This year's wet weather has allowed me to field some interesting calls. One problem in particular I have seen more frequently than usual is the "artillery fungus."
Homeowners usually encounter this fungus when they notice hundreds of tiny black spots on their home's siding, their cars and landscape plants. These spots are often confused with paint overspray, insect eggs or scale insects.
These black spots are the spore packets, or peridioles, of the artillery fungus (sphaerobolus stellatus).
The artillery fungus is a wood-rotting fungus that we most often find on wood mulches around the foundation of homes.
According to Clemson's Joe Williamson, during wet weather and cool temperatures, the artillery fungus produces many small, cup-like fruiting bodies on the wood mulch. Each fruiting body contains a black, sticky spore packet. With moisture present, the spore packets are shot out of the fruiting bodies, up to 20 feet away.
The spore packets contain a substance referred to by many scientists as "nature's super glue."
This makes the tiny black spots extremely difficult to remove.
Most of the artillery fungus cases I have seen have been found on houses containing wood or vinyl siding painted a light color. The artillery fungus is light sensitive, and the fruiting bodies are more likely to point towards lightly colored objects, according to Cornell University.
The presence of spore packets leads many homeowners to believe that their landscape plants have a leaf spot disease. Artillery fungus spores are not harmful to plants. The damage they cause is only in aesthetic value. Their main damage is to buildings and cars.
Removing the black fungal packets from buildings and cars is a tedious process. Many people have tried different chemical cleaning compounds with little success. Even pressure washers have been found ineffective in removing the spots. Scraping the spots off with a scraping tool is the only reliable method.
As of now, there are no known fungicides capable of managing artillery fungus.
Cultural control methods are most useful for its management. Because the artillery fungus is a wood-rotting fungus, mulches with high wood content will cause more issues. Switch to mulches made of at least 85 percent bark. The fungus won't grow as well on the bark. Also, adding a fresh layer of mulch every year can help suppress the existing fungus.
To avoid mulch being piled too high, it is best to remove and replace existing mulch.
Switching to pine straw mulch and adding more groundcover plants will also help prevent artillery fungus.
Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.