When to last use bt safely?

I see people stop using BT when flowers begin to appear. Is this correct, and what about spino? How long is that safe to use?

PioneerValleyOG said:

I see people stop using BT when flowers begin to appear. Is this correct, and what about spino? How long is that safe to use?

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If you read the label both are listed to go on almost up to harvest. That’s bullshit IMO.
I stop in the beginning of September. For plant I harvest in October. It’s effective for 2 weeks.
after one week I spray water on the plants to wash them in the early am of a hot day...

Spinosad during flower will make you fail testing.

This is my first year so can't speak from experience, but one blog I follow by a pretty experienced and knowledgeable woman says she and her husband use Bt beginning when flower starts, stopping "a few days at least" before harvest.

Pretty sure I've seen one of the mods on this forum say they stop at least a couple weeks prior to harvest or else it affects flavor.

Personally I plan to use it weekly because in my area I hear caterpillars are a big threat and can ruin the buds quickly. I'll see how things are going as I get closer to harvest--if no sign of cats might stop spraying at some point. Probably with careful daily inspection you could get away with not using it in the final weeks. But if those worms get a foothold on your plants they can pretty much devastate things.

I'm going to steer clear of Spinosad for now.

Ya I've had good luck with the sticky yellow boards.

waterproof808 said:

Spinosad during flower will make you fail testing.

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Didnt know that. Thank you

I have used BT twice on my girls. Soaked the buds really good. Let them sit in the shade for an hour and then shook the stems to get all the extra off....then let them dry in the sun. I did the two sprays 2 weeks apart....haven’t seen any more caterpillars since and no adverse affects to the girls. There is a brand of BT called Monterey BT. It is 98.35% BT and only 1.65% other ingredients. I learned this after I purchased Thuricide brand which is only 15% BT. After some googling I did read that the other 85% was mostly water and something to prolong the life of the BT in the bottle....that ingredient wasnt listed. They are both marked organic so there’s that....

Gnatrol (BT) is watered through my mix and occasionally in watering water, no ill effects and seems they inhabit my used mixes for a long time.

Green is growing said:

I have used BT twice on my girls. Soaked the buds really good. Let them sit in the shade for an hour and then shook the stems to get all the extra off....then let them dry in the sun. I did the two sprays 2 weeks apart....haven’t seen any more caterpillars since and no adverse affects to the girls. There is a brand of BT called Monterey BT. It is 98.35% BT and only 1.65% other ingredients. I learned this after I purchased Thuricide brand which is only 15% BT. After some googling I did read that the other 85% was mostly water and something to prolong the life of the BT in the bottle....that ingredient wasnt listed. They are both marked organic so there’s that....

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Yes, I have the Montery