Does BT spray act/work as a preventive?

[DuskrayTroubador]

Is it true that you can only spray BT in the evening for it to be effective?

 

[corky1968]

Is it true that you can only spray BT in the evening for it to be effective?

I'm not sure about that. Maybe, it's because it gives the bacteria a better chance to get established when it's darker and cooler.

I have sprayed in daytime so who knows? If that's what it says on the bottle then do it.

 

[Chimera]

Is it true that you can only spray BT in the evening for it to be effective?

Nope, not true at all.

 

[Oakhills]

Is it true that you can only spray BT in the evening for it to be effective?

according to university studies:

Where Bt is applied to plant surfaces or other sites exposed to sunlight, it is deactivated rapidly by direct ultraviolet radiation. To maximize the effectiveness of Bt treatments, sprays should thoroughly cover all plant surfaces, including the undersides of leaves. Treating in the late afternoon or evening can be helpful because the insecticide remains effective on foliage overnight before being inactivated by exposure to intense sunlight the following day. Treating on cloudy (but not rainy) days provides a similar result. Production processes that encapsulate Bt spores or toxins in a granular matrix (such as starch) or within killed cells of other bacteria also provide protection from ultraviolet radiation.

http://miami-dade.ifas.ufl.edu/pdfs/fyn/bt.pdf

 

[Chimera]

It's not the Bacillus that messes with the caterpillars, it's the BT-toxin.

That said, sprays should always be done in the morning or evening (vegging plants).

Wet leaves and sun = no bueno.

 

[corky1968]

It's not the Bacillus that messes with the caterpillars, it's the BT-toxin.

That said, sprays should always be done in the morning or evening (vegging plants).

Wet leaves and sun = no bueno.

It's those bacteria that make that toxin.
So if the bacteria die = no toxin is produced.
Night time is best for establishing most organisms anyway.

 

[Noonin NorCal]

Will BT spray kill predatory mites? Will parasitic wasps kill/eat predatory mites? thanks

 

[Noonin NorCal]

Sorry or green lacewings other then predatory mites for both questions? Thanks

 

[Kernel]

BT is host specific to caterpillars and will not harm other insects.

 

[conradino23]

Does BT-K work well for corn borers? They're the only ones I'm worried about. I just started spraying, and want to do another spraying in September.