Leafy jelly fungus

Leafy jelly fungus (lat. Tremella foliacea) is a basidiomycete fungus that primarily acts as a wood-decay organism. While it is mostly known for colonizing dead, decaying wood, it can also manifest on weakened or physically damaged deciduous trees, making it a subject of interest in plant pathology and forestry management.

The pathogen thrives by decomposing complex organic compounds in wood cells. Its mycelium penetrates the bark and inner layers, where it secretes enzymes that gradually break down the structural integrity of the wood. This process, while slow, can lead to significant weakening of the timber if the initial health of the host plant has already been compromised by drought, frost, or pest infestation.

Common hosts for this fungus include a variety of deciduous trees such as oak, birch, alder, and sometimes fruit trees if they are in poor condition. High humidity and cool temperatures are the primary environmental drivers for the development and rapid growth of its jelly-like fruiting bodies, which often appear in clusters after prolonged rainfall.

Symptoms are easily identifiable by the presence of gelatinous, ruffled, and brain-like structures that emerge from the bark or cracked wood. These structures are characteristically brown to reddish-brown in color. During dry periods, the fungus shrinks into a hard, inconspicuous brown film, only to rehydrate and swell again when favorable moist conditions return.

Effective management and protection strategies focus on maintaining tree vigor and reducing habitats for fungal colonization:

• Prompt removal and disposal of dead or decaying wood from the site.
• Regular pruning of dead branches to improve crown ventilation.
• Application of protective wound sealants to any exposed wood on healthy trees.
• Avoiding waterlogging and soil compaction near the base of tree trunks.