Our crawl space has a dirt floor. There is no vapor barrier. There is a white substance forming on the dirt. Is this mold? Fungus? The crawl space has some vents but apparently not enough. The white stuff is now dry. It's fall/winter here in Minnesota and having the furnace run dries out the crawl space. Does the white stuff need to be removed? Treated? Will a vapor barrier prevent the moisture next summer? Does the vapor barrier need to be covered with something? Three is 2-3 feet headroom and a number of supports in the way. I'm just looking for any suggestions to effectively eliminate the problem (short of moving).