Desarmillaria root rot

Desarmillaria root rot is a destructive plant disease caused by fungi belonging to the genus Desarmillaria. These pathogens are responsible for white rot of the roots and the base of the trunk, leading to severe vascular compromise and eventual death of the affected host plant by disrupting water and nutrient transport.

The disease affects a wide range of woody hosts, including orchard fruits, ornamental trees, and forest species. The pathogen is highly resilient, surviving as a saprophyte on decaying wood, stumps, and root systems, which serves as a long-term reservoir for infection within the soil environment.

Symptoms often manifest as crown thinning, chlorosis, and branch dieback. In advanced stages, the diagnostic sign is the presence of white, fan-shaped mycelial mats under the bark of the root collar, along with dark, cord-like rhizomorphs in the soil that act as the primary structures for invading nearby healthy root systems.

Environmental conditions such as poor soil drainage, high moisture levels, and mechanical stress facilitate the spread of the fungus. The pathogen spreads primarily through direct root-to-root contact or through the growth of rhizomorphs through the soil, allowing the disease to move rapidly from an infested stump to neighboring trees.

Control strategies emphasize the importance of site preparation and sanitation. Key measures include:

• Complete removal of infected stumps and root systems.
• Avoidance of planting susceptible species in sites known to have a history of root rot.
• Maintaining optimal plant vigor through balanced nutrition and proper watering.
• Implementing strict hygiene protocols for gardening tools to prevent cross-contamination.