Pseudomonas fluorescens

Pseudomonas fluorescens is a rod-shaped, gram-negative bacterium that belongs to the Pseudomonadaceae family. While often celebrated for its biocontrol properties, specific strains can act as opportunistic phytopathogens, causing significant damage to various botanical species under favorable environmental conditions.

The primary diseases caused by these bacteria include bacterial leaf spots, vascular wilting, and soft tissue rot. The pathogens secrete extracellular enzymes that dissolve the middle lamella of plant cell walls, leading to tissue collapse, discoloration, and the development of foul-smelling lesions on leaves and stems.

The biology of the organism is characterized by rapid motility and the ability to form biofilms on plant surfaces. The pathogen survives in dormant states within soil aggregates and plant debris. Its proliferation is opportunistic, allowing it to colonize plants when the host's natural defenses are compromised.

Disease outbreaks are typically triggered by high humidity levels and temperature ranges between 15°C and 25°C. Poor drainage, heavy rainfall, and physical damage caused by harvesting equipment or insects create entry points, enabling the bacteria to invade the vascular system and internal parenchyma.

Economic damage is substantial, particularly in greenhouse operations and vegetable production, where the pathogen can spread rapidly between plants. Control measures prioritize prophylactic strategies, such as maintaining optimal irrigation practices, ensuring proper sanitation, and utilizing certified, pathogen-free propagation material.