What is it?
The artillery fungus is a white, wood-decay fungus that likes to live on moist landscape mulch.
The term artillery refers to the fact that the artillery fungus actively uses energy and shoots its spore masses out toward the light. The spores are usually shot only a short distance, but the wind can carry them for longer distances and even up to the second story of a house.
In nature, the artillery fungus shoots its spores towards the sunlight to aid in dispersal. In the absence of direct sunlight, it shoots the spores at highly reflective surfaces, such as white house siding and vehicles. And, of course, the black spots show up better on white surfaces, so they are noticed more easily.
How did I get it?
Pittsburgh has an average of just 59 clear days a year, with 306 cloudy days, according to 2018 data from the National Centers for Environmental Information. That makes it one of the cloudiest cities in the country. Now factor in the rainfall totals.
Pittsburgh hasn’t just felt extremely rainy, decade-end totals from the National Weather Service prove it. 2018 finished with 57.8 inches of rain and 2019 finished with 52.46 inches of rain — some of the wettest years on record since 1871. The last 5 years have been well over the national average of 38 inches.
In short, overcast skies and extended wet conditions are making Artillery fungus much more abundant than in years past.
How do I get rid of it?
The easy answer is to remove the infected mulch and replace it with stone or new mulch. Stone will not develop Artillery fungus, but stone may not be aesthetically pleasing to everyone. According to Penn state university’s guide to Artillery fungus, adding new layers of mulch yearly seem to reduce the occurrence considerably.
As far as removing the spores already present on your siding, windows, and vehicles, there are many resources online for the safest way to remove them based on the location.
Solutions to Artillery Fungus