Artillery Fungus

August 10, 2008

We have had several calls on what people have alternately described as pepper-like material and black spots on the sides of a customer’s home; it does not appear to be an insect or even an arthropod for that matter. It appears more like insect droppings to the uninformed eye.

You are most likely dealing with a fungus called an artillery fungus or the shotgun fungus. The spots you see are actually spores from members of a group of fungi in the genus Sphaerobolus. These fungi colonize dung or other organic matter such as wood mulch, wood benches, woodsheds, etc., especially in moist conditions. Artillery fungi spores do not normally damage houses, cars, plants, etc. The fungus is associated with the popular use of wood products around the home, most notably mulch in landscape beds.

Removing and controlling the fungi is virtually impossible. Scrubbing and scraping with tools or washing with soap and water aids somewhat in removal; however, the use of tools or harsh chemicals may actually damage painted surfaces. No fungicide is labeled for this particular fungus.

One alternative that can be recommended to customers and that helps with general perimeter pest control is to have the customer rake back the mulch and/or remove it. Instead of mulch, an ideal but maybe not as practical situation is to have the customer place a layer of pea sized gravel around the home’s perimeter. The gravel should be about 3 inches deep and form a border of at least a foot wide. If gravel is not an option, the placement of new mulch over old mulch can help to lessen the problem each spring. The use of bark only mulches also helps, as the fungus attacks wood and not bark. Borate treated mulches, though usually more expensive, are also an option to prevent development of the fungus in the first place.

artillery fungus spore packets