Re: [tomato] mycorrhizal Fungi

Thomas Giannou (
Sun, 18 Apr 1999 14:16:35 -0700

Dear Peter,

Again, I am writing this as a strictly amateur gardener, but with some
insight because I have read and studied a lot about this particular
subject.... and tested out several ideas.  I have noticed there are
basically a couple of cultural traditions concerning agricultural methods.
One I call the tradition of using chemical fertilizers.  The other I call
Organic growing.  And I suppose there are combinations of both that people
use.  Most people use what seems to work for them.... they take the path of
least resistance that seems to get good results for them.

In my own experience in working with VAM fungi, specifically Glomus
Intraradicies, I have found that prior cultural practices in the soil don't
seem to make a whole lot of difference.  What is put on after the fungi is
colonized in a plant's roots may have a significant effect.  We also say to
people not to apply VAM within 25 days of fumigating the soil.

VAM treated plants actually require more water than plants not treated with
VAM.  At the same time, up to 50% less water needs to be applied.  That
might seem confusing, but it is logical.  The root systems of VAM treated
plants generally get farther into the soil and thus into water they would
not ordinarily reach.  Thus they are into ground water moisture.  Less water
has to be applied to those plants.  The biomass of roots and top growth of
VAM treated plants is almost always much larger than untreated plants...
thus the requirement for more water.

I've not really read much where "low phosphorus" soils have been mentioned.
What I have read is that low phosphorus fertilizers are required.  I also
know that a lot of superphosphate can be added to the soil and allowed to
sit there a long time (a couple years) and that VAM treated plants can be
planted in such soil and will do just fine.  I have a test plot that is like
that.  It was done mostly out of ignorance on my part.  VAM treated plants
do very well in such soil.

I have spoken to some people who have said there are places in California
that have been burned up with the constant addition of chemical fertilizers
and that almost no crops can be grown in such soils.  I've never seen such
places myself... just talked with people who have.  In such soils, VAM
treated plants do quite well.

The kind of soils that seem to produce well with VAM treated plants are
those that drain well, but retain moisture and have a lot of organic
material available.  Well aged compost seems to be all that is needed in
such soils.  Chuck's description of adding a bit of aged manure to the soil
reminds me of a soil that would support VAM treated plants quite nicely.
Even though less water needs to be added, if one does add what is normal for
chemically treated soils, the VAM plants really do excellent.  Just because
less is required, doesn't mean that more water will have a negative effect.
With more water, VAM treated plants can get quite large.

One trait I have noticed in all plants treated with VAM fungi is a much
higher chlorophyll content in the plants.  They are by far, greener than
non-treated plants.  In the case of turf grasses, 60% more chlorophyll
content is present.  That allows plants to grow in low light situations.
Grass will grow under pine trees normally so dark underneath that non-Vam
treated grass simply won't grow there.  It helps make a big difference in
house plants that don't get much light and seem to always be struggling.

There are many advantages to using VAM fungi with plants.  I took thin
slices of cross sections of the stems of Roses, Maple, Quaking Aspen,
Raspberries, and Spirea plants and compared treated and untreated plants.  I
found that in the VAM treated plants, the xylem vessels which carry water
and minerals from the roots into the plant, were much larger, more numerous,
and were better dispersed in the cambium tissues of the plants.  I also
found that the outer layers of the tissues in the stems had thick divisions
of cells and were very healthy.  I also noticed that the phloem sieve tubes
in VAM treated plants were larger and healthier looking than in untreated
plants.  Those outer layers have a lot to do with plant health and
resistance to diseases.  It is well known that insects tend to leave healthy
plants alone.  Cuttings taken from VAM plants retain their vitality much
longer that cuttings taken from untreated plants.  I took a cutting from an
Asparagus fern and it stayed viable for 8 days before it dried out.  I
looked at a cross section of a stem from the Asparagus plant and found large
xylem tubes present.  The VAM treated plants retain water much better than
untreated plants and when they are really stressed for lack of water, they
bounce back quickly when water is added.... attributed, I believe to the
larger sized and more numerous xylem vessels present.

I applied VAM fungi to my beef steak tomato plants last year and they
matured in two months.  They were producing ripe tomatoes August 1.  That
was about 1.5 months early.  I had more tomatoes and the plants were much
larger.  The tomatoes also tasted better than I had ever had before with
that species.  I noticed that with every food plant that I used VAM fungi on
last year... they tasted a lot better than untreated plants.  That was
always one of the first comments people would make to me as I shared our
fruits and veggies with them.

Last year, was the first year I had used VAM fungi.  I am looking forward to
seeing what my Raspberry plants are going to do this year... now that I have
canes that grew up under the influence of VAM fungi in the roots of those
plants.  Last year, the fruit was plentiful and super flavorful.  This year
.... if I take action against the birds, I should have an excellent crop of

I am also going to try some Bingo tomatoes with VAM fungi.  I'll be saving
the seed from those and if they turn out well, I'll share them with friends.

I have been applying VAM fungi and an Organic fertilizer to lawns this
spring and re-applied it to my lawn this spring... what a difference it

Best Regards,
Thomas Giannou
Spokane, Washington

-----Original Message-----
From: Orchid <>
To: <>
Date: Sunday, April 18, 1999 5:51 AM
Subject: RE: [tomato] mycorrhizal Fungi

>Well, my question here VAMF for people who have low moisture, low
>phosphorous soil and the fungi compensates for it, and the rest of us with
>well watered, good fertilized soil don't need it?  Or is going the low
>phosphorous, VAMF Fungi better in the long run?
>Peter, South Florida, Zone 10
>-----Original Message-----
>From: []
>On Behalf Of ChuckWyatt/Md/Z7
>Sent: Sunday, April 18, 1999 7:48 AM
>Subject: Re: [tomato] mycorrhizal Fungi
>>>In particular, vascular-arbuscular mycorrhizal fungi (VAMF)
>increase yield in peppers grown in low-phosphorous or low-moisture soils.<<
> The key phrase here is "low phosphorous" as well as the combining pepper
>culture with that of tomatoes.  While peppers and eggplant are in the same
>general family, there is danger in grouping their culture.  The most common
>way to get the best in production from tomatoes is to use a high
>phosphorous, low nitrogen fertilizer. 5-10-5 seems to be the most popular.
>Even the VAMF sellers say it should not be used in conjunction with the
>high phosphorous fertilizers such as 5-10-5 that are normally used with
>tomatoes.  Hi Phos. fertilizers and VAMV combined may very well burn the
>roots off your new transplants.
>Good gardening,
>Chuck Wyatt