Mix 1 teaspoon of tea tree oil per 1 cup of water. Spray onto the surface with mold or Mildew & allow to dry, do not rinse. This will kill the mold spores without creating harsh chemical fumes as other cleaners, such as bleach, would.
I think that this may be Rough Honey Myrtle (Melaleuca scabra), although it may be a different species of Melaleuca, or even a species of Kunzea. Photographed beside the Brand Highway (Route 1) north of Perth in Western Australia.