A White Cotton-Like Growth on the Leaves of a Pygmy Date Palm

Pest Identification

• Pygmy date palms are prone to infestation from tiny pests called mealybugs. The exotic species of the pest, namely Palmicultor brownii and Palmicultor palmorum, infest all varieties of palms, most specifically Veitchia spp. Mealybugs are common pests of palms growing in warm, humid climates and can cause serious damage in cases of severe infestation.

Description

• Mealybugs are very small, about 1/8 inch long. The white, soft-bodied pests are covered with a powdery substance that gives the impression of a cotton-like growth on the infested areas of the pygmy palm. The thick covering of fluffy white wax on the insect body is called ovisac. It has white, waxy filaments growing from the rear of its body. The females do not have wings while the males are winged, resembling gnats.

Damage

• Mealy bugs are sap feeders that infest the leaves of the pygmy palm. The pest infestation becomes most noticeable after the first batch of eggs has hatched. In cases of high population, the pests are seen on all plant areas. Damage results in distorted and yellowing foliage. Young leaves are most affected. As the pests feed, they also secrete sticky honeydew that leads to the growth of the sooty black mold on infested areas. Mealybugs multiply rapidly, as eggs hatch within 7 to 10 days.

Management

• The presence of the waterproof, cottony, waxy covering on the bodies of mealybugs and their eggs creates a high resistance to pesticides. This makes control very difficult. The best control option is the use of systemic insecticide, as this makes plant sap toxic for the feeding pests. Contact insecticides are effective only when timed precisely to target newly hatching nymphs. Repeat applications are required when using contact insecticides. Recommended insecticides include flonicamid, imidacloprid, pymetrozine, thiamethoxam or acephate.