Answer: This can happen when plants suddenly get moved from one environment to another. Changes in light and humidity are usually the reasons for leaf drop. Is the plant still getting plenty of bright light? They do best with just a little direct sun -- too much might cause leaf spotting. I haven't been able to find any information on diseases that might afflict plumeria -- they are generally easy to grow and trouble-free. If you'd like, you can send a sample to the extension service for them to diagnose. Call for instructions (ph# 508-362-2511).
It's best to repot plumeria every couple of years -- maybe yours is signalling its need for a new pot. Hope this helps!
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