DonH
Well-Known Member
BT breaks down really fast. That's why you have to apply it every two weeks.Just an observation, but spraying the underside would prevent the rain from washing it away but how fast does it break down to where is not poisonious. Just thinking that if rain doesn't wash it away, you might end up smoking insectides. a 2 day break in the weather is all you might need to get rid of those vermin with a top application and a repeat if necessary on another nice two days.
edit: Just looked it up and found this: http://microbewiki.kenyon.edu/index.php/Bacillus_thuringiensis
in heavy sunlight the half life is 3.8 hours. Which they say is good because insects can't build up a resistance to it.