What would cause ficus leaves to turn white?

If the plant was moved recently from indirect sunlight to direct sunlight, even a couple hours of light through a patio door can cause "sun scorch" which leaves the foliage a washed-out silvery white and usually very dry. A powdery white covering would be powdery mildew which can mean the night temperatures are a little cold. The mildew can be controlled by spraying with a solution of 2 Tablespoons of baking soda in 1 gallon of water.