We have some unusual "spots" on our siding. They are a little larger than a pin head, smell and do not move. They are on several sides of our house and our sidewalk. They are hard to remove and have to be scraped off of windows with a blade. Do you have any idea as to what these are?
The black dots are the spores of artillery or shotgun fungus. This fungus lives in rotting wood or manure and spreads by shooting its spores onto nearby surfaces. Though annoying it does not harm the structure or plants. Reduce the problem by using bark mulch in place of wood mulch, applying a thin layer of fresh mulch over older mulch or using stone rather than wood mulches next to the house. Washing infested areas with soapy water or a bleach solution may soften the spores and reduce their numbers. Test a small area before using cleaners on structures. Some cleaners and extensive scrubbing can damage siding. For more details see Cornell University's fact sheet on artillery fungus.
(Appearance has been cancelled due to extreme weather conditions)
Ebert's Greenhouse Village
Wisconsin State Fair
West Allis, WI
Mequon Nature Preserve