I found this rather interesting. Don't know if it will really work, but it might be worth the effort here in my zone 8.
Darren

http://www.sciencedaily.com/releases/2008/07/080708192842.htm

It sounds interesting. If it is cheap like they say it would certainly be worth a try on a few plants.

Somebody on the banana forum indicated they contacted Dr. Francko and that he said it should be "taking off soon" and that it was expected 1 gallon of concentrate used to make 5 gallons of mixed product should go for about $20. I would readily give it a try on some bananas and a few other things.

As long as it doesn't hurt the plants, or me, I would give it a try.
Darren