I don't know much about houseplants, so I'd appreciate suggestions here. I realize this may be a common question, so forgive me.
I always put my house plants out for the summer. They always love it. It's now time to bring them in, of course.
Unfortunately, several of them spent the summer under the shade of a japanese apricot which developed a black rust which thickly coated not only it's own leaves in a black coal powder, but the houseplants underneath it now also have the same black coating. How do I clean them up? If the disease is really from the apricot, are my houseplants just cosmetically affected, so I just hose off the leaves? Or did the disease actually infect my houseplants and they need more active intervention?
Any help is appreciated.
Here are a couple examples, though not the greatest pictures.
