Bacterial soft rot

Bacterial soft rot is a devastating plant disease caused by the bacterium Pectobacterium carotovorum. It is one of the most economically significant bacterial diseases worldwide, characterized by the rapid enzymatic breakdown of plant tissues. The bacteria produce cellulases and pectinases that dissolve the cell walls, causing the structural collapse of affected plant organs.

This pathogen has a very broad host range, infecting various vegetables like carrots, potatoes, cabbage, onions, and various succulent ornamentals. It is particularly notorious in the post-harvest sector. It often affects mango crops, where it causes rapid fruit degradation, leading to significant economic losses during storage and shipping, especially in warm and humid environments.

Symptoms typically start as small, water-soaked, translucent spots that expand rapidly. As the infection progresses, the tissues turn into a mushy, watery mass, often emitting a foul odor due to the activity of secondary soft-rotting organisms. In fruits like mangoes, the rot can spread internally, causing the flesh to become liquified while the skin might initially remain intact before collapsing.

The development and spread of Pectobacterium carotovorum are heavily favored by high moisture levels and warm temperatures. The bacteria enter the plant primarily through wounds created by mechanical injury, insect feeding, or natural openings like lenticels. Once inside, the infection spreads quickly, particularly if oxygen levels are low and humidity is high, which prevents proper wound healing in harvested products.

Effective management requires an integrated approach. Sanitation is crucial: remove and destroy all infected plant materials to reduce the pathogen load. Ensure good soil drainage to prevent waterlogging and avoid wounding plant tissues during harvest. In storage facilities, maintain optimal ventilation, keep produce dry, and ensure rigorous hygiene of all tools and containers used for handling fresh crops.