bacillus thuringiensis shelf life

[Doug]

Semjase wrote:

> Dan:
>
> This stuff lasts just about forever and areas sprayed with it a contaminated
> for years to come.  It is a destroyer of butterflies of all types par none.
>
> I suggest you burn the damnable stuff or put it in an autoclave at 250
> Farenheit for at least 50 minutes to get rid of it.
>
> Best.
>
> S.

Whooa.  Hold your horses Sorro,..I believe that B.t. is only second to
preserving Leps and other insects (habitat preservation and promotion are best)
when considering that it is used as a replacement for many other toxic
inorganics insecticides that would actually still be environmental contaminants
even after the humorous treatment you proposed above.

Dan, B.t. is a showcase example of the application of science to find solutions
that minimize environmental damage to important human food crops.  If you wish,
I can give you exact answers to your half life question if you describe exactly
(generically) the type of B.t. you have.

B.t. is a natural protein produced in the microorganism by that name which binds
to receptors in the gut of many Lepidoptera (and there are many varieties which
have varying activity against different leps, others have been found for Col's),
and interferes with the digestive metabolism of the poor victim bug.  Thus, B.t.
is a very special product which is thought to be totally inert to humans.

B.t. can be in at least two powdery preparations:
1.  Crystalline B.t.
2.  whole B.t. bacteria

Some list members mentioned the sensitivity of B.t. to UV light.  The reason
some use the unpurified form of B.t. is because it is stabilized in the
bacterial matrix, and lasts twice as long against UV.

B.t., like most proteins is probably water soluble.  When it rains, the stuff is
washed away and harmlessly is harmlessly decomposed.  Typically, B.t. needs to
be applied every one to two weeks to be effective.  It has a long shelf life
when dry and stored in the dark relatively cool.  Always mix it in dark
containers.  It ought to last several months in solution, as long as nothing
starts growing in the solution that might feed on it as a source of protein.
Especially be sure that the bottles you mix it in are opaque.

Regarding strains for the squash vine borer, this is a case where to my
knowledge, no current B.t. is really effective.  (As mentioned above it is not
effective for all Lepidoptera.)  If your crop is relatively small, just slit the
stems and pull out the cats.  If this is boring have a Lepidopterists' party.
Those emerald colored moths are truly beautiful, and are quite easy to rear as
you found out.  Put the cut stems in the soil hopefully promote root formation.

If the manual solution is not workable, Most gardeners use Sevin dust
insecticide to combat the borer.  Methoxychlor is also popular.  Thiodan, Asana,
Ambush, and Pounce also work great for commercial farmers. Be sure to apply the
insecticide around where the root (base area) and runners especially.  Timing is
critical and the optimal is when the plants begin to put out runners, every week
for a month.  You are probably missing your window this season, but try anyway.
After the borer gets into the stem (eggs are laid on the outside and a good cue
to start treatment are the eggs and the yellow fras (poop)) just about any
treatment except the manual one doesn't work.  Also, BE SURE TO DO IT AFTER
DUSK, or you will probably kill the bees that pollinate and have a different
problem. (The flowers should be closed by then).

Oh, don't bother injecting the B.t. or any component into the plant!!  In the
case of B.t., plant antibodies will quickly remove it as any other pathogen -
much like our immune systems would.  An of course, don't inject any inorganic
pesticide, or your contaminated food could make people quite sick...

Hope this was helpful...Let me know how it goes.  Best.  Doug.
_______________________
Douglas David Dawn
N.  25º 37.408'
W. 100º 22.003'
Altitude 910 meters
Sylvania Pinus-Quercus