizers of all sorts throughout the year very minimally, almost feel guilty about lack of fertilizer, but not really..because they all seem to be doing alright, and I’m not trying to force them to grow.

So, I wish folks would use less chemicals sure, but why should I care aside from basic valued understanding of soil science, how much bacteria or fungi are in a completely healthy potted plant, or believe it requisite in a bonsai pot across all taxa I have or may acquire in order to maintain health and growth?

 

[Forsoothe!]

I have a view from the other side of the coin. I have ~100 things in pots of many species, sizes and ages and use one potting mix that is all organic. My potting mix is ~50% by weight of commercial Pine Bark Soil Conditioner which I am counting on as having an abundance of all the critters that experts are talking about, and/or at least a proper environment for those in the roots of plants I repot. I, too, do not feed very much or often, but for the specific reason that I want to reign-in plants. I do not want lots of growth or fast growth. I almost never feed before plants leaf-out to reduce the resources that contribute to leaf size, except after repotting I use a liquid after one or two plain waterings. I feed a couple times in summer to aid second flush and bud building for the next year. I use Bayer 2-in-1 or Rose 3-in-1 in June and September to preempt problems and it seems to work. I have recently taken to a separate application tonic of Fulmic & Humic acid and liquid Kelp at minimum levels (no analysis on any labels) which is suppose to contribute to organic ends. I use a Pyola spray for greenhouse bug problems. So, I'm an "all of the above" kind of guy.

I have good results and I think that's as close to the science as I'm going to get. I have a life outside of bonsai, regardless of what my wife says.