Celery late blight

Celery late blight is a severe fungal disease caused by the pathogen Celavirus apii. It is considered one of the most destructive diseases for celery production worldwide, causing significant aesthetic damage to foliage and reducing overall harvest yield by compromising the health of the plant.

The disease primarily affects celery (Apium graveolens). Both leaf celery and celeriac are susceptible to the pathogen. The fungus targets all aerial parts, including leaves, petioles, and stems, often leading to rapid necrosis and defoliation if left unchecked under favorable environmental conditions.

Symptoms typically begin as small, yellow spots on the outer leaves. As the disease progresses, these lesions turn brown or gray and eventually develop small, black fruiting bodies called pycnidia. These pycnidia are the hallmark of Celavirus apii and are where the spores are produced. Infected leaves often turn yellow, dry up, and die prematurely.

The development of the disease is heavily influenced by wet and cool weather. High humidity, frequent rainfall, and irrigation practices that keep foliage wet for prolonged periods provide ideal conditions for spore germination and spread. The fungus survives in crop debris and can also be seed-borne, which is a major factor in the long-distance spread of the pathogen.

Management of celery late blight requires an integrated approach to maintain crop health:

• Sourcing certified, disease-free seed and treating it properly before planting.
• Implementing a robust crop rotation strategy, avoiding celery in the same field for several years.
• Sanitation practices, such as removing or burying crop residues post-harvest.
• Managing irrigation to avoid prolonged leaf wetness, often using drip irrigation instead of overhead systems.
• Strategic application of protective fungicides during periods of high disease pressure.