Removing ugly brown stains on stucco

Plasmech

On the front of my townhouse, right where the siding meets the stucco above the garage, there are UGLY brown stains. I'm not sure what's causing this, perhaps some nails beneath the sding are rusting and the rust is "dripping" or propagating onto the stucco. How do I remove these stains? I think I need something stronger than the "over the counter" stuff HD sells. Will some sort of acid wash take it off? It's a real eyesore to say the least.

edit: maybe the stains are from the pressure-treated sill plate? Or just the wood itself?

Does pressure-washing work or will this take the stucco itself right off?

Ron6519

I would find out what's causing the rust stains first. Deal with the causes before the effects.
Is this foam backed stucco or traditional wire lath on older houses?
Can you post a picture? Pressure treated wood, in my experience, doesn't bleed rust colored material. If it's at the sill area, there are bolts that hold the sill plates to the foundation, but they should be hot dipped galvanized for the old treated lumber.
Ron