Bulbous honey fungus

The bulbous honey fungus (Armillaria gallica) is a notorious fungal pathogen responsible for causing white rot in the roots and stems of various woody plants. Unlike strictly saprophytic species, this fungus acts as a facultative parasite, actively infecting living hosts and leading to the decay of the root system and death of the plant.

This pathogen affects a wide range of hosts, including ornamental trees, coniferous species, and common fruit crops such as apples, pears, and stone fruits. It typically infiltrates the host through wounds or by spreading through the soil via specialized structures known as rhizomorphs, which attach themselves to healthy roots.

Signs of infection often include stunted growth, premature yellowing and shedding of leaves, and dieback of the crown. Upon examination of the base of the trunk or root collar, one can observe white, fan-shaped mycelium underneath the bark and the presence of dark, shoe-string-like rhizomorphs in the soil surrounding the roots.

The development and spread of Armillaria gallica are highly dependent on soil conditions, thriving in damp, poorly drained soils where woody debris or decaying stumps serve as primary infection reservoirs. The fungus is remarkably resilient, and its rhizomorphs can persist in the ground for years, infecting new hosts that come into contact with them.

Effective management requires a rigorous approach: removing infected trees along with their entire root systems is critical to eliminate the inoculum source. Improving soil drainage, avoiding injury to root collars, and applying biological control agents like Trichoderma species can significantly reduce the risk and impact of this destructive pathogen in home orchards and forest management.

• Stump removal and root excavation.
• Improving soil drainage and aeration.
• Monitoring for rhizomorphs near the root collar.
• Using biological fungicides to suppress pathogen growth.