Plumeria sick.

Question

I live in southern California. A month ago, the leaves began curling. I believed it was an insect issue and sprayed them twice with Bayer 3 in1 insecticide. Now, the leaves are black and yellow. Please see attachments. I have also sprayed them a sulphur based fungacide.

I am worried because it seems like this issue has spread to all of my plumerias. Thank you for any advice you can give me,

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Answer 1

It could be plumeria rust. Look on the underside of the leaf for rust looking spots. check below for approved fungicides. Be sure to pick up fallen leaves and destroy.

https://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-61.pdf