The answer to 'flashing algae growth' is that algae growth on roof flashing is a common problem, often caused by moisture, shade, and organic debris buildup. Symptoms include green or black discoloration, sliminess, and potential damage to the flashing material over time. The best solution is to clean the affected areas and take steps to prevent future algae growth.
For minor cases, homeowners can often clean the flashing themselves using a soft-bristle brush, mild detergent, and water. However, for more extensive growth or difficult-to-reach areas, it's best to call in a professional roofing contractor. They have the tools and expertise to properly clean and treat the flashing to inhibit future algae development.