Select a fungicide containing copper hydroxide or copper salts of fatty acids. If palms are used for food purposes, copper fungides are the only approved fungicides. Use a spreader-sticker compound for good coverage. Apply all chemicals according to directions on the label. False smut or Graphiola leaf spot is caused by an organism related to the smut fungi, Graphiola species.
Infected leaves have small, black, wart-like structures erupting through both leaf surfaces.
Tiny filaments may emerge from the black spots. There are usually no symptoms on the youngest leaves. Do not remove too many fronds, because this will weaken the tree. Fungicides are usually not necessary but can be applied as a preventative treatment. Select a fungicide containing copper hydroxide or copper salts of fatty acids.