rose of sharons have a white substance

Question

My rose of sharons have a white substance at the base of the stems just above the ground level. What is this?

Answer 1

A photo would assist in my identification but I will give this my best shot.

It could be southern blight:
https://www.gardeningknowhow.com/plant-problems/disease/controlling-southern-blight.htm
http://www.apsnet.org/edcenter/intropp/lessons/fungi/Basidiomycetes/Article%20Images/SouthernBlight09.jpg

Or a type of white mold:
http://utahpests.usu.edu/ipm/htm/ornamentals/landscape-insects-and-diseases/white-mold/