Centrospora acerina

The fungus produces septate mycelium and resilient chlamydospores, which enable the pathogen to persist in the soil and on crop debris for several years.

Conidia of this fungus are typically hyaline, needle-shaped, or curved, facilitating their identification under laboratory conditions.

It acts as a facultative parasite, meaning it can thrive both on living plant tissues and as a saprophyte on decaying organic matter.

Transmission of the fungus primarily occurs through splashing water, windborne spores, and contaminated agricultural tools used in the fields.

The fungus is primarily known for causing serious damage to root vegetables, including carrots, celery, parsley, and parsnips, particularly during storage.

Infection results in sunken, dark lesions that progress into soft, watery rot, rendering the vegetables unsalable and unsuitable for processing.

In young plants, the pathogen can cause 'black leg' symptoms, leading to seedling collapse and significantly reducing the plant population in the field.

Beyond vegetable crops, it affects various ornamental plants, such as pansies, causing necrotic leaf spots and overall plant weakening.

Massive outbreaks in storage facilities are common, as the fungus spreads readily from infected roots to healthy ones through direct contact.

The pathogen is highly active during cool and damp conditions. It thrives in moderate temperatures, typically between 15°C and 20°C, making it a threat during spring and autumn.

Field infection usually peaks towards the end of the growing season, shortly before harvest, especially when fields remain waterlogged.

During the winter, Centrospora acerina is particularly dangerous as it remains active at low storage temperatures where other pathogens might be inhibited.

The primary inoculum often arises from infected soil residues left from previous seasons, which become activated under favorable moisture conditions.

Prolonged high humidity levels during the growing season serve as the main trigger for the rapid spread of the disease within the crop canopy.

The initial signs on root vegetables appear as dark, slightly sunken spots that gradually expand into deep, soft lesions.

Under conditions of high humidity, a characteristic greyish or whitish fungal growth may develop on the surface of the lesions.

Leaves of infected plants often exhibit dark brown or black necrotic spots, usually accompanied by a yellow chlorotic halo around the necrotic area.

Internal tissue of carrots and parsnips can show signs of decay even when the external surface appears relatively intact, making visual screening difficult.

• Darkening of the skin on root vegetables.
• Soft, watery lesions on taproots.
• Surface fungal growth in humid conditions.
• Necrotic spots on leaves with yellow halos.

Implementing a strict crop rotation program is the most effective way to prevent the buildup of Centrospora acerina in the soil.

Thorough sanitation practices, including the deep incorporation or removal of crop residues, are essential to reduce the primary inoculum.

To minimize storage losses, it is crucial to handle vegetables gently during harvest to avoid mechanical injuries that serve as entry points for the fungus.

Maintaining optimal storage conditions, such as low temperatures (near 0°C) and excellent air circulation, is vital for long-term product preservation.

Fungicide applications during the growing season may be necessary in areas with a history of severe infections to manage the disease pressure effectively.