I currently maintain a relatively small commercial operation of tropical foliage used in the interior plant-scaping industry in the southern United States. We distribute product out of Hawaii, California, and Florida, and often see a variety of reoccurring pests and diseases from our usual growers. One of the diseases we see more frequently manifests among our Hawaiian-grown Rhapis excelsa palms, and it’s usually a tough one to get rid of completely using common/all-purpose disease control. My thought is it might be a fungal-rust disease but I’m hoping I may ask an expert’s opinion as to what it is exactly, and what may be some of the most effective treatments used in horticulture.
I’m attaching a couple of phone-quality pictures of the apparent disease for anyone interested -- any information would be appreciated!