Your plant carnage was most likely due to the soapy water dunk. More than 15-20 minutes dunking in any liquid is not only unnecessary, but most likely, highly damaging. You don't want to oxygen deprive plants for so long!
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Also... I missed what you used for soap/detergent, but that damage is completely inline with the kind of damage that occurs from stripping leaf wax and oils. It effectively negates the immune system.
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Neem can, and arguably should, where pests are a problem, be applied once every 1-2 weeks. You are missing some eggs somewhere, and until you've disrupted every last one of their reproductive cycles, the nightmare will not end.Â
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What are you emulsifying your Neem oil with?
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