If the outside of your building is covered with small black spots that don't easily come off, your building could be the target of artillery fungus.

What is artillery (cannon) fungus?

Artillery fungus is a type of fungus that grows in old wood. If you have mulch around your building that has aged, you have a breeding ground for this fungus. As the sun heats up your aged mulch, tiny spores are launched out of the fungus as it explodes and land on anything that is around.

Commonly, the artillery fungus will cause more damage to light-colored sided homes. This is because the siding reflects more sun onto the mulch and causes it to heat up more than homes with dark siding. The dark siding absorbs the heat rather than reflecting it.

Does the fungus cause damage?

Those tiny spores that land on everything will begin to take root soon after they land. If not removed soon, those spores can cause the spots that you see to stain the siding on your home, as well as any furniture and décor in the area. Aside from the discoloration, the fungus doesn't cause lasting damage.

Can you prevent artillery fungus?

Yes. To prevent artillery fungus, replace your natural mulch often or replace it with rubber mulch or some other finishing material. If you plan to use natural mulch, look for mulch that is made of bark rather than the woodchips commonly used to make mulch.

Rubber mulch may not sound as attractive as natural mulch, but it can look even better and offer you many benefits. Think about how nice it would be not to have to replace that old mulch year after year. How nice would it be not to have insects making your mulch their homes? Rubber mulch doesn't attract insects, doesn't rot and doesn't absorb moisture like natural mulch does.

How do you clean the spots off of your siding?

Removing the spots can be difficult, if not impossible. Each spot needs to be scraped off, carefully scrubbed with steel wool and then pressure washed. For the easiest solution, talk with a building exterior cleaning company to help you through the removal process. They have experience working with this and many other substances that aren't easy to clean from the exterior of your home.

Act quickly and clean those spots off soon after you notice them. The longer they stay in place, the more difficult the stain will be to remove. Talk with your exterior cleaning specialists to learn more about having your building professionally cleaned.