posted 9 years ago
Tobacco spray used to be staple pesticide for farming before Big Ag. The farmers used the stalks, since the leaves were worth money.
Dry or wet will work. Cutting the flowering stalks off the plant makes the plant produce more nicotine. The best variety to use is Aztec, it doesn't get as big, but has way more nicotine then say Virginia Redleaf.
Tobacco mosaic virus is destroyed at temps just under boiling, so if you bring a pot of leaves up to a boil then turn off the heat, the virus is a non-issue. If you are growing your own, you would know if you had the virus.
I haven't had much luck with even very strong tobacco sprays, which I tried using on aphids. Some would die, but enough would survive and reproduce that control was elusive. I prefer Neem oil sprays for aphids myself, but there's no reason you couldn't use both in the same spray.
The thing to remember when making your own "bug spray" is every species is different. What insects are you trying to control?