For years I've used BT to spray on my cabbage, broccoli, etc., but in the past few years I've noticed it doesn't seem to be working as well for me. I've tried different brands, but always with that same result. It finally occurred to me that I've been using a bit of Dawn dish detergent to add to the solution to help it stick to the leaves, and now that Dawn (and so many other products) are antibacterial I may be just killing off the Bacillus. Does this seem like a logical conclusion -- or is something else probably going on here? (at any rate, I'm planning to try using s little of my Suave shampoo this year, instead of the Dawn)

I am in a rut when it comes to pesticides, I know. I just looked and my favorite - Azamax is listed for Cabbage worms. Perhaps try it out. Gene

Weedwhacker said:For years I've used BT to spray on my cabbage, broccoli, etc., but in the past few years I've noticed it doesn't seem to be working as well for me. I've tried different brands, but always with that same result. It finally occurred to me that I've been using a bit of Dawn dish detergent to add to the solution to help it stick to the leaves, and now that Dawn (and so many other products) are antibacterial I may be just killing off the Bacillus. Does this seem like a logical conclusion -- or is something else probably going on here? (at any rate, I'm planning to try using s little of my Suave shampoo this year, instead of the Dawn)

Are you making sure to get Btk as opposed to other forms of Bt that target other types of pests? If so, are all Dawn detergents sold in the USA antibacterial?

Thanks, Gene -- I've seen you mention Azamax before and may give that a try; I'm still curious about the problem I've had with the BT, though.

Sue, yes, I've been getting the BT for cabbage worms, "kuristaki" or something, I think? I don't know if all the varieties of Dawn are antibacterial -- actually I was just at Walmart today and they had what seemed like 50 different kinds -- but the one I always buy is. Do you think that would kill off the BT?

On a side note, no wonder the stores have to be so large anymore... when Tide detergent takes up half an aisle at Walmart all by itself, in all of its many incarnations....

I wouldn't have thought it would kill it since a lot of references suggest using a spreader-sticker. I suppose it could depend on the spreader-sticker. A couple of other suggestions I've seen are to apply late in the day to avoid sun degrading it, and to start early enough in the season. I've never used it personally so no experience with it.

Well, I do think a "spreader-sticker" is necessary; otherwise it just beads up on the cabbage leaves like water on a duck's back, so to speak. But, not that many years ago all the liquid soap products weren't antibacterial as they now seem to be... I might have to sacrifice some plants to do a comparison trial this summer

A couple of things. First, most forms of soap will kill bacteria. Molecules of soap physically break down the cell walls of bacteria, destroying them. For the most part, anti-bacterial soap is just a marketing gimmick. There is no evidence that it is any more effective at killing bacteria than regular soap under real life conditions. Second, insect populations develop resistance to Bt fairly quickly. It's possible you are dealing with a Bt-resistant population of cabbage worms if they've been exposed to it for several years.

Thanks, Kent! (sort of like marketing sugar as being "sweet," then... )