I have found that Mr. Clean Magic eraser does a very good job of keeping mold and black away, even when the awning is rolled up. I still don't know why folks don't believe this. Maybe it's because it takes a little work to wipe down the awning, instead of simply spraying something on and rolling the awning up. Well, quite obvious, those techniques don't work.
If you wash down your awning with Mr. Clean Magic Eraser, the black and mold will not come back any time too quick. I've successfully made it through several Indiana winters now and come spring, the awning is not moldy when unrolling.
Take the Mr. Clean Eraser and make it wet, but not dripping. Wipe a section about 18 inches square and rinse out the Eraser. If necessary, wipe a second time, but do not scrub. Existing black will melt right off. Now wipe with a dry cloth (do not rinse it), just dry it. No move over to the next section, little by little until you've covered the entire awning.
You can do the top of the awning also. If yours drops down to the side, it's easy to do. If it's an electric awning, you can still do it with the eraser under a long handled brush and follow up with a dry cloth under the brush. Repeat in small sections until it's completely covered.
Work? Yes! Worth it? Yes! You won't have black come back.
In the Summer, use the eraser to touch up removing bugs and different stains that happen because of trees and acid rain. Once you get it clean, it's VERY easy to maintain it. Just touch up any area where bugs get squashed. Take all of 15 seconds then.
You won't have black come back. I clean my with Mr Clean Magic Eraser in the Spring, and then will do a really good touch up in the late fall, about the time I winterize. I haven't had any black in years now.