A rust (fungus) disease, Coleosporium plumeria, defoliates many varieties every year.
Top photo: The rust disease coats the underside of the leaf with orange pustules and causes leaves to turn yellow, then brown and rapidly defoliate in September-October. Bottom photo: Powdery mildew of ‘Bridal Bouquet’ plumeria.
Read more on susceptible frangipani varieties, click here
Frangipani pests, article by Doug Caldwell, click here
A recent report on powdery mildew of Bridal Bouquet frangipani, click here