My apology that I missed this email.  

What plant is this? It looks to be a Camilla.   

I suspect this is pollen.  If it were a fungus, it would cover the entire leaf.  Instead, it is only on the lower portions of the leaf where water would slow and deposit it from where it was collected on leaves above.   Not treatment necessary.  You could use a hose and use a mild dishwashing detergent and spray it down, then rinse it off.  

r/Mart