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Plant Pathology Infobytes

April 7, 1997

The Shotgun Fungus in Home Landscapes

Home landscapers across the state have come to expect the spring appearance of fairy ring mushrooms and slime molds and are aware these fungi generally don't cause plant health problems.

Landscapers may not be familiar with a relatively new fungus which is becoming more common in Mississippi --- the "shotgun fungus." Yes, there is such a microorganism, and although it doesn't appear to be widely distributed in the state, it has become more common over the past few years.

The fungus gets its name because it ejects or "shoots" out a material which is capable of causing a stain if it lands on automobiles or brick walls.

While not a lot is known about Sphaerobolus stellatus (the scientific name for the shotgun fungus), it prefers to live in moist wood mulch and is most likely to appear in spring and fall.

The concern caused by this fungus is not related to plant health, since it doesn't attack plants, but rather from aesthetic problems which occur as a result of one stage of its life cycle.

When this fungus sporulates, it fires spore masses into the air for a distance of six to eight feet. Wherever the spore masses land, they stick like glue. Often the landing site is the side of a building, an automobile, or just about anything with its range. Considering the size of the structure from which the spores are shot is one-eighth inch or less in diameter, this is pretty good range!

Since the spore masses resemble fly speck, or tar spots, after impact and are difficult to remove, the shotgun fungus can rapidly become a nuisance. The spore barrage can last for a period of several days and lead to a good bit of discoloration and homeowner frustration.

The occurrence of the shotgun fungus may relate to the increasing wood content of many mulches which are popular with home landscapers. Woody mulch material composed of hardwood fibers, as opposed to bark, pine straw, and other materials, is the food source of the fungus, and this may explain its appearance in landscapes across the state.

There are few practical solutions for controlling this problem. Adding a layer of bark or another type mulch over the top of shotgun fungus-infested wood mulch may help block the spore masses form reaching nearby vulnerable surfaces. The application of fungicides for the problem is not recommended.

How do you clean up the stains left by the shotgun fungus? You're going to have to use a good detergent and lots of elbow grease.

For additional information on identifying home landscape problems, contact your county Extension office.

Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.