kentia palm leaves turning brown covered in white material not mealy bugs

Thank you for contacting Yates.

Looks like the plant is affected by scales. To control, try 'Yates Pest Oil - Insect Control Spray'. It's available in both a convenient ready-to-use spray and a concentrate form. Controls citrus leaf miner, scales, mites, mealybug, aphids and white fly on citrus, grapes, fruit trees, roses and ornamentals. Click here for more info on this product: https://www.yates.com.au/product/garden-pest-control/yates-pestoil-concentrate