Black spots on your car could be from a nearby fungus in your mulch

Published: Apr. 30, 2019 at 12:01 AM EDT
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You've been to the car wash but can't seem to get those little tiny dots off your vehicle. While a few of them could be bugs, the dots may actually be caused when parking next to a nearby mulch bed filled with a fungus.


The tiny dots are caused by what's called "artillery fungus" that grows in certain types of mulch. It's sometimes referred to as “shotgun fungus” due to the shotgun-like pattern of black specks all over the car, as well as the way the fungus is shot onto the vehicle (more on that later).

It's known as a wood-rot it grows in rotting or decomposing wood. The fungus grows best in very damp mulch after rainy stretches.

The most common source of this rotting wood near your vehicle is mulch. When it finally surfaces, it shoots its spores into the air and these spores land on anything within a 25 foot radius. They embed themselves in the paint or on the siding of your home and are extremely stubborn to remove. It's very unlikely a typical car wash will remove then. You'll need some extra TLC.


While there are many things you could try, you'll want to be careful as to not remove the paint from your vehicle. Using warm, soapy water or an auto soap is an option. Others have taken a credit card to scrape them off.

Keeping your car out of the 25-foot radius of mulch or rotting wood will help keep them off your vehicle. Covering your vehicle is another option, but may not be a practical solution.

There is no fungicide registered as an artillery fungus treatment. There is research to suggest that blending mushroom compost at a rate of 40% with landscape mulch can suppress the spores. Also, the use of gravel or plastic mulch will not cause the formation of the spores. To kill the spores in lighter areas, cover the zone with black plastic and allow the sun to cook the spores out of the bark.