Rust on Plumeria Trees
Every year when I arrive at our home in Baja, my plumeria trees have rust on the leaves. A guy at a nursery in California recommended Neem oil spray; I sprayed them twice a week or 10 days apart, (in the early morning) and within two weeks, all the leaves turned yellow/brown and are falling off. What have I done?
Certified GKH Gardening Expert
If the plant is in very bright sun, it is possible that the oil worked with the sun to burn the leaves. Make sure you are diluting the neem oil to the right mixture and then try applying in the evening, so the mixture has time to be absorbed before the sun comes up. You may also have another issue with the plant, perhaps a pest or a different disease. I would examine the leaves closely for signs of pests. It would be difficult to diagnose from here what is exactly wrong with the plant, as there are many, many things that could be causing yellow leaves.