Re: Compost Tea Confusion

**"Doreen Howard" g*@charter.net**

Carolyn Ulrich wrote:

> At the Symposium in Chicago, I spoke with someone who said that while
> adding mycorrhizae to garden soil was worth doing, it was worthless
> when added to a sterile potting mix such as that used by Monrovia and
> others in the green industry. Does anybody know the truth of this, one
> way or another?
>
I interviewed Dr. Elaine Ingham for a couple of articles, and we discussed
mycorrhizae in potting soil.  She pretty much validated my thoughts on it.
It depends on how the potting soil is stored.  In excessive heat, the spores
die, and if fertilizer with high nitrogen and phosphorous levels is
incorporated into the potting mix, they kill the mycorrhizae.  Ideally, one
should get fresh potting soil that has been stored properly (not stacked in
huge piles outdoors) and incorporate gradual release fertilizers such as
Osmocote or pelleted fish meal. Ingham said that mycorrhizae in a container
will allow plants to thrive with less water, which is a plus for those who
don't water regularly.

About Monrovia.  I interviewed their research director about their use of
mycorrhizae in growing woody shrubs and other nursery stock.  To quote him,
"We do it for the customer down the line, not for our benefit."  They
produce a pot-grown plant that come inoculated with mycorrhizae that should
take off and grow vigorously in any soil--if the buyer uses gradual release
fertilizer or none at all.  BTW, Monrovia uses mycorrhizal inoculants in two
forms at two times--the granular version at potting up and a drench later.
Doreen Howard

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