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Artillery Mold

Shotgun mold

SUMMARY: Artillery Fungus is a problem. These spores of the genus Sphaerobolus will attach themselves to siding, automobiles, or any light colored surface. Though not harmful, it is a nuisance and, if left to set, the spores can cause permanent staining.

What is Artillery Fungus?

Though these specks appear to resemble insect feces, scale crawlers, or air-borne pollutants, they are actually mature spore masses expelled from the fruiting bodies of a fungus known as "artillery" or "shotgun" fungus. (Actually, artillery fungus is what we encounter most of the time, as shotgun fungus grows on horse dung.)













Artillery fungus develops in organic mulch and other organic materials, and is usually a greater problem in spring and fall, when conditions are cool and moist conditions and temperatures range from 50 to 70 degrees.

Artillery fungus is a cream or orange-brown cup containing a black round mass of spores that is difficult to see. The mushroom fungus spreads open like a flower, and seeks out a bright, light source (light colored siding, cars, and the like) and shoots its spores toward the source, thus the name “artillery” or “shotgun”. The fungus can detect downspouts, soffits, windows, cars, sun bouncing off windows, and other bright surfaces. The spores can be "shot" as high as the second floor of a building (about 20 feet).

These spores are one to two millimeters in diameter, black, sticky, and globular in appearance. Scraping the top of the black specks off with a fingernail reveals a reddish or cream color. The spores can ruin the appearance of siding or a wooden deck. It is theorized that artillery fungus can complete its life cycle only on wood (as in hardwood mulch), but not on bark, which has a lower carbon to nitrogen ratio.

Removing Artillery Fungus

Removing the black, tar-like spots from surfaces has, for the most part, been an exercise in futility. If the fungus has not been in place for very long, removing it is possible using:

Unfortunately, the longer the fungus is in place, the harder it is to remove, especially from siding. Attacking the spores no later than two to three weeks after they first appear increases the chances they can be cleaned off.

Preventing Artillery Fungus Bombardment

For locations plagued with this problem, several preventive measures can be taken. Among them are:

  • Change to rot resistant mulches such as cedar, redwood, or cypress – artillery fungus does not grow in these environments.

  • Switch to a non-organic ground cover such as stone, gravel, river rock, or similar product.

  • Add a new layer of fresh mulch that completely covers the old. For added protection, remove the old mulch before the new mulch is put down.

  • Use bark mulch.

  • Avoid using mulch within thirty feet of any surrounding bright surfaces.

  • Avoid mulches made of wood chips or ground up wood pallets.

  • Stir up the mulch regularly to keep it dry and retard the growth of Artillery fungus.

  • Treat the surrounding area with an EPA approved fungicide.

  • Remove any rotting wood and animal droppings, as these present optimum growing conditions for the fungus.

  • Apply a specialty coating to the surface of the siding, designed to inhibit the growth of fungus and mold. Though some spores may still appear, they will be much easier to remove since they will be adhering to the coating, not to the siding.












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