Bacterial soft rot

Causative agent and type of disease
Bacterial soft rot is caused by the bacterium Pectobacterium carotovorum (formerly known as Erwinia carotovora). It is a highly destructive plant disease characterized by the enzymatic degradation of cell wall components, specifically pectins, which causes the internal tissues of the plant to liquefy and collapse.

Affected crops
This pathogen is a polyphage with an extensive host range. It affects a wide variety of vegetables, including potato, carrot, and onion. It also poses significant risks to tropical and agricultural crops such as rice and cocoa, where it can attack stems, roots, and pods, leading to significant yield reduction in diverse climatic zones.

Symptoms and signs of infection
The hallmark of the disease is the rapid softening of infected plant parts. These areas become discolored, watery, and mushy. As the cellular structure breaks down completely, a distinct, foul-smelling odor often develops, frequently attracting various insects that may subsequently assist in the further spread of the bacteria to healthy plants.

Conditions for development and spread
Development is favored by warm, humid environments, typically with temperatures ranging from 20°C to 30°C. The bacteria enter the plant primarily through wounds caused by mechanical damage, weather events, or insect feeding. High soil moisture levels and poor drainage are primary factors that accelerate the spread of the disease across a field.

Harmfulness and protection measures
The disease causes substantial economic losses due to the total decay of the harvest in the field and during storage. Protection strategies include:

• Selection of resistant varieties where available.
• Implementing strict crop rotation and field sanitation.
• Providing good drainage to prevent waterlogging.
• Careful harvesting to minimize physical injuries to plants.
• Controlling insect vectors that carry the bacteria.