White rot of leek

The disease is caused by the fungus Botrytis porri, which is a significant pathogen affecting various species of the genus Allium. It is recognized as a major cause of post-harvest decay and field infection, posing a substantial challenge to the commercial cultivation of leeks, onions, and garlic worldwide.

The primary host range includes cultivated leeks, bulb onions, and garlic. The fungus is highly adapted to these crops and can infect them at various growth stages. In temperate climates, the disease is particularly prevalent, often causing severe damage if control measures are neglected during the critical periods of development.

Typical symptoms include the development of a white or greyish fungal mat on the surface of the infected tissue, often near the neck or base of the plant. As the infection progresses, the plant tissue turns soft and watery. Eventually, the fungus produces small, black sclerotia that remain in the soil or on plant debris as a source of future infection.

The spread of Botrytis porri is heavily favored by cool and damp conditions. Moisture on the foliage and high humidity levels are essential for the germination of spores and the establishment of the infection. The pathogen can persist in the soil for several years through sclerotia, making management through chemical means alone difficult.

• Practicing strict crop rotation to avoid planting susceptible crops on infected soil.
• Ensuring proper soil drainage to minimize humidity around the plant base.
• Implementing careful harvest techniques to avoid wounding the plant tissue.
• Maintaining well-ventilated conditions in storage to prevent the spread of decay.
• Using fungicides selectively based on professional agricultural monitoring.

The economic impact of the pathogen is profound, as it directly reduces yield and drastically lowers the quality of the harvested produce. Infested crops often develop secondary rot, leading to complete loss of market value and significant financial repercussions for farmers relying on storage and post-harvest sales.