bacillus thuringiensis shelf life

Chris Conlan conlan at
Fri Jun 26 01:46:20 EDT 1998

>The stuff is a spore forming organism, very stable when in that form and when
>introduced into the soil.

While it is true that B.t. is a spore forming organism it is not the spores
that are responsible for most of the mortality.  (Forgive me if I'm stating
information you already know, but others reading may not).  The vast
majority of death is caused by the protein toxin (crystal in form) found
within the bacteria.  Commercial formulations are grown to maximize the
amount of this protein so you get a nice bang on the bugs for the first day
or two it's in the field and then those proteins break down in the
sunlight.  Any mortality caused by remaining spores is virtually
negligible.  This stuff does not go hog-wild after being sprayed and
proliferate like crazy in the soil.  Rather, it quickly fades to background
levels and is of little further concern.  Also, if still worried, you can
buy formulations of B.t. that do not contain spores and therefore cannot
proliferate.  Examples of this are products sold under the trade names MVP,
Mattch, M-Trak and a few others.  I hope this helps and I get the feeling
it won't be my last post on this (I had to go and open my mouth!).

conlan at

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