My goodness! My eyes aren't all that good anymore, but that looks like a bad infestation of some critter! Maybe aphids. Can you wipe the stuff off with your fingers?
I would mix a solution of 1 tablespoon real soap -- not a detergent -- with 1 quart of water. Then, use a soft cloth to wipe down the entire plant. After that, spray the mixture on the plant until it's dripping off. Be sure to spray from every direction, so you cover all the surfaces. Repeat the spraying process every 5 to 7 days, for 4 or 5 treatments.
That should take care of any kind of soft-bodied insect, like aphids or spider mites.
If you're convinced it's a fungus, you can spray the plant with a mixture of any kind of milk -- well, I'd avoid chocolate milk
-- mixed with water. You can make the mix 1 part milk to 10 parts water, or even as strong as half milk and half water. Spray the plant until the mixture is dripping off. Repeat about once a week, until the plant looks clean.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams