How to remove black mold from plywood?
It looks like you might have two types of mold - it's difficult to tell what the white fibers are. Good news, all types of mold can be removed using the same procedures.
This article (linked below) suggests using bleach to kill and clean the mildew, but the water-vinger solution is just as effective, and less toxic to other forms of life (humans included). Importantly, spend some time trying to figure out where the moisture is coming from. If the wood is stored outside, moisture will be a common problem. There are paints and sealants that can be used to help prevent a continuing mold problem.