Molds are part of a group called fungi, which can be tiny molds or large mushrooms. Fungi break down organic materials such as plants, leaves, wood fiber and other natural materials. Fungi grow and reproduce by way of spores.
There are more than 100,000 species in the world and they have been on the earth for millions of years.
You need not look far in your house for materials that; under certain conditions can be the breeding ground for mold. Only four things are needed to grow mold; food, suitable temperature, oxygen and moisture. They grow best at between 70 and 85 degrees Fahrenheit.
The key element to have mold grow on wood is moisture.
Discoloration from mold is usually contained to the surface of the wood. Stain fungi are different and penetrate deeply into the wood and darken as they age creating a “blue stain” in the wood.
Decay fungi can grow when and if the wood is exposed to chronic moisture. These fungi, unlike molds attack deep and can reduce the strength and integrity of the wood.
The biggest causes would be leaking pipes or prolonged seeping from outside water sources.
Therefore for the health of the wood, a good maintenance plan for your house is best. Regular checking of all areas and proper treatment will save in the long run.