Answer: Artillery or shotgun fungus has been a ever increasing problem in Ohio. Attempting to remove the black tar-like spots from surfaces is generally futile, and extreme care should be used on aluminum siding and car paint since the finish may be damaged. In our experience, removing the fungus is possible through the use of a high flow rate of water (at least 5.5 g.p.m.) at 3000 psi, with hot water, at 200 degrees Fahrenheit, however, this process is only suitable if the fungus has not been in place for an extended period of time. The longer the fungus has been in place, the harder it is to remove from the siding. Generally, the time span for fairly easy removal, we feel, is approximately 2-3 weeks. Also this process will not work on most aluminum siding as the paint will not hold up to the extreme heat and pressure.
Caution must also be taken on PCV coated siding, as the PCV surface does not withstand extreme temperatures well If the fungus has set in to the point that water removal is not possible, on vinyl, we have found that by washing with the same process, (thus removing the tops of the fungus, leaving only a tan or light brown spot) then rubbing with a fine grade of steel wool will remove the spots. This process is very time consuming though, and is only a last resort to removal of the fungus. This process should not be used on aluminum or PCV coated siding.
For locations plagued with this problem, consider switching to an inorganic mulch such as stone, pea gravel, etc. Or, a yearly addition of fresh mulch, so it completely covers old mulch, may lessen the problem, though it still may reoccur. We recommend complete removal of existing mulch prior to the application of an inorganic mulch, in order to lessen the chance of reoccurrence. It is also theorized that bark mulches may reduce the problem.
If possible remove the mulch or place the mulch at least 30 feet away from any surrounding bright surfaces. Also Shotgun Fungus does not grow on cedar, redwood, or cypress which are on rot resistant woods. Avoid mulches made of wood chips or ground up wood pallets. Stirring up the mulch regularly to keep it dry retards the growth of Shotgun Fungus.
We also recommend treating the surrounding area with a fungicide, as well as cleaning up any animal droppings and rotting wood, as these are also prime conditions for the artillery fungus to grow in.
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