Cubical Brown Rot (Gleophllum spp, etc)
Brown cubical rot is caused by fungi which decay wood and reduce its strength. The fungi often produce a whitish, cottony growth on the surface of wood. They grow only on moist wood. The fungi can be present in the wood when it is brought into the house, or can grow from spores which are always present in the air and soil. Wood decayed by brown-rot fungi is brittle and darkened in color. As the decay proceeds, the wood shrinks, twists, and cracks perpendicular to the grain.
Fungi have four basic requirements to grow and reproduce: moisture, oxygen, adequate temperature, and food. If you deny the organisms from one of these four, then the wood does not decay. For example, wood pilings and posts completely submerged in water do not decay because oxygen is denied to the organisms. Sawmills once stored their saw logs in ponds for this reason. Even today, most modern sawmills store logs through the warmer part of the year under a constant water spray. This retards the growth of fungi by reducing the oxygen content and temperature.