My Foxtail Palms Have a Black Fuzzy Substance on Them

Sooty Mold

• Sooty mold is a fungus attracted to the sweet, sticky substance excreted by sap-feeding insects, like aphids, scales and mealybugs. The mold grows on honeydew, covering leaves and stems with a fuzzy black substance. Sooty mold does not directly damage the plant but it shades out leaves, preventing photosynthesis. To get rid of the mold you must get rid of the insects first. Use strong jets of water to wash insects off of plants weekly during the summer. For small infestations of scales, use a soft rag to wipe them off of plants. Insecticidal soap and horticultural oils can also be effective against insect pests.

Leaf Spots

• There are many different fungi that cause leaf spots and blights, but they all operate in essentially the same manner. Fungal spores germinate and invade leaves where they feed and grow. Typical damage caused by fungal feeding is leaf spotting. These spots range in color from red or yellow to brown or black and can be small or large. As the fungus matures it sends out fruiting bodies that produce the spores necessary for spreading the fungus to other trees. These fruiting bodies are what often give leaf spots and other fungal infections a fuzzy appearance. Sanitation is key to preventing the spread of fungus. Remove heavily infested branches and destroy them. Clean up all leaf litter and destroy it as well. Avoid wetting foliage when you water as this can help spread spores.

Abnormality

• According to the University of Hawaii a harmless leaf abnormality occasionally worries foxtail owners. At the base of petioles, or leaf stems, a black, fuzzy or scaly crust can form. This crust is called scurf and is completely harmless, it just looks unsightly. Wipe it off if you find it bothersome, but it will disappear on its own as the leaves age.

Tips for Growing a Healthy Foxtail

• Foxtail palms are only somewhat drought tolerant and require supplemental irrigation during periods of drought. They require a site with good drainage and a pH between 5.6 and 7.8. Use a well balance palm fertilizer once a year during the spring. The University of Hawaii recommends a slow release fertilizer. Pruning is only necessary in high traffic areas where falling leaves my harm people or property.