My Sago Palm's Leaves are Turning Yellow

Scale

• The cycad aulacaspis scale (Aulacaspis yasumatsui) is an extremely dangerous insect that infests the sago palm and is quite capable of causing the death of the plant. First introduced into the U.S. in the 1990s, this native pest from Southeast Asia causes the leaves of the sago to yellow, then brown and die. The sago typically suffers mortality between six and 12 months after the initial infestation of cycad aulacaspis scale. The yellow leaves on the sago are usually the first indication that the pest is present.

Features

• The scale lives deep underground in the root system of the sago before moving upward in the plant and attacking the lower leaves, sucking away the sap and causing the damage. The female scale is covered by a hard, white armor that protects the insect from predators while it feeds; she also lays her eggs underneath her body as further protection for them. The female typically lays around 100 eggs, which hatch in less than two weeks. These crawlers then spread to other areas of the sago palm.

Considerations

• In addition to the yellowing and dying leaves, the most significant sign that the cycad aulacaspis scale is present on the sago will be a distinct white covering across the leaves and other areas of the plant. This white shield is a massive layer of both dead and living scales; sometimes as many as 3,000 scales will be present per square inch. Controlling these scales with insecticide is difficult. The best management comes in the form of biological control via the black lady beetle (Rhyzobius lophanthae).

Soil and Water

• The sago palm prefers to be planted in rich, well-drained soil. If the plant receives too little or too much water, new leaves are likely to turn yellow in response. The leaves should remain dry, so keep water off the foliage as much as possible. Nutritional deficiencies in the soil in the form of too little magnesium may also lead to a yellowing of the sago leaves. A selection of palm fertilizers can be added to the earth.