Thursday, October 18, 2012

Plumeria Rust

Featured Guest Blogger: Jane Morse, UF/IFAS Commercial Horticulture Extension Agent, Pinellas County

Have you ever wondered “what is wrong with this plant?” or “what is this insect, where did it come from and now what do I do?” or “oh my, what are these black, shiny, wormy looking things on the floor?” We hear questions like these every day at the Lawn and Garden Help Desk, supported by the University of Florida and Pinellas County, and we can usually answer your questions - free of charge.

Plumeria spp.: Photo, Okeechobee County Extension

Recently, we have seen a rash of frangipani or plumeria rust fungus. This disease produces a mass of tiny pockets of rust colored spores on the undersides of the leaves. Infected leaves become yellow-spotted on top and fall off the tree. This disease is most commonly seen during the mid to late part of summer. Although it may look rather menacing it normally does not cause any serious problem for the plant. Since the leaves are getting ready to drop off for the fall anyway, spraying with a fungicide is usually not warranted. It is best to pick up or rake away any infected fallen leaves and dispose of them in the trash. This will help to reduce the amount of spores available to re-infest the tree at a later date.

Early signs of plumeria rust on the underside of a leaf.

Later the underside of the leaf may be completely covered.

Plumeria rust spores under magnification.

For more information about plumeria rust (and other rusts) visit:

You can visit us in person at Pinellas County Extension, 12520 Ulmerton Road, Largo any Monday through Friday from 8 a.m. to 5 p.m. You can call the Help Desk from 9 a.m. to noon and 1 p.m. to 4 p.m. on Mondays, Tuesdays or Thursdays.  Or you can visit our frequently asked questions website at

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