Cars, Homes Damaged By Fungus In Mulch

BELMONT (CBS) - Will Belitz was stumped when he started noticing small black spots all over the hood of his pickup truck.

"At first I thought it was just going through the tar on road constructions," he says.

But the dots got worse, even though he was only driving a few miles to work and he never passed a construction site.

"So then I started asking around at other different offices and the majority of the people had these black spots and we had no idea what they were," he says.

Will and his co-workers were surprised to learn that this was the problem: Ordinary garden mulch near their parking lot, specifically a tiny fungus that grows between the pieces of wood. The black dots are spores.

University of New Hampshire professor Serita Frey says they are artillery fungus. A species similar to mushrooms, it's usually found in forests but can also thrive in mulch. It gets its name from the unusual way it spreads or spores. They can shoot 15 - 20 feet in the air.

A quick look outside her office and Frey quickly found several of the spots on the trim of the building. Just feet away, a bed of mulch with other species of mushrooms clearly visible.

The spots are almost impossible to remove.

Replacing the mulch yearly will help. That's what Will's employer, the town of Belmont did as soon as they heard of the problem.

The type of mulch you chose can also make a difference. Artillery fungus grows easily in wood chip mulch, but doesn't do as well in bark mulch.

If you don't want to take any chances, try stones or a ground cover plant.