Black Streaks on Roof in Nebraska: What They Are, How to Remove Them Safely & How to Stop Them Coming Back (2026)
Black streaks on roofs in Nebraska are caused by Gloeocapsa magma, a blue-green algae that feeds on limestone filler in asphalt shingles. Remove it with a low-pressure soft wash using a 50/50 bleach and water solution. Never pressure wash asphalt shingles. Every spring, homeowners in Lincoln and Omaha spot dark stripes running down their shingles. […]