How is brown rot typically characterized?

Brown rot is characterized by the degradation of wood that leads to a distinct appearance known as "checking," where the surface of the wood shows cracks and splits, often resulting in a square-like shape, especially as the rot progresses. This type of rot primarily affects the cellulose and hemicellulose components of wood, leaving behind the lignin, which can lead to a brittle texture. This structural change in the wood manifests as the typical visual signs associated with brown rot.

The other descriptions do not accurately reflect the signs of brown rot. For example, a smooth finish on wood and wet and soggy appearances would suggest different forms of decay or issues, such as wet rot or other wood deterioration not linked to brown rot. Bright color changes may indicate other types of fungi or decay processes that do not align with the characteristics of brown rot specifically. Thus, the identification of checking or a square look as a hallmark of brown rot is crucial for recognizing and managing this type of wood decay effectively.