Botryobasidium aureum

Botryobasidium aureum is a fungal pathogen belonging to the order Cantharellales. While primarily known for its role in the decomposition of woody organic matter in forest ecosystems, it can manifest as a pathogen on stressed or weakened plants, particularly in agricultural settings where humidity levels remain consistently high.

The fungus typically affects woody perennial plants, including fruit trees and nursery stock. It is characterized by its ability to colonize the bark and stems of plants, often starting from areas where the plant tissue has been damaged by frost, mechanical injury, or poor pruning practices. Over time, it can compromise the structural integrity of the affected areas.

The most visible sign of an infection is the development of a distinct golden-yellow mycelial mat on the surface of the bark. This web-like growth is often fragile but persistent. As the infection progresses, the underlying bark may appear discolored, softened, or sunken, which indicates that the fungus is actively extracting nutrients and causing cell wall degradation.

Development and spread are heavily dependent on environmental conditions. Botryobasidium aureum thrives in environments characterized by high humidity, poor air circulation, and stagnant air. It is most active during periods of moderate temperatures and consistent rainfall, which facilitate the production and dispersal of spores, allowing it to move quickly between host plants in a nursery or orchard environment.

Effective management requires a combination of cultural and chemical strategies. Cultural control involves optimizing plant spacing to ensure adequate ventilation, pruning to remove infected tissue, and maintaining plant vigor through proper nutrition. When infection pressure is high, the application of appropriate fungicides, particularly those targeting basidiomycetes, can help limit the spread of the pathogen and protect vulnerable plant tissues.