What are white spots on African Violets and can you remove with wet paper towel and what are the causes?

Question

Have African Violets in a window in partial sun.

Answer 1

It's most likely powdery mildew. This article should help:

https://www.gardeningknowhow.com/houseplants/african-violet/powdery-mildew-on-african-violets.htm