How to Treat Scale on Sago Palms

The cycad scale insect can kill a sago palm.

The cycad scale insect (Aulacaspos yasumatsui) has inflicted serious damage to sago palms in Florida and Hawaii since its introduction from Thailand around 1996, according to the University of Hawaii College of Tropical Agriculture. This insect sucks sap from the undersides of sago palm leaves, causing them to yellow and die due to their reduced ability to perform photosynthesis. This insect, which is white and 1/16 inch long, can be very difficult to control because of its body armor. Soft-bodied young insects crawl around, while adults attach themselves to the plant and live there for their entire 75-day lifespan.

Things You'll Need

• Lady bird beetles
• Clippers
• Lawn and leaf bags
• Horticultural oil

Instructions

1. Inspect your sago palm for signs of scale and also for any small black lady beetles. The lady beetle (Rhyzobius lophanthae) helps control scale -- so, if you find this lady beetle, do not prune affected fronds from your sago palm.

2. Prune all sago palm leaves that have scale insects, and those that have turned yellow or brown, using your clippers -- if you do not find black lady beetles. Place all pruned plant material into a lawn and leaf bag, seal it and dispose of it at your landfill.

3. Spray your sago palm with a natural horticultural oil if the infestation is severe and other controls fail. Prune affected fronds and then apply the oil four times, every 10 to 14 days.

4. Apply a systemic insecticide such as one containing dinotefuran if all other control methods are ineffective. A systematic insecticide is designed for use on cycad scale infestations and is considered effective.

5. Treat your sago palm with an insect-growth regulator containing the chemicals pyriproxyfen or buprofezin if you believe you cannot control the scale insect using other methods. Whenever you use chemical products, always closely follow label instructions and cautions.

Tips & Warnings

• The University of Hawaii College of Tropical Agriculture recommends against using chemical pesticides, as they are generally ineffective because of the scale's armor and the difficulty in reaching all parts of the plant with any type of spray.

• Some species of sago palm are less prone to the cycad scale. Included are the small-spined cycad, or Dioon spinulosum, which comes from Mexico. The University of Hawaii suggests replacing sago palms with species such as the small-spined cycad.

• Natural horticultural oils are less likely to harm the lady beetle, the natural enemy of the cycad scale insect.

• The University of Hawaii advises against spraying with broad-spectrum insecticides because they kill the lady beetle.

References

• The University of Hawaii College of Tropical Agriculture; Cycad Scale on Sago Palm; Arnold H. Hara et al.