[compost_tea] Biological Control of Soilborne Fungi - Crop Rotation Idea

From: chris reid <reidchris_at_earthlink.net>
Date: Mon, 18 Aug 2003 06:51:42 -0400

There has been much conversation about the use of corn meal to encourage
Trichoderma growth in soils. I have tried to track down research on the
topic, and was pointed in the direction of this article on disease control
in peanut crops. Apparently Texas A&M has done research on this in the
past. Here's the quote and link:

Biological Control of Soilborne Fungi
It is known that certain fungal species in the genus Trichoderma feed on
mycelium and sclerotia of Sclerotinia minor. Sclerotium rolfsii and
Rhizoctonia sp. All peanut fields in Texas tested to date have a natural
population of Trichoderma. For several years, tests have been conducted in
Texas using corn meal to stimulate Trichoderma development as a way to
control the major soilborne disease fungi. When yellow corn meal is applied
to fields in the presence of moist surface soil, Trichoderma builds up very
rapidly over a 5 to 10 day period. The resulting high Trichoderma population
can destroy vast amounts of Sclerotinia, Sclerotium and Rhizoctonia. This
enhanced, natural biological control process is almost identical to the
processes that occur when crop rotation is practiced. The level of control
with corn meal is influenced by: 1) organic matter source 2) soil moisture,
3) temperature, and 4) pesticides used. Seasonal applications of certain
fungicides may inhibit Trichoderma. Testing will continue to determine the
rates and application methods that will give consistent, economical control.

Source: http://stephenville.tamu.edu/~clee/pdncr/index.html

In addition, I located a researcher, Chip Lee, who had done some work of
this type 15 years ago. Here's a quote from his email:

It has been at least 15 years since this work was done. It did not work on
other peanut diseases because they unlike Sclerotinia would also grow on
Cornmeal. Sclerotinia does not grow much on cornmeal and thus allows the
Trichoderma to get ahead.
I think you will find that most fungi have preference in the type organic
mater which they feed on. The secret is to find an organic source that will
host the antagonist and not the parasite. This is basically what you are
getting when you find a successful crop rotation.

I think Chip Lee's quote above stimulates my curiosity in a couple of ways:

The previous conversation about Jeff L's use of baby oatmeal and the other
possible grains on which fungi could be cultured. It would be possible to
accidentally culture an antagonist, would it not? Maybe this is always a
possibility, but seems wise to figure this out somehow.

Second, the comment about crop rotation -- can we look to known crop
rotation sequences for clues as to the possible organic matter on which to
culture beneficial fungi for tea that will help -- or may hurt -- a
particular situation?

As an example, there are certain rotations that will NOT produce good
results -- is it corn followed by wheat that produces more wheat rust? I'm
a reader but I am sure we have a farmer on this list who will know. Are
there other rotations --good or bad -- people can point to for possible
sources fungal growing media?

Chris Reid


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Received on Mon Aug 18 2003 - 10:38:09 EDT

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