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[nafex] Re: Apple and mycorrhizal fungi



Hi,

Here is the response from "Plant Health Care" regarding my myco.
questions.

Tom

--


On Thu, 6 Dec 2001, Mike Kernan wrote:

> I have read your questions.  There may be some mistaken assumptions about the nature of the mycorrhizal association.  Your questions suggest a mistaken understanding that the non-inoculated trees and plants were not associated with mycorrhizal fungi, and therefore, the differences between the treated and untreated trees or plants could be attributed to the presence of mycorrhizal fungi in one group, and its absence in the other.
> In fact, all trees and almost all plants growing in the field are mycorrhizal, whether you inoculate them or not.  If planted in the field rather than in a controlled greenhouse setting, it is nearly impossible to prevent native species of mycorrhizal fungi from colonizing the root system.  Therefore, I am confident that all the apple trees in your example were colonized by mycorrhizal fungi of one kind or another, whether or not the trees were in the inoculated group or the uninoculated group.  You do not mention whether root samples were taken before and after the treatments to determine to what extent the roots were colonized by mycorrhizal fungi.
> There are cultural practices that can mask the beneficial effect of the mycorrhizal association.  Mycorrhizal fungi improve the ability of plants to absorb water and mineral nutrients.  The effect of this is most striking when a plant is stressed under situations of drought or nutrient deficiencies in the soil.  In such cases, the mycorrhizal plants perform dramatically better, and are far more productive.  However, when working with nursery plants, the benefits are not so apparent.  Here, the plants are protected from drought (by irrigation) and from infertile soil, (by fertilization).  So protection against stress is not apparent when there is no stress.
> Inoculated plants typically do not display their value in the nursery.  Rather, the value of the fungi becomes more apparent when they are outplanted to a site where they are left to the whims of nature (more or less).  In an orchard setting, the grower might recover benefits in the reduced need for fertilizer, and better resistance to drought (if his irrigation fails).   Sometimes, the fungi can reverse the effects of certain nutrient deficiencies that the grower has failed to address in his cultural program.  They can also rejuvenate trees in decline.  These are all within the scope of mycorrhizal fungi.  That is not to say that these things will always be achieved by inoculation.
> I do not know why the inoculated trees in your example reportedly grew slower. Apples are ednomycorrhizal trees, and associate only with VA endomycorrhizal fungi.  Were the species of fungi applied to these trees endomycorrhizal fungi?
>
> What were the ingredients of the inoculant used?  Was it merely a mycorrhizal inoculant, or did it contain other ingredients that effect plant growth or soil fertility?  Did the manufacturer have adequate QC to ensure that the intended organisms were actually present, that they remained alive when exposed to the conditions of mixing, packaging, handling and storage, and were the products used appropriately and within the limit of the shelf life?  The above question that I ask all stem from my experience with products produced (or should I say "packaged") by other companies.  Most companies that sell mycorrhizal products are selling copycat formulations.  The companies buy what is purported to be a spore mix and/or mix of root fragments, and they add it to their own formulation, and sell it as a mycorrhizal inoculant, making all the claims that they copied from Plant Health Care's labels.  A closer look at such operations reveals many lethal mistakes:
> (1) Many companies fail to realize that living fungi cannot be treated the same as a nonliving ingredient (lest you kill them). They do not recognize that heat, pressure, and extremes encountered in storage (including aging) can kill the spores and root fragments.
> (2) Many of these companies never considered the fact that you must test your other ingredients to make sure that they do not kill, desiccate, or inhibit the fungi.  They just mix them together, slap on a label, and off it goes.
> (3) Many of these companies have no biologists on staff, or certainly not a fungal biologist skilled in mycorrhizal fungi.  The most basic aspects of handling living things are ignored.
> So when you attribute the problems that your report encounters to the mycorrhizal condition, were all of these things considered? In fact, a trial like that must involve stringent controls and good experimental design.  Otherwise you may be observing effects not planned for, and your conclusions may be quite erroneous.
> Regards,
>
> Michael J. Kernan, Ph.D.
> Technical Services
> Plant Health Care, Inc.
> 440 William Pitt Way
> Pittsburgh, PA 15238
> Tel: (800) 421-9051, x103
>
>


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