It sound as if the insects are the main problem. Fungus/algae is not usually a problem on palms unless humidity is extreme. For the critturs spray the whole tree, including leaves with appropriately diluted Neem Oil. It is a systemic toxin for a wide range of insects and completely harmless otherwise. Good luck. - Ian.

@iangrazil - Thank you so much for the information on the Neem Oil. I applied the N.O. on my RoebeleniiâÂÂs yesterday afternoon.

Q. There is quite a bit of fungus on the tree trunks. How many times would you recommend me applying N.O. on the trunks?

Thanks again,
Scott

I've never had a problem with fungus on palms, so I can't really answer your question. Neem does not need to be applied very often, however. I find that twice a year is sufficient, unless there is any sign of trouble. You might need to apply it more often initially, say, repeat the treatment a month later, then keep up a "maintenance dose". Neem is better for insect control in general, though it is also a fungicide. If it doesn't work try Captan. This is a lot more toxic, however. Good luck. - Ian