Have you noticed powdery yellow or orange spots developing on the underside of your Frangipani (Plumeria Species) leaves? Those spots, along with unsightly blemishes and premature leaf drop are a sure sign of Frangipani Rust (Coleosporium pluemeriae).
Frangipani rust is an airbourne disease that is rife amongst Frangipanis in Brisbane at the moment. The spots rupture and spread spores, passing the disease to other plants. Nasty!
So what can you do about it. Treatment is limited as the specific chemical fungicide is illegal in Australia. Instead, use copper oxychloride and sulfur with mancozeb on infected leaves and apply to the ground under the tree. Apply to Frangipani leaves during the warmer months, and to the ground and the bare tree during winter.
Note: it is important to dispose of the infected leaves via the Brisbane Council yellow bin pick-up (not your green bin, and don't dump these leaves or use them for compost!). Carefully disposing of the leaves will reduce the impact after the winter leaf drop.
The good news is that older trees seem to be developing a resistance to the disease. A healthy Frangipani plant will be able to fend off diseases, so keep your tree well-fertilized each year as a preventative measure.
If you're worried about your Frangipani trees, feel free to contact us and we can chat through any issues you have.