Hi Mark, and welcome. If you could give us a location where you are trying to grow this poor plumeria, that might help. Fill in your personal profile to include your city/state/country please. Then that info will appear in the top right of all your posts.
Climatic conditions and soil problems including too much or too little water can cause that kind of distress.
Have you had a tremendous amount of rain recently, and did the water stand around the plant? An abrupt temperature drop? Extreme high temperatures?
Have you checked your watering system recently? Maybe a sprinkler is broken or clogged and not watering that area?
Sorry for the 20 questions, but we need more info.
