Posts Tagged ‘Black Streaks’

Published ​November 18, 2025 – Last reviewed February 21, 2026 Michael Thorgenson Owner, Aqua Clean Solutions, Inc. Introduction: In a Nutshell Black streaks on roofs in Northern Virginia are primarily caused by Gloeocapsa magma, a cyanobacteria (blue-green algae-like organism) that feeds on the limestone filler in asphalt shingles, forming protective dark pigmented sheaths that create…