Subject: Re: [GWL] Re: gardenwriters Digest, Vol 2, Issue 1

From: LEE REICH <[email-masked]>
Date: Sun, 02 Mar 2003 17:08:30 -0500

Do you have any references indicating that mycorrhizae aid in N nutrition?
Also, I believe that large amounts of P do not kill the fungi, but merely
suppress the development of mycorrhizae. Perhaps the plant chooses the easiest
route: using fertilizer P takes less energy than using P garnered by
mycorrhizae. After all, the fungi need to be fed, too, and use some of the
carbohydrates manufactured by the plants. I am not promoting fertilizer over
mycorrhizae. Nutrients gathered by mycorrhizae are more efficient to the planet
as a whole, not to mention being more "natural." I'd like your comments Doreen.

Doreen Howard wrote:

> Jeff Ball wrote:
> .  The question is where is the
> > web site that talks about the fertilizer issue?  I am assuming that the
> slow
> > release forms of fertilizer, synthetic or organic will not harm
> micorrhizae.
>
> Jeff,
> I've worked with mycorrhizae for 9 years and did a study for the USDA
> Research Station on it and heirloom tomatoes.  I'm a believer in the fungi.
> Here is site will give you info on the fertilizer issue:
>  www.bio-organics.com
> It's a commercial site, but the principles know their stuff.
>
> Dumping large amounts of phosphorous and nitrogen into the soil will kill
> mycorrhizae.  Their hypae are very adept at mining the stuff and trace
> elements from the soil.  That said, mycorrhizae do need some nutrition.  Use
> gradual release sources of N-P-K.  Most take that to be compost and other
> organic matter.  Fish meal pellets are a commercial fertilizer in the
> organic realm that work well with mycorrhizae, as does alfalfa meal and
> cotton seed meal.  I even use Osmocote with success at half the amount
> suggested on the carton.  The trick is to provide small amounts.
> Doreen Howard
>
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---

From: LEE REICH <[email-masked]>
Date: Sun, 02 Mar 2003 12:03:06 -0500

The main effect of fertilizers on the mycorrhizal association is similar to the
effect of N fertilizer on the rhizobium symbiosis of legumes. The major
nutrient benefit of mycorrhiza is in improved P nutrition, because P moves very
little in the soil so roots garner it by root interception and the fungal
threads act essentially as extensions to the roots. Phosphorus fertilization
suppresses the symbiosis. There are sometimes other benefits from mycorrhizae
also, such as disease reduction and improved tolerance to water stress. But, as
I mentioned previously, mycorrhizae are ubiquitous: you'd have a lot more
trouble finding a nonmycorrhizal plant than a mycorrhizal plant, under
cultivation or in the wild. Interestingly, some families, such as the cabbage
family, never form mycorrhizal associations.

Lee Reich, PhD

Jeff Ball wrote:

> Jeff,
> I'm working on a book dealing with trees and am pushing the use of
> mycorrhizae in the planting process.  I was not aware that quick acting
> fertilizers harm those root fungi, but I am not surprised.  They kill lots
> of other microbes and repel worms for weeks.  The question is where is the
> web site that talks about the fertilizer issue?  I am assuming that the slow
> release forms of fertilizer, synthetic or organic will not harm micorrhizae.
> Thanks
> Jeff Ball
>
> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of Jeff Lowenfels
> Sent: Saturday, March 01, 2003 2:42 PM
> To: Garden Writers -- GWL -- The Garden Writers Forum
> Subject: Re: [GWL] Re: gardenwriters Digest, Vol 2, Issue 1
>
> Sorry, for the unclearness.
>
> Ninety percent of plants --o.k. some say 70 or 80%, form a mycorrhizal
> relationship and most  "Yardeners" have no idea what a mycorrhizal fungus is
> nonetheless understands how to garden with them.
>
> Nurseries have taken the lead in using mycorrhizal fungi in their
> products.They do so because they work. These are now available for home use
> but who in your "readership" has really ever even heard of mycorrhizal
> fungi? It is my belief garden writers fill the role of passing on to home
> gardeners the "instructions" and the reasons "why" they might want to use
> them. There are some great websites to start if you want more information.
> Just contact me off list.
>
> One of the problems is that fungi are fragile and salt based fertilizers
> conflict. I am not sure how our fertilizer industry brethren will react to
> any hoopla about mychorrizal because there is an incompatibility between an
> existing industry and a new one.
>
> That is what I meant to say. May be something about B-1 not working, though
> many garden writers push it, but that is all!
>
> Cheers,
>
> Jeff L
>