If your serious about getting into plumeria, then you need to get serious about what you use for pests. I never really had any luck with neem oil and soap, other than burning leaves to a crisp and dropping them in a mass exodus. I tried to do the "natural deterrents" as well, with no high level of efficiency. I started using a rotation of Floromite SC, Minx, and Oberon 4bid with stellar results. Each one of these products is pretty costly, but you can find combo packs of all three 2 oz bottles on eBay for fair affordable prices. With a mix ratio of about a quarter teaspoon per gallon, this should easily be enough to last you for a couple seasons. They have residual killing properties that last anywhere from 30-45 days, and are specifically targeted for mites, so need to worry about butterflies or bees. Also, I haven't experienced any significant leaf drop other than leaves that were pretty ravaged by mite damage. That's about the best advice I can give, the rest is up to you. Good luck.
