RE: [tomato] mycorrhizal Fungi

Orchid (
Sun, 18 Apr 1999 11:19:09 -0400

So I can assume, once colonized with Vam, it should always be given low P.
That can be a minus if you use different methods.  If you shouldn't go over
2% P, and Vam increases uptake by X4, then giving 2% is like giving a P of
8.  So my question is, what is the difference between using Vam Fungi with
low P, and traditional methods using higher P?  Is the results going to be
better than giving tomato a fertilizer with 8 or 10 Phos.?

Peter, South Florida, Zone 10

-----Original Message-----
From: []
On Behalf Of Thomas Giannou
Sent:	Sunday, April 18, 1999 10:58 AM
Subject:	Re: [tomato] mycorrhizal Fungi

Dear Chuck,

It all depends upon when one puts VAM fungi on the plant and when one puts
the fertilizer on the plant.  If a high phosphorus fertilizer and VAM fungi
inoculant are added at the same time, the high phosphorus (any P above 2%)
will prevent the VAM fungi from connecting up with the plant and in this
case, the plant will not be burned.

If the VAM fungi is colonized into the root system, and a high P fertilizer
is added, then there is a high probability one can kiss that plant goodby in
less than a week.  VAM fungi can bring phosphorus into a plant at levels 4
times higher than the root system of a plant that is not colonized with VAM

The best sources of P for plants treated with VAM fungi are not
superphosphate fertilizers, but are fertilizers where P is in complex forms
or in rock phosphate form.  Those forms generally require microbial action
in order to free up the phosphorous.

The above points of view are generally supported by what is said in a book
titled, "Mycorrhizal Symbiosis" second edition, by S.E. Smith and D.J. Read.

There always seem to be exceptions even to what the experts say about these
things...  I had an e-mail from a Rosarian in the Seattle area in which the
person stated they put VAM fungi and superphosphate on roses at the same
time, as was their habit with the phosphate fertilizer and burned up a bunch
of expensive roses they had imported from Canada.  The vendor of the VAM
fungi did not provide any information regarding staying away from high P
fertilizers.  So now, that Rosarian is telling everyone not to use VAM
fungi.  It appears the text book definition above needs work by what this
particular Rosarian experienced.

When I started into the business of selling VAM fungi, I did a fair amount
of research on the subject and noticed that most of the Vendors in the
market place at the time (last year) were not saying much of anything about
this particular problem.  Some were even saying that it was okay to use aged
chicken manure with their products.  IT IS NOT OKAY!  Chicken manure and Bat
Guano are way too high in P and will burn up plants treated with VAM fungi.
Age doesn't make much difference.

We have had to develop our own literature for the retail market place and we
always make it a point to tell people about the problem with high P

There are also other substances that will affect VAM fungi in negative ways.
Certain, but not all, fungicides and systemics may kill VAM fungi and thus
remove the benefits of their working with the plant.  We publish a list of
precautions that we give to our customers about these particular issues as
information on the label of our product (BioVam).  One can only hope people
will read the label information so they don't make mistakes.

Switching, now, to being just another ordinary gardener....  I, like most of
the people in the public, hardly ever read labels on products... because in
the past the traditions that generally work are:  put some fertilizer at
moderate levels in the hole when one plants along with aged compost.  That
won't work if one is using VAM fungi.  Tradition also says, put some 5-10-5
on the tomatoes or 10-10-10 on the Raspberries.   And like you stated, it
will burn the plants up.  I tried some 8-5-1 or 8-5-3 fish pellets as side
dressing around some Raspberry plants which had been treated with VAM fungi
and were colonized very well and lost a few plants as a result.  All of the
plants I applied the fish pellets to were burned in their lower leaves.
That surprised me because that fertilizer was supposed to be Organic.  So,
it seems prudent to me, that if one uses a fertilizer with a P above 2% on
plants treated with VAM fungi... do a test first on one or two plants for at
least two weeks before putting the fertilizer on the rest of the plants.
That way, adverse situations can be avoided.

Thomas Giannou
Spokane, Washington

-----Original Message-----
From: ChuckWyatt/Md/Z7 <>
To: <>
Date: Sunday, April 18, 1999 3:58 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