Chromobacteriosis

Chromobacteriosis is a plant disease caused by the bacterium Chromobacterium prodigiosum (now identified as Serratia marcescens). This facultative pathogen is widely known for causing rapid decay of succulent plant tissues, particularly in harvested vegetables and fruits stored in unfavorable conditions.

The pathogen primarily attacks crops with high water content, including root vegetables, tubers, and various orchard fruits. Infection usually occurs when the bacterial cells gain access to internal tissues through wounds, scratches, or insect feeding sites. Once inside, the bacteria secrete enzymes that degrade the middle lamella of plant cells, leading to rapid tissue collapse.

The visual signs of the disease include the development of water-soaked spots that spread rapidly across the plant surface. A diagnostic hallmark is the production of a bright red pigment known as prodigiosin, which gives the infected area its characteristic appearance. The diseased tissue eventually turns into a slimy, foul-smelling mass as the cellular structure is completely destroyed.

Environmental conditions play a critical role in the prevalence of this disease. Optimal growth for the pathogen occurs at temperatures ranging from 20°C to 30°C combined with high relative humidity. In agricultural settings, poor ventilation in storage facilities or heavy rainfall during the harvest season are major triggers for rapid outbreaks of the infection.

Effective management and prevention of chromobacteriosis depend on rigorous sanitation and proper post-harvest handling. It is essential to minimize mechanical damage during harvesting, as wounds act as the primary entry points for the bacteria. Furthermore, maintaining proper ventilation, controlling warehouse temperature, and discarding infected plant material immediately are necessary steps to prevent the spread of the pathogen to healthy stored produce.