Black Spots on Vinyl Siding

Midwestpro · Posted: Sat Oct 13, 2007 5:59 pm Post subject: Black Spots on Vinyl Siding

Recently more and more home owners have been complaining of tiny black spots appearing on their vinyl siding, down spouts, windows, and even their vehicles. These spots are often mistakenly identified as tar, scale insects, or insect excrement.

The dark spots are 1-2mm in diameter and slightly raised to globular. The black spots are masses of mature spores expelled from fruiting bodies of the fungus Sphaerobolus stellatus Tode. The fungus usually originates in wood-chip mulch that is used around shrubs, flowers and other plants. Wet, rotting mulch breeds small mushrooms that shoot off spores generally in spring and fall when temperatures range between 50 and 68 degrees. This fungus is more commonly referred to as shotgun fungus or artillery fungus because of the way it's discharged which is estimated to generate 1/10,000 hp and can shoot spores up to 20 feet.

"It's just like Super Glue," said Don Davis, professor of plant pathology at Pennsylvania State University's College of Agricultural Sciences. The fungus can be scraped off of glass using a razor blade but that doesn't work as well on vinyl siding. Some pressure washing contractors have reported minimal results using 200 degree water and 3000 psi but this can damage some types of vinyl.

If the fungus lands on wood siding and has the right amount of moisture it can continue to grow, feeding on the wood and causing long term damage. It does not harm vinyl siding or other surfaces, it's just unsightly to look at. Some people have tried to file a claim with their insurance companies and the results have differed. If your house is damaged by artillery fungus, check with the agent handling your homeowners insurance. Most policies do not cover damage from fungus or mildew, but some do.

The best advise to preventing future outbreaks is to change your mulch every year. Freshening up your old mulch with new is only a temporary fix, you should completely remove all your old mulch and bring in new every year. The ultimate fix is to use mulch substance products or to use rocks for landscaping.

DavidT73 · Joined: 23 Oct 2007 Posts: 4 Location: IL

This is great information, I will be changing my mulch every year.

A-PLUS · Posted: Thu Oct 25, 2007 11:16 pm Post subject:

David T
Another thing that will help, is to get something like the garden
weasel and mix up your mulch about once every 30 to 45 days. It keeps the gases from building up.