Leaf infections called “leafspots” are caused by a variety of fungi and some bacteria on many trees. Leaf spots can be circular to elongated, brown and possibly oily in appearance. The spots will vary in size and color depending on the plant, the organism involved and the stage of development. It is difficult to differentiate among the leaf-spotting fungi by visual symptoms alone.
Palm Trees Treatment
Don’t allow irrigation to wet palm foliage. In most cases, leaf spots will not kill the palm tree, and fungicides are usually not necessary. If damage is becoming severe, fungicidal sprays containing copper hydroxide or copper salts of fatty acids can be used. I use Bonide Products Liquid Copper Fungicide. It is very effective against Leaf Spots.
If palm fruits are used for food purposes, copper fungicides are the only approved fungicides. Apply all fungicides at rates and spray intervals according to directions on the label.