This thread needs to be revisited. This Fungus is active in the Spring and Fall. Artillery Fungus or sometimes called Shotgun Fungus is caused by decaying wood chips. The spores from the decaying wood chips are propelled 20 feet in the air and are attracted towards the sun or anything that reflects the light like a white boat, vinyl siding on your house, white cars, motorhomes. In the case of my boat and one case of vinyl siding I heard of, the fungus CAN'T be removed. I'm using 1000 grit wet/dry sandpaper to remove it. My boat is a 22 foot with a hardtop and it's covered from the top to the keel.
Please refer to this link:
http://plantclinic.cornell.edu/FactS...leryfungus.htm
Please keep your toys away from wood chips.