I understand that Bacillus thuringiensis (Bt) breaks down naturally, but I'd like to know how. I'm going to be applying Bt powder, and the instructions say to do it roughly weekly, and especially after it rains.
Now, does this mean that Bt powder loses potency when wet, or just that it gets washed off the plant? Hard to imagine the former since you can keep a spray bottle of the stuff dissolved in water. I know that sunlight breaks it down, but does that mean that if cultivated into the soil it stays there for longer, such that it kills grubs that are just hatching there? I've also read that dry spores have a shelf life of several years (implying that wet spores do not).
Yes, I know you want it on the plant, so I know that you want to reapply if it gets washed off. But what if it just drizzles?