Posting this picture i've had PM a few years ago but never grown like this every leaf looks like this growing in the middle of leaf in lines is it powdery mildew or something else!?
That looks horrible id cut all the effected leaves off,if all the leaves are effected id toss it and then sterilize my grow area.that doesn't even look safe to be around.
Sorry to discourage you but there is a solution,but me personally would toss it or just cut the buds off first if the smaller leaves arent effected too