Are Yellowed Sago Palms Dead?

Cycad Aulacaspis Scale

• The Cycad aulacaspis scale (Aulacaspis yasumatsui) first ventured into this country via Miami, Florida -- by way of Thailand -- in 1996 and now is present nearly everywhere that the sago palm (Cycas revoluta) is able to be grown. This scale insect is exceptionally lethal and normally kills a sago palm within one year of the initial infestation. The first sign of its presence is a yellowing of sago palm leaves, followed by a browning.

Scale Effects

• The scale causes the leaves to yellow by feeding on the underside of the foliage, depriving it of water, nutrition and the ability to properly conduct photosynthesis. The first leaves affected are usually on the bottom of the plant, as the scale lives in the root system of the sago before traveling up the trunk to attack the first leaves it comes across. The female adult scale causes the initial damage, then lays eggs which -- when hatched -- introduce scale larvae to the feeding frenzy.

Warning

• At this point, a yellowed sago palm is not dead, but may soon be if the scale insects are not brought under control. Scales are covered by a hard, white, waxy armor that protects them from predators. As the newborn crawlers distribute across the plant and continue feeding, they cause more damage that may prove lethal to the sago. While they proliferate, a white covering -- comprised of as many as 3,000 scales per square inch -- appears across the plant. A severe infestation normally kills the sago.

Water and Soil Problems

• A sago palm possessing yellow leaves may also be suffering from the more manageable conditions of water or soil deficiencies. The sago enjoys rich, well-drained soil and prefers to be too dry rather than too wet. If the plant is over or under-watered, new foliage on the sago is likely to turn yellow. Additionally, a lack of magnesium in the earth can cause the leaves of the sago to take on a yellow color. In either case, the condition is easily rectified and the plant is capable of returning to full health.