Black Spots on Siding Near Mulch? It's Artillery Fungus

Those black specks are spores from "artillery" or "shotgun" fungus (Sphaerobolus stellatus). It shoots spores at light-colored surfaces — siding, fences, cars. Spores stick tenaciously, nearly impossible to remove. Develops in wood-based mulch under cool, moist conditions. Cypress, cedar, redwood, pine bark resist it.

Penn State tested cleaners for vinyl/aluminum siding. Test inconspicuously first — removal requires effort, may damage siding. Best for vinyl: Westley's Bleech-Wite tire cleaner, Castrol Super Clean. Best for aluminum: Turtle Wax Foaming Wheel Cleaner, Botanic Gold botanical soap. Find at auto stores.