Pseudomonas pseudoalcaligenes

Pseudomonas pseudoalcaligenes is a Gram-negative, motile rod-shaped bacterium recognized as a phytopathogenic agent capable of causing severe bacterial infections in various agricultural and horticultural crops. This pathogen is known for its ability to colonize host tissues, leading to systemic infections that impair the physiological development and vitality of the plants.

The host range of this bacterium includes diverse vegetable and ornamental crops. It primarily infects plants by entering through natural openings like stomata or through mechanical wounds caused by agricultural equipment or insects. Once inside, the bacteria proliferate, breaking down plant tissues and utilizing nutrients, which results in characteristic disease manifestations.

The primary symptoms of infection include water-soaked spots on leaves and stems, which progressively enlarge and turn necrotic, exhibiting a dark brown or black coloration often surrounded by a chlorotic halo. In high humidity conditions, bacterial ooze may become visible on the surface of the lesions, and severe infections can lead to premature leaf drop, stunted growth, and fruit rotting.

Development and spread of the disease are highly dependent on environmental conditions, particularly high relative humidity and temperatures ranging from +20°C to +28°C. The pathogen is disseminated through splashing water, such as rain or overhead irrigation, contaminated planting material, and the movement of tools and equipment between infected and healthy areas of the field or greenhouse.

The economic impact of this disease is significant, as it leads to reduced crop quality, lower yields, and the potential loss of entire harvests. Integrated pest management (IPM) strategies are essential for control, including the use of certified pathogen-free seeds, strict sanitation of gardening tools, balanced irrigation practices, and the application of copper-based bactericides for prevention.