I have no research to back this up /sadface

Any truths to this claim?

I have experienced positive results in both recirculating ebb and flow set ups as well as recirculating DWC. I have used it when root structure is unimpressive, or seems stressed. The results appear within days of treatment. Definitely “dirties” things up, but if you need some help with slow roots… it’s worth the trade off. I hate to end with a plug, but having tried a number of options I find GH’s Sub Culture M to be the best in terms of results.

Good Luck…

Is there a role for arbuscular mycorrhizal fungi in production agriculture?
Megan H. Ryan1,3 & James H. Graham2
1CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia. 2University of Florida, Citrus Research
and Education Center, Lake Alfred, FL 33850, U.S.A. 3Corresponding author∗
Received 21 August 2001. Accepted in revised form 20 February 2002

Conclusion:

“….Intensive horticultural systems with high inputs of P-fertiliser and fungicides may reduce formation of
AMF and negate any potential benefits from AMF for crop nutrition and root health. Under the moderate Plevels that prevail in the majority of field crop systems,
early season colonisation by AMF may often be parasitic, creating a C-drain on crops and reducing yields. Even if P is deficient for plant growth, AMF can not be assumed to enhance growth as in some regions the ability of AMF to enhance host growth appears constrained
by factors we currently do not understand. Hence crop responses to AMF are often unpredictable
and contrary to their reputation as ‘biological fertilisers’.”

Thanks for posting up further research on Mycorrhizae in high P levels. And please keep it coming—it’s fascinating. We are in touch with Dr. Michael Amaranthus, the author of the article, and will be posting up other research papers shortly.

Now then, a polite word in your ear, albeit on a public forum (as you continually make up email addresses we have no other choice!) We are not pushing a mycorrhizae-based commercial agenda. And we are not run by any nutrient or hydroponic wholesale company. The whole point of Urban Garden Mag is that it’s written by growers, for growers. Yes, we all have our friends in the industry. That’s life. That’s human. But we’re not “run” by some shadowy bosses, “manufacturing consent” as you put it. Hey Jimboon, if you want to write a counter article, we’d definitely consider it for publication. You’re clearly well read on the subject. So how about that?

The whole point of the article was to ask the question “Do Mycorrhizae have a role in Hydroponics?” and we cite that some nutrient companies say YES and some say NO. There is evidence that certain strains of Mycorrhizae are more tolerant of high P levels than others. The article also serves to demonstrate the role of mycorrhizae in general.

If you really believe that we get up in the morning to push the agendas of certain parts of the industry then … well, the politest thing we can say is that you grossly underestimate us. But at least give us a chance to prove otherwise.

Abstract (H.-J. Hawkins and E. George)
Linum usitatissimum, Sorghum bicolor and Triticum aestivum plants were further colonised by the arbuscular mycorrhizal fungus, Glomus mosseae, during a four week period of hydroponic culture after a pre-culture period of three weeks with the fungus in perlite substrate. The viability of mycorrhizal colonisation of T. aestivum was indicated by an initial experiment where G. mosseae from mycorrhizal plants colonised non-mycorrhizal plants when the plants were grown together in the same hydroponic container using modified Long Ashton nutrient solution. Intermittant aeration of the plant roots (2 h periods, four times per day) provided a compromise between adequate aeration and minimal disturbance of the fungus. In a second experiment, two nutrient media, modified Long Ashton and modified Knop plus Hoagland medium were compared for culturing G. mosseae on T. aestivum. A significantly higher root dry weight was found for the mycorrhizal versus the non-mycorrhizal wheat plants in modified Long Ashton nutrient medium, which contained 10 µM P and an organic buffer. Modified Knop plus Hoagland nutrient medium contained a high P concentration (0.9 mM) and did not produce viable cultures of mycorrhizal colonisation. In a third experiment, modified Long Ashton medium was used for hydroponic culture of mycorrhizal L. usitatissimum, S. bicolor and T. aestivum. The root colonisation percentages for T. aestivum (73%), S. bicolor (36%) and L. usitatissimum (65%) were within the range of colonisation rates obtained with solid substrate culture in perlite. Viability of the mycorrhizal structures in hydroponic culture was assessed by monitoring activity of fungal succinate dehydrogenase and found to be similar to cultures in perlite. No difference in the P concentration of mycorrhizal and non-mycorrhizal plants was observed, possibly owing to the lack of diffusion limits for P in hydroponic solution. This report describes a system for the viable culture of G. mosseae with different plant species where a high mycorrhizal colonisation rate was produced under conditions of a short culture period using intermittent aeration, a low concentration of P supply and an organic buffer.

“Feel free to post condescending insults!” Well this is indeed an interesting reflection.

Myco spore germination is inhibited by high available P levels. But there are commercial myco products out there comprised of strains that have the ability to handle P. Some types can only handle available P at 20ppm so they are no good for hydroponics. There are other species that do well from 70-100 ppm during spore germination and can then can handle up to 300ppm.

PS those studies below are 20 years old. There is lots more recent info that shows a range of P response.

Influence of Phosphorus on Mycorrhizae:
The benefits listed above are greatest in P-deficient soils and decrease as soil
phosphate levels increase (Schubert & Hayman, 1986).
Very high and very low phosphorus levels may reduce mycorrhizal
infection/colonization (Koide, 1991). It is well established that:
Mycorrhiza and soil phosphorus levels Colorado State University Cooperative Extension … Page 1 of 4
http://www.colostate.edu/Depts/CoopExt/TRA/PLANTS/mycorrhiza.html?PrintWindow 12/28/2004
􀁺 infection by mycorrhizal fungi is significantly reduced at high soil phosphorus
levels (Amijee et al., 1989; Koide & Li, 1990)
􀁺 the addition of phosphate fertilization results in a delay in infection as well as a
decrease in the percentage of infection of roots by mycorrhizae (deMiranda,
Harris & Wild, 1989; Asimi et al., 1989)
􀁺 an increase in the level of soil phosphate results in a reduction in
chlamydospore production by the fungus (Menge, et al. 1978). These spores
are involved in root infection and spread of the fungus through the soil profile.

Please feel free to post condescending insults.