We have these small, black spots that look like specks of tar, all over our white, vinyl siding of our house.
It's on the porch, my windows, but it is worse on the siding. It goes all the way up to my second-story windows, and is even under my soffit and on my gutters. What do you think it is?
Sounds like you have the infamous "artillery fungus". See image for what the spores of the artillery fungus look like on house siding.
I think I have seen some spots on my car. Does the artillery fungus also get on cars?
Yes, this is common on the sides of automobiles when cars are parked near mulched areas that are infested with the artillery fungus. It is especially noticeable on white sports cars - at least these are the owners that complain the most.
In fact, we have had complaints where private companies have artillery spores on 50-100 cars in their parking lots. The next question asked is, "How do we remove the spots from the sides of cars?" We do no know, but some suggestions have included: power washing if the artillery fungus spots are very new and paint/wax on the cars is also new and shiny; automotive-paint rubbing compounds; and removal (if there are only a few spots) with the edge of a credit card. However, you must be very careful not to damage the car's finish. See some car owners' attempts at removing the spots from cars at the end of this section. These are not recommendations!
Why do light-colored houses and cars have more problems than darker cars and houses?
In nature, the artillery fungus shoots its spores towards sunlight. In the absence of direct sunlight, it shoots the spores at highly reflective surfaces, such as white house siding. And, of course, the black spots show up better on white surfaces, so they are noticed more easily.
Are those spots alive? Will they hurt my house, like eat holes in my siding?
Yes, they are alive, but not in the sense that they can hurt your siding. They are dormant, or sleeping, and pose no threat to the siding other than staining it.
How do I get the artillery fungus off my house siding?
The spore masses of the artillery fungus stick like super-glue. We have not found a good, efficient way to get them off without leaving a stain or damaging the siding, especially on old dry siding. Power washing may work on brand new (only) vinyl siding that still has a shiny, oily, sheen.
Each spore mass can be physically scraped, "steel-wooled", or sanded off. Then the stain might be removed with an ink eraser, but this is a pain, literally.
Beware of any cleansers that have claims that sound "too good to be true", with regards to removing the artillery fungus. It is likely that they are, in fact, too good to be true. At the end of this section I have listed some attempts that readers have used to remove artillery fungus.