Pleurotus pulmonarius

Pleurotus pulmonarius, commonly known as the Indian oyster mushroom or the phoenix mushroom, is a wood-decay fungus that acts as a facultative parasite in forest and horticultural environments. While highly valued in mushroom cultivation, it serves as an agent of white rot when it colonizes living but weakened trees.

The pathogen primarily attacks the heartwood and sapwood of deciduous trees. The fungal mycelium penetrates through wounds, pruned branches, or bark lesions, secreting enzymes that degrade lignocellulose. This degradation process is responsible for the characteristic white rot that destabilizes the tree structure over time.

Host plants commonly affected by this fungus include a wide variety of hardwoods such as beech, oak, poplar, and birch, as well as fruit trees like apples and pears. It rarely attacks healthy, vigorous trees, preferring hosts with existing structural damage or compromised natural immune responses.

Symptoms of an infection include the appearance of white to cream-colored shelf-like mushrooms on the trunk or exposed roots. Internally, the wood loses its tensile strength, appearing pale, bleached, and fibrous. This structural weakening significantly increases the risk of branch failure and windthrow during storms.

Management and prevention focus on tree health maintenance and damage control.

• Sanitary pruning of dead or decaying limbs.
• Sealing large wounds with appropriate wound dressings.
• Avoiding mechanical damage to bark during agricultural activities.
• Removing heavily infested tree stumps to prevent spore buildup in the vicinity of healthy crops.