Stains on roof

Hi Everyone,We have been parked for a few months volunteering and the roof has gotten some nasty stains from the trees. I have used only Dawn on the roof, but it is having no effect on the stains. I know anything with petroleum products are not good for it. Wondering if anyone has used Simple Green and what were the results? Any other suggestions to remove the stains would be appreciated.thanksal

Walmart sells a Camco rubber roof cleaner that works well. (ROOF_CLEANER)

I have used it to spot clean my roof. I believe it is an enzyme cleaner and has never caused any bad side effects. Trace

Only the birds can see it and they don't care, but you might try Borax.