I can't really help you with your soaps. Here, I use a product called "7th Generation". Others use blue Dawn dish soap. They've both been proven to work. The ones you gave are just marketing posters. No usefulness, unfortunately.
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I have used Castille in the past, but the Castille soap that I use is liquid. I don't know about hard soaps. Others may chime in.
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I don't typically try to keep the soap out of the medium, but if in doubt...
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Nothing has changed about the advice that you were previously given, with regards to emulsifying the Neem. The soap is to kill in numbers, the Neem afterwards is the insect birth control. You still mix the Neem the same way.
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I have used Castille in the past, but the Castille soap that I use is liquid. I don't know about hard soaps. Others may chime in.
.
I don't typically try to keep the soap out of the medium, but if in doubt...
.
Nothing has changed about the advice that you were previously given, with regards to emulsifying the Neem. The soap is to kill in numbers, the Neem afterwards is the insect birth control. You still mix the Neem the same way.