Licorice rot fungus

Systematic position and pathogen type
Mycocentrospora acerina is a pathogenic fungus classified within the Hyphomycetes class. It is a soil-borne phytopathogen recognized for its wide host range and high environmental adaptability, often causing significant agricultural losses in temperate climates.

Diseases and host plants
This fungus is the causal agent of "licorice rot," a condition primarily affecting umbelliferous crops such as carrots, celery, parsley, and parsnips. Furthermore, it is known to infect various ornamental species, including violas and primulas, where it induces root and stem rot that can quickly lead to plant death.

Biology and life cycle
The pathogen survives in the soil as thick-walled chlamydospores, which are highly resistant to adverse environmental conditions. During favorable periods, it produces conidia that are dispersed by water splashes or infested soil particles. The infection process begins when these spores attach to the host surface and penetrate the plant tissues, often through natural openings or mechanical wounds.

Conditions for development and harmfulness
Mycocentrospora acerina thrives in cool and humid conditions, with an optimal temperature range of 10°C to 18°C. Excess soil moisture significantly accelerates disease progression. In harvested crops, the fungus manifests as dark, sunken lesions on roots, which eventually develop into extensive decay characterized by a distinctive licorice-like odor, rendering the produce unmarketable.

Control and management measures
Managing this pathogen requires an integrated approach focusing on prevention and site sanitation:

• Implementing long-term crop rotation to reduce soil inoculum levels.
• Removing and destroying infected plant debris from fields immediately after harvest.
• Improving soil drainage to prevent stagnant water and high humidity zones.
• Selecting resistant varieties where available and maintaining hygiene in storage facilities.
• Using appropriate fungicide treatments as part of an integrated pest management program.