The primary reason a tree root might appear white, particularly when it is also rotten, is due to a specific fungal disease known as white root rot.
Understanding White Root Rot
Healthy tree roots are typically brown, tan, or sometimes a creamy off-white when very young, depending on the soil type and moisture. A distinct white appearance, especially on older roots coupled with decay, is a significant sign of a problem. This condition, often referred to in the context of decay as "white root," indicates that the root structure is being broken down by certain types of fungi.
The Role of Fungi
According to available information, the white appearance on a tree root that "gets rotten" is caused by the fungus Scytinostroma galactinum. This fungus is one of several that cause white rot in wood, including tree roots.
White rot fungi like Scytinostroma galactinum primarily decompose lignin and cellulose, the major components of wood. Unlike brown rot fungi which leave behind the brown lignin, white rot fungi are efficient at breaking down lignin. The remaining material, which is primarily cellulose, is lighter in color, giving the decayed wood or root a bleached or whitish appearance, hence the term "white rot."
Symptoms and Identification
When a tree root exhibits a white, rotten texture, it's a clear symptom of advanced decay. Other signs that a tree may be affected by white root rot can include:
- Poor vigor or stunted growth
- Yellowing or wilting leaves
- Branch dieback
- Mushrooms or fungal fruiting bodies appearing at the base of the tree or on affected roots
- Soft, spongy, or crumbly root tissue that appears white or bleached
| Symptom | Description | Potential Cause |
|---|---|---|
| White Appearance | Decayed root tissue looks bleached or distinctly white | White Rot Fungi (Scytinostroma galactinum, etc.) |
| Rotten Texture | Root becomes soft, crumbly, or spongy | Fungal decomposition of wood structure |
| Poor Tree Health | Reduced growth, wilting, dieback, leaf issues | Inability of compromised roots to supply water/nutrients |
Addressing White Root Rot
Identifying white root rot early is crucial, though often challenging as the problem is below ground. If a white, rotten root is discovered, it's usually indicative of significant decay. Managing the issue typically involves:
- Accurate diagnosis by a qualified arborist or plant pathologist.
- Removing severely affected trees or large, decayed roots to prevent spread.
- Improving drainage if the area is waterlogged, as wet conditions favor fungal growth.
- Avoiding injuring roots during construction or landscaping.
- Selecting appropriate tree species for the site conditions.
It is critical to understand that a white, rotten root is not naturally white; its color is a symptom of fungal decay. The presence of this condition, specifically linked to fungi like Scytinostroma galactinum, is why the root appears white and simultaneously rotten.
