Areca palm has a nickname: yellow palm. This is because parts of the plant, such as the petiole are naturally yellow. If other parts of the plant are turning yellow, act quickly to diagnose the problem.
When old leaves develop yellow spots which eventually spread to cover the entire leaf, suspect a potassium deficiency. If new leaves are yellow, the areca palm is deficient in micronutrients, either iron, zinc or manganese. If older leaves are turning yellow, suspect spider mites.
Potassium-deficient areca palms require special care. Remove the yellow fronds as they will not recover. Use sulfur-coated potassium sulfate, applied to the soil at the rate on the label. If the areca palm has a micronutrient deficiency, apply a foliar-micronutrient spray, according to manufacturer's instructions. If spider mites are causing the yellowing, use a pesticide labeled for the control of spider mites.
Apply the potassium sulfate directly to the soil, at the rate listed on the package. Repeat the application three more times during the year. The micronutrient spray is applied directly to the foliage. The pesticide should be spot-applied -- directly on the insects.