powdery mildew?

a couple of plants were given to me, sick and needing tlc the leaves are all chalky, they are in pots and outside, i sprayed them down with over the counter fungis mildew spray, and it doesnt seem to be helping, it has been in the low 90s, i let them dry for a few days?

any thoughts? sorry no pics

Really need to get some pictures to know for sure.
Is it on the top of the leaves or the bottom.
In the stems also?
Does it rubb off when wipped?
And how widespread is the infection, because sometimes if it is a small infection you can simply cut off the bad leaf and the rest of the plant will be fine. If you try to cut off some leaves be sure to do it asyeptically. (scissors and fire or alcohol)