Maximizing airflow is perhaps the best way to ensure minimal growth of mushrooms and fungus on your composite decking. The goal is to keep the wood fibers inside the decking as dry as possible. Air movement greatly accelerates drying.
Because at least one leading manufacturer admits its decking does absorb moisture, anyone with composite decking needs to make sure it dries as soon as possible after getting wet. This becomes problematic in areas that experience lots of rain over extended periods. In these locations, it’s probably best to avoid using composite decking materials altogether, unless you know they contain wood fibers that have been treated with chemicals that prevent wood rot.