I just buy a new pint every year. It is not worth worrying about the lack of potency.

Well, if someone actually preserved it by freezing it, we wouldn't be worried about lack of potency. That's what the question was about. I use about a quarter of a pint every year. Seems a waste to just dump the rest.

I had a question a while ago about the very short lifetime of Bt suspension after dilution with water. Lasts less than a day. No one knew why. Sure would be nice to locate someone who actually knows something about this stuff!

I sincerely doubt full potency is preserved by freezing. But I don't know the answer, sorry.

I guess one could decant the concentrate into a few very small containers and freeze. That way, only one container would have to be thawed out every year. (I think that is what you are saying). Why not try it?

It does seem a waste to toss an almost full container every year.

Linda

Yes, I was thinking of making Bt ice cubes! I will try it, and see what happens.

I *think* this is saying it is doable.

http://www.biodiversitylibrary.org/content/part/JAMCA/JAMCA_V08_N2_P149-155.pdf

BT ice cubes...I like it. Let us know how it works after being thawed.

I usually use most of a pint bottle every year because I grow a lot of Brassicas. Most of what I use is in the fall. I also use it during horn worm season on tomatoes and sometimes on trees when they get infested with tent caterpillars.

Are you all indicating that you have separate isolated freezers dedicated for pesticide storage? BT or whatever, if it is a pesticide I would not want any form of it stored near food.

I agree, let us know how it works, Dan! I also don't use a whole bottle in one season so it would be helpful to preserve efficacy.

Bt is a bacterium that is completely innocuous to humans. I'll be keeping these cubes next to my pesto cubes in the freezer. The toxicity of the latter is probably more than the former.

Now, it occurs to me that I use this stuff in a 1/4 gallon spray bottle. Sure would be slick to freeze this stuff in 1 tsp cubes. Just drop one into a full spray bottle and you're good to go! Bt-pills.

I was going to say be careful not to accidentally put the ice cubes in your drinks! The BT that I bought smelled disgusting and I would be wary about spraying it on my greens.

Linda

Yeah, toxicity or no, I sure wouldn't want to eat it or put it next to my food, it smells pretty disgusting.

If you have a self-defrosting freezer it would be best to store your Bt cubes near the center, to avoid temperature swings that can happen near the edges.

Even if it were carrot juice labeled for use as a pesticide I would not store within 10 ft. of food. You have only a base understanding of the active ingredient; often the carrier can be as toxic. In the case of Bt often GMO technology is used in the production to keep costs down. That doesn't bother me but it should sway you into rethinking this project.

Diarrhoeal enterotoxin production by strains of
Bacillus thuringiensis isolated from commercial

Bacillus thuringiensis -based insecticides
Per Hyldebrink Damgaard

You're going to ingest vastly more Bt by spraying it on your plants than you'll get by having it frozen next to something you eat. Do you scrub your cabbage with soap and water? Well, sure, you won't have any cabbage worms in your gut, thank goodness.

Must bother you a lot that the human body is 90% bacteria by weight. We all have E. coli living happily in our intestines.

I think the carrot juice example was really silly and, yes, we have lots of bacteria in our bodies. Those who are hooked on anti-microbials are in for a lot of trouble!

Linda

I should say that I've found that e-bay sells mini-ice cube trays for a few bucks including shipping. The ice cubes look to be about a teaspoon each. That would be marvelous to make Bt cubes with (except the trays are for 160 cubes!) I've placed an order.

Aliquoting and freezing (although in a far colder freezer than households use) is the standard way of preserving stock cultures of bacteria.

Your idea of a "BtCube®" for fast prep and no waste might work.

Barrie, I was a microbiologist. That research paper is twenty years old, and although they say, "the results indicates a potential risk for gastroenteritis outbreak caused by B. thuringiensis" I couldn't find any such outbreaks documented in the 20 years after the publication, despite the widespread use of Bt on food crops by untrained persons.

Bacillus cereus, the other bacteria they tested, is a known problem.

https://www.foodsafety.gov/poisoning/causes/bacteriaviruses/bcereus/

https://en.wikipedia.org/wiki/Bacillus_cereus#Pathogenesis

Good points. I had not realized that colder was better for freezing bacteria. I believe that damage by freezing is routinely avoided by making the solution 10-15% glycerol. Of course, glycerol is just laxative. So it may be available at low cost.

You can get glycerine in most drugstores.

It's worth the experiment, but take good notes, especially on the kill rate or infestation control ability.

I can't assess kill rate or infestation control unless I have a test plot that I'm not using it on. But I'll consider it a qualified success if I don't have caterpillar problems.

From what I can find, Bt formulations are a combination of spores and the toxin crystals that have the effect. It is hard to kill spores, they are bacteria's way to survive in adverse conditions, but freezing may harm the toxin crystal or cause it to aggregate into a form that is too large to work.