essential oils

I seen it tons of times now. People keep saying they use essential oils for their IPM sprays. I have searched Essential oils here and I'm not really getting any good info. So can people please tell me what essential oils to use (recipes) and how they use it. Foliar spray? Soil drench? And what...

For example, if I added orange extract to the res during the final flush, would the buds taste citrus-y at all? If essential oils wouldn't work, what about e-juice flavorings? I can't see them harming the plant in any way, unless they cause the plant to dehydrate or are toxic to it, but in...