Red pine has a large sapwood ring, the temps are just right, so, mold happens. I have use bleach, I also tried hydrogen peroxide diluted with water, Molex or a similar product will cut it. What ever you do you may have to re apply a few times. The key will be to get the timbers dry enough, mold needs three things, proteins in the sap wood, water-moisture content, and the right temperature. They need plenty of air, and keep them dry as possible, with the exception of the spray solutions.
I don't like red pine.
Tim