Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
It just looks to me like there is slight streaks down the tarp right above the mold areas which could be dew dripping. Or as stated if that is the north side, no sun.
I have my wood on a rack with a cover but I'm finding that the wood still gets moldy and grows fungus. I'm looking for ways to prevent it . Wood for smoking can get expensive