Bacterial bulb decay

Pathogen and type of disease
Bacterial bulb decay is a plant disease caused by the bacterium Enterobacter cloacae. This pathogen belongs to the family Enterobacteriaceae and is known to cause systemic or localized infections in various horticultural crops, leading to tissue necrosis and soft rot in bulbous vegetables.

Affected crops
The disease primarily impacts allium species, with bulb onions and garlic being the most susceptible hosts. The infection often remains latent in the field but manifests rapidly during post-harvest handling, storage, or transport if environmental conditions become favorable for bacterial multiplication.

Symptoms and signs of infection
The characteristic symptoms include the softening of internal bulb scales, which take on a translucent, water-soaked appearance. As the decay progresses, the tissue turns brown and releases a distinct, pungent odor. In advanced stages, the entire bulb may collapse into a foul-smelling mass, and the roots may detach from the basal plate.

Conditions for development and spread
The development of the disease is heavily influenced by high humidity and warm temperatures. The bacteria enter the bulb through wounds caused by mechanical damage during harvesting, insect feeding, or through the neck tissues during curing. Poor ventilation in storage facilities further exacerbates the spread of the pathogen from infected bulbs to healthy ones.

Damage and control measures
The economic impact of this disease is significant due to losses in storage and decreased marketable yield. Preventive measures include:

• Implementing strict crop rotation protocols.
• Ensuring bulbs are properly cured before storage to close entry points.
• Managing insect pests that create wounds for bacterial entry.
• Maintaining optimal storage conditions with low humidity and constant airflow.
• Sorting bulbs before storage to remove any damaged or symptomatic individuals.