I use a wettable powder that is very concentrated and add some Dawn or wetting solution to the mix and spray my whole garden with it several times a season. I used to just apply bt to problem areas but found that I was having to mix it up and spray more often. So far this year I have only had a few foliage worms, a couple of pickle worms and two tomato fruit worms. I try to spray about every three weeks or so and it has reduced the usual damage from worms tremendously this year. I wish I knew a way to deal with spider mites as easily because I know they will be here soon with the extreme heat and dry weather we have been having.
This is a link to the product I use and it stores for a long time and a little goes a long way.
https://www.domyown.com/dipel-pro-df...de-p-2361.html
Bill