Morganella morganii

Morganella morganii is a Gram-negative bacterium recognized in phytopathology as an opportunistic pathogen capable of causing severe soft rot in various plant species. While primarily found in soil and water environments, it acts as a significant threat to agricultural productivity, particularly when plants are stressed or damaged by environmental factors or other pests.

This pathogen affects a wide range of host plants, with a strong preference for succulent tissues. Common targets include solanaceous crops like tomatoes, cucurbits such as cucumbers and melons, and various root vegetables. It often initiates infection at the sites of wounds created by insects, mechanical harvesting damage, or primary fungal or bacterial infections.

The characteristic symptom of Morganella morganii infection is tissue maceration, which results in the rapid softening and liquefaction of internal plant structures. As the cell walls are degraded by bacterial enzymes, the affected tissue turns into a watery, slimy mass, often emitting a distinct, foul putrid odor indicative of advanced microbial decomposition.

Environmental conditions play a critical role in the epidemiology of this bacterium. It thrives in environments with high relative humidity and temperatures typically ranging from 25°C to 35°C. In post-harvest scenarios, insufficient aeration in storage facilities and the presence of moisture on the surface of produce create ideal conditions for rapid pathogen multiplication and spread.

Integrated management strategies are essential for limiting the damage caused by Morganella morganii. Producers should focus on the following preventative actions:

• Implementing rigorous sanitation protocols in packing houses and storage facilities.
• Handling produce carefully to prevent cuts, bruises, and skin abrasions during harvest.
• Prioritizing the curing process to heal natural harvest wounds before long-term storage.
• Maintaining strict temperature control to inhibit bacterial enzymatic activity.
• Monitoring crops for secondary infection signs to trigger early removal of diseased produce.